sfn1999

Butt AE, Bowman TD, Novotnev JS, Rogers JL, Tanabi A (1999) Selective lesions of the nucleus basalis magnocellularis in rats do not affect simple association learning. Neuroscience 1999 Abstracts 559.4. Society for Neuroscience, Miami, FL.

Summary: We have previously argued that damage to the cholinergic nucleus basalis magnocellularis (NBM) selectively impairs complex or configural association learning while sparing simple association learning (Butt & Hodge, 1997; Butt et al., 1998, Soc. Neurosci. Abst.). However, contrary to our hypothesis, in an earlier study using the less selective neurotoxin quisqualic acid, we found that simple association learning was moderately impaired in NBM-lesioned rats (see Butt & Hodge, 1997). It remained unclear whether the observed behavioral impairment in that study was due to loss of cholinergic input to neocortex or was instead due to non-specific damage to other brain structures. In the current study, therefore, we used the highly selective immunotoxin Ig-G saporin to create bilateral lesions of the NBM in male Long-Evans rats (350 g) and then tested these rats in a simple association learning paradigm. NBM lesioned rats (n = 4) and sham-operated rats (n = 6) underwent 20 consecutive days of training in a simple operant discrimination between a food-reinforced tone (T+) and a non- reinforced light (L-). Results showed that performance in NBM-lesioned rats was normal in all respects; both groups acquired the task, committing progressively greater numbers of successful responses to T+ and progressively fewer responses to L-, as well as diminishing the number of (non-reinforced) responses committed during the inter-trial interval. The hypothesis that NBM lesions spare simple association learning was thus supported. Despite the absence of impairment in this simple association task, we maintain that the NBM is involved in complex or configural association learning as demonstrated in separate experiments (see Butt et al., 1998, Soc. Neurosci. Abst.). (Supported by a University Research Committee Grant awarded to A. E. Butt by the Indiana State University Office of Sponsored Programs).

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

Wrenn CC, Lappi DA, Wiley RG (1999) Lack of effect of intraventricular OX7-saporin on working memory in the rat. Neuroscience 1999 Abstracts 559.5. Society for Neuroscience, Miami, FL.

Summary: The immunotoxin 192 IgG-saporin (192-sap) has been shown by our laboratory and others to be a highly selective agent for the production of lesions of the rat cholinergic basal forebrain(CBF). Such lesions can be produced by either intraventricular (i.c.v.) or intraparenchymal injection of the immunotoxin and can result in cognitive deficits. One potential shortcoming of i.c.v. injection of 192-sap is that it kills cerebellar Purkinje cells in addition to killing the neurons of the CBF. Thus, it is unclear whether or not cognitive deficits that arise after i.c.v. 192-sap are due to loss of the CBF or loss of Purkinje cells. We addressed this problem by injecting rats i.c.v. with saline, 2 µg 192-sap, 4 µg 192-sap, or 1 µg OX7-saporin(OX7-sap). OX7-sap is an immunotoxin shown by our laboratory to selectively lesion Purkinje cells after i.c.v. injection. The 1 µg dose was chosen based on pilot anatomical work which showed this dose to produce Purkinje cell loss of similar pattern and extent to that produced by 4 µg of 192-sap. These rats were tested in a radial maze working memory paradigm, and it was found that the 4 µg 192-sap group made significantly more working memory errors than either the saline or OX7-sap injected groups. These data suggest that Purkinje cell loss alone is not sufficient to disrupt cognitive processes. (Supported by Departmento f Veterans Affairs and the Vanderbilt Center for Molecular Neuroscience).

Related Products: 192-IgG-SAP (Cat. #IT-01), OX7-SAP (Cat. #IT-02)

Wiley RG, Lappi DA, Vierck CJ (1999) Inhibition of mustard oil-induced thermal hyperalgesia in an operant escape task by substance P-saporin. Neuroscience 1999 Abstracts 271.1. Society for Neuroscience, Miami, FL.

Summary: Substance P (SP) armed with the ribosome inactivating protein, saporin (SAP), selectively destroys neurons expressing the NK-1 receptor, attenuates withdrawal responses after capsaicin injection, after a Chung lesion or CFA and blocks phase 2 of the formalin test. These tests rely on innate “reflex” behaviors (withdrawal or licking) and the primary effects were to mechanical stimuli. In the present study, we sought to determine the effects of lumbar i.t. SP-SAP on reflexes and operant escape responses to thermal stimuli. Rats received lumbar i.t. injections of 175 ng SP-SAP (N=7), 25 ng of [Sar8MetOH11]-SP-SAP (N=8) or PBS with 1 mg/ml BSA (N=8). Nine rats served as naive controls. After recovery from surgery, all rats were adapted to thermal reflex testing and separately trained to escape to a brightly lit room temperature shelf from a dark surface at 47°C, 44°C and 0.3°C. There were no differences between groups at baseline on the escape task or reflex tests at any of the 3 temperatures. When tested at 44°C 3 hours after application of mustard oil to the dorsal surface of both hindpaws, controls spent significantly more time on the escape shelf whereas SP-SAP treated rats did not. In contrast, when tested 3 hrs after mustard oil at 44°C, all rats showed similar reflex responses with decreased latency to licking, more licking and guarding. These results indicate that the SP-SAP lesion of lamina I neurons expressing NK-1 receptor in the spinal dorsal horn prevents enhanced operant escape behavior, but not enhanced reflex responses. That is, the aversive quality of mustard oil-induced thermal hyperalgesia was blocked without interfering with nocifensive reflexes. Also, the anti-hyperalgesia effects ofl umbar intrathecal SP-sap include thermal hyperalgesia. This approach may prove valuable in the treatment of chronic, intractable pain. (This work supported by the NIH and the Department of Veterans Affairs).

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

Vulchanova L, Stone LS, Olson T, Riedl MS, Elde R, Honda CN (1999) Depletion of IB4-binding sensory neurons results in elevated nociceptive thresholds. Neuroscience 1999 Abstracts 272.8. Society for Neuroscience, Miami, FL.

Summary: The lectin IB4 binds to and is specifically taken up by a subset of small sensory neurons, proposed to play a role in nociception. To examine the role of these neurons in sensory transmission we used a conjugate of IB4 and the toxin saporin (IB4-sap). IB4-sap (2 µg/5 µl) was injected in the left sciatic nerve of rats. Three days after the injection, the conjugate was visualized in the left L4 and L5 DRG using antisera to either the lectin or saporin. The cells labeled by these antisera were not stained by the Nissl-like marker ethidium bromide, suggesting disruption of their protein synthesis. Twenty one days after the injection there was a 36% reduction in the total number of neurons and a 50% reduction in IB4-binding neurons in L5 DRG of IB4-sap injected rats. Moreover, in dorsal horn of spinal cord, the projection site of the left sciatic nerve was devoid of IB4 binding. P2X3 immunostaining was also dramatically reduced, while the decrease in staining for SP, CGRP and VR1 was less pronounced. The responsiveness of the IB4-sap treated rats to noxious thermal and mechanical stimuli was examined using radiant heat and von Frey filaments, respectively. There was a significant increase in the withdrawal latency to thermal stimuli at day 10 and the withdrawal threshold to mechanical stimuli at day 14 post-treatment. By day 21 both the thermal and mechanical thresholds returned to baseline levels. We have shown that depletion of IB4-binding sensory neurons results in transient elevation of nociceptive thresholds. These findings suggest that IB4-binding neurons mediate the signaling of noxious stimuli and that an efficient compensatory mechanism appears to be activated within days of their loss. Supported by NIH grants DA09641 and DE07288.

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

Gu Z, Toliver-Kinsky T, Glasgow J, Cain L, Perez-Polo JR (1999) NGF-mediated alteration of NF-κB binding activity after partial immuno-lesions to rat cholinergic basal forebrain neurons. Neuroscience 1999 Abstracts 300.15. Society for Neuroscience, Miami, FL.

Summary: Memory loss and cognitive deficits in die aged and in patients with Alzheimer’s disease (AD) are often associated with cholinergic deficits within the NGF-dependent cholinergic basal forebrain neurons (CBFNs) that project to the cortex, hippocampus, and olfactory bulb. Although the causes of these cholinergic deficits are not fully understood, the increases in activity of the transcription factor NF-κB in the brains from aged and AD patient may reflect chronic transcription enhancement of stress response genes that affect cholinergic expression and neuronal death. In order to ascertain whether endogenous NGF effects on ChAT and NF-κB may account for recovery from stress, a partial immunolesion (PIL) to CBFNs, which is produced by the injection of 192 IgG-saporin, an immunotoxin selectively taken up by low-affinity NGF receptor p75NTR-bearing neurons, was conducted and followed by infusion of anti-NGF. Both PIL and anti-NGF treatment decreased ChAT activity in cortex, hippocampus, and olfactory bulb. NGF protein levels increased significantly in the olfactory bulb, but not the cortex or hippocampus after PIL treatment. Infusion of anti-NGF abolished the PIL-induced NGF increases in cerebrospinal fluid. We also found that NF-κB binding activity to both the κ light chain enhancer and the ChAT promoter specific consensus sequence increased in PIL-induced cortex but not hippocampus after anti-NGF infusion as measured by electrophoretic mobility shift assays (EMSAs). This is consistent with the hypothesis that NF-κB contributes as a repressor to the transcriptional regulation of ChAT by NGF. Taken together with reports of increased levels of NF-κB activity in brains of aged rats and of AD patients, it is likely that NGF-mediated changes in NF-κB activity in part reflect responses to age-associated cholinergic deficits. (Supported in part by NINDS Grant NS 33288)

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

Stowell JR, Bemtson GG, Sarter M (1999) Lesions of basal forebrain cholinergic neurons eliminate the modulatory effects of benzodiazepine receptor ligands on behavioral and cardiovascular reactions in an anxiogenic paradigm. Neuroscience 1999 Abstracts 358.5. Society for Neuroscience, Miami, FL.

Summary: We have previously shown that basal forebrain cortical cholinergic projections mediate potentiation of the cardiovascular defensive response by the putative anxiogenic benzodiazepine receptor partial inverse agonist FG 7142 (Bertnson et al., 1998). The present study assessed the effects of lesions of the basal forebrain cholinergic neurons on operant responding in a conditioned suppression paradigm and the modulating effects of benzodiazepine receptor (BZR) ligands in this paradigm. Nine animals received basal forebrain infusions (0.18 µg/hemisphere) of the immunotoxin 192 IgG-saporin. Lesioned and control (n=9) animals were trained in a conditioned suppression paradigm using a tone for the conditioned stimulus (CS) and a rear panel light for a contextual cue. FG 7142 (8 mg/kg), chlordiazepoxide (CDP, 8 mg/kg), and vehicle were administered i.p. in subsequent extinction sessions. In control animals, operant responding was suppressed during presentation of the CS and contextual cue. The BZR partial inverse agonist FG 7142 exaggerated this suppression,while CDP attenuated it. Lesioned animals were less suppressed than controls across stimulus conditions, with the largest difference between groups observed during presentation of the contextual cue. Presentation of the contextual cue was also associated with a cardioacceleratory response in control animals, and this response was significantly attenuated in lesioned animals. Furthermore, the modulatory effects of BZR ligands on behavioral and autonomic reactions observed in control animals were eliminated in lesioned animals. These data support an important role for cholinergic basal forebrain neurons in the behavioral and autonomic response to anxiety. Funded by HL54428.

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