雌性大鼠血浆游离DNA水平:过度训练的新监测指标?

Plasma Cell Free DNA:A New Molecular Marker of Overtraining in Female Rats?

目的:在证明过度训练的雄性大鼠血浆游离DNA(cell free DNA,cf DNA)水平显著升高的前期研究基础上,研究血浆cf DNA水平能否成为雌性大鼠过度训练的新监测指标。方法:30只雌性SD大鼠随机分为3组:安静对照组、大强度训练组和过度训练组,每组10只。后两组大鼠进行9周的运动训练,每周训练6天。前6周的递增训练方案完全相同,后3周大强度训练组进行30 min的大强度训练,而过度训练组在此强度下运动至力竭。运动后36 h采集静脉血,real time PCR检测血浆cf DNA水平;ELISA检测血浆睾酮(T)、皮质酮(Cort)的水平、计算T/C比值。比色法等检测血浆肌酸激酶(CK)、丙二醛(MDA)水平和超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)活性。结果:1过度训练组大鼠出现过度训练,表现为体重负增长,血浆T和T/C比值显著降低,血浆CK、Cort显著增加;而大强度训练大鼠体重停止增长、血浆Cort显著增加,T/C比值显著降低,血浆T和CK水平无显著变化。2大强度训练组和过度训练组大鼠血浆cf DNA水平均显著增加(均值分别是对照组的2.04倍和4.46倍左右);且过度训练组大鼠血浆cf DNA水平增加更显著(均值约为大强度训练组的2.19倍)。3过度训练组大鼠血浆MDA显著升高,血浆SOD和GSH-Px活性无显著变化;而大强度训练组大鼠无显著变化。4皮尔森相关性分析表明,过度训练组血浆cf DNA水平与血浆Cort、T/C比值具有显著相关性,相关系数分别是0.834、-0.459;而与血浆T、CK水平和GSH-Px、SOD活性没有相关性。结论:1大强度和过度训练雌性大鼠血浆cf DNA水平均显著增加,且后者增加得更明显,提示血浆cf DNA水平增加得越显著越可能出现过度训练。2雌性大鼠血浆cf DNA水平与反映过度训练的多个指标如T/C比值、血浆Cort有相关性,提示雌性大鼠血浆cf DNA水平能成为过度训练的新的监测指标。3过度训练雌性大鼠血浆cf DNA水平的增加可能与氧化增强、骨骼肌损伤无关。

Objective To confirm if plasma cell free DNA（cf DNA） is a new molecular marker of overtraining for female rats. Methods Thirty female SD rats were randomly divided into three groups（10 rats /group）：control group（sedentary）,high intensity training group and overtraining group. Rats in the two training groups underwent treadmill exercise with an incremental load for 9 weeks. In the last three weeks,the 30-min training speed and slope of rats in high intensity training group increased to 35 m/min and 5%,and rats in overtraining group were forced to exercise till exhaustion. Body weights of the rats were determined every week. Plasma cf DNA and levels of testosterone（T）and corticosterone（Cort）,levels of MDA,SOD,GSH-Px,and creatine kinase（CK） were detected 36 hours after the last training. Results 1 Weight of rats in control group increased continuously,while in overtraining group and high intensity training group decreased. 2Obvious reduction of T and T/C ratio as well as distinct enhancement of Cort and CK emerged in overtraining rats. Increased Cort and decreased T/C ratio were found in high intensity training rats. 3 Compared with control group,the plasma cf DNA increased significantly in overtraining group and high intensity training group,and the increase in overtraining group was about 2.19 fold of high intensity training group. 4Significant increases in CK and MDA were shown in overtraining rats rather than high intensity training rats,while there were no changes in the activities of SOD and GSH-Px among the three groups. 5 The plasma cf DNA was closely related to plasma Cort and T/C ratio（correlation coefficent：0.834 and-0.459,respectively）. Conclusions 1 A remarkable increase in plasma levels of cf DNA was found in female rats of high intensity training and overtraining groups,especially in overtraining groups,suggesting that the higher level of the plasma cf DNA,the increased possibility of overtraining existed. 2 There were close correlations of plasma cf DNA with Cort and T/C ratio in female rats,suggested that plasma cf DNA could be a new molecular marker of overtraining in female rats.