Acute Exercise Induce PGC-1α Gene Transcription In Skeletal Mucle Of Rat

Objective: As the control center of energy metabolism, mitochondria could product superoxide radical O2·-, and further generate hydrogen peroxide (H2O2) and other reactive oxygen species (ROS) through the electron leak of respiratory chain. Accordingly, it is considered most likely to be both redox stress factors of the origin, but also the redox signaling and the primary regulatory factor of cells. ROS play a very important role in some processes, including gene transcription, cell signal transduction and activity of stressed-signaling kinase and activity of some kinases involving in redox integration process. Accumulating evidences also have revealed that H2O2 participates in the cross-talking between mitochondria and the nucleus, whereas the underlying mechanism is not clear. In our research, we try to determine whether H2O2 most likely induce PGC-1αgene transcription by activation of p38 MAPK signal transduction pathway acting as a cell signal factor.Methods: First, Sprague-Dawley rats were divided into control group(C)and exercise groups including exercise for 45min (E45),90min (E90),120min (E120),150min (E150),and post-exercise groups including 3h (R3h),6h (R6h),12h (R12h),18h (R18h)and 24h (R24h) randomly.Rats from exercise groups were forced to perform an acute bout of incremental treadmill running.Rats were sacrificed at rest and immediately at each time point after exercise. The skeletal muscle were harvested for analyzing the H2O2 concentration,the expressions of PGC-1αmRNA, p38 MAPK,and the activity of p38 MAPK. In vitro, we analyzed the H2O2 concentration, p38 MAPK and CREB protein level and activity; and CREB after 15min,30min,60min by simulating oxidative stress. And we also studied the determination of p38 MAPK and CREB protein level and activity by adding SB203580 as a specific inhibitor of p38 MAPK. Then, we added the inhibitor of mitochondrial respiratory chain complex I rotenone, and determined ROS, the protein level and activity of p38 MAPK and CREB.Results: In an acute bout of incremental treadmill running, except R12h, muscular H2O2 concentration increased significantly in group E45 gradually to R6h, and there was a decease in R24h group, then increased to the level of R24h group. PGC-1αmRNA expression decreased markedly in group E45～E120 compared with that in group C (P>0.05), but increased significantly in E150and R3h compared with that in group C (P<0.01 and P<0.001). p38 MAPK activity in skeletal muscle increased higtly (P<0.05,P<0.01 and P<0.001) except E45 and R12h. However, p38 MAPK protein level was no significan change during exercise, while it showed increased significantly only in group R3h (P< 0.05) although no change in post-exercise groups. In vitro, p38 MAPK phsophorylated protein level increased significantly (P<0.05) in myoblast stimulated with 20μM H2O2 30min, and reached the climax at 60min compared with the control group. CREB phsophorylated protein expression increased significantly (P<0.05) in myoblast stimulated with 20μM H2O2 15min, 30min and 60min compared with the relative control groups (P<0.05). p38 MAPK signal transduction pathway is blocked by the inhibitor of p38 MAPK-SB203580. p38 MAPK phsophorylated and CREB phsophorylated protein level increased significantly (P<0.05) in myoblast stimulated with 10ng/ml rotenone 60min and 5ng/ml rotenone 120min compared with the control group. However, H2O2, the inhibitor of p38 MAPK-SB203580 and rotenone had no effect on p38 MAPK and CREB protein level.Conclusion: Our data suggested that during/after an acute bout of exercise, increased significantly(p<0.05), and there is a time-dependent sequence between H2O2 concentration, the activity of p38 MAPK and the expression of PGC-1αmRNA in muscular. H2O2 during movement could activate p38 MAPK phosphorylation, induce PGC-1αtranscriptional up-regulation. In vitro, through simulate oxidative stress model by the myoblast culture in vitro, we suggested that H2O2 is a signaling molecule, activating p38 MAPK signal transduction pathway, in turn activate downstream CREB.