Abstract
The neuropeptide kisspeptin is necessary for reproduction, fertility, and puberty. Here, we show strong kisspeptin innervation of hypothalamic anorexigenic proopiomelanocortin (POMC) cells, coupled with a robust direct excitatory response by POMC neurons (n > 200) to kisspeptin, mediated by mechanisms based on activation of a sodium/calcium exchanger and possibly opening of nonselective cation channels. The excitatory actions of kisspeptin on POMC cells were corroborated with quantitative PCR data showing kisspeptin receptor GPR54 expression in the arcuate nucleus, and the attenuation of excitation by the selective kisspeptin receptor antagonist, peptide 234. In contrast, kisspeptin inhibits orexigenic neuropeptide Y (NPY) neurons through an indirect mechanism based on enhancing GABA-mediated inhibitory synaptic tone. In striking contrast, gonadotropin-inhibiting hormone (GnIH and RFRP-3) and NPY, also found in axons abutting POMC cells, inhibit POMC cells and attenuate the kisspeptin excitation by a mechanism based on opening potassium channels. Together, these data suggest that the two central peptides that regulate reproduction, kisspeptin and GnIH, exert a strong direct action on POMC neurons. POMC cells may hypothetically serve as a conditional relay station downstream of kisspeptin and GnIH to signal the availability of energy resources relevant to reproduction.
Publication types
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Research Support, N.I.H., Extramural
MeSH terms
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6-Cyano-7-nitroquinoxaline-2,3-dione / pharmacology
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Animals
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Arcuate Nucleus of Hypothalamus / cytology*
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Axons / metabolism
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Calcium Channel Blockers / pharmacology
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Chelating Agents / pharmacology
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Dose-Response Relationship, Drug
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Egtazic Acid / analogs & derivatives
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Egtazic Acid / pharmacology
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Excitatory Amino Acid Agonists / pharmacology
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Excitatory Amino Acid Antagonists / pharmacology
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Excitatory Postsynaptic Potentials / drug effects*
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Excitatory Postsynaptic Potentials / physiology
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Female
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Gene Expression Regulation / drug effects
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Gene Expression Regulation / genetics
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Green Fluorescent Proteins / genetics
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Imidazoles / pharmacology
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In Vitro Techniques
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Kisspeptins
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Male
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Membrane Potentials / drug effects
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Mice
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Mice, Inbred C57BL
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Mice, Transgenic
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Neurons / cytology
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Neurons / drug effects*
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Neurons / metabolism
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Neuropeptide Y / metabolism*
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Patch-Clamp Techniques / methods
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Pro-Opiomelanocortin / metabolism*
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RNA, Messenger / metabolism
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Receptors, G-Protein-Coupled / genetics
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Receptors, G-Protein-Coupled / metabolism
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Receptors, Kisspeptin-1
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Renilla / genetics
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Sodium-Calcium Exchanger / antagonists & inhibitors
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Thiourea / analogs & derivatives
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Thiourea / pharmacology
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Tumor Suppressor Proteins / metabolism
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Tumor Suppressor Proteins / pharmacology*
Substances
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2-(2-(4-(4-nitrobenzyloxy)phenyl)ethyl)isothiourea methanesulfonate
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Calcium Channel Blockers
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Chelating Agents
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Excitatory Amino Acid Agonists
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Excitatory Amino Acid Antagonists
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Imidazoles
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Kiss1 protein, mouse
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Kiss1r protein, mouse
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Kisspeptins
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Neuropeptide Y
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RNA, Messenger
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Receptors, G-Protein-Coupled
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Receptors, Kisspeptin-1
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Sodium-Calcium Exchanger
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Tumor Suppressor Proteins
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enhanced green fluorescent protein
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Green Fluorescent Proteins
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Egtazic Acid
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Pro-Opiomelanocortin
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6-Cyano-7-nitroquinoxaline-2,3-dione
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Thiourea
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1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole
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1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid