An Increase in Murine Skeletal Muscle Peroxisome Proliferator-Activated Receptor-γ Coactivator-1α (PGC-1α) mRNA in Response to Exercise Is Mediated by β-Adrenergic Receptor Activation

A single bout of exercise increases expression of peroxisome proliferator-activated receptor-γ coactivator (PGC)-1α mRNA, which may promote mitochondrial biogenesis in skeletal muscle. In brown adipose tissue, cold exposure up-regulates PGC-1α expression via adrenergic receptor (AR) activation. Because exercise also activates the sympathetic nervous system, we examined whether exercise-induced increase in PGC-1α mRNA expression in skeletal muscle was mediated via AR activation. In C57BL/6J mice, injection of the β2-AR agonist clenbuterol, but not α-, β1-, or β3-AR agonists, increased PGC-1α mRNA expression more than 30-fold in skeletal muscle. The clenbuterol-induced increase in PGC-1α mRNA expression in mice was inhibited by pretreatment with the β-AR antagonist propranolol. In ex vivo experiments, direct exposure of rat epitrochlearis to β2-AR agonist, but not α-, β1-, and β3-AR agonist, led to an increase in levels of PGC-1α mRNA. Injection of β2-AR agonist did not increase PGC-1α mRNA expression in β1-, β2-, and β3-AR knockout mice (β-less mice). PGC-1α mRNA in gastrocnemius was increased 3.5-fold in response to running on a treadmill for 45 min. The exercise-induced increase in PGC-1α mRNA was inhibited by approximately 70% by propranolol or the β2-AR-specific inhibitor ICI 118,551. The exercise-induced increase in PGC-1α mRNA in β-less mice was also 36% lower than that in wild-type mice. These data indicate that up-regulation of PGC-1α expression in skeletal muscle by exercise is mediated, at least in part, by β-ARs activation. Among ARs, β2-AR may mediate an increase in PGC-1α by exercise.