神经甾体激素PGN对大鼠脑片SCN神经元电生理学的影响

目的：通过观察孕烷醇酮（PGN）对大鼠离体脑片视交叉上核神经元（SCN）细胞外单位放电的影响，分析PGN中枢镇静和麻醉作用的可能机制。方法：大鼠离体脑片灌流给药，应用细胞外神经元单位放电记录方法记录SCN胞外放电，并观察给予PGN、γ-氨基丁酸(GABA)及γ-氨基丁酸A型(GABAA)受体阻断剂荷包牡丹碱(Bic)后，SCN胞外放电的变化。结果：灌流给予PGN,SCN神经元放电受到抑制，抑制率为(49.72±16.28)%；PGN与GABA同时灌流可以抑制SCN神经元的活动，抑制率为(71.54±19.62)%，两者比较差异有显著性（P<0.05）。预先应用GABAA受体阻断剂Bic可使PGN引起的放电抑制效应明显减小，抑制率为(29.85±6.20)%(P<0.05）。结论：PGN可以通过对SCN神经元细胞膜上的GABAA受体的作用来影响SCN神经元的兴奋性；PGN还有可能改变GABAA受体的结构而促进GABA和GABAA受体的结合而增强其对中枢的抑制作用。

Influence of neural steroid hormones PGN on electrophysiology of SCN neurons in rat brain slices

Objective To observe the effect of pregnanolone(PGN) on suprachiasmatic nucleus(SCN) neurons of rat brain slices,and analyze the possible mechanism of central sedation and anesthesia effects of PGN. Methods PGN,GABA,and Bic were perfused into the rat brain slices,the extracellular discharge changes of SCN were recorded after perfusion with extracellular discharge record method.Results After perfusion of PGN,the activity of SCN neurons was inhibited,the inhibitory rate was (49.72±16.28)%;Co-application of PGN and GABA could enhance the inhibitory effect on SCN neurons,the inhibitory rate was (71.54±19.62)%,there was significant difference between them(P<0.05 );pre-application of GABA blockers Bic could block the effects of PGN,the inhibitory rate was (29.85± 6.20)%(P<0.05).Conclusion PGN may directly affect the SCN neuron membrane excitability.Its role may be related to GABAA receptor on SCN neuron membrane.PGN can increase the combination of GABA and GABAA receptors to enhance the function of GABA.