Electroacupuncture Enhances The Proliferation Of NPCs After Cerebral Ischemia-Reperfusion Via Activation Of Wnt/β-catenin Pathway

Objective:To investigate electroacupuncture (EA) at Quchi and Zusanli enhances the proliferation of nerve precursor cells (NPCs) in cerebral ischemia-reperfusion injured rats via Wnt/β-catenin pathway and to clarify the possible mechanism of electroacupunctue in treatment of cerebral ischemia.Methods:A total of81male adult SD rats were randomly divided into Sham group. MCAO group (ischemic rats without EA stimulation) and EA group (ischemic rats with EA stimulation). Middle cerebral artery occlusion (MCAO) was performed to establish the focal cerebral ischemia-reperfusion (I/R) injury model. The EA stimulation parameter were disperse-dense waves of1-20Hz of frequency and current intensity was just below the level that induced visible muscle contraction,30minutes each time, once a day. The treatment on ipsilateral side was started the next day after operation and continued until the animals were sacrificed. Sham and MCAO groups did not undergo any EA, which was administered for3days. The neuroprotective effect of EA stimulation on the ischemic rats was evaluated by neurological deficit scores, cerebral infarct volumes and the movement function of paralyzed limb. The proliferation and differentiation of NSCs in cerebral I/R injured rats was determined by immunohistochemical staining. Activation of Wnt/B-catenin signaling pathway was detected by Western blotting and reverse transcription PCR analysis.Results:(1) The neuroprotective effect of EA stimulation on the ischemic rats was evaluated by neurological deficit scores, catwalk quantitative gait analysis test and cerebral infarct volumes. There was no significant difference between MCAO and EA groups at2h after cerebral I/R. However, EA at Quchi (LI11) and Zusanli (ST36) acupoints for3d significantly alleviated neurological deficits (MCAO:2.08±0.79, EA:1.42±0.67P=0.037) and recoverd the Stride Length of right forepaw (P=0.037).(2) Moreover, EA at Quchi and Zusanli significantly reduced infarct volumes (MCAO:22.39±5.59%, EA:35.39±3.48%P=0.002), demonstrating the therapeutic efficacy of EA against cerebral ischemia. (3) The electric needle stimulation obviously enhanced the proliferation of nerve stem/progenitor cells (Nestin+/GFAP+) in cortical peri-infarct area after stroke, but not in dentate gyrus.(4) It was known that the activation of Wnt/β-catenin pathway was inhibited after cerebral ischemia. Conversely, the protein and mRNA levels of Wntl and β-catenin were increased, while GSK3transcript was suppressed by EA.Conclusion:The up-regulatory effect of EA on Wnt/β-catenin signaling pathway may promote the proliferation nerve precursor cells (NPCs) in peri-infarct cortex, which to elucidate the therapeutic mechanisms of electroacupuncture in cerebral ischemia.