Leptin, but not a β3-adrenergic agonist, upregulates muscle uncoupling protein-3 messenger RNA expression:: short-term thermogenic interactions

The short-term effects of leptin and a beta(3)-adrenoceptor agonist on thermogenesis and expression of uncoupling proteins (UCPs) in brown adipose tissue (BAT) and muscle and their possible interactions were assessed. One hour after administration of the beta(3)-adrenoceptor agonist Trecadrine, a statistically significant increase in UCP1 messenger RNA (mRNA) expression in BAT was observed, whereas UCP1 and UCP3 in both BAT and gastrocnemius muscle were unaffected. Leptin induced an upregulation of UCP3 mRNA in muscle, with no changes in BAT UCP1 mRNA. A statistical interaction was found between leptin and Trecadrine in rectal temperature. The present study provides evidence, for the first time, of the induction of UCP3 mRNA expression in skeletal muscle by leptin in nongenetically obese animals.