降钙素基因相关肽参与运动预适应对急性力竭大鼠心脏保护作用的研究

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

目的探讨运动预适应（EP）对急性力竭运动（EE）模型大鼠的心肌保护作用及机制。方法健康雄性SD大鼠80只，按随机数字表法分为安静对照组（C组）、单纯EP组、单纯EE组、EP＋EE组，每组20只。EP组和EP＋EE组大鼠按照每日游泳60 min（游泳15 min、休息5 min、重复3次）、每周6 d的标准分别训练3周；EE组和EP＋EE组于第3周的最后1 d尾部负重3%体重的重物游泳1次进行EE。于EE后2 h取腹主动脉血和心脏；用酶联免疫吸附试验（ELISA）检测血清肌酸激酶同工酶（CK-MB）和降钙素基因相关肽（CGRP）水平；光镜下观察心肌组织超微结构改变，用ELISA检测心肌组织丙二醛（MDA）和超氧化物歧化酶（SOD）水平，用反转录-聚合酶链反应（RT-PCR）检测心肌组织CGRP mRNA表达，用蛋白质免疫印迹试验（Western Blot）检测心肌组织CGRP蛋白表达。结果与C组比较，EE组、EP＋EE组血清CK-MB和心肌MDA含量显著升高，血清CGRP含量、心肌SOD活性及心肌CGRP mRNA和蛋白表达均显著降低。EP可显著降低急性EE大鼠血清CK-MB和心肌MDA水平〔CK-MB（U/L）：13.11±0.77比15.55±0.90，MDA（μmol/L）：389.57±49.60比709.08±160.49〕，增加血清CGRP含量及心肌CGRP mRNA和蛋白表达〔CGRP含量（ng/L）：120.41±9.07比97.97±9.05，CGRP mRNA（2 -ΔΔCT）：0.45±0.09比0.14±0.02，CGRP蛋白（灰度值）：0.78±0.08比0.41±0.04，均P〈0.05〕，减轻心肌损伤程度。单纯EP组各指标与C组比较差异均无统计学意义。结论EP对急性EE大鼠心肌有保护作用，其作用机制与内源性保护物质CGRP密切相关。

ObjectiveTo observe the heart protective effect of exercise preconditioning （EP） in the acute exhaustion exercise （EE） rats, and explore its action mechanism further.MethodsEighty 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.ResultsCompared 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.ConclusionEP has the heart protective effect for the acute EE rats, and the mechanism is closely related to the endogenous protective substance CGRP.