Effects of acute bouts of running and swimming exercise on PGC-1 protein expression in rat epitrochlearis and soleus muscle

Terada, Shin, and Izumi Tabata. Effects of acute bouts of running and swimming exercise on PGC-1 protein expression in rat epitrochlearis and soleus muscle. Am J Physiol Endocrinol Metab 286: E208–E216, 2004. First published October 21, 2003; 10.1152/ ajpendo.00051.2003.—The purpose of this study was to elucidate the mechanisms underlying low-intensity exercise-induced peroxisome proliferator-activated receptorcoactivator-1 (PGC-1 ) protein expression in rat skeletal muscles. Rats (5–6 wk old) swam without a load and ran on the treadmill at a speed of 13 m/min, respectively, in two 3-h sessions separated by 45 min of rest. PGC-1 content in epitrochlearis muscle (EPI) was increased by 75 and 95%, immediately and 6 h after swimming, respectively, with no increase in PGC-1 content in the soleus (SOL). After running, PGC-1 content in EPI was unchanged, whereas a 107% increase in PGC-1 content was observed in SOL 6 h after running. Furthermore, in EPI and SOL as well as other muscles (triceps, plantaris, red and white gastrocnemius), PGC-1 expression was enhanced concomitant with reduced glycogen postexercise, suggesting that expression of PGC-1 occurs in skeletal muscle recruited during exercise. PGC-1 content in EPI was increased after 18-h in vitro incubation with 0.5 mM 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) and 4 mM caffeine. However, AICAR incubation did not affect PGC-1 content in the SOL, whereas caffeine incubation increased it. These results suggest that exercise-induced PGC-1 expression in skeletal muscle may be mediated by at least two exercise-induced signaling factors: AMPK activation and Ca elevation. The number of factors involved (both AMPK and Ca , or Ca only) in exercise-induced PGC-1 expression may differ among muscles.