Effect of a fatty acid synthase inhibitor on food intake and expression of hypothalamic neuropeptides

The fatty acid synthase inhibitor, C75, acts centrally to reduce food intake and body weight in mice. Here we report the effects of C75 on the expression of key orexigenic neuropeptide Y (NPY), agouti-related protein (AgRP), and melanin-concentrating hormone and anorexigenic pro-opiomelanocortin (POMC) and cocaine-amphetamine-related transcript (CART) neuropeptide messages in the hypothalami of lean and obese (ob/ob) mice. In lean mice, C75 rapidly and almost completely blocked food intake and prevented fasting-induced up-regulation of hypothalamic AgRP and NPY mRNAs, as well as down-regulation of CART and POMC mRNAs. Thus, in lean mice C75 seems to interrupt the fasting-induced signals that activate expression of NPY and AgRP and suppression of POMC and CART. In obese mice, C75 rapidly suppressed food intake, reduced body weight, and normalized obesity-associated hyperglycemia and hyperinsulinemia. Like its effect in lean mice, C75 prevented the fasting-induced increase of hypothalamic NPY and AgRP mRNAs in obese mice, but had no effect on the expression of POMC and CART mRNAs. The suppressive effect of C75 on food intake in lean mice seems to be mediated both by NPY/AgRP and POMC/CART neurons, whereas in obese mice the effect seems to be mediated primarily by NPY/AgRP neurons. In both lean and obese mice, C75 markedly increased expression of melanin-concentrating hormone and its receptor in the hypothalamus.