[Effect on p53 and caspase-3 of hippocampal neuron in the rats with cerebral ischemia-reperfusion injury treated with electroacupuncture preconditioning at the acupoints on the basis of biao and ben relationship]

Abstract

Objective: To explore the protective effect and apoptosis-related mechanism of electroacupuncture (EA) preconditioning in the rats with cerebral ischemia-reperfusion injury.

Methods: Sixty male SD rats, 3 months old, at SPF grade were randomized into a sham-operation group, an ischemia-reperfusion group and an EA preconditioning group, 20 rats in each one. In the ischemia-reperfusion group and EA preconditioning group, the modified MCAO suture-occlusion method was adopted to exert ischemia for 2 h and reperfusion for 3 h, and thus, the models of focal cerebral ischemia-reperfusion injury were prepared on the right side. In the sham-operation group, the right common carotid artery was separated and no more management was given. In the EA preconditioning group, EA at "Baihui" (GV 20), "Shenshu" (BL 23) and "Sanyinjiao" (SP 6) was provided before modeling, with disperse-dense wave, at 2 Hz/100 Hz, 1 mA in intensity. The stimulation for 15 min was taken as one unit (meaning electric stimulation for 10 min and needle retaining for 5 min without electric stimulation). Such preconditioning was repeated continuously for 4 times, totally for 1 h. The neuroethologic condition was assessed in 3 h of reperfusion in each group. TTC staining method was used to determine the percentage of cerebral infarction zone, TUNEL method was to determine the apoptosis index (AI) in hippocampal neuron and the immunohistochemical method (IHC) was to determine the protein expression of p53 and caspase-3.

Results: Compared with the sham-operation group, the neuroethologic score, the percentage of cerebral infarction zone and neuronal AI were all increased obviously in the ischemia-reperfusion group (all P<0.01). Compared with the ischemia-reperfusion group, the neuroethologic score, the percentage of cerebral infarction zone and neuronal AI were all reduced obviously in the EA preconditioning group (all P<0.01). p53's nuclei and caspase-3's cytoplasms were stained. The positive cells of both of them were brown-yellow in color. In the sham-operation group, the structure of the right hippocampal CA3 neurons of rats was clear, with few positive cells. In the ischemia-perfusion group, the positive expressions of p53 and caspase-3 in the right hippocampal CA3 were increased obviously (P<0.01). Compared with the ischemia-reperfusion group, the positive expressions of caspase-3 and p53 in the right hippocampal CA3 were significantly reduced in the EA preconditioning group (P<0.01).

Conclusion: Electroacupuncture preconditioning relieves ischemic injury in brain tissue of rats probably through inhibiting the expressions of p53 and caspase-3 to resisting neuronal apoptosis.

Keywords: apoptosis; caspase-3; cerebral ischemia-reperfusion injury; electroacupuncture preconditioning; p53.