Effect of Electroacupuncture on Neurological Deficit and Activity of Clock and Bmal1 in Cerebral Ischemic Rats

Abstract

Acute focal cerebral ischemic stroke (IS) is a leading cause of morbidity and mortality worldwide. Acupuncture is an emerging alternative therapy that has been beneficial to acute brain ischemia. However, the underlying protective mechanism of its neuroprotective effect remains unclear. Human original circadian rhythm will be lost after IS, which seriously affects the quality of life and functional recovery of stroke patients. We hypothesize that acupuncture treats IS by regulating the balance of Clock and Bmal1. This study aims to explore the effect of acupuncture at acupoints GV20 and BL23 on neuroprotection and anti-apoptosis in middle cerebral artery occlusion (MCAO) rats and expression of apoptosis and circadian rhythm related proteins. Male Sprague-Dawley (SD) rats were randomly divided into five groups: normal group (Normal), sham model group (Sham MCAO), MCAO model group (MCAO), sham electroacupuncture group (Sham EA) and electroacupuncture group (EA). The MCAO model was prepared by electrocoagulation. The first acupuncture treatment was performed within 2 h after surgery, and then acupuncture therapy was performed on 1st day, 2nd day and 3rd day respectively. After their neurological examination at 72 h of ischemia, the rats from each group were sacrificed. Triphenyltetrazolium chloride (TTC) staining was used to evaluate the brain infarct size. Ultrastructural observation on cerebral ischemic cortex and serum inflammatory cytokines were evaluated. TUNEL staining was used to detect cell apoptosis of brain tissue. The expression levels of proteins Bax, bcl-2, caspase-3, Clock and Bmal1 in the cerebral ischemic region were detected by immunofluorescence staining. Here, we presented evidence that EA at GV20 and BL23 could significantly improve the neurological deficit score and infarct size, and alleviate the cell apoptosis of brain tissue. Moreover, acupuncture treatment upregulated the anti-apoptotic Bcl-2/Bax ratio and reversed the upregulation of caspase-3 following 72-h cerebral ischemia. In addition, the expression levels of circadian proteins Clock and Bmal1 were upregulated in EA group while compared with MCAO group. Our study demonstrated that acupuncture exerted neuroprotective effect against neuronal apoptosis after stroke and the mechanism might be related with regulation of circadian rhythm proteins Clock and Bmal1.

Keywords: acupuncture; anti-apoptosis; circadian rhythms; middle cerebral artery occlusion.