Abstract: In this study,the protective effects of astaxanthin (AS) on long time and intensive exercise-induced myocardial injury of rats were investigated.56 Male Wistar rats were divided into 4 groups randomly:control group (C group,n=12),general training group (M group,n=12),overtraining group (OM group,n=16) and AS+Overtraining group (AM group,n=16).The rats (OM group) were given with 20 mg/kg·d AS for 56 d increasing load swimming training.The serum cardiac troponin I (cTnI),myocardial superoxide dismutase (SOD),malondialdehyde (MDA),serum and myocardial endothelin (ET) and calcitonin gene related peptide (CGRP) content and related biochemical indexes were measured after the last training.The results showed 8 weeks of training lead to exerciseinduced myocardial injury in rats.(1) Serum cTnI levels,there was no significant difference between C and M (P>0.05);OM increased significantly compared with C (P<0.01);AM was significantly lower than that of OM (P<0.05).(2) SOD activity,OM and AM group was significantly lower than that of C (P<0.01,P<0.05),AM group was significantly higher than OM group (P<0.05);Myocardial MDA content of OM and AM group was significantly higher than that of group C (P<0.01,P<0.05),AM was significantly lower than OM group (P<0.05).(3) The content of serum and myocardial endothelin,OM and AM was significantly higher than that of group C (P<0.01,P<0.05),AM was significantly lower than OM group (P<0.01);Serum,myocardial CGRP,OM and AM was significantly lower than that of group C (P<0.01, P<0.05),AM group was significantly higher than OM group (P<0.05).Hence,these results indicated that supplement of AS effectively promoted the activity of antioxidant enzymes,and removed excess free radicals;It inhibited the secretion of ET and promoted the secretion of CGRP,then ensured that the balance of ET and CGRP.In conclusion,AS prevented the myocardial injury caused by long time and intensive training.

Key words: astaxanthin, exercise-induced myocardial injury, cardiac troponin I, endothelin, calcitonin gene related peptide