Effects of capsaicin and isothiocyanate on thermogenesis of interscapular brown adipose tissue in rats.

To clarify whether capsaicin or isothiocyanate, which are found in common spices, activate brown adipose tissue (BAT) function, BAT temperature, mitochondrial guanosine diphosphate (GDP) binding (a thermogenic indicator), and mitochondrial oxygen consumption were measured in interscapular brown adipose tissue (IBAT) of rats. Intramuscular injection of capsaicin (0.7 mg/kg) or isothiocyanate (3.0 mg/kg) increased significantly IBAT temperature without affecting the rectal temperature, a possible side effect, and increased significantly GDP binding and mitochondrial oxygen consumption in IBAT, as did administration of ephedrine (0.375 mg/kg). Therefore, the administration of capsaicin or isothiocyanate activates BAT function in rats.