海马神经元α7型烟碱样乙酰胆碱受体的失敏特征

The desensitization characteristics of α7-nAChR in hippocampal neurons

目的研究大鼠海马神经元α7型烟碱样乙酰胆碱受体(α7-nAChR)的失敏特征。方法在培养大鼠海马神经元上,以胆碱作为工具药,采用膜片钳全细胞记录方式研究胆碱诱发α7型烟碱样乙酰胆碱受体失敏的电生理学特征。结果在培养大鼠海马神经元上,喷射胆碱可诱发出一内向电流,能被α7-nAChR选择性拮抗剂methyllycaconitine(10 nmol.L-1)和α-bungarotoxin(100 nmol.L-1)明显阻断;延长高浓度胆碱(10 mmol.L-1)的给药时间不影响α7-nAChR的失敏和失敏态的恢复,但可以延长其处于完全失敏态的时间;灌流低浓度胆碱(50、100μmol.L-1)可以使α7-nAChR缓慢失敏,失敏程度与胆碱浓度有关。结论高浓度胆碱诱发α7-nAChR的快速失敏及恢复与给药时间无关,低浓度胆碱诱发受体的缓慢失敏及恢复与浓度有关。

Aim To investigate the desensitization characteristics of α7-nAChR in rat hippocampal neurons.Methods The Whole-cell recording configuration of patch-clamp technique was used to study the electrophysiological features of desensitization of α7-nAChR in cultured rat hippocampal neurons by the application of choline.Results An inward current was elicited by the application of choline in cultured rat hippocampal neurons,which could be significantly blocked by selective antagonists of α7-nAChR,methyllycaconitine（10 nmol·L-1） and α-bungarotoxin（100 nmol·L-1）,which were selective antagonists of α7-nAChR.Prolonging the durations of high-concentration choline（10 mmol·L-1） did not influence the desensitization and recovery from desensitization of α7-nAChR,but extend the period of the state of full desensitization.α7-nAChR desensitization was also slowly produced by the perfusion of low-concentration choline（50,100 μmol·L-1）,and desensitized extent was related to the concentration of choline.Conclusions Fast desensitization and recovery from desensitization of α7-nAChR elicited by high-concentration choline are not correlated with the durations of choline,while slow desensitization and recovery of α7-nAChR elicited by low-concentration choline are related with concentration of choline.