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

Abstract

Previous studies in mammalian obesity models have suggested that central transforming growth factor-β (TGF-β) controls the gene expression of appetite-regulating neuropeptides and peripheral energy metabolism. In the present study, we investigated the possible involvement of central TGF-β/Smad signaling in feeding regulation in chickens. Central administration of TGF-β1 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-β/Smad signaling suppresses feed intake in chicks but it might not occur in response to feeding status.

Recent Research on Mechanisms of Feeding Regulation in Chicks

“…These findings suggest that hypothalamic AMPK activation stimulates food intake in chicks, similar to mammals. ICV injection of recombinant human transforming growth factor-β1 induces hypothalamic Smad2 phosphorylation and suppression of food intake in chicks[ 84 ]. However, phosphorylated Smad2 is not detected under ad libitum feeding, fasting, and refeeding conditions in the hypothalamus of chicks[ 84 ].…”

“…ICV injection of recombinant human transforming growth factor-β1 induces hypothalamic Smad2 phosphorylation and suppression of food intake in chicks[ 84 ]. However, phosphorylated Smad2 is not detected under ad libitum feeding, fasting, and refeeding conditions in the hypothalamus of chicks[ 84 ]. These findings suggest that hypothalamic Smad activation suppresses food intake in chicks, but may not occur in response to feeding conditions[ 84 ].…”

“…However, phosphorylated Smad2 is not detected under ad libitum feeding, fasting, and refeeding conditions in the hypothalamus of chicks[ 84 ]. These findings suggest that hypothalamic Smad activation suppresses food intake in chicks, but may not occur in response to feeding conditions[ 84 ]. A recent study using a synthetic inhibitor suggests that JAK2/3 stimulates food intake in chicks[ 85 ].…”