Effects Of Electroacupuncture On The Expression Of BDNF,Sema3A,and NRP-1 In Rats With Focal Cerebral Infarction

Objective:To observe the effect of electroacupuncture on the expression of brain-derived neurotrophic factor（BDNF）,semaphorin 3A（Sema3A）in the contralateral cerebral cortex and motor function in rats with unilateral focal cerebral infarction,and to explore the possible mechanism of electroacupuncture to promote the recovery of nerve function.Methods:SPF male Sprague-Dawley rats were randomly divided into surgery group（n=99）and sham operation group（n=48）.The rats in the operation group were treated with Longa modified suture method to prepare the right middle cerebral artery occlusion（MCAO）rat model.The neurological function scores of MCAO rats were evaluated by Bederson 4 points and 5methods and select the rats which score of 3-4 in this experiment.At 24h after surgery,3 MCAO rats in the operation group were randomly selected for TTC staining to observe the location of cerebral infarction.The rats in the operation group were randomly divided into the model group（n=48）,the electroacupuncture group（n=48）,then the sham operation group,the model group,and the electroacupuncture group were divided into four subgroups（n=12）of 3d,7 days,14 days,and 28 days,respectively.Rats in the electroacupuncture group were treated with bilateral Neiguan and Zusanli electroacupuncture,and the model group and the operation group were bundled at the same time.At each time point,6 rats from each subgroup were randomly selected.Brain tissue was isolated and fixed after perfusion with 4%paraformaldehyde.HE staining and Nissl staining were used to observe the brain tissue structure and nerve of rats with cerebral infarction.The changes of BDNF,Sema3A and NRP-1 in the healthy cerebral cortex were detected by immunohistochemical method;the fresh brain tissue was taken for real-time fluorescence quantitative PCR（QT-PCR）,the relative expression levels of BDNF,Sema3A and NRP-1 mRNA in the healthy cerebral cortex were detected.Results:（1）Neurological function and motor function scores showed that there was no significant difference between the electroacupuncture group and the model group on the 3^th（P>0.05）,and neurological function and footstep error test scores on the 7^th,14^thh and 28^thh days gradually decreased,and electroacupuncture group was significantly lower than the model group（P<0.05）.（2）TTC staining showed that obvious infarcts in the right cerebral cortex,including sensorimotor areas,but no infarcts in the left brain.（3）HE staining showed that compared with the sham operation group,the number of nerve cells in the contralateral cerebral cortex of the model group and the electroacu-puncture group decreased on the third day after the operation,with partial solid shrinkage forming a triangle,deep nuclear staining,increased cell spacing and disordered arrangement.From the 7th day to the 28th day,the number of neurons gradually increased,and the morphology basically returned to normal with an orderly arrangement.The number of neurons in the electroacupuncture group increased faster than that in the model group.（4）Nissl staining showed that on the 3rd day after operation,the rats in the model group and the electroacupuncture group had slight lysis of the Nissl bodies in the cerebral cortex.At 7 days after surgery,the number of nissl bodies decreased and the nerve cells were slightly swollen,which was more obvious in the model group than in the electroacupuncture group.After 14 to 28 days,the number of Nissl bodies gradually returned to normal.（5）The results of immunohistochemistry showed that there was no significant difference in the mean optical density of BDNF between the electroacupuncture group and the model group on the third day after operation（P>0.05）.On the 7th,14th and 28th days after the operation,the average density of the electroacupuncture group was significantly higher than the model group（P<0.05）.There was no significant difference in the average density of Sema3A and NRP-1 between the electroacupuncture group and the model group on the third day after surgery（P>0.05）,and on the 7th,14th and 28th day the difference between the two groups was statistically significant（P<0.05）.（6）Real-time fluorescence quantitative PCR results showed that there was no significant difference in the relative expression of BDNFmRNA between the electroacupuncture group and the model group on the third day after surgery（P>0.05）.The expression level of the electroacu-puncture group on the 7th,14th and 28th postoperative day was significantly higher than that of the model.Group（P<0.05）.There was no significant difference in the relative expression levels of Sema3A and nrp-1 mrna between the electroacupuncture group and the model group on the 3rd day after surgery（P>0.05）,and the expression levels on the 7th,14th and 28th days were significantly lower than model group（P<0.05）.Conclusions:The contralateral cerebral cortex participates in the remodeling of nervous function after cerebral infarction.Electroacupuncture can compensate part of the function by regulating the contralateral cerebral cortex and improve the symptoms of neurological deficit and motor function recovery in rats.Its mechanism may be related to up-regulation of BDNF,promotion of nerve cell growth,down-regulation of Sema3A and NRP-1,and alleviation of the inhibition of axonal regeneration.