Dueling Hunger Hormones
Researchers have identified a new appetite-suppressing hormone in rats that, paradoxically, is a sibling to ghrelin, the hormone that increases appetite. In a paper published in the 11 November issue of Science, the authors said the new hormone is processed from the same protein precursor that ghrelin comes from. Using a bioinformatics approach, which involved comparing ghrelin gene sequences in different organisms, Jian V. Zhang and colleagues identified the hormone they named "obestatin."
Studies with rodents indicated that a synthetic version of this hormone had the opposite physiological effect as ghrelin and suppressed food intake. Obestatin binds to and activates the receptor GPR39, which shares sequences with, but is distinct from, the receptor targeted by ghrelin. "A better understanding of the roles of ghrelin and obestatin in the intricate balance of energy homeostasis and body weight control may be essential for successful treatment of obesity," the authors write.
A related "Perspective" article notes that obestatin's effects on the rodents'
body weight were subtle and that the effects of obestatin in humans have
yet to be determined.
For more information, listen
to an audio file of a teleconference with the study's authors (MP3).
10 November 2005