The anorexic effect of alpha-melanocyte-stimulating hormone is mediated by corticotrophin-releasing factor in chicks.
Alpha-melanocyte-stimulating hormone (alpha-MSH) is recognized as an anorexic peptide in the brain of vertebrates, but its mechanism of action has not been identified in birds. Therefore, we investigated whether the anorexic effect of alpha-MSH is mediated by corticotrophin-releasing factor (CRF) in the domestic chick. Firstly, we found that intracerebroventricular (i.c.v.) injection of alpha-MSH dose dependently increased plasma corticosterone (CORT) concentration. This effect was partly attenuated by co-injection of astressin, a CRF receptor antagonist, demonstrating that alpha-MSH stimulated CORT secretion by activating CRF neurons. The alpha-MSH-elicited CORT release was not attenuated by the injection of agouti-related protein, an endogenous melanocortin-4 (MC4) receptor antagonist, suggesting that alpha-MSH stimulated CRF neurons through MC4 receptor-independent pathways. Finally, we found that the anorexic effect of alpha-MSH was partly attenuated by astressin. The present results suggest that the anorexic effect of alpha-MSH in the chick brain is mediated in part by activation of CRF neurons.
Tachibana
Tetsuya
T
Department of Animal Science, Division of Animal and Marine Bioresource Sciences, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan. tetsu@agr.ehime-u.ac.jp
Oikawa
Daichi
D
Takahashi
Hirokazu
H
Boswell
Tim
T
Furuse
Mitsuhiro
M
D054369:Agouti-Related Protein; D000818:Animals; D000855:Anorexia / Q000139:chemically induced / Q000378:metabolism*; D002645:Chickens / Q000502:physiology*; D003345:Corticosterone / Q000097:blood / Q000378:metabolism; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology*; D005247:Feeding Behavior / Q000187:drug effects; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000494:pharmacology; D008297:Male; D010446:Peptide Fragments / Q000494:pharmacology; D018019:Receptors, Corticotropin-Releasing Hormone / Q000037:antagonists & inhibitors; D000521:alpha-MSH / Q000494:pharmacology*
C515198:AGRP protein, human; D054369:Agouti-Related Protein; D036341:Intercellular Signaling Peptides and Proteins; D010446:Peptide Fragments; D018019:Receptors, Corticotropin-Releasing Hormone; C104416:astressin; D000521:alpha-MSH; D003346:Corticotropin-Releasing Hormone; D003345:Corticosterone