The anorexigenic effect of beta-melanocyte-stimulating hormone involves corticotrophin-releasing factor and mesotocin in birds

Abstract

Beta-melanocyte-stimulating hormone (β-MSH), when centrally injected, induces anorexigenic effects in rodents and chickens but its mechanism remains unclear. Thus, the primary goal of this research was to elucidate the hypothalamic mechanism using chickens. Intracerebroventricular injection of 0.3, 1.0 and 3.0 nmol of β-MSH decreased food intake for 540 min. Expression of hypothalamic mRNAs were affected by β-MSH injection, including corticotrophin-releasing factor (CRF) and its receptor subtype 1 (CRFR1), mesotocin (MT) and its receptor (MTR), pro-opiomelanocortin, cocaine- and amphetamine-regulated transcript (CART), growth hormone secretagogue receptor (GHSR) and neuropeptide Y (NPY) receptor subtype 5 (NPYR5). Within the arcuate nucleus, expressions of NPY, agouti-related peptide, MT and MTR were increased by β-MSH injection. β-MSH-treated chicks had more CRF, CRFR1, CRF receptor subtype 2, GHSR, NPY receptor subtype 1 (NPYR1) and NPYR5 mRNA but lower levels of CART and ghrelin, in the paraventricular nucleus. Greater amounts of mRNA for MTR, GHSR, NPYR1 and NPYR5 and less CRF expression were observed in the ventromedial hypothalamus. In conclusion, central injection of β-MSH potently reduced food intake and was associated with changes in mRNA expression of some anorexigenic factors in a hypothalamic nucleus-specific manner.