Central and peripheral administration of human relaxin-2 to adult male rats inhibits food intake

Methods: The human form of relaxin, human relaxin-2 (H2) was administered centrally and peripherally to male Wistar rats and food intake measured. Behaviour was also assessed. Results: Intracerebroventricular (ICV) administration of H2 significantly decreased 1-h food intake in the early dark phase [2.95 +/- 0.45 g (saline) vs. 0.95 +/- 0.18 g (180 pmol H2), p < 0.001]. ICV administration of H2 decreased feeding behaviour and increased grooming and headdown behaviour. Intraparaventricular injections of H2 significantly decreased 1-h food intake in the early dark phase [3.13 +/- 0.35 g (saline) vs. 1.35 +/- 0.33 g (18 pmol H2), p < 0.01, 1.61 +/- 0.31 g (180 pmol H2), p < 0.05 and 1.23 +/- 0.32 g (540 pmol H2), p < 0.001]. Intraperitoneal (IP) administration of H2 significantly decreased 1-h food intake in the early dark phase [4.63 +/- 0.46 g (vehicle) vs. 3.08 +/- 0.15 g (66 nmol H2), p < 0.01, 3.00 +/- 0.17 g (200 nmol H2), p < 0.01 and 2.26 +/- 0.36 g (660 nmol H2), p < 0.001]. Conclusions: Central and peripheral administration of H2 reduces the food intake in rats. This effect may be mediated via the PVN and/or other brain regions.