The Mechanism Of Electroacupuncture AmelioratingLearning And Memory Ability In Rats Wim Focal Cerebral Ischemia Via Oxidative Stress And Signal Transduction Pathway Of CREB

Objective:To investigate the effect of electroacupuncture (EA) at shenting and baihui ameliorating learning and memory ability in rats with focal cerebral ischemia via inhibiting oxidative stress and profoundly activating CREB signaling, resulting in the inhibition of cerebral cell apoptosis in the ischemic penumbra. And to clarify the possible mechanism of EA in treatment of cognitive impairment after cerebral ischemia.Methods:A total of 96 male adult SD rats were randomly divided into Sham group, MCAO group (ischemic rats without EA stimulation); EA group (ischemic rats with EA stimulation) and NO-point group (ischemic rats with EA at no-point stimulation). Middle cerebral artery occlusion (MCAO) was performed to establish the focal cerebral ischemia injury model. The EA stimulation parameter were disperse-dense waves of 1-20 Hz of frequency and current intensity was just below the level that induced visible muscle contraction,30minutes each time, once a day. The treatment 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 for 7 days. The neuroprotective effect of EA stimulation on the ischemic rats was evaluated by neurological deficit scores and cerebral infarct volumes.The learning and memory ability was tested by Morris water maze. The expression intensity of cleaved caspase-3 in the surrounding brain ischemia was determined by immunohistochemical staining. Activation of CREB signaling pathway was detected by Western blotting and reverse transcription PCR analysis.Using chemical assay to detect the oxidative stress productive of SOD,MDA and GSH-PX.Results:(1) The neuroprotective effect of EA stimulation on the ischemic rats was evaluated by neurological deficit scores, Morris water maze analysis test and cerebral infarct volumes. EA at shenting and baihui acupoints significantly alleviated neurological deficits compared with MCAO and NO-point group (P<0.05).(2) EA stimulation improved the promotion of cognitive impairment after cerebral ischemia in rats.The rats in the MCAO group had longer latency periods and took longer routes to reach the hidden platform, whereas the number of times that these rats crossed the location of the platform was significantly lower than that of the rats in the sham group (P<0.01). However, compared with the MCAO group and NO-point group, the rats in the EA group had a shorter latency and route length, and the number of times they crossed the platform was higher (P<0.05).(3) TTC result that:Compared with Sham, the infarct volumes of MCAO and NO-point group are increased (P<0.01); Moreover, EA at shenting and baihui significantly reduced infarct volumes compared with MCAO and NO-point group (P<0.05). Demonstrating the therapeutic efficacy of EA against cerebral ischemia.(4) EA stimulation chould inhibit oxidative stress. MDA content, an index of lipid peroxidation, increased significantly after cerebral injury (P<0.01). EA treatment significantly decreased the MDA content in comparison to the MCAO group and NO-point group (P<0.05). Furthermore, the activities of antioxidant enzymes, including SOD and GSH-Px, decreased in the MCAO group compared with the sham group (P<0.01). However, EA treatment induced a significant elevation of SOD and GSH-Px activities compared with the MCAO group and NO-point group (P<0.05).(5) EA ameliorated learning and memory ability in rats with focal cerebral ischemia via activating CREB’signaling and the inhibition of cerebral cell apoptosis in the ischemic penumbra. Compared with the sham group, the expression of p-CREB and Bcl-2 were decreased and the expression of Caspase-3 and Bax protein were increased in MCAO group (P<0.01), demonstrating that ischemic injury induced neuronal apoptosis. EA could promote the expression of p-CREB and Bcl-2 and inhibit the expression of Caspase-3 and Bax, and thus play its anti-apoptotic neuroprotection.Conclusion:EA on the Baihui (DU20) and Shenting (DU24) acupoints can improve cognitive impairment after cerebral ischemia. The protective effect of EA was associated with its anti-apoptotic mechanism via activation of the CREB and inhibition of oxidative stress.