Study On The Mechanism Of Electroacupuncture Based On Irisin-related Pathway To Improve Motor Function In Rats With Cerebral Ischemi

Objective:The positive muti-level therapeutic effect of electroacupuncture on ischemic stroke injury through multiple mechanisms has been confirmed,but these mechanisms have not been fully understood.In this study,we observed the effect of electroacupuncture on the expression of peroxisome proliferator-activated receptor gamma coactivators-1-alpha（PGC-1α）/fibronectin type Ⅲ domain-containing protein5（FNDC5）/brain-derived neurotrophic factor（BDNF）in the ischemic hemispheric cortex,hippocampus and local skeletal muscle around the acupoint zone of rats with focal cerebral ischemia reperfusion,and the effect of intramuscular injection of ¹²⁵I-Irisin at the acupoint of hemiplegic limb,so as to investigate the Irisin-related pathway mechanism to the improvement of cerebral ischemia reperfusion injury induced by electroacupuncture.Methods:Sprague Dawley（SD）rats were randomly divided into sham-operation group,model group and EA group;¹²⁵I-Irisin label sham-operation group,¹²⁵I-Irisin label model group and ¹²⁵I-Irisin label EA group.The focal cerebral ischemia reperfusion injury（CIRI）model was established by transient middle cerebral artery occlusion（t MCAO）.EA group selected“Quchi”（LI 11）and“Zusanli”（ST36）on the opposite side of cerebral ischemia as the intervention acupoints for 20 min each time,once a day for 7 days.Zea-Longa’s Score and Balance Beam Score were used to determine and observe if model’s establishment was successful or not and the degree of motor function recovery in each group.Using 2,3,5-triphenyltetrazolium chloride（TTC）staining to detect the infarcted volume of the brain.The expression levels of PGC-1α,FNDC5 and BDNF proteins in the ischemic hemispheric cortex,hippocampus and local skeletal muscle that had EA were detected by Western Blot.Irisin was labeled with I-125 by Iodogen method,and the quality of ¹²⁵I-Irisin protein was analyzed by instant thin-layer chromatography（i TLC）.The distribution of ¹²⁵I-Irisin in vivo was obtained by single photon emission computed tomography（SPECT）.Results:Compared with sham-operation group,Zea-Longa’s Score and Balance Beam Score were increased（P<0.01）,the percentage of cerebral infarct volume was significantly increased（P<0.01）,and the expression levels of PGC-1α,FNDC5 and BDNF proteins in ischemic hemispheric cortex and hippocampus were significantly decreased（P<0.01,P<0.05）,the expression levels of PGC-1α,FNDC5 and BDNF proteins in muscle were not changed（P>0.05）.Compared with the model group,Zea-Longa’s Score and Balance Beam Score in EA group were significantly decreased（P<0.01）,the percentage of cerebral infarct volume was significantly decreased（P<0.01）,the expression levels of PGC-1α,FNDC5 and BDNF proteins in ischemic hemispheric cortex were significantly increased（P<0.01）,and only the expression level of BDNF protein in the ipsilateral hippocampus was significantly increased（P<0.05）,the expression levels of PGC-1αand FNDC5 were not changed（P>0.05）,the expression levels of PGC-1α,FNDC5 and BDNF proteins in muscle were not changed（P>0.05）.i TLC analysis showed that the radiochemical purity of ¹²⁵I-irisin was over 90%.SPECT imaging showed that ¹²⁵I-irisin in muscle could quickly enter the blood and be absorbed and metabolized by the gallbladder and kidney.The retention of ¹²⁵I-irisin in the brain was similar to that in general tissues,and there was no significant difference in the distribution of ¹²⁵I-irisin between the three groups.Conclusion:1.Electroacupuncture can improve motor function and reduce cerebral infarction volume in t MCAO rats,and the mechanism may be related to the activation of PGC-1α/FNDC5/BDNF pathway in the ischemic cortex.2.¹²⁵I-irisin is rapidly metabolized and cleared by the gallbladder and kidney within 48 hours.Electroacupuncture of LI11 and ST36 with short treatment period had little effect on the brain’s uptake of peripheral Irisin and the regulation of PGC-1α/FNDC5/BDNF pathway in skeletal muscle.3.Compared with peripheral FNDC5/Irisin,the up-regulation of BDNF in the brain by short-time electroacupuncture intervention may be more influenced by central PGC-1α/FNDC5/BDNF pathway.