Electroacupuncture-like stimulation at Baihui and Dazhui acupoints exerts neuroprotective effects through activation of the brain-derived neurotrophic factor-mediated MEK1/2/ERK1/2/p90RSK/bad signaling pathway in mild transient focal cerebral ischemia in rats

BACKGROUND: This study was designed to evaluate the effects of electroacupuncture-like stimulation at Baihui (GV20) and Dazhui (GV14) acupoints (EA at acupoints) following mild cerebral ischemia-reperfusion (I/R) injury. Furthermore, we investigated whether brain-derived neurotrophic factor (BDNF)-mediated activation of extracellular signal-regulated kinase (ERK)1/2 signaling pathway is involved in the neuroprotection induced by EA at acupoints. METHODS: Rats were subjected to middle cerebral artery occlusion (MCAo) for 15 min followed by reperfusion for 3 d. EA at acupoints was applied 1 d postreperfusion then once daily for 2 consecutive days. RESULTS: Following the application of EA at acupoints, initiated 1 d postreperfusion, we observed significant reductions in the cerebral infarct area, neurological deficit scores, active caspase-3 protein expression, and apoptosis in the ischemic cortex after 3 d of reperfusion. We also observed markedly upregulated BDNF, phospho-Raf-1 (pRaf-1), phospho-MEK1/2 (pMEK1/2), phospho-ERK1/2 (pERK1/2), phospho-90 kDa ribosomal S6 kinase (pp90RSK), and phospho-Bad (pBad) expression, and restored neuronal nuclear antigen (NeuN) expression. Pretreatment with the MEK1/2 inhibitor U0126 abrogated the effects of EA at acupoints on cerebral infarct size, neurological deficits, active caspase-3 protein, and apoptosis in the ischemic cortex after 3 d of reperfusion. Pretreatment with U0126 also abrogated the effects of EA at acupoints on pMEK1/2, pERK1/2, pp90RSK, pBad, and NeuN expression, but did not influence BDNF and pRaf-1 expression. CONCLUSION: Overall, our study results indicated that EA at acupoints, initiated 1 d postreperfusion, upregulates BDNF expression to provide BDNF-mediated neuroprotection against caspase-3-dependent neuronal apoptosis through activation of the Raf-1/MEK1/2/ERK1/2/p90RSK/Bad signaling cascade after 3 d of reperfusion in mild MCAo.