2-花生四烯酸甘油对海人酸诱导损伤的大鼠尾状核神经元电压门控钠电流的调制作用

Modulatory effect of 2-arachidonoylglycerol on voltage-gated sodium currents in rat caudate nucleus neurons with kainic acid-induced injury

目的探讨内源性大麻素2-花生四烯酸甘油(2-AG)对海人酸(KA)损伤的大鼠尾状核神经元电压门控钠通道电流(INa)的调制作用及其分子机制。方法原代培养大鼠尾状核神经元,分为空白对照组、KA组、2-AG+KA组、RIM(CB1受体拮抗剂)+2-AG+KA组。培养7 d后,各组细胞于培养基中处理12 h;其中,2-AG+KA组和RIM+2-AG+KA组在添加2-AG、RIM 30 min后添加KA。应用全细胞膜片钳技术检测大鼠尾状核神经元电压门控钠通道电流:包括各组电流密度的变化、通道的电流-电压特性、通道的激活动力学特性和失活动力学特性。结果在培养的大鼠尾状核神经元中,与对照组相比,KA显著增加神经元电压门控钠通道电流密度(P=0.009);并使VGSCs的激活电压曲线向超极化方向偏移,半激活电压绝对值明显增大(P=0.008)。与KA组相比,直接给与2-AG提高2-AG水平可阻止KA诱导的钠电流密度增加(P=0.009)和钠电流激活曲线超极化方向移动(P=0.009),且2-AG的这种作用是通过CB1受体依赖性途径介导的。2-AG本身对尾状核神经元电压门控钠通道电流密度、激活及失活等电流特性均不产生效应。结论2-AG可通过CB1受体途径调控尾状核神经元VGSCs电流朋而起到神经保护作用。

Objective To investigate the modulatory effect of 2-arachidonoylglycerol(2-AG)on voltage-gated sodium currents(VGSCs)in rat caudate nucleus(CN)neurons with kainic acid(KA)-induced injury and explore the molecular mechanism underlying the neuroprotective effect of 2-AG.Methods Primary cultures of CN neurons isolated from neonatal SD rats were treated with KA,2-AG+KA,RIM(a CB1 receptor antagonist)+2-AG+KA,or vehicle only(as control).After 7 days in primary culture,the neurons were treated with corresponding agents for 12 h(RIM and 2-AG were added at the same time;KA was added 30 min later)before recording of current density changes,current-voltage characteristics,activation and inactivation kinetics of VGSCs(INa)using whole-cell patch clamp technique.Results In cultured CN neurons,KA significantly increased current density of VGSCs(P=0.009)as compared with vehicle treatment.KA also produced a hyperpolarizing shift in the activation curve of INa and significantly increased the absolute value of V1/2 for activation(P=0.008).Addition of 2-AG in the culture medium obviously prevented KA-induced increase of INa(P=0.009)and hyperpolarizing shift in the activation curve of INa,and significantly reduced the value of V1/2 for activation(P=0.009)in a CB1 receptor-dependent manner.2-AG alone did not affect the density,activation or deactivation of VGSCs in rat CN neurons.Conclusion In excitotoxic events,endogenous 2-AG can offer neuroprotection by modulating VGSCs in the CN neurons through a CB1 receptor-dependent pathway.