Dynamic changes of neuronal protein expression and apoptosis in rats with cerebral ischemic penumbra

Objective To observe the dynamic changes of neuronal protein expression and apoptosis in rats with cerebral ischemic penumbra after focal ischemia/reperfusion(I/R).Methods Fortyeight male Wistar rats were randomly divided into sham operation group(n= 8) and model group (n= 40).The model group was further divided into 6,24,48 h,3 d and 5 d I/R groups(8 in each group).Bcl-2 and Bax protein expressions were detected in ischemic penumbra of different groups by immunohistochemistry,and dynamic changes of neuronal apoptosis in corresponding regions were detected with TUNEL staining.Results The number of Bcl-2 and Bax positive cells was significantly greater in model group than in sham operation group 6 h after I/R.The number of Bcl-2 positive cells decreased gradually with the porlongation of time and reached its minimium 48 h after I/R,while that of Bax positive cells increased gradually and reached its peak 48 h after 1/ R.The ratio of Bcl-2/Bax was consistent with the number of Bcl-2 positive cells.Neuronal apoptosis occurred at different time points and reached its peak 48 h after I/R(P0.01).Correlation analysis showed that the neuronal apoptosis was positively related with the expression of Bax protein (r=0.352,P0.05) and negatively related with the expression of Bcl-2 protein and the ratio of Bcl-2/Bax(r=-0.517,r=-0.529,P0.01).Conclusion Neuronal apoptosis occurs in rats with cerebral ischemic penumbra,which may be related with the imbalanced ratio of Bcl-2/Bax.