Effect of N~G-nitro-L-arginine(L-NA) on neuronal apopotosis induced by focal cerebral ischemia in rats / 中国药理学通报

ABSTRACT

Aim To investigate the effect of L-NA on cerebral ischemic injury and the possible mechanism by evaluating the effect of N~G-nitro-L-arginine(L-NA) on neuronal apopotosis induced by transient focal cerebral ischemia in rats.Methods Male SD rats weighing 250～300 g were randomly divided into 3 groups sham operation group(SH),ischemic group(IS) and LNA group(L-NA).IS and L-NA group were further divided into 3 subgroups according to the duration of ischemia 2 h,6 or 12 h(n=6).In L-NA group,L-NA(20 mg?kg~(-1),ip) was administrated,2 times per day,for 3 consecutive days.Saline was administrated in IS group.The focal cerebral ischemic model(MCAO) was made by thread embolism of left middle cerebral artery.In sham operation group,the external carotid artery was surgically prepared for insertion of the filament,but the filament was not inserted.Rats were killed at the scheduled time.Apoposis was detected with FCM.The expression of caspase-3 protein was observed using Western blot analysis and immunohistochemistry.The expression of bcl-2 and Bax protein was measured using immunohistochemistry and FCM.Results After MCAO significant DNA fragmentation was detected.The percentage of apoptotic cells and the expression of caspase-3 and Bax protein were increased.The ratio of bcl-2/Bax was decreased.The difference of bcl-2 protein between IS group and L-NA group was not statistically significant.In L-NA 12 h group,the percentage of apoptotic cells and the expression of caspase-3 and Bax protein were decreased.The expression of bcl-2 and the ratio of bcl-2/Bax were increased.There was no significant difference in the percentage of apoptotic cells and the expression of caspase-3,Bax,bcl-2 protein and bcl-2 /Bax between L-NA 2,6 h group and IS group.Conclusion L-NA has beneficial effect on late stage ischemic brain of rats.The protective mechanism is that administration of L-NA could reduce the expression of caspase-3,increase the expression of bcl-2 protein,and regulate the balance between bcl-2 and Bax protein.