Effects of NGF against cerebral ischemia-reperfusion injury in gerbils

Objective To investigate the effect of pretreatment with nerve growth factor(NGF) on apoptosis of neurons following global cerebral ischemia-reperfusion (I/R) injury in gerbils. Methods Fifty-four gerbils were randomly divided into five groups of sham operation(C,n=6),I/R(n=12),low dose of NGF(L,n=12),middle dose of NGF(M,n=12) and high dose of NGF(H,n=12).Groups I/R,L and H were divided into 2 subgroups according to the time from reperfusion to taking specimens,24-h and 72-h.Global cerebral I/R injury model was induced by occlusion of bilateral carotid arteries.NGF was injected into the lateral ventricle.Neural apoptosis was identified by TUNEL method and the expressions of Bcl-2 and Bax in the cerebral cortex were detected wih immunohischemistry assay.Results The number of apoptotic neurons and the positive expression of Bax protein in the cerebral cortex were increased and the positive expression of Bcl-2 protein was decreased as the duration of reperfusion prolonged in groups I/R,L,M and H,which were significantly more in groups L,M and H than those in group I/R and more in 72-h subgroup than those in 24-h subgroup(P0.05 or P0.01). Conclusion The neuronal cell apoptosis is involved in the progress of cerebral I/R injury.The pretreatment with different doses of NGF can significantly decrease the number of apoptotic neuronal cells in the cerebral cortex in a dose-dependent manner,which may be related to inducing Bcl-2 expression and inhibiting Bax expression.