Effects of early electroacupuncture on the expression of brain derived neurotrophic factor-m RNA in the bilateral cerebral cortex after local cerebral ischemia in rats

Objective: To examine the temporal effects of electroacupuncture(EA) on the changes of brain derived neurotrophic factor(BDNF)- m RNA in bilateral cerebral cortexes after local cerebral ischemia in rats in order to approach the mechanism of cross education of EA on hemiplegia.Method: Fifty-four SD rats with middle cerebral artery occlusion(MCAO) were established the local ischemic models and randomly divided into three groups: control group(CG, n=18), unaffected limb therapy group(UALTG, n=18), and affected limb therapy group(ALTG, n=18). EA groups received EA at 24 h after the onset of MCAO model. Six rats in each group were sacrificed in a random order, at the 7th, 14 th and 21 st d after modeling. Ischemic cerebral and the contralateral cortex were dissected quickly. The specimens were frozenin liquid nitrogen before analyse for BDNF-m RNA expression by RT-PCR.Result: 1The up-regulation expression of BDNF-m RNA in the ischemic cortex of ALTG demonstrated significantly higher than that of CG at the 7th d,14 th d,21 st d(P0.01),The level of BDNF-m RNA in UALTG was higher than that of CG at the 7th d,21 st d,meanwhile,which was higher than that of ALTG(P0.01);2There was also a quickly high expression of BDNF- m RNA in the contralateral cortex of ALTG at the 7th d and14 th d,which was higher than that of CG(P0.01). The expression of BDNF-m RNA in UALTG become higher than that of CG at the 14 th d(P0.01),but lower than that of ALTG(P0.01), the levels of both EA groups were significantly lower than that of CG at the 21 st d(P0.01).Conclusion: The up-regulation expression of BDNF-m RNA level in ischemic and contralateral cortex were observed after EA on both side limbs, which indicated the effectiveness of cross-education.From the 7th d to the21 st d,The expression of BDNF- m RNA consecutively kept high level in ischemic cortex in EA groups,higher expression of BDNF gene induced by EA intervention on the unaffected limb, which showed EA intervention on the unaffected limb at earlier time might promote nerve-regeneration better in ischemic cortex, facilitate the balance of both side cortexes.This plasticity may be one of the mechanisms that promote better recovery and lower mortality in rats with MCAO.