甘氨酸和γ-氨基丁酸对小鼠游离脊髓的初级传入终末兴奋性的作用

本工作在正常离体小鼠(天龄10—15d)脊髓进行。实验结果表明:电刺激邻近记录电极的背根,微电泳GABA及GABA的协同剂Thip、Thiomuscimol和甘氨酸(Glycine)均能引起小鼠脊髓单一初级传入纤维终末的兴奋阈值下降,兴奋性增高,说明终末发生了去极化的变化。同时电泳荷包牡丹碱(Bicuculline)能逆转GABA及其协同剂的去极化作用,但对Glycine的去极化作用无效。而士的宁(Strychnine)能逆转Glycine的去极化作用,对GABA的去极化作用无效。说明在小鼠脊髓初级传入终末存在GABA_A受体及Glycine受体,而且在传入终末区Glycine受体类型可能与脊髓内其它部位的相同。

EFFECTS OF GLYCINE AND GABA ON PRIMARY AFFERENT TERMINAL EXCITABILITY IN MOUSE SPINAL CORD

The effects of GABA,glycine and their antagonists on primary afferent ter-minal excitability were observed on isolated spinal codrd of 10--15 day-old mouse.The results indicated that electrical stimulation of an ajacent dorsal root and elec-trophoresis of GABA,Thip.,thiomuscimol and glycine can evoke a fall in thresh-old,the excitability of single Primary afferent.terminal was increased.Bicucul-line,an antagonist of GABA receptor,can block effects of GABA,Thip.and thio-muscimol,but it has no effect on glycine.Howwever,strychnine,an antagonistofglycine,can block the effect of glycine but not to GABA.These results suggestthat there are GABA and glycine receptors on primary afferent terminals of mousespinal cord and the type of glycine receptor may be the same as neuron body.