The Effects And Mechanism Of NGF On The Expression Of P53 After Focal Cerebral Ischemia Reperfusion In Rats

Objective: To observe p53 expression and neuron apoptosis after focal cerebral ischemia reperfusion in rats, to explore the effects and mechanism of NGF on the ischemic brain tissue.Methods: Making animal test, middle cerebral artery occlusion (MCAO) was employed to make focal cerebral ischemia. sixty-six SD rats were randomized into 3 groups: Sham-operation group(n=6), ischemia-reperfusion group(n=30) and NGF treatment group(n=30). I/R group, NGF group were subdivided into 6,12,24,48 and 72h group after 2h MCAO.6 rats in each group. After been executed, brains of all rats were taken out, and fixed at special time. The pathological changes were observed by HE staining. The expression of p53 protein was detected by immunchistochemical staining technique in ischemic region. And the cell apoptosis was also characterized by flow cytometry.Result: 1. Histopathologic changes in hippocampus: In sham group, neurons were arranged orderly and intactness; the neurons in I/R group were swollen, arranged asymmetrically, the cellular interspace widened, the volume of some cells decreased with nuclear pyknosis and dyed darkly. 2. p53 protein positive cells were not found in sham group, and were found in I/R group after 6h reperfusion. The number of the positive cells reached the peak at 24h, then decreased gradually. Under microscope, immunoreactive products were brown, mainly expressed in nuclear, slightly in cytoplasm. The average optical density of p53 protein positive cells in NGF group was obviously lower than that in I/R group(P<0.05). 3. The flow cytometry was applying to test the apoptosis proportion. The apoptosis proportion in I/R group was higher than that in sham group.Conclusion: Apoptosis is one of the neuronal death'means after cerebral ischemia- reperfusion. P53 protein joined the cerebral ischemia's injury, it could accelerated the neuronal apoptosis, and something effective would be done to intervene the apoptosis correctly. NGF downregulate the expressions of p53 protein, which might be one of the molecular mechanisms for protecting the function of ischemic neurons.