title: Melanin-concentrating hormone directly inhibits GnRH neurons and blocks kisspeptin activation, linking energy balance to reproduction.
abstract: A link between energy balance and reproduction is critical for the survival of all species. Energy-consuming reproductive processes need to be aborted in the face of a negative energy balance, yet knowledge of the pathways mediating this link remains limited. Fasting and food restriction that inhibit fertility also upregulate the hypothalamic melanin-concentrating hormone (MCH) system that promotes feeding and decreases energy expenditure; MCH knockout mice are lean and have a higher metabolism but remain fertile. MCH also modulates sleep, drug abuse behavior, and mood, and MCH receptor antagonists are currently being developed as antiobesity and antidepressant drugs. Despite the clinical implications of MCH, the direct postsynaptic effects of MCH have never been reported in CNS neurons. Using patch-clamp recordings in brain slices from multiple lines of transgenic GFP mice, we demonstrate a strong inhibitory effect of MCH on an exclusive population of septal vGluT2-GnRH neurons that is activated by the puberty-triggering and preovulatory luteinizing hormone surge-mediating peptide, kisspeptin. MCH has no effect on kisspeptin-insensitive GnRH, vGluT2, cholinergic, or GABAergic neurons located within the same nucleus. The inhibitory effects of MCH are reproducible and nondesensitizing and are mediated via a direct postsynaptic Ba(2+)-sensitive K(+) channel mechanism involving the MCHR1 receptor. MCH immunoreactive fibers are in close proximity to vGluT2-GFP and GnRH-GFP neurons. Importantly, MCH blocks the excitatory effect of kisspeptin on vGluT2-GnRH neurons. Considering the role of MCH in regulating energy balance and of GnRH and kisspeptin in triggering puberty and maintaining fertility, MCH may provide a critical link between energy balance and reproduction directly at the level of the kisspeptin-activated vGluT2-GnRH neuron.
authors.affiliation: Department of Psychiatry, Yale University School of Medicine and the Ribicoff Research Facilities, Connecticut Mental Health Center, New Haven, CT 06508, USA.
authors.forename: Min
authors.initials: M
authors.lastname: Wu
authors.forename: Iryna
authors.initials: I
authors.lastname: Dumalska
authors.forename: Elena
authors.initials: E
authors.lastname: Morozova
authors.forename: Anthony
authors.initials: A
authors.lastname: van den Pol
authors.forename: Meenakshi
authors.initials: M
authors.lastname: Alreja
mesh_terms: D000818:Animals; D001921:Brain / Q000166:cytology / Q000254:growth & development; D004734:Energy Metabolism / Q000187:drug effects*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000235:genetics / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007028:Hypothalamic Hormones / Q000378:metabolism / Q000494:pharmacology*; D007150:Immunohistochemistry; D059648:Kisspeptins; D008297:Male; D008543:Melanins / Q000378:metabolism / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008822:Mice, Transgenic; D008856:Microscopy, Fluorescence; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D018408:Patch-Clamp Techniques; D010446:Peptide Fragments / Q000494:pharmacology*; D010907:Pituitary Hormones / Q000378:metabolism / Q000494:pharmacology*; D017481:Receptors, Somatostatin / Q000378:metabolism; D012098:Reproduction / Q000187:drug effects*; D013997:Time Factors; D025521:Tumor Suppressor Proteins / Q000737:chemistry; D050599:Vesicular Glutamate Transport Protein 2 / Q000235:genetics / Q000378:metabolism
chemical_list: D007028:Hypothalamic Hormones; C491407:Kiss1 protein, mouse; D059648:Kisspeptins; C491209:Mchr1 protein, mouse; D008543:Melanins; D010446:Peptide Fragments; D010907:Pituitary Hormones; D017481:Receptors, Somatostatin; C493477:Slc17a6 protein, mouse; D025521:Tumor Suppressor Proteins; D050599:Vesicular Glutamate Transport Protein 2; D049452:Green Fluorescent Proteins; D007987:Gonadotropin-Releasing Hormone; C019463:melanin-concentrating hormone