sfn2000

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)

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)

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)

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)

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)

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)

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)

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)

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)

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)