References

Miller SA, Lappi DA, Wiley RG (2002) Enhanced morphine analgeisa after spinal dermorphin-saporin. Neuroscience 2002 Abstracts 218.1. Society for Neuroscience, Orlando, FL.

Summary: Dermorphin-saporin (derm-sap) is a neuropeptide toxin conjugate which is selective for neurons expressing the mu-opiate receptor (MOR). The dermorphin moiety of the conjugate binds MOR which is then internalized by the neuron, carrying the toxin with it. The saproin moiety inactivates ribosomes resulting in cell death. In the present study we sought to determine the effect of destroying MOR expressing neurons in Lamina II of the spinal cord dorsal horn on baseline thermal pain sensitivity and response to systemic morphine analgesia. 456 ng derm-sap (n=8) and vehicle (n=8) were injected into the lumbar CSF of adult male Sprague Dawley rats using a subarachnoid catheter inserted through the atlanto-occipital membrane and passed cadually to the level of the lumbar enlargement. 10 minutes following toxin injection, the catheters were withdrawn and the animals allowed to recover. When tested on a hotplate at 52C and on tail-flick assay, toxin rats did not differ from rats injected with vehicle. However, the dose-response curves for subcutaneous morphine were significantly shifted to the left (increased potency) in the toxin treated rats when compared with vehicle controls. Histological analysis of multiple dorsal root ganglia failed to reveal evidence of any primary afferent cell loss. We interpreted these findings to indicate that the neurons destroyed by derm-sap are lamina II MOR expressing neurons and play a role in morphine analgesia at high stimulus intensities.

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

Tait DS, McGaughy JA, Latimer MP, Brown VJ (2002) 192-IgG-saporin lesions of the cholinergic basal forebrain do not impair attentional set-shifting, but do increase latency to dig. Neuroscience 2002 Abstracts 286.2. Society for Neuroscience, Orlando, FL.

Summary: The cholinergic neurons of the basal forebrain which project to cortex, the thalamic reticular nucleus and the amygdala, have been implicated in vigilance and attention (Sarter and Bruno, 2000). This study examined the effects of basal forebrain cholinergic depletion on a shifting of attentional set. Male Lister hooded rats were stereotaxically injected with 192-IgG-saporin into basal forebrain to effect cholinergic depletion. Doses of 0.20mg or 0.25mg resulted in a loss of cholinergic cells in the basal forebrain and depletion of cholinergic input to frontal cortex and the thalamic reticular nucleus. The test of attentional set shifting task for the rat (Birrell and Brown, 2000) measures acquisition, reversal learning and shifting of attention between stimulus dimensions. Trials to criterion and latency to dig were recorded. There was no evidence of impairment in acquisition, reversal learning or set-shifting performance in the rats with cholinergic depletion compared to controls. There was a significant effect on dig latency. This was apparent only when the lesioned rats first approached an incorrect (i.e. unbaited bowl): although no more likely to dig in the incorrect bowl, the lesioned rats took longer to then move to the correct bowl. No effects were seen on dig latency if the rat by chance approached the correct bowl first. We conclude that attentional set-shifting is spared following basal forebrain lesions. Changes in latency in the task might be account for by deficits in sustained attention (attention to task) or related to frustration.

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

Kolasa K, Harrell LE (2002) Apoptotic affect of cholinergic denervation and hippocampal sympathetic ingrowth following selective immunolesioning with 192-IgG-saporin in rat hippocampus. Neuroscience 2002 Abstracts 295.16. Society for Neuroscience, Orlando, FL.

Summary: In rat, injection of specific cholinotoxin, 192IgG-saporin, into the medial septum (MS) results not only in a selective denervation of hippocampus(CD), but in an ingrowth of peripheral sympathetic fibers, originating from the superior cervical ganglion, into the hippocampus(HSI). A similar process, in which sympathetic axons invade hippocampus, may also occur in Alzheimer’s disease(AD). Our previous studies using MS electrolytic lesions suggested that HSI and CD appear to induce opposite effect on apoptotic markers. Apoptosis has also been implicated in some aspects of AD. By using 192IgG-saporin we have been able to more specifically and precisely study the affect of apoptosis on HSI and CD. Thus, 12 weeks after injection we measured apoptotic protein expression and DNA degradation using Western blot and in situ techniques e.x. TdT-mediated dUTP nick end labeling(TUNEL). Choline acetyltransferase activity (ChAT) and norepinephrine (NE) level was also detected. Like the previous results, we have found increase in apoptotic markers in CD group, while HSI reduced or normalized apoptotic effect to the control group level. We also found decrease in ChAT activity in HSI and CD groups of dorsal hippocampus.The results of the study suggest that cholinergic denervation is responsible for most of the proapoptotic responses, while hippocampal sympathetic ingrowth produced protective effect in the process of programmed cell death in rat dorsal hippocampus.

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

Tavares I, Cobos AR, Almeida A, Lima D (2002) The dyssynaptic pathway from the caudal ventrolateral medulla to the spinal cord is relevant for pain modulation. Neuroscience 2002 Abstracts 351.21. Society for Neuroscience, Orlando, FL.

Summary: The caudal ventrolateral medulla (VLM) exerts α2-adrenoreceptor mediated inhibition of pain transmission at the spinal cord. Anatomical studies described a dysynaptic pathway, connecting the VLM with the spinal cord through the A5 noradrenergic cell group, in which the spinally-projecting A5 noradrenergic neurons give collaterals to the VLM. In order to evaluate the role of the VLM-A5-spinal pathway in pain modulation, retrograde transport of the neurotoxin saporin-anti-dopamine-β-hydroxylase (SAP-anti-DBH) from the VLM was used. The VLM of Wistar rats was injected with 0.5μl of a 1% SAP-anti-DBH solution or saline (control group). Four days later, all animals were injected with 50 μl of 5% formalin in the ipsilateral hindpaw, and pain behavior and noxious-evoked spinal c-fos expression, were evaluated. In the SAP-anti-DBH group, a 27% decrease in DBH-immunoreactive neuronal population at the A5 noradrenergic cell group was detected and neuronal death was confirmed by Fluojade staining. Hyperalgesia was detected in the second phase of the formalin test. The numbers of Fos-immunoreacted neurons in the spinal dorsal horn increased. The data suggest that the VLM-A5-spinal pathway participates in pain modulation. It remains to be ascertained whether the lack of effect at the first-phase of the formalin test is due to an insufficient destruction of the A5 noradrenergic cell group or whether it points to a differential effect of this pathway in the two phases of the formalin test.

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

Helm KA, Ziegler DR, Gallagher M (2002) Habituation and dexamethasone (DEX) suppression of the stress response following selective lesions of cholinergic input to hippocampus in rats. Neuroscience 2002 Abstracts 370.1. Society for Neuroscience, Orlando, FL.

Summary: Hippocampal neurons have been identified as targets for glucocorticoids that exert inhibitory control over hypothalamic-pituitary-adrenocortical (HPA) axis activity. Prior research has shown that selective removal of cholinergic input to the hippocampus reduces mRNA expression for low-affinity glucocorticoid receptors, while leaving unaffected both mineralocorticoid receptor mRNA and basal levels of circulating corticosterone (CORT). The current study investigated the possibility that loss of cholinergic support from cells in the basal forebrain alters the CORT response to stress. Cholinergic lesions were made by microinjections of the immunotoxin 192 IgG-saporin into the medial septum/vertical limb of the diagonal band, and 3 weeks later rats were subjected to six daily sessions of 30 min restraint stress. Blood samples taken before, during and after stress on Day 1 revealed a prolonged elevation of CORT in response to acute stress in cholinergic lesioned rats. After 5 days of chronic stress, however, both groups significantly habituated to the stressor, as indicated by similarly low CORT profiles throughout both the response and recovery period. Against this similar background, rats were administered a Dexamethasone (DEX) challenge on Day 6, and DEX-induced suppression of endogenous CORT before, during and after stress was attenuated in lesioned rats. These results indicate a mechanism whereby loss of cholinergic function (e.g. in aging and Alzheimer’s Dementia) may compromise the dynamic range of sensitivity to glucocorticoid mediated stress pathways in the brain.

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

Ohara PT, Boudah A, Jasmin L (2002) Long-term effects on pain behavior of decreased spinal noradrenaline in neuropathic rats. Neuroscience 2002 Abstracts 351.22. Society for Neuroscience, Orlando, FL.

Summary: We sought to determine if a permanent reduction in the noradrenergic (NA) input to the spinal cord in adult rats would alter the pain behavior associated with nerve injury. Selective NA denervation of the lumbo-sacral cord was achieved by intrathecal injection of anti-dopamine beta-hydroxylase antibodies conjugated to the toxin saporin in 12 female rats. Spinal NA denervation was confirmed histologically in all animals. Saline injected rats served as controls. Two weeks after toxin or saline treatment, a unilateral peripheral neuropathy was induced by tight ligation of the left L5 spinal nerve in both groups. Unexpectedly, the same degree of mechanical hyperalgesia was present in the neuropathic paw of rats in both the toxin and saline treated groups. Rats lacking NA spinal afferents, however, were less responsive to the antinoiceptive effects of morphine administered systemically or intracerebroventricularly. Also, toxin treated rats did not display opioid dependant stress analgesia. Finally, toxin treated rats were more responsive to the antinociceptive effect of the NK1 antagonist CP 96,345 but not to its enantiomer CP 96,344. From these results we conclude that the permanent loss of spinal NA does not alter neuropathic pain behavior, possibly because of compensatory changes in the CNS. The decreased response to opioids is consistent with the previous suggestions of an interaction between noradrenergic and opioidergic systems in producing analgesia. The increased response to NK1 antagonists shows that NA tonically inhibits substance.

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

Yoder RM, Pang KCH (2002) Effects of gabaergic or cholinergic medial septal lesions on anxiety. Neuroscience 2002 Abstracts 378.1. Society for Neuroscience, Orlando, FL.

Summary: The hippocampus (HPC) is a structure important for spatial learning and memory. GABAergic and cholinergic neurons in the medial septal area (MSA) provide the two major projections to HPC. Complete destruction of HPC or MSA impairs spatial memory. MSA lesions have an anxiolytic effect, and rats with MSA damage appear be more exploratory. Spatial learning and memory may therefore be influenced by anxiety information reaching HPC through MSA. The present study assessed the effects of MSA GABAergic or cholinergic lesions on anxiety in the elevated plus maze and open-field task. Control rats received intraseptal saline; GABAergic lesions were induced by intraseptal domoic acid; cholinergic lesions were induced by intraseptal 192 IgG-saporin. An elevated plus maze was constructed with 2 open arms and 2 closed arms. Following habituation, each rat was placed in the center of the maze, then observed for 5 minutes. Time spent in the open vs. closed arms and number of entries into open vs. closed arms were compared between groups. The open-field task utilized a square arena with center and outer sections delineated on the floor. Following habituation, each rat was placed into the outer section, then observed for 5 minutes, during which the number of line crossings and amount of time spent in center vs. outer sections were calculated for comparison between groups. In both tasks, frequency of freezing, rearing, head dips, stretched-attend posture, grooming, and defecation was also compared between groups. Results of the present study may help elucidate the role of MSA in the effects of anxiety on learning and memory.

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

Wright KM, Yoder RM, Pang KCH (2002) Spatial strategies in rats with cholinergic or GABAergic lesions of the medial septum. Neuroscience 2002 Abstracts 378.2. Society for Neuroscience, Orlando, FL.

Summary: The major projection neurons of the septohippocampal (SH) system are GABAergic and cholinergic. When both populations of neurons are damaged together, deficits in learning and memory occur. However, when only one population is damaged, spatial memory in the water maze and radial arm maze is intact. The present study evaluated whether spatial strategies differed between rats with either GABAergic or cholinergic septal lesions. Domoic acid or 192 IgG saporin (sap) was injected into the medial septum (MS) to damage GABAergic or cholinergic neurons, respectively. Spatial strategies were examined on the plus maze and water maze. In the plus maze, rats were started from a single arm and trained to enter a goal arm containing both the reward and an intra-maze cue. Probe trials assessed whether the rats used place, response or cue strategies. During a probe trial, the starting location and the intra-maze cue were moved from that during training. In the water maze, animals were trained for 9 days in 3-day cycles. The first two days of the cycle used a visible platform and the third day of training was performed with a submerged platform. A single probe trial was conducted on day 10. On the probe trial, the first quadrant visited determined whether rats were using cue, place, or response strategies. Preliminary results show that rats treated with domoic acid use the place strategy on all probe trials in the plus maze, but do not use a consistent strategy in the water maze. Sap-treated animals also use mainly a place strategy. The results of this study may help determine the role of MS neurons in spatial strategy selection.

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

Butt AE, Hamilton DA, Duerkop MS, King DD, Gibbs RB, Sutherland RJ (2002) Spatial memory impairments in rats with 192 IgG-saporin lesions of the nucleus basalis magnocellularis. Neuroscience 2002 Abstracts 378.5. Society for Neuroscience, Orlando, FL.

Summary: In three experiments we test the hypothesis that the nucleus basalis magnocellularis (NBM) is involved in spatial learning and memory. Rats received 192 IgG-saporin lesions of the NBM or sham surgeries prior to testing in the Morris water maze task. In Exp. 1, rats were trained to find a hidden platform, receiving 4 trials per day. In Exp. 2, rats were trained with the hidden platform located in one position on the first 3 trials and in a second position on the 4th trial each day. In Exp. 3, rats were trained in a novel environment with the hidden platform located in a new position every 2 days. In Exp. 1, the NBM lesion group showed longer mean latencies to locate the platform than controls on the first several days of testing. Group differences were greatest on the earlier trials within the 4-trial blocks, with performance in the NBM lesion group recovering to control levels on later trials. In Exp. 2, performance in the NBM lesion group was again impaired, with greater group differences occurring on earlier trials within the 4-trial blocks. In Exp. 3, performance during the first block of trials for the different platform locations did not differ between groups, whereas performance on the 1st trial within the second block of trials was impaired in the NBM lesion group. Analysis of AChE staining and assay of ChAT activity confirm the selectivity of the lesions to the cortically-projecting neurons of the NBM and the sparing of cholinergic medial septal projections to hippocampus. Data suggest that NBM lesions interfere with consolidation of memory for spatial locations.

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

Mohapel P, Leanza G, Lindvall O (2002) Alterations in forebrain acetylcholine influence hippocampal neurogenesis in the adult rodent. Neuroscience 2002 Abstracts 23.9. Society for Neuroscience, Orlando, FL.

Summary: Little is known about how various experiential, environmental and pathological factors regulate neurogenesis in the adult hippocampus. Since the hippocampus receives abundant cholinergic innervation and contains some of the densest distributions of acetylcholine (ACh) fibers, we investigated its potential role in adult neurogenesis. Adult rats received multiple bromodeoxyuridine (BrdU) injections 3 weeks following lesions of the adult rodent forebrain cholinergic projections by intracerebroventricular infusions of 192 IgG-saporin. The day following BrdU administration we observed a significant 20% to 30 % decrease in proliferation in the subgranular cell layer of the dentate gyrus with ACh lesioning. This decrease persisted through to 4 weeks after BrdU administration, when most proliferated cells co-expressed neuronal markers. Conversely, in a separate experiment, naive rats receiving simultaneous injections of the ACh agonist physostigmine and BrdU demonstrated a 30 % increase in proliferated cells (1 day later) and neurons (4 weeks later) in the subgranular cell layer. Our data indicate that cholinergic mechanisms in the forebrain are involved in the regulation of neurogenesis and that this effect may be indirect or direct in the hippocampus.

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