Neural mechanism of inhibitory syvaptie Trans mission of crayfish local circuil neurones

本研究旨在阐明克氏原螯虾（Procambarus clarkii Girard）尾足运动中局部回路神经元抑制连接的突触机制。(1)GABA作为抑制性递质是最有效的候选物质，我已经研究了通过Lucifer黄染色和免疫细胞化学染色对GABA进行双重标记来鉴定GABA能间神经元。(1)感觉非尖峰局部间神经元，LDS具有节间上行间神经元的横向横向抑制作用，是gaba能间神经元。（ii）尾足运动神经元本质上受运动前非尖峰局部间神经元的单侧结构控制，这些非尖峰间神经元分为PL和AL组。所有的左脑非尖峰间神经元都是gaba能神经元，而大约一半的左脑非尖峰间神经元不是gaba能神经元。(2)对上行间神经元gaba能受体的电生理特性进行了表征。根据对GABA_A拮抗剂、双核碱和picrotoxin的反应，上行中间神经元可分为picrotoxin-sensitive和picrotoxin-insensitive两类。经鉴定，上行中间神经元VE-1和RO-4的药理特征与经典的GABA_A受体相似。双球茎碱和微毒素均可可逆地降低ipsp的振幅。另一种确定的上行中间神经元CA-1、RO-1和RO-2没有受到GABA_A和GABA_B拮抗剂的显著影响，尽管低氯盐盐水可以逆转感觉刺激的ipsp。与picrotoxin-insensitive型中间神经元相比，picrotoxin-sensitive中间神经元IPSPs的时间进程更快，持续时间更短。

This research is aimed to clarify the synaptic mechanisms of inhibitory connections of the local circuit neurones underlying uropod movements of crayfish, Procambarus clarkii Girard.(1)GABA is the most potent candidate as inhibitory transmitter and I have investigated to identify GABAergic interneurones by using double labelling of intracellular staining with Lucifer yellow and immunocytochemical staining against GABA.(i)Sensory nonspiking local interneurone, LDS has a role of lateral transverse inhibition of intersegmental ascending interneurones and I found LDS is a GABAergic interneurone.(ii)Uropod motor neurones are essentially controlled by premotor nonspiking localinterneurones with unilateral stucture and these nonspiking interneurones are classified into PL and AL groups. All the PL nonspiking interneurones are GABAergic neurones while about half of AL nonspiking interneurones are not GABAergic.(2)The properties of GABAergic receptors of ascending interneurones are characterizedelectrophysiologically. According to the response to GABA_A antagonists, bicuculline and picrotoxin, ascending interneurons were classified into two types, picrotoxin-sensitive and picrotoxin-insensitive interneurons. Identified ascending interneurons, VE-1 and RO-4 showed a pharmacological profile similar to classical GABA_A receptor of the vertebrates. Bath application of both bicuculline and picrotoxin reversibly reduced the amplitudes of IPSPs. Another identified ascending interneurons, CA-1, RO-1 and RO-2 were not affected significantly by the bath application of GABA_A and GABA_B antagonists, though bath application of low chloride saline reversed the sensory-stimulated IPSPs. IPSPs of the picrotoxin-sensitive interneurons had rather faster time course and shorter duration in comparison with that of the picrotoxin-insensitive interneurons.