Effect Of Inula Britannica On The Caspase-3and Cytochrome C Following Overtraining-induced Acute Myocardial Injury In Rats

Objective：Overtraining has become a research hotspot in sport medicineand military medical. Overtraining-induced acute myocardial injury (OTIAMI)is one of the most important causes resulted in sudden death of athlete onarena. At present, there is only a few effective drug therapy of OTIAMI inclinical. Therefore, it is very important to clarify the pathogenesis and to findthe methods to prevent and treat OTIAMI. In our study, we developed theanimal model of overtraining-induced acute myocardial injury by exhaustiveswimming. To investigate the role of Caspase-3and Cytochrome c (Cyt-c) andthe effect of Inula Britannica on overtraining-induced acute myocardial injuryin rats.Methods: Forty-eight male Wistar rats weighing200~220g wererandomly divided into3groups: control group (group CN, n=8), exhaustiveswimming group (group ES, n=24), Inula Britannica (IB, n=16). The animalmodel of overtraining-induced acute myocardial injury was established byexhaustive swimming. The rats of group CN were with no treatment. The ratsof group ES swimed to exhaustive state and collected inferior vena cava bloodand heart samples then sacrificed at immediately (ESI),6hour (ES6h)and24hour (ES24h) after exhaustive swimed. The rats of group IB were took orallyInula Britannica at the dose of25ml/kg body weight at two point, which is24h before swimming and immediately before swimming, then swimed toexhaustive condition. The rats of group IB were sacrificed at6hour (IB6h) or24hour (IB24h) after exhaustive swimming. Inferior vena cava blood andheart samples of the rats of group IB were collected and then sacrificed at6hour and24hour after exhaustive swimed. The heart samples for pathologicexamination with light microscope. The myocardial cell apoptosis wasmeasured by the method of terminal-deoxynucleotidyl transferase mediated d-UTP nick end labeling(TUNEL). The Cardiac TroponinⅠ (cTnⅠ) levels inserum were measured (by ELISA).The expression of Caspase-3and Cyt-cwere observed by immunohistochemistry.Results:1. The changes of histopathology on moycard in rats HEstaining showed that group C rat myocardial cells were oval or short spindle,and cardiac muscle fibers connected to each other tightly packed, can be seenclearly stripes. Only part of the myocardial fiber were swollen andhypertrophic and myocardial interstitial blood vessels and blood capilarydilated at instantly after exhaustive swimming in group ES; at6hours afterexhaustive swimming the nucleus of myocardial cells were deep stained,myocardial fiber were obviously swollen, hypertrophic, disorganized andirregular fracture; the swell and hypertrophy of myocardial fiber werealleviated at24hours after exhaustive swimming, myocardial cells scattered ina large number of inflammatory infiltration foci. The pathological changes ofmyocardial in group IB at6h and24h after exhaustive swimming weresignificantly reduced.2. The changes of the levels of cTnI of rats serum in different groupsCompared with group C the levels of cTnI were increased in groupESand group IB (P<0.05).Compared with group ES the levels of cTnI weredecreased in group IB (P<0.05). The levels of cTnI at the immediately afterexhaustive swimming were lower than6hour after exhaustive swimming inthe group ES. The levels of cTnI at6hour after exhaustive swimming werehigher than24hour after exhaustive swimming in the group ES (P<0.05).3. The changes of the apopatic index of myocardial cell in differentgroupsCompared with group C the apopatic index of myocardial cell wereincreased in group ES and group IB (P<0.05). Compared with group ES, theapopatic index of myocardial cell were decreased in group IB (P<0.05).Theapoptosis index of myocardial cell at6hour after exhaustive swimming werehigher than immediately and24hour after exhaustive swimming in the groupES (P<0.05). 4. The changes of the expression of Caspase-3and Cyt-c of ratsmyocardial in different groupsCompared with group C, the expression of caspase-3and Cyt-c wereincreased in group ES and group IB (P<0.05).Compared with group ES, theexpression of Caspase-3and Cyt-c were decreased in group IB(P<0.05). Theexpression of Caspase-3and Cyt-c at the immediately after exhaustiveswimming were lower than6hour and24hour after exhaustive swimming inthe group ES. The expression of Caspase-3and Cyt-c at6hour afterexhaustive swimming were higher than24hour after exhaustive swimming inthe group ES (P<0.05).Conclusions:1. The exhaustive swimming could induced acutemyocardial injury, but the injury could be repair partly afer24hour.2. The exhaustive swimming could induced myocardial cell apoptosis,prompts that myocardial cell apoptosis maybe the physiopathologymechanism of the OTIAMI.3. The Caspase-3and Cyt-c in rats myocardial participant the processof exhaustive swimming induced myocardial cell apoptosis. It prompts thatcaspase-related mitochondrial signal pathway mediating myocardial apoptosiswere startuped in process of OTIAMI.4. Inula Britannica can reduce overtraining-induced acute myocardialinjury in rats by inhibiting Caspase-3and Cyt-c expression.