A new hormone involved in controlling hunger has been reported. Obestatin is a derivative of the precursor to ghrelin that has an opposing effect (ie, stopping hunger).
Many hormones are actually larger fragments of proteins“ depending on how the protein gets cut up, different hormones result. In this case, everyone's been looking at ghrelin, but the ghrelin precursor also apparently can get cut differently to make this "new" horomone obestatin.
Lots of questions to address: since ghrelin is up in PWS, is obestatin (wouldn't seem to make sense, but who knows)? Is the ratio of ghrelin to obestatin off kilter in PWS or typical obesity? Will this be an effective "drug" for obesity and PWS? Much remains to be done to characterize this new peptide and its role in hunger control.
Obestatin, a peptide encoded by the ghrelin gene, opposes ghrelin's effects on food intake. Zhang JV, Ren PG, Avsian-Kretchmer O, Luo CW, Rauch R, Klein C, Hsueh AJ. Science 310(5750):996-9, 2005.