Central angiotensin 1–7 triggers brown fat thermogenesis

Abstract

Abstract We tested the hypothesis that third ventricular (3V) injections of angiotensin 1–7 (Ang 1–7) increases thermogenesis in brown adipose tissue (BAT), and whether the Mas receptor mediates this response. First, in male Siberian hamsters (n = 18), we evaluated the effect of Ang 1–7 in the interscapular BAT (IBAT) temperature and, using selective Mas receptor antagonist A‐779, the role of Mas receptor in this response. Each animal received 3V injections (200 nL), with 48 h intervals: saline; Ang 1–7 (0.03, 0.3, 3, and 30 nmol); A‐779 (3 nmol); and Ang 1–7 (0.3 nmol) + A‐779 (3 nmol). IBAT temperature increased after 0.3 nmol Ang 1–7 compared with Ang 1–7 + A‐779 at 20, 30, and 60 min. Also, 0.3 nmol Ang 1–7 increased IBAT temperature at 10 and 20 min, and decreased at 60 min compared with pretreatment. IBAT temperature decreased after A‐779 at 60 min and after Ang 1–7 + A‐779 at 30 and 60 min compared with the respective pretreatment. A‐779 and Ang 1–7 + A‐779 decreased core temperature at 60 min compared with 10 min. Then, we evaluated blood and tissue Ang 1–7 levels, and the expression of hormone‐sensitive lipase (HSL) and adipose triglyceride lipase (ATGL) in IBAT. Male Siberian hamsters (n = 36) were killed 10 min after one of the injections. No changes were observed in blood glucose, serum and IBAT Ang 1–7 levels, and ATGL. Ang 1–7 (0.3 nmol) increased p‐HSL expression compared with A‐779 and increased p‐HSL/HSL ration compared with other injections. Ang 1–7 and Mas receptor immunoreactive cells were found in brain regions that coincide with the sympathetic nerves outflow to BAT. In conclusion, 3V injection of Ang 1–7 induced thermogenesis in IBAT in a Mas receptor‐dependent manner.

Keywords

• brown adipose tissue
• central angiotensin 1–7
• lipolysis and thermogenesis
• Mas receptor