Abstracts from Society for Neuroscience (SFN) – New Orleans, LA | November 4-9, 2000

40 entries found for : sfn2000

Attentional demand-related alterations in medial prefrontal neural activity of aged rats during sustained visual attention.

Gill TM, Yurrita MM, Givens B (2000) Attentional demand-related alterations in medial prefrontal neural activity of aged rats during sustained visual attention. Neuroscience 2000 Abstracts 837.6. Society for Neuroscience, New Orleans, LA.

Summary: Neural activity within the medial prefrontal cortex (mPFC) exhibits distinct relationships to sustained visual attentional performance in young male Long-Evans rats. Cortical cholinergic input substantially modulates attentional performance, mPFC neural activity, and attentional-demand related alterations in mPFC neural activity. The present study sought to investigate the relationship between sustained attention, mPFC neural activity, and cholinergic input within aged rats. Rats were operantly trained to discriminate between the presence and absence of brief, unpredictable visual signals under testing conditions that varied the level of attentional demand by the presence of a visual distractor. Aged rats were bilaterally implanted with pairs of stereotrodes into the mPFC at 25 months. The overall firing rate of mPFC units recorded during sustained attention was higher in the aged rats (2.39 spikes/s) relative to young rats (1.65 spikes/s). Moreover, a larger percentage of mPFC units exhibited attentional demand-related increases or decreases in firing rate in the aged rats (29%) relative to young rats (18%). Conversely, the magnitude of attentional demand-related increases in activity was smaller in the aged rats (64% increase) relative to young rats (81% increase). The modulatory role of cortical cholinergic input on the overall firing and attentional demand-related alterations in mPFC activity will also be determined and contrasted to the effects in young rats using 192 IgG-saporin infusions into the mPFC.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Effects of intra-basalis infusion of d-cycloserine upon sustained attention performance in rats.

Sarter M, Turchi J (2000) Effects of intra-basalis infusion of d-cycloserine upon sustained attention performance in rats. Neuroscience 2000 Abstracts 837.10. Society for Neuroscience, New Orleans, LA.

Summary: As basal forebrain NMDA receptor modulation has been hypothesized to play a significant role in tasks taxing attentional processes (Turchi & Sarter 1999), positive NMDA receptor modulation via the glycine site might attenuate the substantive impairments of sustained attentional processing observed following specific lesions of corticopetal cholinergic neurons (McGaughy, Kaiser & Sarter, 1996). Rats were trained in a sustained attention task (McGaughy & Sarter 1995) requiring animals to discriminate between unpredictably occurring visual signals of varying lengths (25, 50, 500 msec) and non-signal events. Upon attaining stable performance, chronic guide cannula were implanted bilaterally for the infusion of an NMDA receptor glycine site ligand into the SI/NB; one group of these animals also received bilateral infusions of 192 IgG-saporin (0.21μg/μl; 0.5 μl/hemisphere), while the other group received infusions (0.5 μl/hemisphere) of the vehicle for the immunotoxin. The effects of administrations of D-cycloserine (DCS: 0.5 & 5 μg in 0.5 μl/hemisphere) were tested in these two groups of animals (lesioned and sham-lesioned). Administration of the higher dose of DCS partly attenuated the lesion-induced decrease in hits in the sustained attention paradigm. This finding suggests that impairments of sustained attention incurred by damage to the basal forebrain cholinergic system may be effectively ameliorated by positive NMDA receptor modulation via the partial agonism of the glycine site.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Nucleus basalis magnocellularis and enriched housing: Partners in neural patterns of attention?

Westhead C, Saari RK, Morrison P, Williams PT, Saari MJ (2000) Nucleus basalis magnocellularis and enriched housing: Partners in neural patterns of attention?. Neuroscience 2000 Abstracts 837.3. Society for Neuroscience, New Orleans, LA.

Summary: Diminished levels of cholinergic markers in the brains of Alzheimer's patients led to the belief that central cholinergic systems play a major role in cognitive processes including attention and memory. Recent evidence from our laboratory suggests that housing rats in a complex environment alters neuronal attentional circuitry. These findings led to the design of the current experiment. After weaning, groups of female Wistar rats received either a bilateral infusion of 192-IgG saporin or vehicle solution into the basal forebrain. Following recovery, rats were either housed in an enriched condition or in isolated housing for two weeks, thus creating four treatment groups. Open field testing revealed the expected Housing by Minute interaction but no lesion related effects. The rats were also tested in an incidental learning paradigm. Briefly, half of the rats were pre-exposed to the testing apparatus in the testing room, whereas the other half were placed in a similar arena but in a separate room without task-specific cues. Analysis of the results revealed a significant interaction between the lesion and housing condition as a function of the pre-exposure. As expected, pre-exposure facilitated learning for all sham operated rats but the lesioned enriched rats performed in a paradoxical manner. These rats appeared to be confused by the pre-exposure to the testing apparatus. The findings suggest an inability of enriched lesioned subjects to distinguish between behaviourally relevant and irrelevant stimuli and are in general agreement with the findings of Kilgard and Merzenich (1998). (Approved by the Animal Care Committee, Nipissing University).

Related Products: 192-IgG-SAP (Cat. #IT-01)

Anatomical evidence for glial activation after intrathecal lumbosacral HIV-1 glycoprotein; gp120-induced allodynia.

Holguin A, Armstrong CB, Twining CM, Milligan ED, Hansen MK, McGorry M, O’Connor KA, Quan N, Martin D, Lappi DA, Maier SF, Watkins LR (2000) Anatomical evidence for glial activation after intrathecal lumbosacral HIV-1 glycoprotein; gp120-induced allodynia. Neuroscience 2000 Abstracts 733.4. Society for Neuroscience, New Orleans, LA.

Summary: Intrathecal (IT) HIV-1 glycoprotein, gp120: (a) produces thermal hyperalgesia & low threshold mechanical allodynia, and (b) increases interleukin-1β (IL1β) protein levels in lumbosacral (LS) spinal cord tissue & surrounding cerebrospinal fluid (CSF). Activated astrocytes & microglia (glia) release IL1β in response to gp120, and IT IL1 receptor antagonist or glial metabolic inhibitors prevent IT gp120-induced allodynia and thermal hyperalgesia. We determined whether IT gp120 produces glial activation and increased expression of glial IL1β as well as allodynia. LS spinal cord was collected 1.5 & 3 hrs after IT gp120 injection & verification of allodynia for immunocytochemistry (ICC) & in situ analysis of IL1β protein & mRNA. ICC for glial activation markers was performed 4,8 & 18 hrs after IT gp120 in LS & cervical spinal cords, as upregulation of these markers is delayed relative to behavioral changes. IT gp120 produced allodynia & increased IL1β protein ICC expression in LS spinal white (astrocytes) & gray matter (cells not identifiable) at 1.5 but not 3 hrs after injection. Increases in in situ IL1β mRNA were not detected. RT-PCR analysis of IL1β mRNA is underway. Glial activation (ICC) was observed in LS tissue 8 & 18 hrs after IT gp120. We are examining IT gp120 allodynia & hyperalgesia after an IT microglia-specific toxin (Saporin-linked Mac-1 antibody) injection that disrupts glial function. ICC procedures will verify Mac-1 Saporin microglial toxicity.

Related Products: Mac-1-SAP mouse/human (Cat. #IT-06)

Responses of spinal dorsal horn neurons to capsaicin following intrathecal pretreatment with substance p-saporin toxin.

Khasabov SG, Rogers SD, Mantyh PW, Simone DA (2000) Responses of spinal dorsal horn neurons to capsaicin following intrathecal pretreatment with substance p-saporin toxin. Neuroscience 2000 Abstracts 635.13. Society for Neuroscience, New Orleans, LA.

Summary: Intrathecal (i.t.) application of the cytotoxic substance P-saporin (SP-SAP) conjugate is internalized by dorsal horn neurons expressing the SP receptor (SPR) and results in loss of SPR-expressing neurons. Loss of SPR+ neurons attenuates the nocifensive behavior and hyperalgesia produced by intraplantar injection of capsaicin (CAP). Here we determined the effect of SP-SAP on CAP-evoked excitation and sensitization of dorsal horn neurons to heat and mechanical stimuli. Separate groups of rats were given i.t. injection of vehicle (VEH) or SP-SAP (5´10-6mM in 10ml) 10 or 30 days prior to electrophysiological experiments. Extracellular recordings were obtained from nociceptive dorsal horn neurons classed as high threshold (HT) or wide dynamic range (WDR). Responses to mechanical (von Frey monofilaments) and heat (35°C-51°C) stimuli were obtained before and after injection of 10 mg CAP into the receptive field. In VEH-treated animals, CAP produced an intense activation of HT and WDR neurons with a mean peak discharge rate of 52.2±11.2 Hz. In addition, the mean number of impulses evoked by mechanical stimuli increased 267±33% following CAP and mean heat thresholds decreased from 44.7±1.6°C to 37.7±0.7°C. In SP-SAP treated animals, however, the peak response evoked by CAP was decreased by 61±11% as compared to control. Moreover, CAP did not significantly alter responses to mechanical or heat stimuli. These data suggest that dorsal horn neurons that possess the SPR play a critical role in the development of sensitization to mechanical and heat stimuli following CAP.

Related Products: SP-SAP (Cat. #IT-07)

Contribution of IB4-positive sensory neurons to NGF-induced hyperalgesia in the rat.

Tarpley JW, Martin WJ, Baldwin BS, Forrest MJ, MacIntyre DE (2000) Contribution of IB4-positive sensory neurons to NGF-induced hyperalgesia in the rat. Neuroscience 2000 Abstracts 633.18. Society for Neuroscience, New Orleans, LA.

Summary: Sensory information is transmitted from the periphery to the spinal cord by distinct subsets of primary afferent neurons, including two major classes of C-fibers that are distinguished by their ability to bind the lectin IB4. IB4-positive neurons are primarily non-peptidergic, express the receptor tyrosine kinase, Ret, and are preferentially sensitive to the neurotrophic factor, GDNF. By contrast, the nerve growth factor (NGF) receptor tyrosine kinase, trkA, is predominantly expressed in IB4-negative neurons that contain substance P. Previous work suggested that depletion of IB4-positive neurons increases acute nociceptive thresholds to noxious thermal stimuli. The extent to which these non-peptidergic neurons mediate changes in nociception after injury is unknown. Here, we examined the contribution of IB4-positive, non-peptidergic, neurons to thermal and mechanical sensitivity after acute tissue injury. Baseline thermal (radiant heat) and mechanical (von Frey) thresholds were measured in rats prior to injection of IB4-saporin (5 ug/5 ul) into the left sciatic nerve. By two weeks, IB4-saporin-treated animals exhibited pronounced increases in their nociceptive thresholds to thermal and mechanical stimuli. At this time, treatment with NGF (5 ug/50 ul, i.pl.) increased paw thickness in both control and IB4-saporin-treated rats. However, nociceptive thresholds were significantly lowered in control rats, but not in those treated with IB4-saporin. This suggests that IB4-positive neurons contribute to injury-induced changes in thermal and mechanical sensitivity and provide insight into the function of this unique set of primary afferent neurons.

Related Products: IB4-SAP (Cat. #IT-10)

Intracortical injection of DBH-saporin targets noradrenergic axons in the medial prefrontal cortex of the rat.

Mazei MS, Wiley RG, Deutch AY (2000) Intracortical injection of DBH-saporin targets noradrenergic axons in the medial prefrontal cortex of the rat. Neuroscience 2000 Abstracts 639.8. Society for Neuroscience, New Orleans, LA.

Summary: The medial prefrontal cortex (mPFC) is innervated by both dopaminergic and noradrenergic neurons. While the densities of the two types of catecholamine axons are different in subregions of the mPFC, axons of both types are present in most of the mPFC. The goal of this study was to selectively lesion noradrenergic axons in the rat mPFC while sparing dopaminergic axons, using microinjection of the immunotoxin dopamine β-hydroxylase (DBH)-saporin. DBH-saporin (10- 100 ng/μ1) was unilaterally injected into three brain regions, the mPFC, caudate-putamen (CP) and cerebellum. Rats were sacrificed 2-10 days post-injection and the lesion was characterized by tyrosine hydroxylase (TH), DBH, and norepinepherine transporter (NET) immunohistochemistry. DBH-saporin administration resulted in discrete lesions. There appeared to be a decrease in the number of immunoreactive (ir) axons after DGH-saporin infusion into the mPFC: surviving axons were swollen and dystrophic. However, the effect of DBH-saporin appears more pronounced when examining DBH-ir than with NET-ir. Intrastriatal injections of DBH-saporin did not decrease TH-ir, suggesting that dopaminergic axons were spared. Since DBH-saporin acts by entry into DBH-containing vesicles, a longer time course may be necessary to observe loss of the NET marker than DBH. Studies are in progress to examine this possibility.

Related Products: Anti-DBH-SAP (Cat. #IT-03)

Prevention and treatment of a spontaneous pain-like behavior following excitotoxic spinal cord injury (SCI) by ablation of neurons expressing the substance P receptor.

Yezierski RP, Yu CG, Wiley RG (2000) Prevention and treatment of a spontaneous pain-like behavior following excitotoxic spinal cord injury (SCI) by ablation of neurons expressing the substance P receptor. Neuroscience 2000 Abstracts 733.9. Society for Neuroscience, New Orleans, LA.

Summary: Intraspinal injection of the AMPA/metabotropic agonist quisqualic acid (QUIS) leads to the onset of excessive grooming behavior with an average onset time of 11-15 days. This behavior has been proposed as a model of chronic central pain following SCI (Yezierski et al., 1998). An important histological correlate of this behavior is a pattern of neuronal loss that includes the neck of the dorsal horn with sparing of the superficial laminae. Previously, we speculated that laminae I projection neurons might be part of the substrate responsible for the onset and progression of injury induced excessive grooming behavior. To test this hypothesis we evaluated the effects of the [Sar9,Met(OH)11]substance P-saporin (SSP-SAP) neurotoxin delivered directly to the dorsal surface of the cord in 'prevention' and 'treatment' protocols. Two groups of animals were injected with 125mM QUIS. One group received a treatment of SSP-SAP (10μl; 15 or 30ng/μl) for ten minutes immediately after QUIS injection. The second group was treated with 30ng/μl within 5 days after the onset of excessive grooming behavior. The results showed that only 30% (3/10) of the animals receiving SSP-SAP in the prevention protocol developed excessive grooming behavior compared to a norm of 80-90%, and those that developed the behavior had a delayed onset (18-26 days) and small skin area targeted for grooming. Animals receiving SSP-SAP treatment after the onset of grooming had significantly less grooming than animals not receiving treatment. Staining for the NK-1R receptor showed that animals with minimal grooming behavior had a significant decrease in lamina I staining with normal staining around the central canal and IML. In conclusion the results have shown that ablation of lamina I substance P receptive neurons significantly delayed the onset and progression of a spontaneous pain-like behavior induced by excitotoxic SCI.

Related Products: SSP-SAP (Cat. #IT-11)

NGF-induced rapid functional plasticity in the adult rat somatosensory cortex is mediated by fibers originating in the basal forebrain cholinergic system.

Prakash N, Cohen-Cory SC, Frostig RD (2000) NGF-induced rapid functional plasticity in the adult rat somatosensory cortex is mediated by fibers originating in the basal forebrain cholinergic system. Neuroscience 2000 Abstracts 722.6. Society for Neuroscience, New Orleans, LA.

Summary: We have previously demonstrated, by using intrinsic signal optical imaging in vivo, that topical application of nerve growth factor (NGF) to the somatosensory cortex of an adult rat augments the functional representation of a whisker, within minutes after NGF application (Prakash et al. Nature 381:702-6, 1996). In addition, we have shown that the NGF receptor, TrkA is found on fibers projecting to the cortex. We have now tested the hypothesis that these TrkA-positive fibers originate in basal forebrain cholinergic system (BFCS) and that NGF augments the size and amplitude of a cortical representation by enhancing the release of ACh from these fibers. To this end we demonstrate: 1) that BFCS fibers indeed express TrkA receptors by co-localizing TrkA and ChAT immunostaining to single cortical fibers; 2) that removal of these cortical BFCS-fibers by injection of a specific cytotoxin, 192 IgG-saporin, prevented the NGF-induced augmentation; and 3) that topical application of the ACh agonist carbachol induced a rapid augmentation of the whisker functional representation similar to the one observed with NGF. Thus, these results firmly support our hypothesis that NGF-induced effects on cortical functional representations are mediated by the BFCS projection fibers and provide a mechanism for NGF-induced rapid plasticity in vivo.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Elimination of microglia suggests their involvement in neuronal plasticity.

Siddiq MM, Tsirka SE (2000) Elimination of microglia suggests their involvement in neuronal plasticity. Neuroscience 2000 Abstracts 507.2. Society for Neuroscience, New Orleans, LA.

Summary: Reorganization of mossy fibers occurs in the mammalian hippocampus during consolidation of learning and memory. Induced low level seizures with kainic acid (KA) result in the development of new synapses and the reorganization of existing ones along the mossy fiber pathway. The serine protease tissue plasminogen activator (tPA) is expressed along the mossy fiber pathway and has been implicated in neurite remodeling after stimulation of neuronal activity. Both neurons and microglia secrete tPA. Microglial cells are thought to function only in pathological situations in the CNS, as they exhibit neurotoxic properties. However, a protective role has been observed in the regenerating optic nerve, where intervening activated microglia were involved in tissue remodeling. To investigate whether there is a role for microglia in mossy fiber remodeling, microglia were eliminated in C57/BL6 mice by immunolesioning. The reorganization of mossy fibers was evaluated. Kainate-injected wild-type mice had pronounced mossy fiber reorganization in the dentate gyrus of the hippocampal formation as detected by Timm staining, while the immunolesioned mice had significantly less and shorter mossy fibers. It is therefore suggested that activated microglia may play a role in active remodeling of mossy fibers in the hippocampus after KA-induced seizures.

Related Products: Mac-1-SAP mouse/human (Cat. #IT-06)

Schwann cells are removed from the rat spinal cord after effecting recovery from paraplegia.

Janni G, Moallem T, Lappi DA, Ohara PT, Jasmin L (2000) Schwann cells are removed from the rat spinal cord after effecting recovery from paraplegia. Neuroscience 2000 Abstracts 516.8. Society for Neuroscience, New Orleans, LA.

Summary: Remyelination of the CNS is necessary to restore neural function in a number of demyelinating conditions such as multiple sclerosis. Schwann cells, the myelinating cells of the periphery, are good candidates for this purpose, having more robust regenerative properties than their central homologues, the oligodendrocytes. While the ability of Schwann cells to remyelinate the CNS and effect functional recovery has been demonstrated, their long term survival in the CNS after myelinating central axons is largely unknown. We use saporin conjugated to the cholera toxin B-subunit to demyelinate the rat lumbar spinal cord, remove macroglia, and produce paraplegia. This treatment is followed by a spontaneous proliferation of large numbers of endogenous Schwann cells which remyelinate spinal cord axons with concomitant functional recovery from paraplegia within 75 days. During the following weeks, however, quantification on thin sections shows that Schwann cells are progressively replaced by oligodendrocytes, without any lapse in behavioral recovery. This removal of Schwann cells is confirmed by ultrastructural examination and by immunocytochemistry for Schwann cells and oligodendrocytes. Our results indicate that Schwann cell remyelination of the spinal cord might not be permanent. They can be induced to demyelinate and desheath through endogenous mechanisms that remain to be characterized.

Related Products: CTB-SAP (Cat. #IT-14)

The behavioral and neurochemical effects of acute and incremental cholinergic lesions on visual attention during a 5-choice serial reaction time task.

McGaughy JA, Dalley JW, Robbins TW, Everitt BJ (2000) The behavioral and neurochemical effects of acute and incremental cholinergic lesions on visual attention during a 5-choice serial reaction time task. Neuroscience 2000 Abstracts 563.1. Society for Neuroscience, New Orleans, LA.

Summary: Previously studies have shown that infusions of 192 IgG-saporin (SAP)into the nucleus basal magnocellularis (nbm) produce severe,persistent impairments in visual attention that correlate with the extent of cortical cholinergic deafferentation. After one bilateral infusion of a low dose (0.15 μg/μl; LX1) of SAP into the nbm, rats performing in a 5 CSRTT show specific behavioral impairments when tested with an increased event rate (ITI=2sec). In vivo microdialysis performed while rats were tested under standard conditions (ITI=5sec) in the 5CSRTT showed that LX1 rats had an increased basal acetylcholine (ACH) efflux in the prefrontal cortex (PFC) relative to sham-lesioned animals on the first day of testing, but no difference in task related efflux on either day of testing. The current study investigated the effects of larger cholinergic lesions on attentional perfomance to determine if they would produce large decreases in cortical ACH efflux and consequently impair attention. Rats were trained in a 5 CSRTT prior to receiving intra-nbm infusions of SAP or vehicle (VEH). Lesioned animals were subjected to repeated infusions of a low dose of the toxin (0.15 μg/μl), a single high dose (0.45 μg/μl) or vehicle. The (0.45 μg/μl) dose of SAP produced profound impairments under baseline conditions that correlated with low levels of ACH efflux in the PFC. These impairments were not attenuated by systemic nicotine or physostigmine. The cumulative lesions were hypothesized to increase sensitivity to attentional demands and pharmacological intervention.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Combined cholinergic denervation of the hippocampus and posterior cingulate cortex fails to impair working memory performance but may produce deficits in behavioural flexibility in the rat.

Winters BD, Dunnett SB (2000) Combined cholinergic denervation of the hippocampus and posterior cingulate cortex fails to impair working memory performance but may produce deficits in behavioural flexibility in the rat. Neuroscience 2000 Abstracts 563.2. Society for Neuroscience, New Orleans, LA.

Summary: Selective cholinergic denervation of either the hippocampal formation (HPC) or posterior cingulate cortex (pCCX) with the immunotoxin 192 IgG-saporin produces negligible effects on rats’ performance of the delayed nonmatching-to-position (DNMTP) task. Yet, fimbria-fornix transection, which disrupts the cholinergic input to both of these limbic regions, causes a delay-dependent deficit in this working memory task. In the current study, rats were trained in a standard DNMTP procedure and then divided into three groups: Group SAP (n=6) received injections of 192 IgG-saporin into both HPC and pCCX; Group NMDA (n=4) received similar injections of the excitotoxin N-methyl-D-aspartic acid; and Control rats (n=10) received vehicle injections. Following surgery, NMDA rats performed significantly worse than SAP and Control rats at all delays in the DNMTP task (p<0.05); SAP rats did not differ from Controls. All groups then acquired a matching-to-position task (i.e., reversal) over four sessions; however, SAP rats performed significantly more perseverative errors during the first reversal session, resulting in a significant Group x Session interaction (p<0.01). It is suggested that, while the cholinergic projections to the HPC and pCCX are not crucial for working memory performance in the DNMTP task, the cholinergic innervation of these limbic regions may influence behavioural flexibility by modulating a circuit mediating habit-like performance.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Reduced anxiety related behavior following ablation of amygdala neurons expressing substance P receptor.

Rogers SD, Salak-Johnson JL, Schwei MJ, Pomonis JD, Mantyh PW (2000) Reduced anxiety related behavior following ablation of amygdala neurons expressing substance P receptor. Neuroscience 2000 Abstracts 571.2. Society for Neuroscience, New Orleans, LA.

Summary: The neurokinin substance P (SP) is localized in brain regions that coordinate stress response and may play a role in modulating anxiety. Effects of ablation of substance P receptor (SPR)-expressing neurons by administration of a substance P-toxin conjugate, substance P-saporin (SP-SAP), in the amygdala (a brain region known to modulate stress and anxiety responses) were examined immunohistochemically and behaviorally thirty days following SP-SAP treatments. Rats were bilaterally injected in basolateral amygdala nuclei with 5μl of sterile saline, 1 μM saporin (SAP), or 1 μM SP-SAP. SPR-immunofluoresence levels and number of SPR-IR positive neurons in amygdalar subnuclei decreased following SP-SAP treatment. SP-SAP did not induce significant gliosis or non-specific neuronal death. Interestingly, after SP-SAP treatment, the number of NPY-IR neurons were also decreased, and combined SPR and NPY immunofluorescence demonstrated a large number of NPY-IR neurons colocalize with SPR-IR neurons in the amygdala. Thirty days following SP-SAP treatment, rats were tested in elevated plus maze (EPM) and open field (OF). Anxiety level and exploratory behavior displayed by SP-SAP treated rats were altered; they had significantly more entries into and spent more time in EPM open arms than did saline- or SAP-injected rats. In the OF, SP-SAP treated rats spent less time frozen than saline or SAP treated rats. These results suggest that SPR expressing neurons in the amygdala plays a pivotal role in generation of anxiety behaviors and that SP may play a modulatory role in stress-induced anxiety behavior.

Related Products: SP-SAP (Cat. #IT-07)

A specific cholinergic immunotoxin in mice.

Berger-Sweeney JE, Murg SL, Baxter MG, Stearns NA, Lappi DA (2000) A specific cholinergic immunotoxin in mice. Neuroscience 2000 Abstracts 563.13. Society for Neuroscience, New Orleans, LA.

Summary: We have shown previously that 192 IgG-saporin, a p75 (nerve growth factor [NGF] receptor) antibody linked to the ribosome-inactivating protein saporin, is an effective lesioning agent for cholinergic basal forebrain neurons in rats (Berger-Sweeney et al., J. Neurosci. 14:4507-4519). The 192 IgG antibody, however, does not crossreact with the mouse NGF receptor, making it unsuitable for mouse studies. Here, we tested the efficacy of a new immunotoxin targeting the mouse p75 receptor. A rat monoclonal antibody (Advanced Targeting Systems) to the extracellular domain of the mouse p75 receptor, which can be internalized and transported retrogradely in mouse neurons (Rossner et al., Metab. Brain Dis. 15:17-28), was coupled to saporin. Different doses of the toxin, or saline (0.5 µl) were injected into the lateral ventricle (icv) of adult C57BL/6 mice (n = 3–6/ group). Two weeks later, brains were processed for choline acetyltransferase (ChAT) neurochemistry or ChAT immunocytochemistry (to examine lesion efficacy), and glutamic acid decarboxylase (GAD) neurochemistry or calbindin/parvalbumin immunocytochemistry (to examine lesion specificity). Toxin doses ranging from 0.4 – 3.6 µg reduced hippocampal and neocortical ChAT activity in a dose-dependent fashion. Immunocytochemistry confirmed a significant loss of ChAT-positive neurons in the basal forebrain. These same doses did not alter hippocampal or neocortical GAD activity, or alter calbindin or parvalbumin staining (non-cholinergic neurons) in the basal forebrain. These data suggest that we have created a specific cholinergic immunotoxin for use in mice.

Related Products: mu p75-SAP (Cat. #IT-16)

Selective destruction of basal forebrain cholinergic neurons impairs acquisition of a spatial memory task.

Johnson DA, Zambon NJ, Gibbs RB (2000) Selective destruction of basal forebrain cholinergic neurons impairs acquisition of a spatial memory task. Neuroscience 2000 Abstracts 563.3. Society for Neuroscience, New Orleans, LA.

Summary: The effects of selective cholinergic vs. non-selective lesions of the septum and diagonal band on acquisition of a spatial memory task were studied. Adult male S-D rats received intraseptal injections of either the selective immunotoxin 192 IgG-saporin (SAP; 1.0 μg in 1.0 μl) or the non-selective neurotoxin ibotenic acid (IBO; 5 μg in 1.0 μl). Two weeks following injection, the animals were food deprived, adapted to a T-maze, and trained to perform a delayed matching-to-position (DMP) task. Rats received 8 trial pairs/day until they reached a criterion of 15/16 correct choices. Seven days after reaching criterion, rats were tested for 2 days with no intertrial delay, then 1 day with a 60s delay, then 2 days with a 90s delay. Following euthanasia brain tissues were analyzed for either choline acetyltransferase (ChAT) activity or immunohistochemical detection of cholinergic neurons. Animals treated with SAP, but not IBO, had lowered ChAT activity in cortical, hippocampal, and basal forebrain tissues and a significant impairment in DMP acquisition compared to controls. SAP-treated animals required an average of 23.7 days to reach criterion compared to 13.1 days for controls (P<0.05). IBO-treated animals required 17.8 days to reach criterion which did not differ significantly from controls. There were no significant differences in post-criteria performance between any of the treatment groups. These data suggest that basal forebrain cholinergic projections play an important role during acquisition of the DMP task.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Orexin-B conjugated to saporin lesions LH and TMN neurons and produces narcoleptic-like sleep in rats.

Gerashchenko D, Greco MA, Salin-Pascual R, Kilduff TS, Lappi DA, Shiromani PJ (2000) Orexin-B conjugated to saporin lesions LH and TMN neurons and produces narcoleptic-like sleep in rats. Neuroscience 2000 Abstracts 566.27. Society for Neuroscience, New Orleans, LA.

Summary: A dysfunction of the hypocretin/orexin (Hcrt/Ox) system was recently linked with the sleep disorder, narcolepsy. To provide an experimental method that could be used to inactivate Hcrt/Ox receptor bearing neurons, we linked the toxin, saporin, to the orexin receptor binding ligand, orexin-B. Eighteen male Sprague-Dawley rats (400-450 g) were administered orexin-saporin (0.5 ul; 490 ng) to the lateral hypothalamus (LH) (where Hcrt/Ox containing neurons are located) or tuberomammillary nucleus (TMN) (where Hcrt/Ox receptor containing neurons are present) and sleep was recorded for 3 weeks. A significant reduction in the numbers of TMN and Hcrt/Ox neurons in the LH was detected 3 to 5 days after toxin administration and complete loss occurred by 2 weeks. Rats with extensive cell loss exhibited more REM sleep, nonREM sleep, and multiple sleep onset REM periods during the night. In the only two available animal models of human narcolepsy, the dysfunction in the orexin system is inherited and in the entire animal which makes it difficult to localize specific brain regions or circuits underlying narcolepsy. Orexin-saporin provides a method of determining the contribution of a specific Hcrt/Ox innervation in the regulation of behavior.

Related Products: Orexin-B-SAP (Cat. #IT-20)

Preservation of reactivity to spatial novelty in adult rats after specific basal forebrain 192 IgG-saporin lesions.

Ricceri L, Baxter MG, Frick KM, Berger-Sweeney J (2000) Preservation of reactivity to spatial novelty in adult rats after specific basal forebrain 192 IgG-saporin lesions. Neuroscience 2000 Abstracts 563.4. Society for Neuroscience, New Orleans, LA.

Summary: We have shown previously that neonatal intracerebroventricular (icv) injections of the selective cholinergic immunotoxin 192 IgG-saporin induce marked cholinergic loss in both hippocampus and cortex. These lesions also have long-term behavioral effects in adulthood, impairing reactivity to spatial novelty in a spatial open field test with five objects. In the present study, we analyzed behavioral and neurochemical effects of intraparenchymal injections of 192 IgG-saporin in the medial septal area (MS, 175 ng) or nucleus basalis magnocellularis area (nBM, 70 ng per side) of adult Wistar rats. Animals were then tested in the spatial open field test. NBM cholinergic lesions significantly reduced object exploration in the initial phase of the test, whereas locomotor activity, spatial and object novelty responses were unaffected by either the MS or nBM lesion. A loss in cortical (-61%) and hippocampal (-92%) choline acetyl-transferase activity was found following nBM and MS lesions, respectively. These data show that, although interrupting cholinergic basal forebrain innervation of neocortex and hippocampus in the first postnatal week induces long-term deficits in reaction to spatial rearrangement of familiar objects, the removal of the cholinergic inputs in adulthood does not compromise the same behavioral responses. These data suggest that the same MS and nBM neurons play differential roles in regulating reactivity to spatial changes at different maturational stages.

Related Products: 192-IgG-SAP (Cat. #IT-01)

A test of negative patterning reveals selective impairment in configural association learning in rats with 192 IgG-saporin lesions of the nucleus basalis magnocellularis.

Butt AE, Allen K, Arthur K, Cole C, Cook S, Gerth A, Hoichi M, Long C, Noble M, Rea T, Rogers J (2000) A test of negative patterning reveals selective impairment in configural association learning in rats with 192 IgG-saporin lesions of the nucleus basalis magnocellularis. Neuroscience 2000 Abstracts 563.5. Society for Neuroscience, New Orleans, LA.

Summary: We have previously argued that the nucleus basalis magnocellularis (NBM) is selectively involved in configural and not simple association learning, although the experiments used to support our position have involved comparatively non-selective NBM lesions. In the current experiment, rats with bilateral lesions of the NBM created using the highly selective cholinergic immunotoxin 192 IgG-saporin (n = 6) and sham-operated rats (n = 6) were trained in the negative patterning paradigm. In this task, operant responses made in the presence of a light (L) or a tone (T) are reinforced (+) when either stimulus is presented alone, but responses made when these stimuli are presented in compound (LT) are not reinforced (-). We hypothesized that rats in the NBM lesion group would learn to respond to L+ and T+, which requires the ability to learn simple associations, but would fail to learn to withhold responding to the LT- compound, which requires the ability to form configural associations. Responding to L+ and T+ was normal in the NBM lesion group, suggesting an intact ability to learn simple associations, but these animals failed to learn to discriminate between the reinforced stimulus elements L+ and T+ and the nonreinforced compound LT-, suggesting an impairment in configural association learning. The greater level of LT- responding observed in the NBM lesion group did not reflect an overall response disinhibition, as responding during the inter-trial interval did not differ between groups.

Related Products: 192-IgG-SAP (Cat. #IT-01)

The role of medial septal cholinergic and GABAergic neurons in social memory.

Secor AJ, Bishop J, Pang KCH (2000) The role of medial septal cholinergic and GABAergic neurons in social memory. Neuroscience 2000 Abstracts 563.6. Society for Neuroscience, New Orleans, LA.

Summary: Electrolytic lesions of the septum alters social behavior, increasing the number of social contacts with a conspecific. Furthermore, lesions of the septum impair both spatial and non-spatial memory. These findings lead researchers to invetigate the role of the septum in social memory. A recent study has demonstrated that administration of vasopressin antagonists into the lateral septum impairs social memory following a 30 minute delay. Social memory was measured as a decreased amount of exploaration of a familiar juvenile compared to a novel juvenile. The present experiment will investigate the role of the cholinergic and GABAergic projection neurons in the medial septum/diagonal band (MS/DB) in social memory. 192-IgG saporin and kainic acid will be administered into the MS/DB to destroy cholinergic and GABAergic MS/DB neurons, respectively. The effects of the drugs on social recognition will be assessed. Each adult rat will be allowed to explore a juvenile rat for 30 seconds. Following various delays (5, 30, 120 minutes), adult rats will be re-exposed to the same or a novel juvenile rat. The amount of time that the adult rat explores the juvenile rat in 1 minute and 3 minute periods will be measured. Differences in exploration time between the control and drug treated rats will provide evidence for alterations in social memory.

Related Products: 192-IgG-SAP (Cat. #IT-01)

192 IgG-saporin immunolesioning causes marked facilitation of dopamine-mediated locomotor activity in adult rats.

Mattsson A, Ögren SO, Olson L (2000) 192 IgG-saporin immunolesioning causes marked facilitation of dopamine-mediated locomotor activity in adult rats. Neuroscience 2000 Abstracts 563.7. Society for Neuroscience, New Orleans, LA.

Summary: Recent studies have indicated a possible link between changes in cholinergic mechanisms and schizophrenia. However there is limited information regarding the functional consequences of changes in ACh transmission on DA functions, which in turn are believed to be involved in schizophrenic symptoms. 192 IgG-saporin targets cells that express the low-affinity p75 neurotrophin receptor. Intracerebroventricular injection causes severe lesions of the cholinergic projections and may also damage Purkinje neurons. We have compared intracerebroventricular injections of 192 IgG SAP to adult rats (5 μg) with injections to neonate rats (0.4 μg day 4 or 0.4 μg day 4 + 0.8 μg day 13). As expected, treated adult rats are markedly impaired in the Morris swim maze both in terms of time to find the platform and in search behavior when the platform is removed, i.e. memory impairment. When tested as adults, neonatally treated animals were only modestly impaired. Interestingly, adult treated animals showed increased spontaneous motility and locomotion and markedly increased locomotor responses to amphetamine (1.5 mg/kg) as evidenced by increased rearing, motility and locomotion. These animals also responded to apomorphine (1 mg/kg) with an increased amount of rearing. There were no marked changes of locomotor activity in rats treated with 192 IgG SAP at 4 days or 4 and 13 days of age. Our results suggest that cholinergic denervation of the forebrain causes a marked enhancement of the behavior responses related to increased dopaminergic activity. However, it cannot be fully excluded that damage to non-cholinergic systems, e.g. Purkinje cells, might contribute to the effects. The striking overreaction to dopaminergic stimuli presumably caused by the cholinergic deficit is possibly relevant in relation to the role of cholinergic malfunctioning in schizophrenia.

Related Products: 192-IgG-SAP (Cat. #IT-01)

DBH-saporin lesions the locus coeruleus, but does not produce cataplexy or abnormal REM sleep triggering.

Blanco-Centurion CA, Salin-Pascual R, Gerashchenko D, Greco MA, Lappi DA, Kilduff TS, Shiromani PJ (2000) DBH-saporin lesions the locus coeruleus, but does not produce cataplexy or abnormal REM sleep triggering. Neuroscience 2000 Abstracts 566.17. Society for Neuroscience, New Orleans, LA.

Summary: Recently, canine narcolepsy was associated with a mutation in the hypocretin-2 receptor (Lin et al., 1999), which binds the neuropeptide hypocretin, also known as orexin. The locus coeruleus receives a very heavy projection of HCRT/OX fibers, and the LC also contains HCRT/OX receptor mRNA. Silence of LC neurons is hypothesized to be key in triggering cataplexy and REM sleep. To test this hypothesis, DBH-saporin was used to selectively lesion the LC. Male Sprague-Dawley rats (400-450 g) instrumented for recording sleep were given DBH-saporin (n=4) (500ng/0.5ul) via a micropipette to the LC. Control rats were administered 192-saporin (n=3), or saline (n=4). Two days later, sleep recordings were obtained for 7 consecutive days. The rat's behavior was videotaped at night. To identify whether cataplexy was induced, the alpha antagonist, Prazosin was administered (1500h, 500mg/kg, IP) and then sleep and video recordings were made for three hours. Brains were removed for histology. DBH-saporin completely lesioned the LC neurons. However, there were no changes in wakefulness, nonREM or REM sleep. Video recordings also did not reveal any cataplexy episodes. The application of Prazosin did not induce cataplexy or diminish muscle tone in DBH-saporin LC treated rats. Historically, LC lesions have never been found to induce cataplexy. Use of DBH-saporin provides a more specific lesion restricted to the LC neurons where the HCRT/OX receptor mRNA is localized. Our findings indicate that LC neurons are not essential for maintaining muscle tone or wakefulness.

Related Products: Anti-DBH-SAP (Cat. #IT-03)

Contribution of the cholinergic basal forebrain to proactive interference between stored odor memories during associative learning in rats: 192 IgG-saporin immunotoxic lesions.

De Rosa E, Hasselmo ME, Baxter MG (2000) Contribution of the cholinergic basal forebrain to proactive interference between stored odor memories during associative learning in rats: 192 IgG-saporin immunotoxic lesions. Neuroscience 2000 Abstracts 563.8. Society for Neuroscience, New Orleans, LA.

Summary: Previous electrophysiological studies and a computational model suggest that cholinergic neuromodulation may reduce olfactory associative interference during learning (Hasselmo & Bower, 1993; Hasselmo et al., 1992). Using a simultaneous discrimination task where rats were required to learn a baseline odor pair (A+B-) and then two novel odor pairs: A-C+ (with an overlapping component A) and D+E- (with no overlapping component), De Rosa & Hasselmo (2000) demonstrated that a 0.25 mg/kg systemic dose of scopolamine (SCOP) selectively increased proactive interference. Under the influence of SCOP, the rats were impaired on acquiring the odor pair AC and not the odor pair DE relative to their normal saline performance. To localize this effect male Sprague-Dawley rats, with bilateral selective cholinergic lesions of the horizontal limb of the diagonal band of Broca (HDB group) or of all of the cholinergic nuclei of the basal forebrain (BF group), were tested on our task. Neither lesion impaired normal acquisition of either odor pair relative to the sham-operated control rats. However, the BF group, but not the HDB and control groups, were sensitive to a lower dose of SCOP (0.125 mg/kg) than in the previous study: this dose selectively impaired the BF group on acquiring the odor pair AC and not the odor pair DE relative to their normal saline performance, suggesting that weaker cholinergic modulation after removing the majority of cholinergic neurons in the basal forebrain makes the system more sensitive to proactive interference during blockade of remaining cholinergic effects.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Anti-dβh-saporin injection into the paraventricular nucleus of the hypothalamus selectively abolishes 2DG-induced feeding without causing nonspecific tissue destruction.

Ritter S, Dinh TT, Bugarith K (2000) Anti-dβh-saporin injection into the paraventricular nucleus of the hypothalamus selectively abolishes 2DG-induced feeding without causing nonspecific tissue destruction. Neuroscience 2000 Abstracts 502.8. Society for Neuroscience, New Orleans, LA.

Summary: The toxin-antibody complex, saporin conjugated to a monoclonal antibody against dopamine-β-hydroxylase (anti-dβh-sap), selectively destroys dβh-containing catecholamine neurons. Previously we reported that PVH anti-dβh-sap injections abolish feeding and expression of Fos-immunoreactivity (-ir) in the PVH in response to 2DG-induced glucoprivation and cause selective destruction of dβh-containing neurons innervating the hypothalamus. To test the behavioral and neurochemical specificity of this lesion, anti-dβh-sap or control solution (saline or unconjugated saporin) was injected bilaterally into the PVH (n=6 per group). Beginning three weeks later, rats were tested for stimulation of feeding by 2-deoxy-D-glucose (2DG, 200 mg/kg) and mercaptoacetate (MA, 68 mg/kg), which reduce glucose and fatty acid oxidation, respectively, and for suppression of feeding by cholecystokinin octapeptide (CCK, 4 ug/kg). 2DG-induced feeding was abolished by anti-dβh-sap injection, but was not impaired by unconjugated saporin. Neither MA nor CCK responses were altered by anti-dβh-sap. The nonspecific toxicity of anti-dβh-sap at the injection site was assessed. We found that PVH magnocellular neurons at the injection site express oxytocin-ir and do not appear to be disrupted by the anti-βh-sap injection. Further, the ability of PVH neurons at the injection site to express Fos in response to a non-glucoprivic stimulus was not impaired by anti-dβh-sap since lateral ventricular injection of senktide, an NK3 receptor agonist, induced Fos ir in the PVH. PVH injections of anti-dβh-sap impair 2DG-induced feeding and PVH Fos expression by selective destruction of catecholamine neurons. PHS#DK 40498.

Related Products: Anti-DBH-SAP (Cat. #IT-03)

Crossed unilateral lesions of the cholinergic basal forebrain (by me20.4IgG-saporin) and fornix from inferior temporal cortex produce severe learning impairments in rhesus monkeys.

Easton A, Ridley RM, Baker HF, Gaffan D (2000) Crossed unilateral lesions of the cholinergic basal forebrain (by me20.4IgG-saporin) and fornix from inferior temporal cortex produce severe learning impairments in rhesus monkeys. Neuroscience 2000 Abstracts 205.8. Society for Neuroscience, New Orleans, LA.

Summary: Section of the anterior temporal stem, amygdala and fornix in monkeys results in a dense anterograde amnesia. We have proposed that this impairment is a result of isolating the medial temporal lobe and inferior temporal cortex from their basal forebrain afferents. Evidence suggests that the cholinergic cells of the basal forebrain are important for learning and memory. In the present experiment we have made an immunotoxic unilateral lesion (ME20.4IgG-saporin), specific for the cholinergic cells of the basal forebrain, in combination with unilateral fornix damage in the same hemisphere, and a lesion of the inferior temporal cortex in the opposite hemisphere to disconnect these cholinergic cells from the medial temporal lobe and inferior temporal cortex. These monkeys were severely impaired at scene learning and concurrent visual discrimination learning, both of which are sensitive to sections of the anterior temporal stem, amygdala and fornix. This deficit is strongly correlated with the degree of acetylcholine loss in the basal forebrain in the hemisphere with the immunotoxic lesion. This result strengthens the proposal that the cholinergic cells of the basal forebrain are essential for new learning, and that their interaction with the medial temporal lobe and inferior temporal cortex is required for normal learning in monkey and man.

Related Products: ME20.4-SAP (Cat. #IT-15)

Distribution of mu-opioid receptors and activated G-proteins in rat cingulate cortex and alterations following removal of noradrenergic afferents.

Vogt LJ, Sim-Selley LJ, Childers SR, Wiley RG, Vogt BA (2000) Distribution of mu-opioid receptors and activated G-proteins in rat cingulate cortex and alterations following removal of noradrenergic afferents. Neuroscience 2000 Abstracts 238.1. Society for Neuroscience, New Orleans, LA.

Summary: Anterior cingulate cortex (ACC) is involved in acute and chronic pain processing. Here we define opioid architecture throughout rat cingulate cortex, relate mu-opioid receptor and G-protein stimulated binding in particular layers, and localize binding to noradrenergic terminals with immunotoxin lesions (anti-DBH-saporin). [3H]DAMGO binding was highest in areas 32 and 24 with a peak in layer I. Midcingulate area 24' and posterior area 29 had lower and homogeneous binding. DAMGO stimulated [35S]GTPγS binding in area 24' was similar to that in areas 32 and 24, while area 29 had very low and homogeneous binding. Undercut lesions reduced [3H]DAMGO binding in all layers with greatest loss in layer I, while DAMGO-stimulated [35S]GTPγS binding losses occurred only in layers I-III. Since neurons in the midline thalamic nuclei and locus coeruleus synthesize mu-opioid receptors, noradrenergic afferents were removed with anti-DBH-saporin. This toxin reduced [3H]DAMGO binding only in layer I of areas 32 and 24, while DAMGO-stimulated [35S]GTPγS binding increased in layer II of areas 32 and 24, had no changes in area 24', and decreased binding in layer I of area 29. Thus, in addition to their actions on ACC neurons, other sites of opiate drug actions are through mu-opioid heteroreceptors on glutamatergic thalamic and noradrenergic locus coeruleus afferents to ACC.

Related Products: Anti-DBH-SAP (Cat. #IT-03)

Intrathecal injections of saporin conjugated substance-P alter the development of renal hypertension.

Ciriello J, Rosas-Arellano MP, Solano-Flores LP (2000) Intrathecal injections of saporin conjugated substance-P alter the development of renal hypertension. Neuroscience 2000 Abstracts 310.2. Society for Neuroscience, New Orleans, LA.

Summary: We have recently shown that there is an up-regulation of mRNA encoding Substance-P (SP) in dorsal root ganglia in the two kidney, one clip (2K1C) model of renal hypertension. In this study, the effect of intrathecal injections of the toxin saporin conjugated to SP (SAP; 5 x 10-6 M) on the development of 2K1C hypertension was investigated in male Wistar rats. Rats were randomly assigned to 2 groups and instrumented with an intrathecal cannula that ended at the T10-T12 spinal level. Arterial pressure (AP) and heart rate (HR) were recorded using the indirect tail-cuff method. After a 1 week control period, one group of animals received a single 10 µl injection of SAP and the other an equal volume of the saline vehicle (control). Two weeks later a clip was placed on the left renal artery in all animals. Injections of either SAP or the vehicle did not alter AP and HR compared to pre-injection levels. In addition, AP and HR were not altered in the SAP group compared to controls for the 2 week period prior to the renal clip. However, during the 4 weeks after the renal clip, AP and HR in the SAP group were significantly lower compared to the control animals. These data suggest that dorsal horn neurons containing SP receptors and that receive afferent renal nerve inputs are involved in renal hypertension.

Related Products: SP-SAP (Cat. #IT-07)

Chronic noradrenergic spinal denervation in rats does not produce long-term hyperalgesia.

Jasmin L, Arsenault P, Ohara PT, Marchand S (2000) Chronic noradrenergic spinal denervation in rats does not produce long-term hyperalgesia. Neuroscience 2000 Abstracts 243.7. Society for Neuroscience, New Orleans, LA.

Summary: Pharmacological studies have established that noradrenaline tonically inhibits spinal nociceptive transmission. We tested the hypothesis that chronically decreasing spinal noradrenaline would result in a disinhibition of nociceptive afferents resulting in behavioral hyperalgesia. We destroyed noradrenergic cells innervating the spinal cord using dopamine beta-hydroxylase antibodies linked to the neurotoxin saporin (anti-DBH-Sap). Male rats (n=6) were injected intrathecally with 4µg/10µl of anti-DBH-Sap, and their responses to nociceptive and non-nociceptive stimuli was monitored over a period of 65 days. Compared to controls (n=6), a significant (p< 0.05) decrease to hot plate (46oC) nociceptive responses could be observed during the first week post-treatment, but no differences were found at later times. At no point was there any altered response to innocuous stimuli. When tested for response to cold water stress, both treated and control animals showed analgesia, demonstrating that descending pain inhibition could still be activated. At 65 days, a formalin test showed no difference between treated (1.1 +/-0.5) and control (0.8 +/-0.5) groups. Post-mortem immunostaining of spinal cords for DBH, however, confirmed that noradrenergic denervation of the spinal cord had occurred in treated animals. These results suggest that a reorganization of the spinal cord following noradrenergic denervation is sufficient to reestablish normal nociceptive responses.

Related Products: Anti-DBH-SAP (Cat. #IT-03)

Altered operant and reflex responses to noxious heat in rats with central noradrenergic lesions using antiDßH-saporin.

Vierck CJ, Belford PM, Iqbal MA, Camara C, Kline RH, Lappi DA, Wiley RG (2000) Altered operant and reflex responses to noxious heat in rats with central noradrenergic lesions using antiDßH-saporin. Neuroscience 2000 Abstracts 247.10. Society for Neuroscience, New Orleans, LA.

Summary: We sought to determine effects of a selective lesion of pontine NA neurons on thermal sensitivity, using an operant escape task and hotplate tests. 8 rats received ICV injections of 10 ìg of anti-DβH-saporin, an immunotoxin that selectively destroys NA neurons, or vehicle. The rats were trained to escape a dark chamber with a hot floor to a brightly lit room-temperature shelf. There was no difference between groups at 39o, 44oor 47o C. However, at 44o C, application of mustard oil to the dorsal surface of both hindpaws or 0.94% capsaicin cream to the plantar surfaces increased escape durations only for vehicle rats. Also, at 44o C, toxin-treated rats were more sensitive than vehicle rats to morphine (0.5-5 mg/kg, s.c.) and clonidine (0.125 mg/kg, s.c.). The toxin-injected rats were insensitive to yohimbine (2.5 and 5 mg/kg, s.c.). Postmortem analysis for DβH showed that toxin-treated rats lost all pontine NA neurons, with preservation of medullary NA cells. To determine the role of NA projections to the spinal cord, two groups of rats were injected with 200-300 ng of antiDβH-saporin or vehicle via a lumbar intrathecal catheter. There were no consistent changes in baseline responses, and no differences between toxin and vehicle injected rats to 44o C after capsaicin or morphine (2.5 mg/kg, s.c.). However, the toxin treated rats were more sensitive to clonidine (0.03 mg/kg, s.c.). Thus, spinally projecting NA neurons appear not to mediate some modulatory effects of pontine NA neurons on nociception.

Related Products: Anti-DBH-SAP (Cat. #IT-03)

Role of IB4-binding sensory neurons in the effects of intradermal capsaicin injection.

Vulchanova L, Olson TH, Elde R, Honda CN (2000) Role of IB4-binding sensory neurons in the effects of intradermal capsaicin injection. Neuroscience 2000 Abstracts 212.7. Society for Neuroscience, New Orleans, LA.

Summary: We have shown previously that a unilateral injection of a conjugate of the lectin IB4 and the toxin saporin (IB4-SAP) into sciatic nerve of rats results in loss of IB4-binding neurons and transient increase in thermal and mechanical nociceptive thresholds. The thresholds were maximally increased 10 days post-treatment and returned to baseline levels by day 21. In the present study, we examined the responses of IB4-SAP treated rats after intradermal injection of capsaicin, which results in acute nocifensive behavior followed by thermal and mechanical hyperalgesia. The nocifensive behavior of IB4-SAP treated rats 10, 21 and 42 days post-treatment was 6%, 36% and 47%, respectively, of the behavior of control treated rats. IB4-SAP treated rats injected with capsaicin did not develop thermal or mechanical hyperalgesia at any of the time points examined. These results suggest that the increase in thermal nociceptive thresholds after IB4-SAP treatment is due to loss of VR1-expressing IB4-binding neurons since the nocifensive behavior is most likely mediated by the capsaicin receptor VR1, which also transduces noxious thermal stimuli. In addition, VR1 in surviving neurons may contribute to the recovery of thermal nociceptive thresholds. Finally, our results suggest that IB4-binding neurons are required for development of capsaicin-mediated hyperalgesia, and that the recovery of the responsiveness of IB4-SAP treated rats to noxious stimuli under normal conditions is not accompanied by recovery of the mechanisms underlying hyperalgesia.

Related Products: IB4-SAP (Cat. #IT-10)

Focal hippocampal hyperexcitability after focal interneuron ablation in the rat by substance P-saporin.

Martin JL, Sloviter RS (2000) Focal hippocampal hyperexcitability after focal interneuron ablation in the rat by substance P-saporin. Neuroscience 2000 Abstracts 389.13. Society for Neuroscience, New Orleans, LA.

Summary: Hyperexcitability after prolonged seizures or head trauma may result from interneuron malfunction or loss; but a causal relationship is in doubt because global insults produce widespread brain damage and other effects. We have therefore sought to destroy interneurons selectively using stable Substance P-saporin (SSPsap; ATS); a neurotoxin internalized by SP receptor (SPR)-expressing neurons. Improved immunofluorescent methods revealed that most GABA-; parvalbumin (PV)-; and somatostatin (SS)-positive (+) cells of all hippocampal regions (dentate gyrus and areas CA1-CA3) are SPR+; but that granule cells; mossy cells; and CA1-3 pyramidal cells are not. Intrahippocampal injections of SSPsap or vehicle were made under urethane anesthesia in 3 sites (20nl/site) of the dorsal hippocampus of 6 male Sprague-Dawley rats/group. After 5-90 days; rats were blindly evaluated in two sites for CA1 pyramidal cell and dentate granule cell responses to perforant path stimulation (PPS). SSPsap-treated rats exhibited relatively normal responses in some sites; but pathophysiology at other sites that was virtually identical to that seen after prolonged PPS or kainate (multiple population spikes and paired-pulse disinhibition in response to 0.1-2.0Hz perforant path (PP) stimuli). Abnormal responses were observed at the earliest time tested (5 days); and at 90 days. Anatomical analysis revealed selective loss of SPR+; PV+; SS+; and GABA+ neurons; and survival of principal cells and extrinsic afferents. Importantly; "epileptic" pathophysiology was observed exclusively in areas of interneuron loss. These data indicate that the pathophysiology produced by status epilepticus or head trauma can be replicated focally by selective interneuron loss alone; and provide the first direct evidence that highly focal interneuron loss per se is capable of replicating "epileptic" disinhibition and hyperexcitability. In addition; the pathophysiology is restricted to the region of the affected interneuron somata; suggesting a highly localized influence of inhibitory interneurons. Supported by: NIH grant NS18201.

Related Products: SSP-SAP (Cat. #IT-11)

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Regulation of sympathetic vasomotor tone and arterial pressure by the rostral ventrolateral medulla after elimination of C1 neurons in rat.

Schreihofer AM, Stornetta RL, Guyenet PG (2000) Regulation of sympathetic vasomotor tone and arterial pressure by the rostral ventrolateral medulla after elimination of C1 neurons in rat. Neuroscience 2000 Abstracts 310.7. Society for Neuroscience, New Orleans, LA.

Summary: The rostral ventrolateral medulla (RVLM) tonically stimulates sympathetic preganglionic neurons to maintain arterial pressure (AP). Although the C1 neurons in the RVLM may have a sympathoexcitatory function, it is not known whether they are the essential presympathetic RVLM neurons. In the present study, we selectively destroyed spinally projecting C1 cells (∼84%) with bilateral microinjections (spinal segments T2-T3) of an anti-dopamine-betahydroxylase antibody conjugated to saporin (anti-DβH-SAP). 3-5 weeks later these rats had a normal AP and splanchnic nerve activity (SNA) under chloralose anesthesia. Extracellular recording and juxtacellular labeling of bulbospinal barosensitive neurons in RVLM revealed that after anti-DβH-SAP only the lightly myelinated RVLM neurons with no or very low levels of tyrosine hydroxylase immunoreactivity were preserved. In these rats, inhibition of RVLM (muscimol 100 pmol/100 nl/side) eliminated SNA and decreased AP as seen in control rats. However, treatment with anti-DβHSAP reduced the sympathoexcitatory and pressor responses to electrical stimulation in RVLM. Although treatment with anti-DβH-SAP also eliminated A5 noradrenergic cells, rats with selective lesions of A5 cells (local microinjection of 6-hydroxydopamine) displayed no deficits to stimulation of the RVLM. These data suggest basal sympathetic vasomotor tone relies primarily on non-catecholaminergic presympathetic cells in the RVLM. In contrast, bulbospinal adrenergic neurons are important for the increased SNA and AP produced by stimulation of the RVLM.

Related Products: Anti-DBH-SAP (Cat. #IT-03)

Dermorphin-saporin targets tonic descending facilitation in the rostral ventromedial medulla to block and reverse neuropathic pain.

Burgess SE, Vanderah TW, Mantyh PW, Malan Jr TP, Ossipov MH, Lappi D, Lai J, Porreca F (2000) Dermorphin-saporin targets tonic descending facilitation in the rostral ventromedial medulla to block and reverse neuropathic pain. Neuroscience 2000 Abstracts 243.6. Society for Neuroscience, New Orleans, LA.

Summary: The hypothesis that chronic pain from L5/L6 spinal nerve ligation (SNL) is due to tonic activation of descending pain facilitation mechanisms was explored by selective targeting mu (μ) opioid receptor expressing cells in the RVM (i.e., presumably, ON cells). Rats were treated with a single RVM injection of dermorphin (DERM)(μ agonist), saporin (SAP), or dermorphin-saporin conjugate (DERM-SAP) and responses to non-noxious (von Frey filaments) or noxious (Hargreave's test) stimuli characterized. DERM-SAP retained high affinity for μ receptors and acutely produced antinociception (tail-flick test), indicating agonist actions of the conjugate. Decreased staining of μ receptor-expressing cells was seen in superficial dorsal horn and in dorsal root ganglia 28 days after intrathecal injection of DERM-SAP, but not DERM or SAP. RVM DERM-SAP, DERM or SAP did not significantly alter baseline thresholds to von Frey filaments or noxious heat applied to the paw over 28 days. At day 28, RVM pretreated rats were subjected to sham- or SNL surgery and responses to tactile and heat stimuli monitored 7 days later (i.e., 35 days after the RVM pretreatment). DERM and SAP pretreated SNL rats showed the expected development of tactile allodynia and thermal hyperalgesia, while DERM-SAP pretreated rats did not. The RVM pretreatments did not alter responses in sham-operated controls. Administration of RVM DERM-SAP, but not SAP or DERM, to SNL rats showed full reversal of established allodynia/hyperalgesia by day 14. RVM pretreatment with β-funaltrexamine (β-FNA; opioid μ antagonist) prevented the antiallodynic and antihyperalgesic effects of subsequent DERM-SAP injection. These data, together with findings of blockade of SNL pain with RVM lidocaine or lesions of the dorsolateral funiculus, support the possibility of tonic activation of descending facilitation as a basis for chronic neuropathic pain.

Related Products: Dermorphin-SAP / MOR-SAP (Cat. #IT-12)

Differential input to a nociceptive specific reflex by trka-positive and trka-negative small diameter DRG afferents.

Petruska JC, Johnson RD (2000) Differential input to a nociceptive specific reflex by trka-positive and trka-negative small diameter DRG afferents. Neuroscience 2000 Abstracts 354.7. Society for Neuroscience, New Orleans, LA.

Summary: The cutaneus trunci muscle (CTM) reflex is a nociceptive specific reflex in the rat. We examined whether particular subtypes of afferents may be differentially involved in the reflex. In particular, we wanted to determine if there were differences in input to the reflex between those expressing trkA receptors, and those lacking trkA receptors. We approached this question with two techniques. The selective neurotoxin 192-saporin was injected into the left T13 DRG to destroy the p75 receptor-bearing neurons. Two to three weeks following injection, the ability of the injected DRG to elicit the CTM reflex was examined in contrast to uninjected DRG. The ganglia were also retrieved for histochemical examination. In all cases where histochemical examination revealed a clear depletion of the neurotrophin-bearing neurons the injected DRG lacked the ability to induce the CTM reflex. Histochemical markers for the trkA-negative small diameter afferents appeared normal in all cases. The second approach utilized the trans-synaptic neuronal tracer pseudorabies virus (PRV). PRV was injected into the CTM to generate a retrograde tracing of the reflex circuit, including the afferents involved. This resulted in specific labelling of many small diameter DRG neurons, the vast majority of which expressed trkA. The CTM reflex may therefore not be a suitable monitor for inputs from the trkA-negative small diameter afferents, especially as regards its use in collateral sprouting experiments. These data indicate that inputs from the two populations of afferents are likely processed differently.

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Intrathecal dermorphin-saporin decreases morphine effect in hotplate algesia testing.

Miller SA, Lappi DA, Wiley RG (2000) Intrathecal dermorphin-saporin decreases morphine effect in hotplate algesia testing. Neuroscience 2000 Abstracts 212.8. Society for Neuroscience, New Orleans, LA.

Summary: The targeted cytotoxin, dermorphin-saporin, selectively destroys cells expressing MOR. In the present study, we gave dermorphin-saporin by lumbar i.t. injection and sought to determine if destroying dorsal horn neurons expressing MOR would alter thermal sensitivity and/or response to systemic morphine (MS) using hotplate testing under various conditions. 16 male Sprague-Dawley rats were tested on constant temperature (0.3, 44 and 47 C) and incremental (0.1 C/sec from 28 to 57 C) hotplates. Then 8 rats received lumbar intrathecal injections of derm-sap (465 ng) and 8 received vehicle using a subarachnoid PE-10 catheter that was removed 10 mins after injection. Retesting rats after toxin/vehicle injection showed no change in responses to any of the hotplate conditions. However, vehicle but not derm-sap rats showed increased lick latency on the incremental hotplate 20 mins after MS, 2.5 mg/kg, s.c. At 5 mg/kg of MS, vehicle and dermorphin-saporin rats showed identical responses. Capsaicin cream (0.94%) applied to the plantar surface of both hindpaws 3 hrs before testing on the 44 C hotplate produced decreased lick latencies in both groups of rats. MS, 5 mg/kg, s.c., produced increased lick latencies in capsaicin treated vehicle but not derm-sap rats. At 10 mg/kg, MS produced identical effects in capsaicin treated vehicle and toxin rats. These results indicate that i.t. derm-sap produced no change in baseline thermal sensitivity but did diminish the effect of low dose MS under conditions that preferentially test C nociceptor function suggesting that MOR-expressing dorsal horn neurons play a role in the analgesic action of low dose MS.

Related Products: Dermorphin-SAP / MOR-SAP (Cat. #IT-12)

Feedback HPA axis to stress is impaired in rats with selective removal of hippocampal cholinergic input.

Han JS, Bizon JL, Chun HJ, Maus CE, Gallagher M (2000) Feedback HPA axis to stress is impaired in rats with selective removal of hippocampal cholinergic input. Neuroscience 2000 Abstracts 388.16. Society for Neuroscience, New Orleans, LA.

Summary: Activation of intracellular glucocorticoid receptors (GRs) may play a permissive role in mechanisms that lead to degeneration of hippocampal neurons in pathological conditions such as Alzheimer's disease (AD). A previous study demonstrated that loss of cholinergic input from cells in the basal forebrain, a prominent feature of AD, reduced glucocorticoid receptor mRNA expression in the hippocampus in rats (Bizon et al., 1999). This experiment was conducted to see if reduced GRs after loss of cholinergic input would impair the function of the HPA axis in response to acute restraint stress. The cholinergic lesion was made by microinjections of the immunotoxin 192-IgG-saporin into the medial septal area and the vertical limb of the diagonal band. About 2 weeks later, rats were prepared with intravenous silastic catheters in the right jugular vein. After 5 days recovery, restraint stress for 1 hr was performed at 9:00 (a.m.). Blood (∼|50ul) was sampled repeatedly via the jugular catheter immediately (0 min) and at various times following the termination of the stressor (1 hr, 2 hr, 4 hr). For each group, negative feedback after a peak response to restraint was evident as a general trend of decreasing corticosterone that approached basal values by four hours after the cessation of stress. However, the speed of recovery to baseline differed between groups. Rats with loss of cholinergic input had higher corticosterone concentrations for a longer period after restraint stress than control rats, reflecting a diminished negative feedback function. These results suggest a mechanism whereby loss of basal forebrain cholinergic neurons in AD could contribute to a dysregulation of the HPA axis and more protracted exposure to high amounts of glucocorticoids. As an extension of the glucocorticoid cascade hypothesis, glucocorticoids might then be a factor in endangering hippocampal neurons in this disease.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Immunohistochemical detection of alpha-7 nicotinic receptor expression by two distinct cell types in the dorsal raphe and locus coeruleus of rat.

Bitner RS, Nikkel AL, Decker MW (2000) Immunohistochemical detection of alpha-7 nicotinic receptor expression by two distinct cell types in the dorsal raphe and locus coeruleus of rat. Neuroscience 2000 Abstracts 41.7. Society for Neuroscience, New Orleans, LA.

Summary: The α7 nicotinic acetylcholine receptor (nAChR) subunit can be assembled to form a homomeric-pentamer with high permeability to calcium, in contrast to other neuronal nAChR subunit-comprised ligand-gated cation channels. Although the expression of the α7-nAChR has been demonstrated throughout the CNS, the neurochemical phenotype of neurons expressing α7 remains to a large extent unknown. Using a polyclonal antibody raised against the carboxyl terminus (amino acids 460-479) of the α7 nAChR subunit (goat IgG, Santa Cruz Biotech.), immunohistochemical staining was observed in rat dorsal raphe (DR) and locus coeruleus (LC), serotonergic and noradrenergic brainstem nuclei, respectively. In both the DR and LC, there appeared to be two histologically distinct α7-expressing cell types as distinguished by size, i.e. large vs. small diameter. In rats treated with either a selective serotonergic (5,7-dihydroxytryptamine 150 μg i.c.v.) or noradrenergic (anti-dopamine-β-hydroxylase saporin 5 μg i.c.v.) neurotoxin, α7 immunostaining was seen only in small diameter cells, suggesting that the large diameter α7-expressing cells were serotonergic DR and noradrenergic LC neurons. Indeed, double-labeling experiments revealed in the large, but not small, cell types coexpression of α7 with tryptophan hydroxylase in the DR and tyrosine hydroxylase in the LC of saline-treated rats. In contrast, there was no coexpression in the neurotoxin-treated rats due to the loss of serotonergic or noradrenergic neurons, with only small diameter α7-expressing cells remaining. The results of these studies suggest that both serotonergic and noradrenegic neurons express α7 nAChRs. In addition, there appears to be a small diameter, non-serotonergic/noradrenergic cell-type in both the DR and LC that also expresses α7.

Related Products: Anti-DBH-SAP (Cat. #IT-03)

Local immunotoxin treatment prevents transneuronal labeling of the intermediolateral column; but not the ventral horn; of the spinal cord after tracer injection into lumbar epaxial muscle.

Daniels D, Miselis RR, Flanagan-Cato LM (2000) Local immunotoxin treatment prevents transneuronal labeling of the intermediolateral column; but not the ventral horn; of the spinal cord after tracer injection into lumbar epaxial muscle. Neuroscience 2000 Abstracts 77.13. Society for Neuroscience, New Orleans, LA.

Summary: Pseudorabies virus (PRV) has been used as a transneuronal tracer to study central neural circuits that control various peripheral targets. Our laboratory has injected PRV into the lumbar epaxial muscles that produce the lordosis posture to label sequentially specific brain regions along the neuraxis. However, concomitant uptake of PRV through sympathetic innervation of nearby vasculature has made the interpretation of higher-order labeling problematic. To avoid this confound, we have designed a procedure for focal sympathetic denervation using dopamine-β-hydroxylase immunotoxin (DHIT). Five days after injecting DHIT (5 μg) into the medial portion of lateral longissimus, the Bartha strain of PRV was injected into the pre-treated area. After survival times of 72 or 96 h, animals were sacrificed and the spinal cords were immunostained for PRV. In preliminary studies, DHIT treatment was not effective in all animals, as determined by PRV labeling in the sympathetic preganglionic neurons that reside in IML. However, at each survival time, in 50% of the animals DHIT virtually eliminated PRV-labeling in cells within IML of the thoracic and lumbar spinal cord, whereas robust labeling of motoneurons in the ventral horn was retained. These preliminary results suggest that this procedure for local sympathectomy may allow for selective transneuronal labeling of somatic motor pathways.

Related Products: Anti-DBH-SAP (Cat. #IT-03)

Depletion of cholinergic amacrine cells does not perturb the segregation of on and off cone bipolar cell projections.

Gunhan-Agar E, Choudary P, Landerholm TE, Chalupa LM (2000) Depletion of cholinergic amacrine cells does not perturb the segregation of on and off cone bipolar cell projections. Neuroscience 2000 Abstracts 119.3. Society for Neuroscience, New Orleans, LA.

Summary: The pathways signaling onset and offset of light are segregated in the retina with On-cone and Off-cone bipolar cells terminating on the stratified dendrites of On and Off retinal ganglion cells (RGCs). During development the axons of On and Off cone bipolar cells form two strata in the IPL in a remarkably precise manner, without any obvious refinements. Moreover, such a precise ingrowth pattern occurs even after RGCs have been depleted (J. Neurosci., 2000, 201:306-314). Here we show by immunostaining that two bands of cholinergic processes are present in the rat retina as early as P1, some 7 days before the formation of segregated bipolar inputs. Double labeling of retinal sections with the antibody to recoverin (that recognizes On and Off cone bipolar cells) and the antibody for VACHT (which labels cholinergic processes) revealed that the segregated terminals of cone bipolar cells are juxtaposed with the two bands of cholinergic fibers. These observations suggested that the cholinergic fibers could serve as a scaffold for the later ingrowing bipolar cell axons. To test this hypothesis, we devised a novel method for depleting retinal cholinergic amacrine cells with a VACHT-saporin immunotoxin. A single treatment of the developing retina with this immunotoxin was found to eliminate virtually all cholinergic cells and processes. Recoverin labeling of bipolar cells showed that the axons of these neurons still form two stratified terminal bands within the IPL. Thus, neither RGCs nor cholinergic amacrine cell processes are required for the formation of segregated ON and Off cone bipolar cell projections.

Related Products: Custom Conjugates

Sensory training improves the ability to process stimuli in barrel cortex after basal forebrain lesion.

Rahimi O, Tatham D, Juliano SL (2000) Sensory training improves the ability to process stimuli in barrel cortex after basal forebrain lesion. Neuroscience 2000 Abstracts 51.22. Society for Neuroscience, New Orleans, LA.

Summary: Lesions of the basal forebrain deplete the cerebral cortex of acetylcholine and result in decreased ability to process stimuli. Using a model of unilateral basal forebrain lesion (BFL), we previously determined that the ability to perceive simple touch to the whiskers is impaired after BFL, but improves over time. Functional responses in barrel cortex, however, as measured by 2-deoxyglucose uptake (2DG) or electrophysiological recordings, remain reduced even after long survival times. We questioned whether the impaired cortical responses could be improved with behavioral training involving sensory discrimination using the whiskers. To do this, one group of rats was trained to discriminate between different textures using the whiskers on one side of the face, which projected to the lesioned hemisphere. After learning the task, this group of rats received a BFL using the immunotoxin, 192-IgG Saporin. They then continued the sensory discrimination task for at least 2 months. The second group of rats received a BFL, but no sensory training. They survived after the lesion for comparable periods of time; each rat of both groups then underwent a 2DG experiment. During the 2DG study, 1-4 matched sets of whiskers on both sides of the face were stimulated using an electromagnetic device. The magnitude of the response was measured in barrel cortex by preparing 2-dimensional maps of the label evoked by whisker stimulation. The area of barrel cortex activated in each hemisphere by whisker stimulation was measured and expressed as a ratio of the lesioned to normal hemisphere. We found that the evoked response in the lesioned hemisphere remained diminished compared to the normal side regardless of training. When the magnitude of response was compared between the trained and untrained group, however, the area of 2DG uptake in each barrel in response to stimulation was significantly increased in the animals receiving sensory discrimination training. These findings suggest that sensory training plays a role in improving cortical responses to stimulation after lesion of the basal forebrain.

Related Products: 192-IgG-SAP (Cat. #IT-01)