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Synaptic reoponses in Olivocochlear neurons of the rat.

大鼠橄榄耳蜗神经元的突触反应。

基本信息

批准号：
10680764
负责人：
KOYANO Konomi
金额：
$ 2.11万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

Olivocochlear (OC) neurons are efferent auditory neurons that project to the cochlea, and regulate the peripheral signal processing. We have previously reported on their intrinsic membrane properties in slice preparation of the rat using the whole-cell patch recording configuration (J. Neurophysiology 77,2788,1997). In this study, we further investigated the synaptic inputs to these neurons. We recorded EPSCs from two groups of OC(LOC and MOC)neurons and the principal neurons of the lateral superior olive(LSO neurons)which is the afferent auditory neurons, as a reference. Both non-NMDA and NMDA receptor mediated postsynaptic currents were present in the three groups of neurons. Individual neurons of these three groups showed glycinergic and GABAergic synaptic responses. Besides these amino acid responses, LOC neurons also showed dtubocularine-sensitive nicotinic receptor mediated responses when acetylcholine was puff applied. Previous anatomical studies have reported the presence of recurrent collateral axons in LOC neurons that innervate LSO including LOC neurons themselves. Since LOC neurons are known to be cholinergic, these observations suggest a synchronous excitation mechanism among neighbored LOC neurons. LOC neurons are supposed to be arranged tonotopically in LSO, and to project to the corresponding characteristic frequency region of the cochlea. Therefore, the synchronous excitation of a group of LOC neurons might effectively enhance the auditory signals in a particular frequency region.

橄榄耳蜗神经元是投射到耳蜗区的传出听神经元，调节外周信号的处理。我们之前已经报道了它们在使用全细胞膜片记录配置的大鼠切片制备中的固有膜特性(J神经生理学，77,2788,1997)。在这项研究中，我们进一步研究了这些神经元的突触输入。我们记录了两组OC(LOC和MOC)神经元和作为传入听觉神经元的外侧上橄榄主神经元(LSO神经元)的EPSCs作为参考。非NMDA和NMDA受体介导的突触后电流均存在于三组神经元中。三组神经元均表现出甘氨酸能和GABA能突触反应。喷施乙酰胆碱时，除上述氨基酸反应外，LOC神经元还表现出对烟碱敏感的烟碱受体介导的反应。以往的解剖学研究已经报道，在支配LSO的LOC神经元中存在反复的侧枝轴突，包括LOC神经元本身。由于LOC神经元是胆碱能神经元，这些观察结果提示相邻LOC神经元之间存在一种同步兴奋机制。在LSO中，LoC神经元被认为是音调排列的，并投射到耳蜗区相应的特征频率区域。因此，一组LOC神经元的同步兴奋可以有效地增强特定频率区域内的听觉信号。