Expression changes of nitric oxide synthase after cerebral ischemia/reperfusion injury in rats and the effect of timosaponin on it

Objective To observe the changes of nitric oxide synthase (NOS) expression after cerebral ischemia/reperfusion injury in rats,and study the effect of saponins from Rhizoma Anemarrhenae (SAaB) on these changes.Methods SAaB or normal saline was administered intragastrically into the rats and kept for 7 d.Then the model of 22-hour reperfusion injury was made after cerebral ischemia (MCAO) by occluding the middle cerebral artery for 2 h.Behavior changes due to cerebral apoplexy were observed.Then the rats were killed to detect the expressions of three types of NOS by immunohistochemical method.Results After statistical analysis,we could find that the expression of nNOS had been enhanced obviously while eNOS slightly by the ischemia injury.And in the SAaB low dose(50 mg/kg) and high dose (100 mg/kg) groups,the behavior grade of cerebral apoplexy was much lower than that in control group (P＜0.05).Besides,SAaB could significantly decrease the nNOS expression and induce the up-regulation of eNOS expression in ischemic areas.Conclusion All types of NOS play very important roles in the cerebral ischemia/reperfusion injury.And SAaB exerts definitive cerebral protective effects against ischemia/reperfusion injury thought the mechanism of decreasing nNOS expression and increasing eNOS expression.