Segal M
Center for Neuroscience, Weizmann Institute of Science, Rehovot, Israel.
Neuroscience. 1990;36(3):631-41. doi: 10.1016/0306-4522(90)90006-p.
Activity of hippocampal neurons was recorded in an in vitro slice preparation. Topical application of serotonin produced hyperpolarization, blockade of a slow afterhyperpolarization which follows a burst discharge and blockade of a slow inhibitory postsynaptic potential. The slow inhibitory postsynaptic potential evoked by stimulation of the apical dendritic region of the hippocampus is more sensitive to serotonin than the membrane potential or conductance. The effects of serotonin on the inhibitory postsynaptic potentials are blocked by the 5-HT1a antagonist spiperone, and not by mianserin, a 5-HT2 antagonist. The attenuation of the inhibitory postsynaptic potentials is not accompanied by a change in postsynaptic reactivity to GABA or baclofen. Serotonin blocks repetitive large inhibitory postsynaptic potentials evoked in hippocampal neurons by topical application of 4-aminopyridine. Putative interneurons are more sensitive to topical application of serotonin than pyramidal neurons. Fenfluramine, a serotonin releaser mimics the effects of topical application of serotonin indicating that synaptically released serotonin can produce the changes in membrane potential and reactivity to afferent stimulation. It is suggested that serotonin attenuates slow inhibitory postsynaptic potentials by inhibiting feed forward inhibitory interneurons which impinge upon the recorded pyramidal neurons.
在体外脑片制备中记录海马神经元的活动。局部应用血清素可产生超极化，阻断爆发性放电后的缓慢超极化以及阻断缓慢抑制性突触后电位。刺激海马顶端树突区域诱发的缓慢抑制性突触后电位比膜电位或电导对血清素更敏感。血清素对抑制性突触后电位的作用可被5-HT1a拮抗剂螺哌隆阻断，而不被5-HT2拮抗剂米安色林阻断。抑制性突触后电位的衰减并不伴随着突触后对γ-氨基丁酸（GABA）或巴氯芬反应性的改变。血清素可阻断通过局部应用4-氨基吡啶在海马神经元中诱发的重复性大抑制性突触后电位。假定的中间神经元比锥体神经元对局部应用血清素更敏感。芬氟拉明，一种血清素释放剂，模拟局部应用血清素的作用，表明突触释放的血清素可产生膜电位变化以及对传入刺激的反应性变化。提示血清素通过抑制投射到记录的锥体神经元上的前馈抑制性中间神经元来减弱缓慢抑制性突触后电位。
