Peripheral Injection of Chicken Growth Hormone-Releasing Hormone Inhibits Feeding Behavior in Chicks

Growth hormone-releasing hormone (GHRH), a stimulator of growth hormone (GH) secretion, is known to have several physiological roles such as the regulation of feeding behavior in mammals. Recently, we have reported that central injection of chicken GHRH decreased food intake in chicks, however, its peripheral role on feeding behavior has not been clarified. The purpose of the present study was to investigate the effect of peripheral injection of GHRH on feeding behavior in chicks (Gallus gallus). Intraperitoneal (IP) injection of GHRH47 (1 nmol), full length form of chicken GHRH significantly decreased food intake in chicks although the injection of GHRH27 and GHRH27-NH(2), short forms of chicken GHRH had no effect. The IP injection of GHRH47 did not induced any abnormal behavior, suggesting that GHRH47-induced anorexia might not be related to abnormal behavior such as sleeping, hyperactivity and convulsion. The anorexigenic effect of GHRH47 seemed not to be related to GH because IP injection of bovine GH did not affect feeding behavior in chicks. Collectively, these results suggest that peripheral GHRH is related to inhibit feeding behavior in chicks.