Weight is controlled by a complex neuroendocrine system. Circulating hormones convey information about the energy needs to the neural pathways that control eating and energy output, but many of the molecules involved in this system have remained unknown. In August 8 Nature, Rachel Batterham and colleagues at Imperial College Faculty of Medicine, London, UK, show that the hormone PYY_3-36 — released from the gut postprandially in proportion to the calorie content of the meal — physiologically inhibits food intake and reduces weight gain (Nature 2002, 418:650-654).

Batterham et al. observed that in both humans and rodents, peripheral injection of PYY_3-36 inhibited eating for up to 12 hours and reduced food intake by up to one third. In addition they showed that in mice, PYY_3-36 activity involves the arcuate nucleus in the hypothalamus and works in part through the autoinhibitory neuropeptide Y receptor Y2R.

"From the clinical perspective, analogues PYY_3-36 and other molecules that reduce food consumption by activating the Y2 receptor will no doubt generate interest for their potential in treating obesity" write Michael Schwartz & Gregory Morton at the Harborview Medical Center, University of Washington, Seattle, in an accompanying News and Views article.