Inhibitory effect of ghrelin on food intake is mediated by the corticotropin-releasing factor system in neonatal chicks.
It is known that, in rats, central and peripheral ghrelin increases food intake mainly through activation of neuropeptide Y (NPY) neurons. In contrast, intracerebroventricular (ICV) injection of ghrelin inhibits food intake in neonatal chicks. We examined the mechanism governing this inhibitory effect in chicks. The ICV injection of ghrelin or corticotropin-releasing factor (CRF), which also inhibits feeding and causes hyperactivity in chicks. Thus, we examined the interaction of ghrelin with CRF and the hypothalamo-pituitary-adrenal (HPA) axis. The ICV injection of ghrelin increased plasma corticosterone levels in a dose-dependent or a time-dependent manner. Co-injection of a CRF receptor antagonist, astressin, attenuated ghrelin-induced plasma corticosterone increase and anorexia. In addition, we also investigated the effect of ghrelin on NPY-induced food intake and on expression of hypothalamic NPY mRNA. Co-injection of ghrelin with NPY inhibited NPY-induced increase in food intake, and the ICV injection of ghrelin did not change NPY mRNA expression. These results indicate that central ghrelin does not interact with NPY as seen in rodents, but instead inhibits food intake by interacting with the endogenous CRF and its receptor.
Saito
Ei-Suke
ES
Laboratory of Advanced Animal and Marine Bioresources, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka 812-8581, Japan.
Kaiya
Hiroyuki
H
Tachibana
Tetsuya
T
Tomonaga
Shozo
S
Denbow
D Michel
DM
Kangawa
Kenji
K
Furuse
Mitsuhiro
M
D000818:Animals; D000831:Animals, Newborn; D000855:Anorexia / Q000139:chemically induced; D001921:Brain / Q000378:metabolism; D002645:Chickens; D003345:Corticosterone / Q000378:metabolism; D003346:Corticotropin-Releasing Hormone / Q000378:metabolism*; D005247:Feeding Behavior / Q000187:drug effects*; D054439:Ghrelin; D007031:Hypothalamus / Q000502:physiology; D008297:Male; D009478:Neuropeptide Y / Q000378:metabolism; D036361:Peptide Hormones / Q000378:metabolism / Q000494:pharmacology*; D010455:Peptides / Q000737:chemistry; D010913:Pituitary-Adrenal System / Q000502:physiology; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors
D054439:Ghrelin; D009478:Neuropeptide Y; D036361:Peptide Hormones; D010455:Peptides; D012333:RNA, Messenger; D003346:Corticotropin-Releasing Hormone; D003345:Corticosterone