Melanin-concentrating hormone stimulates human growth hormone secretion: a novel effect of MCH on the hypothalamic-pituitary axis.
Melanin-concentrating hormone (MCH), a 19-amino acid orexigenic (appetite-stimulating) hypothalamic peptide, is an important regulator of energy homeostasis. It is cleaved from its precursor prepro-MCH (ppMCH) along with several other neuropeptides whose roles are not fully defined. Because pituitary hormones such as growth hormone (GH), ACTH, and thyroid-stimulating hormone affect body weight and composition, appetite, insulin sensitivity, and lipoprotein metabolism, we investigated whether MCH exerts direct effects on the human pituitary to regulate energy balance using dispersed human fetal pituitaries (21-22 wk gestation) and cultured GH-secreting adenomas. We found that MCH receptor-1 (MCH-R1), but not MCH receptor-2, is expressed in both normal (fetal and adult) human pituitary tissues and in GH cell adenomas. MCH (10 nM) stimulated GH release from human fetal pituitary cultures by up to 62% during a 4-h incubation (P < 0.05). Interestingly, neuropeptide EI (10 nM), which is also cleaved from ppMCH, increased human GH secretion by up to 124% in fetal pituitaries. A milder, albeit significant, induction of GH secretion by MCH (20%) was seen in cultured GH-secreting pituitary adenomas. A comparable stimulation of GH secretion was seen when cultured mouse pituitary cells were treated with MCH. Treatment of cultured GH adenoma cells with MCH (100 nM) induced extracellular signal-regulated kinases 1 and 2 phosphorylation, suggesting activation of MCH-R1. In aggregate, these data suggest that MCH may regulate pituitary GH secretion and imply a potential cross-talk mechanism between appetite-regulating neuropeptides and pituitary hormones.
Segal-Lieberman
Gabriella
G
Institute of Endocrinology, Sheba Medical Center, Tel-Hashomer, Israel 52621. gabriella.lieberman@sheba.health.gov.il
Rubinfeld
Hadara
H
Glick
Moran
M
Kronfeld-Schor
Noga
N
Shimon
Ilan
I
D000818:Animals; D002478:Cells, Cultured; D005333:Fetus; D015870:Gene Expression / Q000235:genetics; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology; D019382:Human Growth Hormone / Q000378:metabolism*; D006801:Humans; D007028:Hypothalamic Hormones / Q000494:pharmacology*; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects* / Q000378:metabolism; D008543:Melanins / Q000494:pharmacology*; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D010902:Pituitary Gland / Q000166:cytology / Q000378:metabolism; D010907:Pituitary Hormones / Q000494:pharmacology*; D010911:Pituitary Neoplasms / Q000378:metabolism / Q000473:pathology; D017481:Receptors, Somatostatin / Q000235:genetics; D014407:Tumor Cells, Cultured
D007028:Hypothalamic Hormones; C103263:MCHR1 protein, human; D008543:Melanins; D009842:Oligopeptides; D010907:Pituitary Hormones; D017481:Receptors, Somatostatin; C522850:neuropeptide EI; D019382:Human Growth Hormone; C019463:melanin-concentrating hormone; D013007:Growth Hormone-Releasing Hormone; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3