茶氨酸在大鼠脑缺血/再灌注过程中对大鼠海马c-Jun氨基末端激酶和P38信号通路的作用

目的 探讨茶氨酸在大鼠脑缺血/再灌注(ischemia/reperfusion,I/R)过程中对大鼠海马c-Jun氨基末端激酶(c-Jun N-terminal kinases,JNK)和P38信号通路所发挥的作用.方法 雄性SD大鼠108只,体重290~310 g,采用随机数字表法分成假手术组(SH组)、I/R组、茶氨酸组(TH组),每组36只.每组根据再灌注时间分为2、6、12、24、48、72 h 6个亚组,每亚组6只.采用4-VO法建立SD大鼠全脑缺血模型,在预定时间点行灌注、固定、取脑、石蜡包埋切片,免疫组化检测磷酸化JNK(phosphorylate JNK,p-JNK)和磷酸化P38(phosphorylate P38,p-P38)的表达变化,光镜下计数CA1区存活细胞,TUNEL法检测CA1区凋亡细胞.结果 与SH组比较,I/R组海马CA1区各时点p-JNK和p-P38表达明显增加(P<0.01),于再灌注2 h时即明显升高灰度值分别为(163.5±3.8)和(163.0±1.9)],24 h到高峰灰度值分别为(132.3±4.9)和(141.0±5.7)].TH组p-JNK和p-P38的表达则无明显增高,各时点与I/R组比较差异均有统计学意义(P<0.05).海马CA1区神经元存活数目TH组明显高于I/R组(P<0.01),凋亡细胞数显著低于I/R组(P<0.01).结论 在大鼠全脑I/R损伤过程中,茶氨酸通过抑制JNK和P38信号通路的激活可对脑I/R损伤导致的细胞损伤起到保护作用,对临床脑缺血的治疗有一定的指导意义.

Effects of theanine on c-Jun N-terminal kinases and P38 signaling pathways in rat hippocampus after ischemia/reperfusion

Objective To discuss the effects of theanine(TH) on c-Jun N-terminal kinases (JNK) and P38 signaling pathways in the hippocampus after brain ischemia/reperfusion (I/R). Methods One hundred and eight adult SD rats (290-310 g) were randomly divided into 3 groups:sham operation group (SH group), I/R group, and TH+I/R group (TH group). Transient general brain ischemia was induced by four-vessel occlusion, and the rats were sacrificed at 2, 6, 12, 24, 48 h and 72 h after reperfusion. Phosphorylated c-Jun N-terminal kinases (p-JNK) and phosphorylated P38 (p-P38) in hippocampal CA1 region were detected by immunohistochemistry. Survival and apoptotic neurons in hippocampal CA1 region were counted by histochemistry and TUNEL. Results In comparison with SH group, I/R group showed higher levels of p-JNK and p-P38 in hippocampal CA1 region 2-72 h after reperfusion, and the difference reached maximum at 24 h after reperfusion. Interestingly, TH injection 4 h before ischemia prevented the decrease of p-JNK and p-P38 after I/R, and maintained their levels similar to SH group. Additionally, TH also improved neuronal survival and attenuated neuronal apoptosis in hippocampal CA1 region in response to I/R. Conclusions TH protected hippocampal CA1 neurons against I/R-induced apoptosis by inhibiting the phosphorylation of JNK and P38, and might be a therapeutic approach for brain I/R injury.