缺血预处理和缺血后处理对大鼠脑缺血再灌注时糖原合酶激酶-3β活性的影响

Effects of ischemic pre- and postconditioning on cerebral glycogen synthase kinase-3 beta activity in a rat model of cerebral ischemia-reperfusion

目的 探讨缺血预处理和缺血后处理对大鼠脑缺血再灌注时糖原合酶激酶-3β（GSK-3β）活性的影响.方法 雄性Wistar大鼠40只,体重200～230 g.随机分为4组（n=10）,假手术组（S组）仅分离双侧颈总动脉;缺血再灌注组（I/R组）分离双侧颈总动脉,夹闭10 min后恢复灌注;缺血预处理组（IPR组）分离双侧颈总动脉,夹闭10 s,开放30 s,反复3次,最后夹闭10min后恢复灌注;缺血后处理组（IPO组）分离双侧颈总动脉,夹闭10 min,开放30s,夹闭10 s,反复3次后恢复灌注.于术后2 d时取脑组织,计数大脑皮质凋亡神经元,测定脑梗死体积、磷酸化GSK-3β（p-GSK-3β）、Bcl-2、Bax、Caspase-3表达.对神经元凋亡数、脑梗死体积与p-GSK-3β水平做直线相关分析.结果 与S组比较,I/R组、IPR组和IPO组凋亡神经元、脑梗死体积增加,p-GSK-3β水平降低,Bcl-2表达下调,Bax和Caspase-3表达上调（P＜0.05）;与I/R组比较,IPR组和IPO组凋亡神经元和脑梗死体积降低,p-GSK-3β水平升高,Bcl-2表达上调,Bax和Caspase-3表达下调（P＜0.05）;IPR组和IPO组间上述指标比较差异无统计学意义（P＞0.05）.凋亡神经元、脑梗死体积与p-GSK-3β水平呈负相关（P＜0.05）.结论 缺血预处理和缺血后处理通过抑制GSK-3β活性而减轻大鼠脑缺血再灌注损伤.

Objective To investigate the effects of ischemic pre- and postconditioning on cerebral glycogen synthase kinase-3 beta （GSK-3β） activity in a rat model of global cerebral ischemia-reperfusion （I/R）.Methods Forty male Wistar rats weighing 200-230 g were randomly allocated into 4 groups （n =10 each） ： Ⅰ group sham operation （group S）; Ⅱ group I/R; Ⅲ group ischemic preconditioning （group IPR） and Ⅳ group ischemic postconditioning （group IPO）. The animals were anesthetized with intraperitoneal 10% chloral hydrate 0.4 ml/100 g. Global cerebral ischemia was induced by four-vessel-occlusion in group Ⅱ , Ⅲ and Ⅳ. Bilateral vertebral arteries were cauterized and bilateral carotid arteries were occluded for 10 min. In group IPR cerebral ischemia was preceded by 3 cycles of 10 s ischemia followed by 30 s reperfusion. The group IPO received 3 cycles of 30 s reperfusion followed by 10 s ischemia at the end of 10 min cerebral ischemia. The animals were killed 2 days later. The brains were immediately removed for determination of neuronal apoptosis in the cortex （by TUNEL）, the infarct size （by TTC）, p-GSK-3β activity （by spectrum assay） and the expression of Bcl-2, Bax and Caspase-3 （by SP）. Linear correlation of p-GSK-3β activity with the number of apoptotic neurons in the cortex and cerebral infarct size was analyzed. Results Cerebral I/R significantly increased the number of apoptotic neurons in the cortex and infarct size, decreased p-GSK-3β activity, down-regulated Bcl-2 expression and up-regulated Bax and Caspase-3 expression in group I/R as compared with group S. Ischemic pre- and postconditioning significantly attenuated these cerebral I/R-induced changes. The p-GSK-3β activity was negatively correlated with the number of apoptotic neurons in the cortex and cerebral infarct size. Conclusion Ischemic pre- and postconditioning reduces cerebral I/R injury through inhibiting the activity of GSK-3β.