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Identification of synapse pairs between neurons in the basal forebrain nuclei

前脑基底核神经元之间突触对的识别

基本信息

批准号：
11680808
负责人：
MOMIYAMA Toshihiko
金额：
$ 2.37万
依托单位：
Okazaki National Research Institute
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

Brain slices containing basal forebrain nuclei (BF) obtained from 10-14 day-old rats were used. Paired whole-cell recordings were made from visually identified large (>25 μm) and small (<15 μm) neurons within the BF.Large neurons were identified as cholinergic since their electrophysiological properties conformed to the reported ones. When a depolarizing pulse was applied to the small neuron through the recording pipette, a synaptic current was evoked in the large neurone in 10 % of the recorded pairs. The evoked synaptic currents were blocked by bicuculline (10 μM), suggesting that the small neurons are GABAergic. The separate series of morphological studies have clarified that somatostatin-containing GABAergic neurons make synaptic contacts with cholinergic neurons, indicating the existence of functional interactions between these two types of neurons.Neuronal activities of ventral tegmental dopaminergic neurons which project to the BF are regulated by glutamatergic inputs fro cortex or brain stem. Dopamine-induced modulation of non-NMDA glutamatergic synaptic transmission onto dopaminergic neurons was elucidated using slice patch-clamp technique. The findings suggest that afferent glutamatergic fibers terminating dopaminergic neurons possess presynaptic D_2-like dopamine receptors, activation of which inhibits glutamate release by reducing Ca^<2+> influx (Koga ＆ Momiyama, 2000).BF is often compared with striatum in both morphological and functional aspects. GABAergic synaptic transmission and its modulation by dopamine in striatal cholinergic interneurons were also investigated. The results suggest that activation of D_2-like receptors in the GABAergic terminals selectively block N-type to reduce GABA release. Thus is the first report that identified the Ca^<2+> channel subtype unvolved in presynaptic dopamine receptor-mediated modulation of synaptic transmission (Momiyama ＆ Koga, 2001).

使用从10-14日龄大鼠获得的含有基底前脑核（BF）的脑切片。配对全细胞记录从视觉识别的大（>25 μm）和小（<15 μm）的BF内的神经元。大神经元被确定为胆碱能神经元，因为它们的电生理特性与报道的一致。当去极化脉冲通过记录吸管施加到小神经元时，在10%的记录对中的大神经元中诱发突触电流。诱发的突触电流被荷包牡丹碱（10 μM）阻断，表明小神经元是GABA能的。一系列的形态学研究表明，含生长抑素的GABA能神经元与胆碱能神经元之间存在突触联系，表明这两类神经元之间存在功能性相互作用，投射到BF的腹侧被盖多巴胺能神经元的活动受来自皮层或脑干的多巴胺能输入的调节。用膜片钳技术研究了多巴胺对多巴胺能神经元非NMDA能突触传递的调制作用。这些发现表明，终止多巴胺能神经元的传入纤维具有突触前D_2样多巴胺受体，其激活通过减少Ca^<2+>内流来抑制谷氨酸的释放（古贺& Momiyama，2000）。本研究还探讨了纹状体胆碱能中间神经元的GABA能突触传递及多巴胺对其的调节作用。结果提示，GABA能终末D_2样受体的激活可选择性地阻断N-型，从而减少GABA的释放。这是第一份鉴定出与突触前多巴胺受体介导的突触传递调节无关的Ca^<2+>通道亚型的报告（Momiyama &古贺，2001）。