Effects Of High Intensity Exercise And Heavy Load Training On Cell Free DNA Level In Rats And Human And Its Significance

1. Objects:Overtraining is an important issue in sports. At present comprehensive evaluation of multiple indexs are being used to determine whether overtraining is exist. So far there are short of sensitive, specific and simple monitoring indicators or evaluation methods to evaluate overtraining. This study is to establish a method for detecting plasma cell free DN A(cfDNA) of rats and human by real time PCR and explore the possibility of mechanism: a new molecular marker of overtraining in rats and human? 2. Materials and Methods:Twelve male SD rats were randomly divided into control group and overtraining group(6rats/group). The overtraining group rats which was characterized by high intensity exercise were undertaken overtraining on a motor-driven treadmill for 5 weeks; Thirty female SD rats were randomly divided into three groups(10 rats /group): control group, high intensity training group and overtraining group, the 9 weeks training protocol of high intensity training group was similar to overtraining group, but overtraining group which was caused mainly by heavy load training exercise to exhaustion; 13 youth boxers complete a period of three weeks of highintensity training and heavy load exercise, there have a interval of 4 week washout period between two training period. 36 h after the last training, all the rats and boxers were drawn blood at pre-training and after-high intensity exercise and heavy load training to detect plasma levels of cfDNA, testosterone(T) and corticosterone(Cort) as well as total antioxidant capacity(T-AOC, U / ml), malondialdehyde(MDA, nmol / ml), superoxide dismutase(SOD, U/ml) and glutathione peroxidase(GSH-Px) activity and creatin kinase(CK).The plasma level of cfDNA was detected by real time PCR(amplity abundant Alu repetitive sequences of human genome and most abundant B1 repeat sequences of rats genome which was homologous to human Alu sequences).The plasma levels of T-AOC, MDA, CK as well as activity of SOD, GSHPx was determined by Colorimetry. Assey the levels of erythrocytes(RBC, 1012/L) number, hemoglobin(Hb, g/L) and BUN(blood urea nitrogen, mmol/L) level of boxers by Automatic biochemical analyzer. Measure the level of anaerobic endurance of boxers by Wingate anaerobic power test bicycle. 3. Results:(1)Effects and mechanis m of overtraining on plas ma cell free DNA levels in male SD rats and its significance.Compared with control group, the plasma levels of testosterone, total antioxidant capacity and T/C ratio decreased obviously in overtraining group of SD male rats, while the plasma levels of corticosterone, creatine kinase and cfDNA in overtraining rats increased obviously(about 5.43 fold). Significant relativity were found between cfDNA and plasma levels of T, Cort, T/C ratio and MDA.(2) Effects and mechanism of high load training and overtraining on plas ma cell free DNA levels in fe male SD rats and its significance.Compaerd with control group, the plasma levels of testosterone and T/C ratio decreased obviously, while corticosterone and cell free DN A levels(about 2.04 and 4.46 fold) increased significantly in high intensity exercise group and overtraining group. Compaerd with control group, the plasma levels of creatine kinase obviously increased in overtraining group. Significant relativity were found between cfDNA and plasma levels of Cort, T/C ratio and exercise capacity.(3) Effects and mechanism of chronic high intensity training and heavy load exercise on plas ma cell free DNA levels in boxers and its significance.Compaerd with baseline value, the plasma levels of cell free DNA after 3weeks of high intensity exerciseand heavy load training increased obviously with a similar degree(4.1 fold,p<0.01). Compaerd with baseline value, after 3 weeks of high intensity exercise, the plasma levels of creatine kinase and MDA increased significantly, after 3 weeks of heavy load training the plasma levels of MDA and BUN obviously increased. In addition, the exercise performance of 3weeks of high intensity exercise and heavy load training were both weakened, compared with baseling value(p<0.05). 4. Conclusions:(1) A real time PCR method was established specifically to amplify cfDN A of rats and human.(2) The plasma levels of cfDN A increased significantly in high intensity group and overtraining group rats, with a high degree in overtraining group. And at the early(5 weeks) and late(9 weeks) stages of overtraining, overtraining caused by high intensity exercise and heavy load training could both make a significant increase in plasma level cfDNA.(3) The boxers plasma level of cfDNA were both obviously increased after 3 weeks of high intensity exercise and 3 weeks of heavy load training.(4) Both rats and human plasma level of cfDN A have relativity with Some physiological indexes of culluently reflect overtraining, which suggest that cfDNA may be a new monitoring indicators of overtraining.(5) Overtraining, high intensity exercise and heavy load training induced the increase of plasma cfDNA level may related with enhanced oxidative stress rather than muscle damage.