Alliin and volatile sulfur-containing compounds in garlic enhance the thermogenesis by increasing norepinephrine secretion in rats

The effects of alliin and volatile sulfur-containing compounds in garlic on thermogenesis were investigated in rats. Rats were fed high-fat diet with or without a ethanol extracted-garlic powder (EE-garlic) supplemented at 0.8% for 28 days. After feeding, mitochondrial protein content in interscapular brown adipose tissue (IBAT) and plasma norepinephrine secretion were significantly greater in rats given EE-garlic as compared with control rats. The effects of the administrations of EE-garlic and alliin on norepinephrine secretions were evaluated in anesthetized rats. The norepinephrine concentrations of arterial blood were significantly increased by EE-garlic and alliin administration, and these increases were dose dependent. The administration of allylsulfides having a different number of sulfur atoms (diallyldisulfide and diallyltrisulfide) also significantly increased the norepinephrine secretion. The effects of the administration of EE-garlic, alliin, and diallyldisulfide on thermogenesis were examined by the direct measurement of IBAT and rectal temperatures in anesthetized rats. The temperatures were significantly increased by the administration of these compounds, and the effect of diallyldisulfide disappeared in the presence of beta-adrenergic blocker. These results suggest that the administration of alliin and volatile sulfur-containing compounds in garlic enhance the thermogenesis by increasing norepinephrine secretion via beta-adrenergic action. (C) Elsevier Science Inc. 1998.