Enhancement by Capsaicin of Energy Metabolism in Rats through Secretion of Catecholamine from Adrenal Medulla

Abstract

Capsaicin (CAP), a pungent principle of hot red pepper, enhances energy metabolism in rats fed a high fat diet. In this study, the site of action of CAP in rats was investigated in vivo with the serum glucose level as an index of energy metabolism. Administration of CAP (4 mg/kg, ip) caused a significant increase in the serum glucose level. Treatment with hexamethonium bromide (5 mg/kg, ip) and atropine sulfate (1 mg/kg, ip) did not affect the serum glucose response to CAP. Rats treated with 6-hydroxydopamine hydrobromide (30 mg/kg, ip) or reserpinie (5 mg/kg/day for 5 days) also responded to CAP. Adrenodemedullation, however, completely prevented the response to CAP, and injection of epinephrine into the adrenodemedullated rats significantly increased the serum glucose level. These results suggest that the CAP-induced enhancement of the energy metabolism in rats occurs via the secretion of catecholamine from the adrenal medulla.