Dueling Hunger Hormones?

Ghrelin, a circulating peptide hormone produced in the stomach, has attracted much attention because of its stimulatory effect on food intake, but the effect of ghrelin may represent only half the story. Using a bioinformatics approach, Zhang et al. (see the Perspective by Nogueiras and Tschöp) show that ghrelin encodes a second peptide hormone that is processed from the same protein precursor as ghrelin. In rodents, a synthetic version of this hormone, obestatin, has the opposite physiological effect as ghrelin--it suppresses food intake. Obestatin mediates its actions through an orphan G protein-coupled receptor, GPR39, which shares sequences with, but is distinct from, the receptor targeted by ghrelin. J. V. Zhang, P.-G. Ren, O. Avsian-Kretchmer, C.-W. Luo, R. Rauch, C. Klein, A. J. W. Hsueh, Obestatin, a peptide encoded by the ghrelin gene, opposes ghrelin's effects on food intake. Science 310 , 996-999 (2005). [Abstract] [Full Text] R. Nogueiras and M. Tschöp, Separation of conjoined hormones yields appetite rivals. Science 310 , 985-986 (2005). [Summary] [Full Text]