sfn2001

Rodefer JS, Jonasson Z, Cahill JF, Tobey RE, Baxter MG (2001) Effects of basal forebrain cholinergic lesions on spatial learning in male and female rats. Neuroscience 2001 Abstracts 314.16. Society for Neuroscience, San Diego, CA.

Summary: Studies with a selective toxin for basal forebrain cholinergic neurons have consistently found little spatial learning impairment in rats with lesions limited to basal forebrain cholinergic neurons. However, the basal forebrain cholinergic system is extensively modulated by estrogen and related sex hormones. Furthermore, female mice are more susceptible than male mice to scopolamine-induced impairments in water maze performance (Berger-Sweeney et al., 1995). Hence, behavioral effects of selective cholinergic lesions may differ between male and female rats, a possibility that has not been directly assessed experimentally. In the present study, male and female Long-Evans rats were given injections of 192 IgG-saporin into the medial septum/vertical limb of the diagonal band (MS/VDB), or a control surgery, and postoperatively tested on several spatial learning tasks in the Morris water maze. On place acquisition, female control rats performed worse than male controls; MS/VDB-lesioned rats performed identically to male controls, regardless of sex. Male rats performed better than female rats on reversal of place discrimination, regardless of lesion status. In a test of place learning strategy, cholinergic lesions appeared to enhance the use of a spatial (vs. a motor response strategy) in rats of both sexes. Hence, female rats are not more susceptible to place learning impairment following loss of cholinergic input to the hippocampus; indeed these lesions seem to enhance place learning in female rats. Furthermore, removal of cholinergic input to the hippocampus seems to enhance the selection of a spatial strategy.

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

Bartness TJ, Demas GE (2001) A novel method for localized sympathetic nervous system denervation of peripheral tissue using guanethidine. Neuroscience 2001 Abstracts 309.10. Society for Neuroscience, San Diego, CA.

Summary: A simple technique for the functional deactivation of the sympathetic nervous system innervation of peripheral tissues is described using the local application of guanethidine. Multiple unilateral microinjections of guanethidine were made into one inguinal or epididymal white adipose tissue (IWAT and EWAT) pads of hamsters, whereas the contralateral pad received equivolumetric saline vehicle injections. Guanethidine treatment virtually abolished the sympathetic innervation of both EWAT and IWAT, as measured by the absence of significant norepinephrine (NE) tissue content two weeks later and as suggested by the two-fold increase in IWAT mass characteristic of surgically induced WAT denervation. IWAT and EWAT NE content and mass were unaffected in the contralateral control pads. Guanethidine injections into the spleen also lead to a function sympathectomy as indicated by significant depletions of NE content. Because guanethidine treatment did not decrease body mass nor induce ptosis, no chemical-induced malaise or global sympathetic denervation, respectively, was suggested. We compared the effects of local guanethidine treatment on IWAT NE content and pad mass with the local application of the sympathetic neurotoxin, anti-dopamine beta hydroxylase saporin, and with local surgical IWAT denervation. Guanethidine treatment significantly reduced IWAT NE content to a greater degree than for the alternative sympathectomy methods. These results suggest that locally applied, chemical sympathectomy with guanethidine provides an effective, restricted method for denervating WAT and likely other peripheral tissues.

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

Butt AE, Noble MM, Barrett H, Brinegar S, Hixon A, Kester B, Levey D, Rea T, Ryan M, Schulze S, Vogel L (2001) 192 IgG saporin lesions of the nucleus basalis magnocellularis impair working but not reference memory in a delayed non-match-to-position y-maze task. Neuroscience 2001 Abstracts 314.17. Society for Neuroscience, San Diego, CA.

Summary: The current experiment tests the hypothesis that the cortically projecting cholinergic neurons of the nucleus basalis magnocellularis (NBM) are selectively involved in working and not reference memory. Male Long-Evans rats received extensive pre-operative training in a delayed non-match-to-position (DNMTP) task in a Y-maze. In this task, 0-s, 1-min, or 2-min delays were interposed between consistently food-reinforced “sample runs”, where rats were allowed access to only one arm of the maze, and “choice runs”, where rats were allowed access to both arms of the maze but were reinforced only for entering the arm opposite that entered on the previous sample run. Upon completion of pre-operative training, rats were matched for performance and were randomly assigned to a sham lesion group or to the NBM lesion group, which received bilateral infusions of the cholinergic immunotoxin 192 IgG-saporin into the NBM. As predicted, post-operative performance in the NBM lesion group was normal at the 0-s delay but was severely impaired at the 1-min and 2-min delays. Results suggest that the NBM is critically involved in supporting normal spatial working memory but that previously acquired reference memory for the non-matching rule remains intact following selective NBM lesions.

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

Estacio MA, Tsukamura H, Reyes BA, Maeda KI (2001) Noradrenergic inputs to the paraventricular nucleus (PVN) is involved in estrogen receptor α expression in the PVN of 48-h fasted and 2DG-injected female rats. Neuroscience 2001 Abstracts 409.6. Society for Neuroscience, San Diego, CA.

Summary: Involvement of noradrenergic inputs to the paraventricular nucleus (PVN) in estrogen receptor α (ERα) expression in the PVN during 48-h fasting and 2DG-induced glucoprivation in female rats was determined by examining the effect of destroying the noradrenergic inputs to the PVN using the saporin-conjugated anti-dopamine-β-hydroxylase (anti-DBH-saporin). Ovariectomized rats were injected bilaterally with anti-DBH-saporin in the PVN. After two weeks, animals were either fasted for 48 hours or injected intravenously with 2DG, then perfused with 4% paraformaldehyde. Brain sections were processed for ERα and DBH immunocytochemistry. Forty-eight-hour fasting or 2DG injection siginificantly increased the number of ERα-immunoreactive (ERα-ir) cells in the PVN in control animals. Anti-DBH-saporin injection prevented fasting- or 2DG-induced increase in ERα-ir cells in the PVN. The DBH-ir axons in the parvocellular PVN were severely reduced following anti-DBH-saporin injection in both fasted and 2DG injected rats. Among the brainstem noradrenergic cell groups examined, there was a significant decrease in the number of DBH-ir cells in the A2 region of both fasted and 2DG injected rats treated with anti-DBH-saporin. There was no obvious reduction in the number of DBH-ir cells in the A1 and A6 regions in the anti-DBH-saporin-injected fasted- or 2DG-injected rats. The results suggest that the A2 noradrenergic input to the PVN plays a major role in increasing ERα expression in the PVN in response to 48-h fasting or 2DG-induced glucoprivation.

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

Wiley RG, Kline IV RH, Lappi DA (2001) Dose-dependent effects of intrathecal substance P-saporin and SSP-saporin. Neuroscience 2001 Abstracts 281.11. Society for Neuroscience, San Diego, CA.

Summary: Selective destruction of lamina I dorsal horn neurons expressing the neurokinin-1 receptor (NK-1R) can attenuate responses to capsaicin injection and thermal hyperalgesia/mechanical allodynia in models of inflammatory, persistent or neuropathic pain. In the present study, we sought to determine the relationships between spinal intrathecal dose of substance P-saporin or the related toxin, SSP-saporin, the loss of NK-1R neurons and reduction of phase II formalin responses. Rats were injected intrathecally with 10 ul of either vehicle, 175 ng, 350 ng or 700 ng of SP-sap. Others were injected with either vehicle, 25 ng, 50 ng or 100 ng of SSP-sap. After 2 weeks, nocifensive behavior was scored for 90 min after a unilateral hindpaw injection of dilute formaldehyde. The amount of phase II nocifensive behavior from 20-90 min post injection was totaled for each animal. Rats were sacrificed and transverse lumbosacral spinal cord sections were stained for NK-1R using indirect immunoperoxidase technique. Digital micrographs of the superficial dorsal horn were captured and the number of pixels in the darkest intensity values were expressed as percent of the analysis area for each dorsal horn. Significant correlations were noted for dose vs dark pixel percentage and for dark pixel percentage vs phase II formalin behavior. The greater the toxin dose the greater the loss of NK-1R staining and the greater the attenuation of phase II formalin behavior. These results indicate that the toxin effects on pain behavior are proportional to the degree of loss of lamina I NK-1R expressing neurons.

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

Savage LM, Buzzette R, Ramirez D (2001) The role of the cholinergic basal forebrain in learning, memory and reward expectancies. Neuroscience 2001 Abstracts 314.18. Society for Neuroscience, San Diego, CA.

Summary: The cholinergic basal forebrain degenerates in Alzheimer’s Disease and the degree of this degeneration correlates with a decline in cognitive processing. In the present study we have modeled this degeneration in the rat by the selective immunotoxin 192 IgG-Saporin. This immunotoxin destroys cholinergic neurons in the basal forebrain nuclei in rats and thus allows for the study of the impact of cholinergic deafferentation on learning, memory, and other cognitive processes without direct effects on other neuronal systems. After intracerebroventricularly infusions of the immunotoxin or vehicle solution, male rats were allowed to recover for three weeks before being tested in a matching-to-position task. The matching-to-position task was altered to influence the type of cognitive strategies a subject would use to solve the task. The main behavioral manipulation was the use of the differential outcome procedure (DOP). The DOP involves correlating each to-be-remembered event with a distinct reward condition. We found that cholinergic lesions did not dramatically impair learning the matching rule. However, the memory performance of subjects with cholinergic lesions was dramatically impaired – if subjects were not trained with the DOP. When subjects were trained with the DOP, and relied on reward expectancies to solve the delayed-matching-to-position task the cholinergic lesion had little effect. These findings demonstrate that cholinergic immunolesions by 192IgG-saporin induce specific cognitive impairments—dependent on task demand characteristics.

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

Hamaue N, Yamazaki Y, Ohmori H, Sumikawa K (2001) Nicotine enhances N-methyl-D-aspartate receptor responses and facilitates long-term potentiation in the hippocampus from rats with cholinergic lesions. Neuroscience 2001 Abstracts 376.5. Society for Neuroscience, San Diego, CA.

Summary: Nicotine reverses cognitive impairments caused by lesion of the cholinergic system and improves performance of Alzheimer’s patients. The mechanisms underlying these effects of nicotine, however, are unknown. Because nicotine facilitates the induction of N-methyl-D-aspartate receptor (NMDAR)-dependent long-term potentiation (LTP) in the hippocampal CA1 region, we examined whether nicotine enhances NMDAR responses and facilitates LTP induction in the hippocampus from rats with cholinergic lesions. Selective cholinergic denervation of rat hippocampus was performed by the immunotoxin 192 IgG-saporin. We then recorded burst NMDAR responses in hippocampal slices prepared from 192-IgG-saporin-treated rats and found that nicotine (1 μM) enhanced burst NMDAR responses. When GABAergic transmission was completely blocked by picrotoxin, nicotine had no effect on burst NMDAR responses. We also monitored the induction of LTP in 192-IgG-saporin-treated hippocampi and found that a weak tetanus (20 pulses at 100 Hz), which induced LTP in PBS-treated hippocampi, failed to induced LTP. However, in the presence of nicotine (1 μM), a same weak tetanus induced LTP in 192-IgG-saporin-treated hippocampi. Our results suggest that nicotine potentiates NMDAR responses by disinhibition of pyramidal cells and facilitates LTP induction in the hippocampus from animals with cholinergic lesions. The observed nicotine effects may represent the cellular mechanism underlying the compensatory action of nicotine in the presence of cholinergic deficits.

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

Yoder RM, Reuss SA, Pang KC (2001) Maze strategy in rats with GABAergic or cholinergic lesions of medial septum. Neuroscience 2001 Abstracts 418.7. Society for Neuroscience, San Diego, CA.

Summary: Cholinergic and GABAergic neurons are the two major cell types that project from medial septum to hippocampus. Although complete lesions of hippocampus or medial septum impair spatial memory, selective lesions of cholinergic or GABAergic neurons do not impair spatial abilities on an 8-arm radial or Morris water maze. Control and lesion rats possibly use different strategies to solve these tasks. Previous studies show that normal rats initially use a place strategy, then switch to a response strategy. In contrast, rats with hippocampus inactivated rely on a response strategy. Our preliminary results suggest that rats with GABAergic lesions of medial septum preferentially use a response strategy. The present study assessed whether rats with cholinergic (192-IgG saporin) or GABAergic (kainic acid) lesions of the medial septum preferentially use a place, response, or cue strategy to solve a plus maze task. During training, one arm contained food (goal) and an adjacent arm served as the starting location. The room contained distal cues and a proximal cue near the food. Probe trials were used every 4th day to assess the maze strategy used by the rat. During probe trials, the start location was located on the arm opposite the original start arm, and the proximal cue was located in the original start location. This study determines whether rats with loss of cholinergic or GABAergic medial septal neurons preferentially use different strategies to solve maze tasks.

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

Burk JA, Herzog CD, Porter MC, Mahoney J, Bruno JP, Sarter M (2001) Interactions between partial cortical cholinergic deafferentation and aging on sustained attention performance in rats. Neuroscience 2001 Abstracts 202.5. Society for Neuroscience, San Diego, CA.

Summary: Previous studies have provided only limited support for the idea that aging alone impairs the functions of basal forebrain corticopetal cholinergic neurons. Conversely, aging has been hypothesized to exacerbate the functional consequences of prior insult to, or degenerative processes in, the basal forebrain cholinergic system. The present study assessed the effects of aging on the sustained attention performance of rats with moderate lesion-induced loss of cortical cholinergic inputs. Previous studies on the effects of extensive (> 70 %) cortical cholinergic deafferentation indicated that the integrity of this system is necessary for the animals’ ability to detect rare and unpredictable visual signals. In the present longitudinal experiment, moderate (< 50 %) 192 IgG-saporin-induced loss of cortical cholinergic inputs, produced in well-trained, 16 month-old rats, did not – as was intended - immediately affect their attentional performance. Animals continued to undergo attentional performance training for the remainder of their lives. At the age of 31 months, impairments in performance began to emerge in lesioned animals. Compared to their sham-lesioned counterparts, lesioned animals exhibited a steeper decrement in their ability to detect hits in the course of a test session. At this age, the performance of sham-lesioned animals did not differ from their earlier performance prior to and immediately after the lesion. These results support the general hypothesis that aging serves to exacerbate the effects of pre-existing degeneration of the basal forebrain cholinergic system.

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

Rinaman L, Wonders CP (2001) Targeted destruction of A2/C2 catecholamine neurons alters hypothalamic responses to vagal stimulation. Neuroscience 2001 Abstracts 131.4. Society for Neuroscience, San Diego, CA.

Summary: Central catecholamine (CA) pathways participate in viscerosensory modulation of hypothalamic neuroendocrine function. Different brainstem CA cell groups may relay different types of viscerosensory signals to different classes of hypothalamic effectors. The present study sought to determine the role of dorsal medullary A2/C2 neurons in hypothalamic responses to exogenous cholecystokinin (CCK), which activates gastrointestinal vagal sensory inputs to the caudal brainstem. Saporin toxin conjugated to dopamine-beta-hydroxylase antibody (anti-DbH-sap; 10 ng in 100 nl) or control toxin was microinjected unilaterally or bilaterally into the A2/C2 region of the dorsal vagal complex in adult male rats. After 10-14 days, rats were injected i.p. with CCK (10 ug/kg) and perfused with fixative 1 hr later. Brainstem and forebrain sections were processed for dual immunocytochemical detection of cFos (a marker of neural activation) and DbH (to define the lesion). Additional forebrain sections were processed for cFos and either oxytocin (OT), vasopressin (AVP), or corticotropin-releasing factor (CRF) to identify hypothalamic neurons activated by CCK. Anti-DbH-sap destroyed the majority of A2/C2 neurons within the microinjection site(s), with minimal non-specific damage. A2/C2 lesions markedly attenuated CCK-induced activation of OT neurons and, to a lesser extent, attentuated CRF activation. Conversely, CCK-induced cFos expression was significantly increased in AVP neurons. The latter effect was observed only after bilateral lesions. These results indicate that A2/C2 neurons participate in vagal sensory-mediated stimulation of OT neurons and CRF neurons, and inhibition of AVP neurons.

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