The Mechanism Of Resistance Training Enhancing Skeletal Muscle Function By Activating NOX

Objective:Long-term appropriate exercise can promote adaptive changes in skeletal muscle,which is manifested by strengthening skeletal muscle function and improving skeletal muscle quality.MAPK and HSP70 are two important effector proteins for skeletal muscle adaptation to motor stimulation,and existing studies have found that the reactive oxygen species(ROS)produced by exercise mediate the expression of MAPK and HSP70 proteins in skeletal muscle,which play an important role in skeletal muscle motor adaptation.The NADPH oxidase(NOX)/ROS pathway is the primary source of ROS production in skeletal muscle during exercise,however,it is unclear whether resistance training enhances skeletal muscle function by activating NOX,thereby promoting p38 MAPK and HSP70 protein expression.In this study,the effect of NOX/ROS pathway on MAPK signaling pathway and HSP70 protein expression was initially revealed that resistance training by activating NOX-mediated MAPK signaling pathway and HSP70 protein expression was preliminarily revealed,with a view to providing theoretical and experimental basis for improving skeletal muscle function by activating NOX-mediated MAPK signaling pathway and HSP70 protein expression.Methods:32 male C57BL/6 mice at 8 weeks old with an average weight of 19±0.28 g were selected and divided into 4 groups of 8 mice,namely quiet group(group C),quiet inhibitor group(group NC),exercise group(group E),and exercise inhibitor group(group NE).Mice in the NC and NE groups were injected with NOX inhibitors 6times a week at a dose of 10 mg/kg,and the C and E groups were injected with the same amount of normal saline.Mice in group E and NE were trained for 6 weeks,3time/week,3 groups/times,5 trips/group,the 3 RM test was carried out before the official start of training,with 80% 3 RM as the starting training intensity,10% 3RM per week,and the 3RM test was performed again for the final training,and the triceps of mice with calf triceps were collected by the end of the next day.Precision electronic weighing of mouse calf triceps weight,phthalol self-oxidation method to detect skeletal muscle SOD activity,thiobarbituric acid method to measure skeletal muscle MDA content,Western Blot method to detect NOX2,NOX4,p38 MAPK,p-p38 MAPK,HSP70 and MAFbx protein expression.Results:1)After 6 week of training,the 3RM and 3RM/body weight ratio of the motor mice were significantly higher than those in the C group(P(27)0.01).2)After 6 weeks of training,the ratio of calf triceps to body weight in mice in group E increased significantly(P(27)0.05)compared with group C,suggesting that resistance training increased skeletal muscle mass.3)Compared with group C,the Skeletal muscle SOD activity and MDA content in NC group,E group and NE group decreased significantly(P(27)0.01);Compared with group E,SOD activity and MDA content in the NE group decreased significantly(P(27)0.05).4)Compared with group C,the expression of NOX2 and NOX4 proteins in skeletal muscle in group E was significantly increased(P(27)0.05);Compared with the E group,the expression of NOX2 proteins in skeletal muscle in the NE group decreased significantly(P(27)0.05).5)After 6 weeks of training,there was no significant difference between skeletal muscle p38 MAPK protein expression groups;Compared with group C,skeletal muscle p38 MAPK phosphorylation in group E was significantly increased(P(27)0.01);Compared with group E,the phosphorylation expression of skeletal muscle p38 MAPK in the NE group decreased significantly(P(27)0.01);Compared with group C,the ratio of p38 MAPK/p-p38 MAPK in group E was significantly increased(P(27)0.05),and the ratio of skeletal muscle p38 MAPK/p-p38 MAPK in group NE decreased significantly compared with group E(P(27)0.05).6)Compared with the significant increase in protein expression of skeletal muscle HSP70 in mice in group E(P(27)0.01);Compared with group E,the expression of Skeletal muscle HSP70 protein in mice in the NE group decreased significantly(P(27)0.01).7)Compared with group C,the expression of skeletal muscle MAFbx protein in NC group and group E was significantly increased(P(27)0.05),and the expression of Skeletal muscle MAFbx protein in group NE was significantly increased compared with group E(P(27)0.05).Conclusions:1)Long-term resistance training upregulated the expression of NOX2 and NOX4 proteins in mouse skeletal muscle,and apocynin could weaken the increase in exercise-mediated NOX2 expression in skeletal muscle.2)Resistance training mediates an increase in the level of phosphorylation of p38 MAPK by activating skeletal muscle NOX.3)Resistance training mediates HSP70 protein expression in mouse skeletal muscle by activating skeletal muscle NOX.4)Resistance training makes the MAPK signaling pathway-mediated skeletal muscle protein synthesis greater than the MAFbx-mediated skeletal muscle protein degradation,and the skeletal muscle mass and muscle strength increase.5)The NOX/ROS pathway is involved in the improvement of skeletal muscle function mediated by resistance training.