Effect of Short-Term Endurance Exercise on COX IV and PGC-1a mRNA Expression Levels in Rat Skeletal Muscle

Abstract

Endurance exercise induces specific skeletal muscle adaptation by increasing mitochondrial oxidative phosphorylation eficiency and mitochondrial biogenesis. Many previous studies suggesting both PGC-1a and COX IV as a potential biomarker of skeletal muscle adaptation induced by exercise. But most of them only studied the effect of long-term endurance exercise, whereas the effect of short-term exercise remains unclear. To investigate short-term physiological adaptation induced by endurance exercise on expression of COX IV and PGC-1a mRNA in rat skeletal muscle. Twenty healthy male Wistar rats (Rattus norvegicus) aged 10-11 weeks old were used in this experiment. Rats were randomly assigned into 4 groups based on the time period of exercise: 1) control (C; n=5), 2) three days of exercise (E3; n=5), 3) six days of exercise (E6; n=5), 4) fifteen days of exercise (E15; n=5). The exercise groups were run at 20m/s for 30 minutes on the rat treadmill and the stationary control group was only placed inside treadmill with the machines turned off. On the last day of exercise, the rats were sacrificed then RNA from skeletal muscle was extracted. COX IV and PGC-1a mRNA expressions were measured by Reverse Transcriptase PCR. The results showed that there were statistically significant differences of PGC-1a mRNA expression levels in both soleus (F(3,16)=3.740, ps=0.033) and gastrocnemius (F(3,16)=3.969, pg=0.027) muscles. The COX IV mRNA expression levels in soleus (F(3,16)=3.801, ps=0.031) and gastrocnemius (F(3,16)=5.429, ps=0.009) muscles were also significantly increased. There were significant increases of PGC-1a and COX IV expressions in fifteen days of exercise group compared to control group in both muscles. Short-term endurance exercise induced mitochondrial biogenesis marker and mitochondrial activity marker by increasing the PGC-1a and COX IV mRNA expression levels in rat skeletal muscle significantly following the time periods of exercise.