Neuronal apoptosis and protective effect of nerve growth factor in hippocampal CA1 region after cerebral ischemia in rats

Objective To investigate the mechanism underlying apoptosis and protective effect of nerve growth factor (NGF) in hippocampal CA1 region after cerebral ischemia/reperfusion. Methods Wistar rats were inflicted with four vessel occlusion for global ischemia, and those in NGF group were given intraventricular injection of NGF after ischemia. Immunohistochemistry staining was used to detect P75NTR, Bcl 2 and Bax, and TUNEL method to detect apoptosis. Results The expression of Bax was positive, while the apoptosis and the expressions of P75NTR and Bcl 2 were negative in normal control. After ischemia/reperfusion, the expression of Bcl 2 was still negative, while the expression of P75NTR and Bax increased and reached its summit in day 3. TUNEL positive neurons were seen in day 2 and reached a peak in day 3. In NGF group, the expression of Bcl 2 was increased, while the expression of Bax, P75NTR and TUNEL positive cells were obviously decreased. Conclusion These findings suggest that the increased expression of P75NTR and Bax in hippocampal CA1 region after cerebral ischemia/reperfusion may be one of the main reasons for apoptosis after ischemia. Intraventricular NGF might have protective effect on neuronal apoptosis after cerebral ischemia via regulation the expression of Bcl 2 and Bax by regulated NGF receptor.