Research of the heart protective effect of exercise precondition mediated by calcitonin gene related peptide on acute exhaustion rats

Abstract

To observe the heart protective effect of exercise preconditioning (EP) in the acute exhaustion exercise (EE) rats, and explore its action mechanism further. Eighty healthy male Sprague-Dawley (SD) rats were divided into control group (C group), EP group, EE group, and EP+EE group randomly, with 20 rats in each group. The rats in EP and EP+EE groups were trained for 3 weeks according to the daily swimming for 60 minutes (swimming 15 minutes, resting 5 minutes, repeating 3 times) with 6 days each week. The rats in EE and EP+EE groups on the last 1 day after 3 weeks, 3% weight heavy weight was carried once for swimming EE. Two hours after the last EE, abdominal aortic blood and heart was harvested, the levels of serum MB isoenzyme of creatine kinase (CK-MB) and calcitonin gene related peptide (CGRP) were determined by enzyme linked immunosorbent assay (ELISA); the ultrastructure of myocardium was observed by optical microscopy; the levels of myocardial malondialdehyde (MDA) and superoxide dismutase (SOD) were determined by ELISA, the mRNA expression of myocardial CGRP was assayed by reverse transcription-polymerase chain reaction (RT-PCR), and the protein expression of myocardial CGRP was assayed by Western Blot. Compared with C group, the levels of serum CK-MB and myocardial MDA were significantly increased, serum CGRP content, myocardial SOD activity, and mRNA and protein expressions of myocardial CGRP were significantly decreased in EE group and EP+EE group. Compared with EE group, the levels of serum CK-MB and myocardial MDA in EP+EE group were decreased [CK-MB (U/L): 13.11±0.77 vs. 15.55±0.90, MDA (μmol/L): 389.57±49.60 vs. 709.08±160.49], the level of serum CGRP, and mRNA and protein expressions of myocardium CGRP were increased [serum CGRP (ng/L): 120.41±9.07 vs. 97.97±9.05, CGRP mRNA (2 -ΔΔCT): 0.45±0.09 vs. 0.14±0.02, CGRP protein (gray value): 0.78±0.08 vs. 0.41±0.04, all P < 0.05], the degree of myocardial injury was obviously alleviated. There was no significant difference in the indexes between the EP group and C group. EP has the heart protective effect for the acute EE rats, and the mechanism is closely related to the endogenous protective substance CGRP.