蟾蜍神经－肌接头小终板电位季节性变化的激素原因初探

A Preliminary Study on the Hormonal Causes of Seasonal Change in Miniature Endplate Potentials at the Neuromuscular Junctions of the Toad

在春季和秋季分别滴加Ｌ－甲状腺素钠和雌酮于浴液，用细胞内记录方法研究了成年中华亚型大蟾蜍离体的缝匠肌纤维神经－肌接头小终板电位（ＭＥＰＰ）振幅季节性变化的激素原因。结果表明：①Ｌ－甲状腺素钠（５０μｍｏｌ／Ｌ）无论在春季或秋季都不能改变ＭＥＰＰ振幅；②雌酮（１００μｍｏｌ／Ｌ）在春、秋季均引起ＭＥＰＰ振幅明显增加。据此推测蟾蜍ＭＥＰＰ振幅的季节性变化与甲状腺激素作用的关系可能不密切，而与体内性激素的季节变化有关。

The hormonal causes of seasonal change in amplitudes of miniature endplate potentials (MEPP) in the adult toad (Bufo bufo gargarizans) were studied with intracellular recordings of MEPP at the neuromuscular junction of sartorius muscle fiber in vitro by adding L thyroxine sodium and estrone to the bath medium during spring and autumn respectively. The results showed that L thyroxine sodium (50μmol/L) could not change the amplitude of MEPP, regardless of spring or autumn, but estrone (100μmol/L) could cause a clear increase in MEPP amplitude in both seasons. From these results it was presumed that thyroxine might be less related to the seasonal changes in MEPP amplitude whereas the seasonal fluctuations of gonadal hormones in the body might play a role.