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

利用细胞内记录技术在哺乳动物盆腔副交感神经节体外测定了两种类型的同突触促进[1 & 2(1)]和一种类型的异突触抑制[2(2)]。兔膀胱盆腔神经节神经支配膀胱神经节中大部分突触具有高通滤波器的功能；只有当神经节前神经元的动作电位发生在高频率（如10 Hz）时，尼古丁快速EPSP才能引起正正交动作电位。滤光器的作用机制包括嘌呤能低截止滤光器和发射机释放的频率依赖性增加。前者由内源性ATP和突触前抑制P_2受体组成。后者可以用“残钙”假说来解释。盆腔神经刺激的作用盆腔神经（PN）的重复刺激（10赫兹，30秒）增强了猫副交感神经元膜电位的自发振荡，称为去极化膜振荡（DMO）。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刺激作用，肌碱可模拟pn刺激作用。(2)刺激下胃神经的作用相反的反复刺激下胃神经（HGN）经常抑制DMO，将自发放电的神经元转化为沉默的神经元。育亨宾可部分拮抗hgn刺激作用，去甲肾上腺素可模拟hgn刺激作用。这些结果提供了一种新型的烟碱突触自身抑制以及副交感神经节交感神经和副交感神经分裂之间的相互作用。

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.