Leptin, but not a beta(3)-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 ther mogenesis and expression of uncoupling proteins (UCPs) in brown adipose tis sue (BAT) and muscle and their possible interactions were assessed. One hou r after administration of the beta(3)-adrenoceptor agonist Trecadrine, a st atistically significant increase in UCP1 messenger RNA (mRNA) expression in BAT was observed, whereas UCP1 and UCP3 in both BAT and gastrocnemius musc le were unaffected. Leptin induced an upregulation of UCP3 mRNA in muscle, with no changes in BAT UCP1 mRNA. A statistical interaction was found betwe en leptin and Trecadrine in rectal temperature. The present study provides evidence, for the first time, of the induction of UCP3 mRNA expression in s keletal muscle by leptin in nongenetically obese animals.