sfn2009

Rennie KE, Ward C, Fréchette M, Pappas BA (2009) Effects of combined neonatal cholinergic lesion and chronic cerebral hypoperfusion on CA1 cytoarchitecture. Neuroscience 2009 Abstracts 736.23/M38. Society for Neuroscience, Chicago, IL.

Summary: Neonatal lesioning of the basal forebrain cholinergic (BFC) system alters cytoarchitecture of pyramidal cells in both the hippocampus and neocortex of the adult rat, indicating a role for the BFC in forebrain development. In addition to altering forebrain development, neonatal cholinergic lesion may also exacerbate the brain’s response to pathological factors that emerge as the brain ages. One factor that might interact with BFC lesion is reduced cerebral blood flow (hypoperfusion). Examining this interaction is especially interesting because both BFC degeneration and reduced cerebral blood flow are characteristics of Alzheimer’s disease. In the rat, chronic cerebrovascular insufficiency by itself reportedly causes the degeneration of hippocampal CA1 pyramidal cells, alters amyloid processing and produces spatial memory impairments. We hypothesized that neonatal cholinergic lesion using the cholinotoxin 192-IgG-saporin would render the hippocampus more vulnerable to the neuropathological effects of chronic forebrain hypoperfusion induced by permanent bilateral occlusion of the carotid arteries (2VO). We previously reported that combined BFC lesion and 2VO impaired working memory in the Morris water maze and increased anxiety-like behaviours on the elevated plus apparatus, whereas neither of these treatments alone caused any of these effects. Here we report the effects of neonatal BFC lesion, 2VO, or their combined application on hippocampal CA1 cytoarchitecture using quantitative Golgi analysis. Rats subjected to 2VO showed increased apical branch length and spines, and increased basal spines. Neonatal BFC lesion on its own had only restricted effects on apical branch length at certain branch orders and no effect on spines. However, at a number of branch orders the stimulating effect of 2VO on apical spines occurred only in animals subjected to neonatal BFC lesion, indicating that this lesion modulated the response to 2VO. To our knowledge, this is the first examination of the effects of 2VO on CA1 neuron cytoarchitecture. Surprisingly, it increased rather than decreased dendritic length and spines. Furthermore, while the BFC lesion had minimal effects on its own, it was permissive to some of the effects of 2VO on dendritic spines. Taken together with our previous data, this study suggests that pre-existing cholinergic dysfunction alters aspects of both the behavioural and neural consequences of chronic hypoperfusion. These results may have implications for Alzheimer’s disease where cholinergic dysfunction and hypoperfusion are co-expressed

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

Coons KD, Munoz F, Osborne MC, Sengelaub DR (2009) Dendritic atrophy following partial motoneuron depletion: Time course of recovery and protection with androgens and estrogens. Neuroscience 2009 Abstracts 743.2/R17. Society for Neuroscience, Chicago, IL.

Summary: We have previously demonstrated that partial depletion of motoneurons innervating the quadriceps muscles induces dendritic atrophy and loss of function in remaining motoneurons. Furthermore, treatment with testosterone is neuroprotective, and dendritic atrophy and loss of function following partial motoneuron depletion are attenuated in a dose-dependent fashion, and in both male and female rats. In the present study, we assessed dendritic atrophy after partial motoneuron depletion at a variety of time points to determine its time course and pattern with and without testosterone treatment. We also examined the potential neuroprotective effects of the androgenic and estrogenic metabolites of testosterone. Motoneurons innervating the vastus medialis muscle were selectively killed by intramuscular injection of cholera toxin-conjugated saporin. Simultaneously, saporin-injected males were given implants containing either testosterone (45mm), dihydrotestosterone (30mm), estradiol (10%, 10mm), or left untreated. At 2, 4, 6, or 10 weeks after partial motoneuron depletion, motoneurons innervating the ipsilateral vastus lateralis muscle were labeled with cholera toxin-conjugated HRP, and dendritic arbors were reconstructed in 3 dimensions. Animals treated with dihydrotestosterone or estradiol were assessed only at 4 weeks post depletion. Dendritic arbors were also assessed in a group of untreated normal males. Quadriceps motoneuron dendrites underwent a rapid atrophy and protracted recovery following partial motoneuron depletion. Dendritic atrophy in remaining quadriceps motoneurons was apparent at 2 weeks after motoneuron depletion, with a decrease of over 50% in dendritic length, and this atrophy remained through 6 weeks post-depletion; dendritic length recovered by 10 weeks post-depletion. Treatment with testosterone attenuated induced dendritic atrophy at all time points, and recovery to normal lengths was present at 6 weeks post-depletion. Treatment with dihydrotestosterone or estradiol was as effective as testosterone in attenuating dendritic atrophy in remaining quadriceps motoneurons. These results suggest that treatment with testosterone is neuroprotective, both attenuating induced dendritic atrophy and accelerating recovery. Furthermore, this effect can be achieved with both androgenic and estrogenic metabolites, further supporting a role for hormones as neurotherapeutic agents in the injured nervous system.

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

Savage ST, Lundströmer K, Olson L, Mattsson A (2009) Alterations in dopaminergic and glutamatergic systems following cortical cholinergic denervation. Neuroscience 2009 Abstracts 839.14/M21. Society for Neuroscience, Chicago, IL.

Summary: Alterations in cholinergic signaling in the brain have been implicated as a contributing factor in the pathogenesis of schizophrenia. We have previously shown that cholinergic denervation of cortex cerebri by stereotaxic infusion of the immunotoxin 192 IgG-saporin in the nucleus basalis magnocellularis (nbm) in adult rats leads to an enhanced sensitivity to both amphetamine and the NMDA receptor antagonist phencyclidine (PCP). The enhanced sensitivity to amphetamine shown as a potentiated dopamine release in nucleus accumbens, along with a marked increase in locomotor activity in response to both amphetamine and PCP, suggested that the disruption of cortical cholinergic activity can lead to disturbances of glutamatergic and dopaminergic transmission. To further evaluate the consequences of cortical cholinergic denervation on the dopamine and glutamate systems, we are conducting an in depth in situ hybridization and immunohistochemistry analysis of nbm 192 IgG-saporin lesioned rats. Preliminary data from these investigations show an enhancement of expression levels of TH and DAT mRNA in the VTA and substantia nigra of the cholinergically denervated rats. The data suggests that cortical levels of NMDAR1 mRNA are not altered in the lesioned animals. However, preliminary data indicate that the induction of c-fos mRNA expression in cortex following PCP administration is reduced in denervated animals as compared to sham lesioned controls. These data may suggest hypofunction of NMDA receptors as a consequence of loss of cholinergic innervations. To evaluate the behavioral consequences of cortical cholinergic denervation, we are employing three behavioral paradigms (Locomotor and Rearing behavior, Social Interaction, and the Novel Object Recognition (NOR) task) under normal and drug challenged conditions. Preliminary social interaction studies have found that the saporin lesioned rats spend a significantly less amount of time interacting with each other as compared to control sham operated rats. We are currently investigating how this impairment is effected under drug challenge. Furthermore, we have found that the degree of lesion affects the performance to the novel object recognition task under saline and drug challenged conditions. Our results from the in situ hybridization and behavioral studies indicate that the loss of cortical acetylcholine can lead to alterations in glutamatergic and dopaminergic signaling. These observations are compatible with a possible role of cholinergic deficits in schizophrenia, and provide a possible link between different hypotheses of the disorder.

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

Chatterjee K, Kline IV RH, Wiley RG (2009) Role of brainstem noradrenergic neurons in modulation of operant nocifensive responses to heat: Pharmacology and hyperalgesia. Neuroscience 2009 Abstracts 855.10/X15. Society for Neuroscience, Chicago, IL.

Summary: Many spinal dorsal horn neurons are under direct modulation from various brainstem nuclei which act to modulate nociceptive activity. Nocifensive reflex response modulation by spinally projecting noradrenergic brainstem nuclei has been extensively categorized. Strong evidence supports a role for these neurons in the modulation of reflex nocifensive responses but the role of noradrenergic neurons in the cerebral component of nociception remains to be defined in rats. In the present study, we sought to determine the effects of selectively destroying noradrenergic rostral brainstem neurons (A5,A6,A7) on operant escape from 44°C floor heat under several conditions: 1-baseline (after i.c.v. toxin/vehicle injection), 2- after s.c. injection of morphine, clonidine or yohimbine, 3- three hours after bilateral dorsal hindpaw application of mustard oil (secondary hyperalgesia), and 3- three hours after bilateral plantar application of 0.9% capsaicin cream (primary hyperalgesia). Rats were tested daily until steady operant escape responding (~1 month), then injected i.c.v. with 10µl of PBS (vehicle control, n=8) or antiDBH-saporin (10µg, n=8). After recovery from toxin injection, escape responses decreased in the antiDBH-sap rats. Morphine (0, 0.5, 1.0, 2.0 mg/kg s.c.) 20 min prior to testing, dose dependently attenuated escape from the noxious thermal plate at 44oC for all treatment groups. antiDBH-sap treated rats, however, showed an enhanced morphine effect (more prolonged occupancy of the noxious thermal plate). Three hours after plantar capsaicin, or mustard oil to the dorsal surface of both hindpaws, PBS but not antiDBH-sap rats showed enhanced escape. Systemic clonidine (0.125mg/kg) decreased escape for both PBS and antiDBH-sap treated rats, but the anti-nociceptive effect was greater in antiDBH-sap rats. Systemic yohimbine (1.0, 2.5, 5.0mg/kg) had no effect on escape in antiDBH-sap rats but enhanced escape in PBS rats. In direct contrast to effects on escape responding, antiDBH-sap did not affect hotplate lick/guard initial latencies to nociceptive heat at 44° or 47oC. Escape responses to aversively bright light were also decreased in antiDBH-sap rats suggesting generally decreased responsiveness to aversive stimuli. These results support a significant role for rostral brainstem noradrenergic neurons in modulation of pain and highlight important differences between reflex nocifensive responses (hotplate) and operant (escape) responses.

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

Bukowski RK, Duffy TE, Ryu V, Covasa M, Czaja K, Ritter RC (2009) Attenuated CCK-induced satiation and increased weight gain following destruction of abdominal vagal afferents by intravagal OX7-saporin conjugate. Neuroscience 2009 Abstracts 870.5/DD2. Society for Neuroscience, Chicago, IL.

Summary: Bilateral subdiaphragmatic vagotomy attenuates reduction of food intake by cholecystokinin (CCK) and other GI satiation signals. However, abdominal vagotomy also is associated with mild to moderate reductions of food intake and body weight gain. These sequels of vagotomy may be due to surgical trauma, gastroesphageal dysmotility or, perhaps, hypersensitivity of residual or regenerating afferent vagal fibers and terminals. In an attempt to selectively destroy the abdominal vagal afferents and their cell bodies, we injected the abdominal vagal trunks with OX7-saporin (OX7), a conjugate of the ribosomal toxin, saporin, and a monoclonal antibody against Thy1. This conjugate has been shown to destroy vagal afferent cell bodies in the ipsilateral nodose ganglion following unilateral injection into a cervical vagal trunk. In our study rats received an IP injection of fast blue (FB) which retrogradely labeled cell bodies of abdominal vagal afferents, enabling us to verify their destruction. OX7 was injected into both dorsal and ventral abdominal vagal trunks using a picospritzer and capillary pipettes. Beginning two weeks after OX7, the rats were tested for reduction of food intake by IP injection of CCK-8 (4ug/kg). Subsequently, nodose ganglia from the treated rats and their controls were examined to determine the number of FB-labeled nodose neurons remaining in the ganglia. Successful destruction of nodose neurons varied between animals. However, in OX7-treated rats the number of FB-labeled nodose neurons was reduced by approximately 60%, compared to vehicle injected controls. While CCK injection significantly reduced food intake in control rats, CCK-induced reduction of intake by the OX7 treated group was significantly attenuated. Interestingly, the OX7-treated rats did not exhibit the chronically reduced body weight that is typical of surgically vagotomized rats. In fact OX7 rats actually gained more weight than control rats over the 30 period following vagal injections. Our data indicate that immunotoxic destruction of the abdominal vagal innervation mimics surgical vagotomy in its attenuation of CCK-induced satiation, but does not cause sustained reduction of body weight.

Related Products: OX7-SAP (Cat. #IT-02)

Botly LC, De Rosa E (2009) Using visual search to examine cholinergic contributions to feature binding in the rat. Neuroscience 2009 Abstracts 873.26/EE13. Society for Neuroscience, Chicago, IL.

Summary: According to the feature integration theory of attention, feature binding is an attention-dependent process whereby the different features of an object are simultaneously integrated to form a unified whole. Using a rat digging paradigm that was faithful to this theory of attention, we have previously demonstrated that acetylcholine is critical to the attention-dependent processes required for both crossmodal and intramodal feature binding. Moreover, we demonstrated that cholinergic cells in brain regions that have been implicated in human feature binding, specifically frontal and parietal cortices, supported feature binding in rats. We have now translated the gold-standard test of human feature binding, visual search (VS), for rats. In the present study, sixteen male Long-Evans rats were trained to perform VS using touchscreen-equipped operant chambers and black-and-white shapes. Testing sessions comprised Feature-Search (no feature binding required) and Conjunctive-Search (feature binding required) trials using set sizes of four, six, and eight stimuli. Following acquisition of the VS task, eight rats received bilateral 192 IgG-Saporin immunotoxic lesions of the nucleus basalis magnocellularis (NBM) of the basal forebrain to reduce cholinergic afferentation of the neocortex. Importantly, there was no significant effect of lesion on accuracy for selecting the target stimulus. As expected, relative to sham-lesioned rats, NBM-lesioned rats took significantly longer to locate the target stimulus on Conjunctive-Search but not Feature-Search trials; thus reflecting a less efficient VS. These data confirm that cholinergic contributions from the NBM support feature binding using a rat analog of the VS paradigm.

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

Carter ES, Newman LA, Mcgaughy J (2009) Effect of aging and prefrontal cholinergic deafferentation on working memory for familiar and novel odors. Neuroscience 2009 Abstracts 879.14/EE124. Society for Neuroscience, Chicago, IL.

Summary: Aging is associated with cholinergic fiber loss in the entorhinal cortex (EC). Previous research has shown that acetylcholine (ACh) in this region mediates memory for novel information (Schon et al., 2005), and cholinergic lesions of the EC in young rats impair memory for novel, but not familiar, stimuli at an odor delayed non-match to sample task (DNMS; McGaughy et al., 2005). Currently, we tested whether age-related cholinergic fiber loss in the medial EC of male rats would be sufficient to produce impairments in memory for novel information during the DNMS task. Half of the aged animals were subjected to cholinergic depletion of medial, prefrontal cortex (pACh-lx) including both prelimbic and anterior cingulate cortex prior to the onset of testing. We hypothesized that this previous damage would result in impairments in memory for familiar items and would prevent improvements in memory shown after repeated exposure to novel items. Additionally the effects of increasing the delay between sample and choice portions of the test and memory for list of items were assessed. The pACh-lx animals were not impaired relative to sham-lx animals at memory for familiar information when there was a minimal delay between the sample and choice. However if a 15 minute delay was introduced between the sample and choice phase, pACh-lx rats performed more poorly than sham-lx rats. This suggests that ACh in the medial, prefrontal cortex is necessary for maintaining representations of familiar stimuli over a delay period. Aged rats showed accuracy impairments during sessions that required encoding of novel samples relative to their own performance at sessions requiring encoding of familiar samples. This impairment was greater on trials that required rats to discriminate the novel sample from a familiar non-match than on trials where all stimuli were novel. Though the extent of cholinergic fiber loss in EC due to aging was highly similar to that produced by infusion of the 192 IgG saporin to the EC of young rats, the severity of the cognitive impairments due to aging was not as great as that produced by lesioning. These data suggest that impact of damage to the cholinergic fibers of EC may vary based on whether the deterioration is gradual or has an acute onset.

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

Bailey AM, Enos J, Medley V (2009) Damage to nucleus basalis magnocellularis (nBM) cholinergic target areas produce different effects on the acquisition of learning set. Neuroscience 2009 Abstracts 879.15/EE125. Society for Neuroscience, Chicago, IL.

Summary: Lesions to the nucleus basalis magnocellularis (nBM) using either quisqualic acid or 192 IgG-saporin produce differing effects on the acquisition of learning set. Specifically, quisqualic acid lesions produce severe and long lasting impairments but 192 IgG-saporin lesions produce transient effects on learning set acquisition. One possible explanation for acquisition differences involves altered neuronal activity in the cholinergic target areas of the nBM. We examined two main cholinergic targets of the nBM, namely the amygdala and the prefrontal cortex (PFC). Rats with either NMDA (20 µg/µl) lesions to the basolateral amygdala (n=10) or NMDA (20 µg/µl) lesions to the anterior cingulate PFC (n=6) were tested on an olfactory learning set formation task as well as operant delayed non-matching to-position (DNMTP) and open field activity. The rats with amygdala lesions were additionally tested on a fear conditioning task. Lesions to the PFC significantly impaired acquisition of learning set as measured by chance performance on Trial 2 (M = 56.17%, SD = 7.47). Rats with PFC lesions did not differ from sham animals on the DNMTP task (p > .05) or in activity counts in an open field (p > .05). However, rats with NMDA lesions to the amygdala were significantly higher than chance (50% correct) on Trial 2 (p .05) or percentage correct on the DNMTP task (p > .05). NMDA lesions to the amygdala did, however, significantly decrease time spent freezing to an aversive CS+ in the fear conditioning task (p < .05). In total, the results imply that learning set acquisition differences following either quisqualic acid or 192 IgG-saporin lesions to the nBM are not likely due to damage to the cholinergic projection to the amygdala but may be associated with altered PFC activity.

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

Hernandez MA, Pineda JB, Del Valle-Mondragón L, Alcaraz-Zubeldia M, Ríos C, Pérez-Severiano F (2009) Evaluation of the effect of molsidomine on nitregic system in an experimental model of cognitive impairment. Neuroscience 2009 Abstracts 529.24/J10. Society for Neuroscience, Chicago, IL.

Summary: The relationship between nitric oxide (NO) and cholinergic system in brain has been evidenced by using inhibitors of the nitric oxide synthase (NOS) that blocked cognition, while NO donors can facilitate it. Nevertheless, the participation of NO in the recovery of cholinergic deficit due to the administration of a selective cholinergic immunotoxin, 192 IgG saporin (SAP) has not been studied. The aim in this work was to evaluate the modulation of the nitrergic system after the damage induced by SAP and to measure the response to the administration of a NO donor, molsidomine (MOL). We used adult male Wistar rats allocated into either one of 4 groups: 1) vehicle PBS, 0.1M pH 7.4, 2) intraseptal administration of SAP (0.22 µg), 3) MOL ip 4 mg/kg, 4) SAP+MOL. Striatum, prefrontal cortex and hippocampus were dissected out at different times after treatment and quantification of nitrites, NOS activity and expression were performed. Our results show that SAP induces a reduction on the constitutive NOS activity in prefrontal cortex and striatum (54%, 64% respectively compared with control p<0.05); while hippocampal cNOS tended to decrease. MOL alone improved NOS activity in those regions. Neuronal and endothelial NOS expression (nNOS, eNOS) in the same regions did not change significantly. When the nitrites levels were analyzed, changes were region-specific. We conclude that administration of the NO donor promotes the recovery of cNOS activity in the model of cholinergic denervation associated to 192 IgG SAP. Further cognitive studies are being carried out in order to demonstrate the cholinergic recovery by MOL.

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

Thomsen MS, Hay-Schmidt A, Hansen HH, Mikkelsen JD (2009) Poster: Distinct neural pathways mediate alpha7 nicotinic acetylcholine receptor-dependent activation of the forebrain. Neuroscience 2009 Abstracts 646.2/V14. Society for Neuroscience, Chicago, IL.

Summary: α7 nicotinic acetylcholine receptor (nAChR) agonists are novel drugs candidates for the treatment of cognitive deficits in schizophrenia, which have shown pro-cognitive effects in clinical trials. Selective α7 nAChR agonists, such as SSR180711, activate neurons in the medial prefrontal cortex (mPFC) and shell of the nucleus accumbens (ACCshell) in rats, regions which are important for cognitive function. However, the neural substrates involved in these effects remain elusive. Using retrograde tracing from the mPFC with Cholera Toxin B and immunoreactivity of the immediate-early gene c-Fos, a marker of neuronal activation, we identify the horizontal limb of the diagonal band of broca (HDB) in the basal forebrain as an important site of α7 nAChR activation. Approximately 26% of the cortically projecting neurons in the HDB are activated by acute administration of SSR180711 (10 mg/kg), and the neurons activated by SSR180711 in the HDB are cholinergic. Selective depletion of these cholinergic neurons with 192 IgG-Saporin abolishes the SSR180711-induced activation of the mPFC, but not the ACCshell, demonstrating their critical importance for α7 nAChR-dependent activation of the mPFC. Contrarily, selective depletion of dopaminergic neurons in the ventral tegmental area (VTA) with 6-OHDA abolishes the SSR180711-induced activation of the ACCshell, but not the mPFC or HDB. These results indicate that two distinct neural pathways are activated by SSR180711, involving HDB-to-mPFC and VTA-to-ACCshell projections, respectively. The basal forebrain and mPFC are important for attentional function, and may subserve the pro-cognitive effects of α7 nAChR agonists, whereas activation of the ACCshell is implicated in beneficial effects on the positive symptoms of schizophrenia.

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