Role of Hypothalamic Transforming Growth Factor- (TGF-)/Smad Signaling in Feeding Regulation in Chickens.

Previous studies in mammalian obesity models have suggested that central transforming growth factor- (TGF-) controls the gene expression of appetite-regulating neuropeptides and peripheral energy metabolism. In the present study, we investigated the possible involvement of central TGF-/Smad signaling in feeding regulation in chickens. Central administration of TGF-1 resulted in phosphorylation of Smad2 in the hypothalamus of chicks and suppressed feed intake without changing the gene expression of hypothalamic appetite-regulating neuropeptides (neuropeptide Y, agouti-related protein, proopiomelanocortin, and corticotropin-releasing factor). However, neither fasting nor refeeding induced the phosphorylation of hypothalamic Smad2. These findings suggest that the activation of hypothalamic TGF-/Smad signaling suppresses feed intake in chicks but it might not occur in response to feeding status.