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Homosynaptic and heterosynaptic modulation of the information processing in the mammalian parasympathetic ganglia.

哺乳动物副交感神经节信息处理的同突触和异突触调节。

基本信息

批准号：
06680818
负责人：
NISHIMURA Toshihiko
金额：
$ 1.28万
依托单位：
Kurume University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

Two types of homosynaptic facilitation [1 & 2 (1)] and one type of heterosynaptic depression [2 (2)] were determined in mammalian pelvic parasympathetic ganglia in vitro, utilizing intracellular recording techniques.1. rabbit vesical pelvic ganglia that innervate the urinary bladderMost of synapses in the ganglia function as a high pass filter ; only when the action potentials of preganglionic neurons occur at high frequency such as 10 Hz, the nicotinic fast EPSP can evoke the orthodromic action potentials. Mechanisms of the filter involve the purinergic low-cut-filter and the frequency dependent increase of transmitter release. The former consists of endogenous ATP and presynaptic inhibitory P_2 receptors. The later might be explained by the "residual calcium" hypothesis.2. feline colonic ganglia that innervate colonic effector structures(1) effect of pelvic nerve stimulationRepetitive stimulation (10 Hz, 30 sec) of pelvic nerve (PN) augmented a spontaneous oscillation of membrane potential termed a depolarizing membrane oscillation (DMO) of feline parasympathetic neurons. These augmented DMO triggered an action potential, converting a silent neuron to a spontaneously firing neuron. Effects of PN-stimulation were antagonized by atropine and mimicked by muscarine.(2) effect of hypogastric nerve stimulationContrary repetitive stimulationof hypogastric nerve (HGN) often depressed the DMO,converting the spontaneously firing neuron to the silent neuron. Effects of HGN-stimulation were partially antagonized by yohimbine and mimicked by norepinephrine.These results provide a new type of autoinhibition at nicotinic synapses and interaction between sympathetic and parasympathetic division in the parasympathetic ganglia.

利用细胞内记录技术，在离体哺乳动物盆副交感神经节中测定了两种同突触易化[1 & 2（1）]和一种异突触抑制[2（2）]。兔膀胱盆神经节内的突触大多数起高通滤波作用，只有当节前神经元动作电位以高频（如10Hz）发生时，烟碱快EPSP才能诱发顺向动作电位。滤波机制涉及嘌呤能低截滤波和频率依赖性增加递质释放。前者由内源性ATP和突触前抑制性P_2受体组成。后者可用“残余钙”假说解释.（1）盆神经刺激的作用盆神经（PN）的重复刺激（10 Hz，30 sec）增强了被称为猫副交感神经元去极化膜振荡（DMO）的膜电位的自发振荡。这些增强的DMO触发了动作电位，将沉默的神经元转化为自发放电的神经元。阿托品可拮抗PN刺激的效应，毒蕈碱可模拟PN刺激的效应。(2)腹下神经刺激的影响腹下神经（HGN）的相反重复刺激通常会抑制DMO，将自发放电神经元转变为沉默神经元。HGN刺激的影响被育亨宾部分拮抗，去甲肾上腺素模仿。这些结果提供了一种新的类型的自身抑制在烟碱突触和交感神经和副交感神经节之间的相互作用。