Effects of electroacupuncture pretreatment on survival,brain injury and cognitive function in rats after limb ischemia/reperfusion

AIM：To investigate the effects of electroacupuncture (EA) pretreatment on survival, brain injury and cognitive function in rats after limb ischemia/reperfusion (LI/R). METHODS：One hundred and thirty-two healthy male SD rats weighing 255~300 g were randomly divided into 3 groups (n=44 each)：sham operation group (sham), LI/R group and LI/R plus EA pretreatment (IL/R+EA) group. The LI/R model was made by a method that the bilateral femoral arteries were occluded for 3 h with atraumatic microclips followed by 48 h of reperfusion. In sham group, sham operation was performed. The EA pretreatment was conducted twice a day for 14 d prior to the LI/R event. EA pretreatment included the following acupoints：Baihui (GV20), Zusanli (ST36) and Xuehai (SP10). The survival rate within 7 d following LI/R was calculated. The changes of cognitive function were detected 48 h after reperfusion using Morris water maze test. The cerebral water content was determined by detecting the wet and dry weight. Microglial cells were evaluated following immunolabeling of Iba1 (a marker of microglia). The protein level of cleaved caspase-3 in the hippocampus was measured by Western blotting. The neuronal apoptosis was detected using TUNEL method. Meanwhile, the changes of pathological structure in hippocampus were observed under light microscope. The activity of MPO and SOD, and the content of ROS and MDA were also investigated. RESULTS：Compared with sham group, the Iba1 positive cells, the protein level of cleaved caspase-3, the apoptotic index, and the levels of ROS/MDA and MPO activity in LI/R and LI/R+EA groups increased significantly. The normal hippocampal neurons reduced, and SOD activity decreased significantly in hippocampus. The survival rates of the rats within 7 d decreased, the latency and swimming distance increased, and the number of crossing the platform reduced. Compared with LI/R group, the above indexes in LI/R+EA group were markedly improved. CONCLUSION：EA stimulation improves the survival rate and cognitive dysfunction, and reduces brain damage in LI/R rats by preventing microglial activation and attenuating oxidative stress.