sfn2015

Jones JL, Pitchers KK, Robinson TE, Sarter M (2015) Basal forebrain cholinergic lesions attenuate the reinstatement of cocaine-seeking produced by a discriminative stimulus in goal-trackers but not sign-trackers. Neuroscience 2015 Abstracts 411.15/L-15. Society for Neuroscience, Chicago IL.

Summary: Goal-trackers (GTs), compared to sign-trackers (STs), express higher levels of acetylcholine when performing a cue detection and processing task. We hypothesized, therefore, that GTs utilize their basal forebrain cholinergic systems differently and to a greater extent than STs, such that this system may be critical for signal-induced behavior in GTs but not STs. The purpose of this experiment was to investigate individual variation in the reinstatement of drug-seeking behavior produced by a signal indicating cocaine availability (a discriminative stimulus), as well as the influence of the basal forebrain cholinergic system. STs and GTs were trained to self-administer cocaine using an intermittent access (IntA) procedure. The IntA procedure involved allowing animals access to cocaine for discrete 5-min drug available periods indicated by a light signal (DS+) separated by 25-min no drug available periods indicated by a different signal (DS-) in a different location than the DS+. This procedure results in ‘spiking’ brain levels of cocaine. Once stable performance was achieved on this procedure, animals underwent extinction training where the context remained similar to the IntA procedure but was now devoid of both DSs and an active response no longer had any consequence. STs and GTs did not differ in the acquisition or expression of self-administration or extinction training. After behavior was stably extinguished, half of the subjects received bilateral infusions of the cholinotoxic immunotoxin 192 IgG-saporin into the basal forebrain, while the other half received sham surgeries. Animals underwent 5 days of re-extinction. Finally, they underwent a reinstatement test during which the DS+ was presented non-contingently for 2 sec on a variable time schedule. Current results show that the ST-lesion group and both sham groups reinstated responding upon exposure to the DS+, compared to the last day of extinction. In contrast, the GT-lesion group did not reinstate responding, relative to the last day of extinction and, additionally, showed fewer active responses during the reinstatement test than the GT-sham group. Our findings suggest that the basal forebrain cholinergic system is involved in the reinstatement of drug-seeking behavior produced by a signal indicating drug availability in some animals (GTs), but not others (STs), further supporting the notion that drug cues are processed very differently in STs and GTs.

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

Wiley RG (2015) Nociceptive effects of neurotensin(NTS)- and somatostatin(SST)-toxin conjugates applied to the lumbar dorsal horn in rats. Neuroscience 2015 Abstracts 418.11/O12. Society for Neuroscience, Chicago IL.

Summary: Intrathecal injections of NTS or SST have been reported to be anti-nociceptive, and in the case of SST, analgesic in humans. Preliminary experiments in our lab previously showed that lumbar intrathecal injection of the excitatory neuropeptide, NTS, or the inhibitory neuropeptide, SST, conjugated to the ribosome inactivating protein, saporin (sap), produced compulsive scratching/biting of hindquarters resulting in loss of fur and skin. This was thought likely due to pain and/or itching from selective loss of superficial dorsal horn nociceptive inhibitory interneurons expressing NTS receptors. Subsequent experiments using lumbar intrathecal injections of NTS-cholera toxin A chain conjugate resulted in prolonged anti-nociception on hotplate, tail flick and von Frey testing, that was not reversed by naloxone and lasted several days, likely due to sustained activation of the same neurons. The present study sought to determine if the lesions produced by NTS-sap or SST-sap alter nociceptive responses. In the present study, rats, under isoflurane anesthesia, were injected intrathecally using temporarily-placed subarachnoid catheters over the lumbar enlargement with 10 ul of sterile preservative-free normal saline containing either 300-400 ng of NTS-sap, 1 ug of SST-sap or 1 ug blank-sap (control) from Advanced Targeting Systems, San Diego, CA. Catheters were flushed with an additional 10 ul of saline. After post-surgical recovery, the rats were then observed for scratching/biting their hindquarters, nocifensive responses on the hotplate, von Frey mechanical probing of the hindpaws, and on operant thermal escape. 4 of 11 NTS-saporin rats and 5 of 9 SST-saporin rats, but none of 9 blank-saporin rats began scratching within 8-47 days after toxin conjugate injection. Hotplate nocifensive reflex testing at 44.5°C and 47°C showed no significant difference between the groups. Von Frey, operant thermal escape testing and anatomic studies are in progress to further specify the functional effects of the toxin conjugate injections and to identify the dorsal horn neurons being destroyed. The results to date are interpreted as consistent with a possibly unique role for NTS and/or SST receptor-expressing superficial dorsal horn inhibitory interneurons in nociception and/or itch. Excitatory/activating moieties such as cholera toxin A subunit targeted by conjugation to NTS or SST may offer a novel approach to enhance inhibition in nociceptive dorsal horn neurons and to produce analgesia by a non-opioid mechanism.

Related Products: Neurotensin-CTA (Cat. #IT-60), Neurotensin-SAP (Cat. #IT-56), Blank-SAP (Cat. #IT-21), Custom Conjugates

Zoccal DB, Taxini CL, Gargaglioni LH (2015) Control of sympathetic activity by A5 noradrenergic neurons in the in situ rat preparations. Neuroscience 2015 Abstracts 432.16/X11. Society for Neuroscience, Chicago IL.

Summary: The A5 area represents an important noradrenergic neuronal group located in the ventral pons that receives and sends projections to various medullary areas involved in the cardiorespiratory control. Its involvement in the chemoreflex control was previously studied in anesthetized conditions. In the present study, we explored the contribution of A5 noradrenergic neurons in the processing of sympathetic responses to central and peripheral chemoreceptors stimulation using the in situ working heart-brainstem rat preparation. Juvenile male Holztman rats received bilateral microinjections of either IgG-SAP (50nl, n=7) or toxin anti-dopamine beta-hydroxylase-saporin (anti-DβH-SAP, 4.2 ng/50 nl, n=6) in the A5. One week later, in situ preparations were obtained to record the thoracic sympathetic (tSN) and phrenic nerve (PN) activities; and stimulation of peripheral (KCN, 0.05%, 50nL) and central chemoreceptors (7 and 10% CO2 in the perfusate, 5 min) were performed. Baseline tSN activity (12.5±2.0 vs 12.6±2.4 μV), PN burst amplitude (40.7±9.7 vs 44.8 ±19.9 μV) and frequency (13±1 vs 15±2 bpm) and the respiratory-sympathetic coupling pattern were similar between control and A5-lesioned rats. The sympathetic ([[unable to display character: ∆]]tSN: 110±12 vs 58±8 %, P<0.05), but not the phrenic response to peripheral chemoreflex stimulation was marked attenuated in animals with lesion of A5 noradrenergic neurons. As to the central chemoreflex, the tSN response to 7% CO2 tSN: 9.5±1.4 vs 3.9±1.7%, P<0.05), but not to 10% CO2 (16.4±2.9 vs 10.9±1.6%) was lower in A5-lesioned rats in comparison to controls. On the other hand, the PN response to 7 and 10% CO2 were similar between control and A5-lesioned rats. Our data show that the A5 noradrenergic neurons are critical for the full expression of the sympathetic chemoreflex responses, possibly by providing an excitatory drive to the neurons generating sympathetic activity.

Related Products: Anti-DBH-SAP (Cat. #IT-03), Mouse IgG-SAP (Cat. #IT-18)

Yegla B, Francesconi JA, Forde JC, Parikh V (2015) Cholinergic contributions to PASA and functional compensation in rats. Neuroscience 2015 Abstracts 253.11/V29. Society for Neuroscience, Chicago IL.

Summary: Neuroimaging studies have indicated increased recruitment of prefrontal regions coupled to reduced activation of posterior regions in task-performing older adults. This shift of activity in cortical networks is described as posterior-anterior shift in aging (PASA). What cellular mechanisms contribute to PASA and how it provides functional compensation for age-related decline in cognitive capacities remains unknown? Cortically-projecting forebrain cholinergic neurons modulate cortical networks and facilitate attentional processes. Here we examined whether cortical cholinergic inputs contribute to PASA expression and maintenance of attentional capacities in aging. Young (3 months) and aged (24 months) Wistar rats were trained in a sustained attention task (SAT) that requires them to distinguish between signal and non-signal events. After attaining criterion performance (_70% correct responses for 3 consecutive sessions), rats received bilateral infusions of cholinoselective immunotoxin 192-IgG SAP either into the prefrontal cortex (PFC) or posterior parietal cortex (PPC) to produce partial cholinergic deafferentation. Control animals were infused with saline. Following behavioral testing 4 weeks post-surgery, animals were perfused 45-min after the last session to examine changes in neuronal activity in the PFC and PPC using c-fos immunohistochemistry. Partial prefrontal cholinergic deafferentation in aged rats produced robust deficits in response accuracy on signal trials as compared to aged sham (p=0.04) and young lesion (p=0.03) rats. In general, c-fos expressing neurons were higher in the PFC of aged rats as compared to young rats. Although prefrontal neuronal activity did not differ between the aged sham and PFC lesion group, there was a trend for a higher neuronal activity in the PPC of the latter. Surprisingly, attentional performance displayed a negative correlation with the prefrontal activity. Neuronal activity in the PPC did not correlate with performance. PPC-infused aged rats displayed no lesion effect on SAT and performed better than aged rats infused with 192 IgG-SAP into the PFC (p=0.04). Moreover, partial loss of cholinergic inputs into the PPC reduced PFC recruitment as compared to PFC lesioned aged rats. Collectively, these data suggest that reduced cortical activity in young rats compared to aged rats may represent better neural capacity, or the efficient utilization of normal brain regions, for task performance. Moreover, PASA is not triggered by prefrontal cholinergic inputs, but these inputs may regulate the reciprocal interactions between the PFC and PPC networks to maintain optimal performance in aging.

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

Holschbach MA, Vitale EM, Lonstein JS (2015) Postpartum lesions targeting serotonergic neurons in the dorsal raphe alter various aspects of maternal behavior. Neuroscience 2015 Abstracts 247.17/R3. Society for Neuroscience, Chicago IL.

Summary: The survival and wellbeing of mothers and their young require high levels of maternal care, aggression toward conspecifics, and low anxiety. These behaviors are affected by pharmacological manipulation of serotonin signaling, but no experiments have analyzed in detail the effects of serotonin-specific lesions of the midbrain on all of these postpartum behaviors. We performed serotonin-specific lesions of the dorsal raphe using a saporin-conjugated toxin targeting the serotonin transporter. After dorsal raphe infusion of the toxin or an inactive control conjugate on postpartum day 2, undisturbed maternal behavior was observed daily and retrieval of scattered pups observed every other day for one week after surgery. Anxiety-like behavior was measured in an elevated plus maze and light dark box on postpartum days 8 and 9, respectively, followed by tests of aggression toward a male intruder in the home cage. Serotonergic lesions of the dorsal raphe altered numerous postpartum behaviors. During undisturbed observations, lesioned animals groomed themselves less and showed more crouching over and less licking of pups. Lesions did not greatly affect pup retrieval or anxiety-like behavior, but did reduce the average duration of attack bouts during aggression testing. This experiment indicates new roles for DR serotonin in the suite of behavioral changes occurring during the postpartum period.

Related Products: Anti-SERT-SAP (Cat. #IT-23)

Ermine C, Wright JL, Parish CL, Thompson LH (2015) Direct impact of dopaminergic and noradrenergic systems on adult-hippocampal neurogenesis in adult rats and the relevance to dementia in Parkinson’s disease. Neuroscience 2015 Abstracts 217.06/C66. Society for Neuroscience, Chicago IL.

Summary: A key pathological feature of Parkinson’s disease (PD) is the progressive degeneration of midbrain dopaminergic neurons, causing motor dysfunction. However there are a range of ‘non-movement’ related features (including cognitive dysfunction, dementia and sleep disorder), which are not alleviated by dopamine replacement therapy. We are currently investigating the hypothesis that reduced hippocampal neurogenesis contributes to cognitive dysfunction in PD. We aim to characterise the effect of the dopaminergic and noradrenergic system on the adult-hippocampal neurogenesis in order to identify potential targets for the treatment cognitive impairments related to neurogenesis. We induced lesions of the different systems in adult rats using stereotaxic injections of toxins: 6-hydroxydopamine (dopaminergic system) and anti-dopa-β-hydroxylase-saporin (noradrenergic system). Four weeks later, the new cells were marked by pulses of bromodeoxyuridine (Brd-U) twice daily for 1 week. The animals were then sacrificed 4 weeks later for tissue collection. A high-performance liquid chromatography has confirmed that both lesions were successful: dopamine level in the striatum dropped to 20% and noradrenaline level in the hippocampus dropped to 8.3%. Surprisingly there was no difference in the number of Brd-U positive cells or in the number of double positive Brd-U/NeuN cells between our groups. The results show that while both noradrenergic and dopaminergic systems are implicated in the onsets of non-motor symptoms, they may not act through the regulation of adult-hippocampal neurogenesis like it was previously thought. Importantly our project has allowed reconsideration of how neurogenesis is involved in PD and redirected the therapies to better potential targets for treatment.

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

Nair DV, Al-Badri MM, Peng H, Pachego-Quinto J, Eckman CB, Iacono D, Eckman EA (2015) Preliminary investigation on the antidepressive effect of chronic oxotremorine treatment in a rodent model of Alzheimer’s disease. Neuroscience 2015 Abstracts 40.29/C34. Society for Neuroscience, Chicago IL.

Summary: Alzheimer’s disease (AD) is a progressive neurodegenerative disease and the rate of progression varies from individual to individual. A great deal of evidence supports the idea that depression and other neuropsychiatric conditions co-exist with cognitive decline. However, the neurobiological basis of these symptoms and their influence on the clinical course of AD remain unclear. Our lab has shown previously that the 192-IgG saporin rat model of AD-like basal forebrain cholinergic cell loss exhibits a depression-like phenotype that develops months after the well-described impairment in spatial working memory. Furthermore, we have shown that chronic intracerebroventricular administration of the muscarinic agonist oxotremorine reverses both spatial working memory deficits and the depression-like behavior triggered by cholinergic denervation, and induces hippocampal neurogenesis. Current experiments are focused on determining additional pathological correlates of depression in this model and how they may be modulated by muscarinic agonists. To induce AD-like basal forebrain cholinergic cell loss, adult female Sprague Dawley rats were injected intracerebroventricularly (icv) with the immunotoxin 192-IgG-saporin (SAP) or saline as control (SHAM). After a 5 week recovery period, the rats received either 2 or 6 weeks of icv infusion of either oxotremorine or vehicle (saline) via osmotic minipump. Behavioral testing to assess the depressive phenotype was carried out using the sucrose consumption test every 2 weeks during oxotremorine treatment. The phenotype was further confirmed by forced swim test. The levels of ChAT, tryptophan hydroxylase (TPH), muscarinic receptors and FosB and ΔFosB were assessed in the hippocampus, basal forebrain, and orbitofrontal cortex by western blot and immunohistochemistry. Our preliminary results show increases in TPH, M1 receptors and FosB in the hippocampus, basal forebrain, and orbitofrontal cortex of a subset of treated animals, but no changes ChAT or ΔFosB. Further experiments are in progress to determine if there are changes in the expression of these and additional proteins in other brain regions including the nucleus accumbens, an area involved in activational aspects of motivation which also contributes to behavioral disorders such as to depression. The results of these studies may provide new insight in understanding the molecular basis of depression and antidepressant action of oxotremorine thereby defining new targets for possible therapeutic intervention for depressive symptoms in AD.

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

Pittenger CJ (2015) Modeling Tourette syndrome pathophysiology through targeted manipulation of striatal interneurons. Neuroscience 2015 Abstracts 6.07. Society for Neuroscience, Chicago IL.

Summary: Postmortem studies of Tourette syndrome patients has revealed a reduction in the number of specific striatal interneurons. The authors explored the hypothesis that this neuronal deficit is enough to produce the symptoms of Tourette syndrome in mice. Animals received 90-ng injections of Anti-ChAT-SAP (Cat. #IT-42) into the striatum. Rabbit IgG-SAP (Cat. #IT-35) was used as a control. The data suggest that loss of the striatal interneurons is enough to produce some, but not all, of the symptoms caused by Tourette syndrome.

Related Products: Anti-ChAT-SAP (Cat. #IT-42), Rabbit IgG-SAP (Cat. #IT-35)

See Also:

• Xu M et al. Targeted ablation of cholinergic interneurons in the dorsolateral striatum produces behavioral manifestations of Tourette syndrome. Proc Natl Acad Sci U S A 112:893-898, 2015.