脑缺血后钠通道Na(v)1.6的表达变化

目的 观察大鼠缺血脑组织中Na(v)1.6的表达变化及钠通道阻滞剂Riluzole对其表达的影响,探讨Na (v)1.6与脑缺血的关系.方法 105只SD大鼠按随机数字表法分假手术组(n=15)、脑缺血组(n=45)和Riluzole治疗组(n=45),后2组应用线栓法制作成大鼠右侧大脑中动脉永久性闭塞模型,Riluzole治疗组在造模后30 min按8 mg/kg静脉注射给药,1次/d.缺血后6 h、1 d、2 d、3 d、7 d时观察大鼠神经功能缺损情况,应用免疫荧光染色和实时定量PCR方法检测纹状体区Na(v)1.6的表达,TTC染色检测脑梗死体积的变化.结果 缺血组和Riluzole治疗组大鼠神经功能缺损在缺血后2 d表现最严重,相同时间点缺血组较Riluzole治疗组神经功能评分增高,比较差异有统计学意义(P＜0.05).免疫荧光染色显示缺血组和Riluzole治疗组Na(v)1.6表达均在缺血后1 d达高峰,随后下调.实时定量PCR显示缺血组Na(v)1.6 mRNA在缺血后6 h、1 d表达上调,2 d、3 d、7 d表达下调;Riluzole治疗组Na(v)1.6 mRNA缺血后6 h～7 d表达均呈下调趋势;相同时间点Riluzole治疗组Na(v)1.6 mRNA较缺血组表达下调,比较差异有统计学意义(P＜0.05).缺血组和Riluzole治疗组脑梗死体积均在缺血后3 d时最大,相同时间点Riluzole治疗组脑梗死体积比缺血组小,比较差异有统计学意义(P＜0.05).结论 Riluzole可以下调Na(v)1.6表达,减轻缺血性脑损伤,Na(v)1.6可能参与缺血性脑损伤的发病过程.

Abstract：

Objective To observe the changes of Na(v)1.6 expression in rats after acute cerebral ischemia and the effect of Riluzole (the sodium channel blocker) on these changes, and discuss the relationship between level of Na(v)l.6 and cerebral ischemia. Methods One hundred and five healthy SD rats were randomly divided into sham-operated group (n=15), ischemia control group (IC, n=45) and Riluzole therapy group (RT, n=45). Rat models of focal acute cerebral ischemia in the later 2 groups were established by permanent occlusion of right middle cerebral artery. Riluzole at a dosage of 8 mg/kg was given once daily to the rats of the RT group 30 min after ischemia. Tissues from the striatum were collected at different time points (6 h, and 1, 2, 3 and 7 d after ischemia); the expressions of Na(v)1.6 in the striatum were detected by immunofluorescence staining and real-time quantitative PCR at each time point; and the infarct volume was observed by triphenyltetrazolium chloride staining at each time point.Results The rats in the IC group and RT group showed neurologic impairment, especially 2 d after ischemia; rats of the IC group presented significantly higher scores of neurological function scale than those of the RT group at the same time point (P＜0.05). Immunofluorescence staining showed that the expression of Na (v)1.6 was up-regulated, and reached its peak level 1 d after ischemia but then, was down-regulated both in the IC group and RT group. Real-time quantitative PCR showed that the expression of Na(v)1.6 in the IC group was up-regulated 1 d after ischemia, and then down-regulated 2, 3 and 7 d after ischemia, however, that in the RT group was down-regulated 6 h after ischemia; the mRNA expression of Na (v)1.6 in the RT group was obviously down-regulated as compared with that in the IC group at the same time point (P＜0.05). The infarction volume became the largest 3 daRer ischemia both in the IC group and RT group; the infarction volume in RT group was smaller than that in IC group at the same time point (P＜0.05). Conclusion The expression of Na(v)1.6 is down-regulated after cerebral ischemic injury to mitigate acute cerebral ischemic injury, indicating that Na (v)1.6 might involve in the development of cerebral ischemic injury.