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Cholinergic depletion in nucleus accumbens impairs mesocortical dopamine activation and cognitive function in rats.
Laplante F, Zhang ZW, Huppe-Gourgues F, Dufresne MM, Vaucher E, Sullivan RM (2012) Cholinergic depletion in nucleus accumbens impairs mesocortical dopamine activation and cognitive function in rats. Neuropharmacology 63(6):1075-1084. doi: 10.1016/j.neuropharm.2012.07.033
Summary: Current thought is that loss of cholinergic function in the nucleus accumbens (N.Acc) is associated with schizophrenia. This deficit is accompanied by low dopaminergic activity in the prefrontal area, which adversely affects working memory. Rats received bilateral injections totaling 500 ng of anti-ChAT-SAP (Cat. #IT-42) into the N.Acc; rabbit IgG-SAP (Cat. #IT-35) was used as a control. Lesioned animals had markedly reduced mesocortical dopamine activation, which corresponded with cognitive impairments. The data suggest that loss of cholinergic neurons in the N.Acc causes loss of dopamine function in the mesocorticolimbic system.
Related Products: Anti-ChAT-SAP (Cat. #IT-42), Rabbit IgG-SAP (Cat. #IT-35)
Cholinergic depletion in the nucleus accumbens: Effects on amphetamine response and sensorimotor gating.
Laplante F, Lappi DA, Sullivan RM (2011) Cholinergic depletion in the nucleus accumbens: Effects on amphetamine response and sensorimotor gating. Prog Neuropsychopharmacol Biol Psychiatry 35(2):501-509. doi: 10.1016/j.pnpbp.2010.12.005
Summary: Disruption of dopamine and acetylcholine balance in the striatum may play a role in conditions such as Parkinson’s and schizophrenia. In this work the authors lesioned cholinergic neurons in the nucleus accumbens (N.Acc) with the novel toxin Anti-ChAT-SAP (Cat. #IT-42). Rats received 0.25-µg bilateral injections of the toxin into the N.Acc. Rabbit IgG-SAP (Cat. #IT-35) was used as a control. The results of this lesion produced responses that may parallel the loss of cholinergic neurons seen in schizophrenia.
Related Products: Anti-ChAT-SAP (Cat. #IT-42), Rabbit IgG-SAP (Cat. #IT-35)
Depletion of cholinergic neurons in the nucleus accumbens impairs dopamine function in the prefrontal cortex in the rat.
Laplante FP, Dufresne M, Lappi DA, Sullivan RM (2009) Depletion of cholinergic neurons in the nucleus accumbens impairs dopamine function in the prefrontal cortex in the rat. Neuroscience 2009 Abstracts 341.7/O16. Society for Neuroscience, Chicago, IL.
Summary: Studies of post mortem schizophrenic brains have revealed a selective loss of cholinergic interneurons, most pronounced in the ventral striatal region. We have previously shown in the rat, that a novel saporin immunotoxin coupled with an antibody targeting choline acetyltransferase (ChAT) and microinjected (0.5 _g/_l; 0.5 _l) into the nucleus accumbens (N. Acc) of adult rats, reduces the number of cholinergic neurons in N. Acc. by 40-50 %. Such lesions result in a markedly heightened response to the locomotor activating effects of amphetamine and impair prepulse inhibition of the acoustic startle response. We proposed that this local cholinergic deficit leads to a hyperresponsiveness in subcortical dopamine (DA) systems of relevance to schizophrenic symptomatology. Presently, we hypothesize that the same local cholinergic defect may trigger broader changes in cortical/subcortical networks, specifically prefrontal cortex (PFC) deficits in DA-mediated functions, also proposed in schizophrenia. Young adult male Srpague-Dawley rats were injected bilaterally in the N. Acc. as described above with either the cholinergic immunotoxin or vehicle. Two weeks later, they were trained in a working memory task dependent on PFC function, using the delayed alternation paradigm in the T-maze. Lesioned rats took significantly longer to reach criterion performance during training than controls. During testing, lesioned rats were significantly impaired in the percentage of correct arm choices across delay intervals, but especially with longer (40 sec) delays. The same animals were then implanted with voltammetric recording electrodes in the ventromedial PFC to examine the increases in in vivo extracellular DA release in response to a brief tail pinch stress. Lesioned rats showed a significantly reduced activation of the mesocortical DA system compared to controls. Taken together, the data suggest that reduction in the density of cholinergic neurons in the N. Acc also triggers deficits in prefontally-mediated function known to be under mesocortical DAergic regulation. This raises the possibility that ventral striatal cholinergic deficits may be causally linked to cortical/subcortical functional imbalances proposed to exist in schizophrenia.
Related Products: Anti-ChAT-SAP (Cat. #IT-42)
Depletion of cholinergic neurons in the nucleus accumbens and its possible involvement in schizophrenic symptomatology
Laplante FP, Dufresne M, Lappi DA, Sullivan RM (2008) Depletion of cholinergic neurons in the nucleus accumbens and its possible involvement in schizophrenic symptomatology. Neuroscience 2008 Abstracts 761.18/FF34. Society for Neuroscience, Washington, DC.
Summary: Schizophrenia is a mental disorder characterized by dysfunctions in several neurotransmitter systems including the central cholinergic system. While alterations in cholinergic neurotransmission have been demonstrated in schizophrenic brains, their biological significance remains to be established. Post-mortem studies of schizophrenic patients have shown a reduction in the density of cholinergic interneurons in the striatum, most prominently in the ventral striatum or nucleus accumbens (N. Acc). Intra-accumbens acetylcholine interacts functionally with the mesolimbic dopaminergic system and is believed to dampen the effects of excessive dopamine (DA) release. Therefore, we hypothesize that a reduction in the density of cholinergic neurons in the N. Acc will be behaviorally relevant, if not causal, to the enhanced (ventral) striatal dopaminergic neurotransmission described in schizophrenia and may contribute substantially to the emergence of schizophrenic symptomatology. In this study we aimed to reproduce in rats a selective reduction in N.Acc. cholinergic cell density, and study the neurophysiological and behavioural consequences of these lesions, relevant to the neuropsychopathology of schizophrenia. A novel saporin immunotoxin coupled with an antibody targeting choline acetyltransferase (ChAT) has been developed. We microinjected this immunotoxin bilaterally (0.5 μg/μl; 0.5 μl) into the N. Acc (core and shell) of adult male Srpague-Dawley rats. Using immunohistochemistry to quantify ChAT staining, we have confirmed that this toxin caused a 40-50 % loss in the number of cholinergic neurons in this region within two weeks post-injection. Lesioned rats exhibited significantly higher spontaneous locomotor activity than control rats and were shown to be hypersensitive to the locomotor activating effects of amphetamine and quinpirole. Furthermore, in separate groups of animals, we have observed in lesioned rats, a reduction in the prepulse inhibition of the acoustic startle response. Taken together, it is proposed that reduction of cholinergic neurons in the N. Acc triggers an enhanced DA responsivity in the N.Acc which may prove highly effective in reproducing behavioral abnormalities analogous to those found in schizophrenia. The neurophysiological consequences of these lesions on DA neurotransmission will be further addressed by measuring both pre- and postsynaptic indices of DA function in this region.
Related Products: Anti-ChAT-SAP (Cat. #IT-42)