title: Murine arcuate nucleus kisspeptin neurons communicate with GnRH neurons in utero.
abstract: Puberty is a transition period of reproductive development from juvenile stages to adulthood and depends upon the activity of gonadotropin-releasing hormone (GnRH) neurons. GnRH neurons are initially activated in utero but remain quiescent throughout the juvenile period. Premature reactivation of GnRH neurons results in precocious puberty in mice and humans, but the mechanisms underlying developmental control of GnRH neuron activity remain unknown. The neuropeptide kisspeptin, a potent activator of GnRH neurons that is implicated as a critical permissive signal triggering puberty and a major regulator of the adult female hypothalamus-pituitary-gonadal axis, is paradoxically produced by neurons in the developing brain well before puberty onset. Thus, the neural circuits controlling the timing of reproductive maturation remain elusive. Here, we delineate the underlying neural circuitry using conditional genetic transsynaptic tracing in female mouse embryos. We find that kisspeptin-producing neurons in the arcuate nucleus (ARC) already communicate with a specific subset of GnRH neurons in utero. We show that ARC kisspeptin neurons are upstream of GnRH neurons, and that GnRH neuron connectivity to ARC kisspeptin neurons does not depend on their spatial position in the brain. Furthermore, we demonstrate that the neural circuits between ARC kisspeptin and GnRH neurons are fully established and operative before birth. Finally, we find that most GnRH neurons express the kisspeptin receptor GPR54 upon circuit formation, suggesting that the signaling system implicated in gatekeeping puberty becomes operative in the embryo.
authors.affiliation: Department of Pharmacology and Toxicology, University of Saarland School of Medicine, D-66421 Homburg, Germany, and Center for Molecular Neurobiology, D-20253 Hamburg, Germany.
authors.forename: Devesh
authors.initials: D
authors.lastname: Kumar
authors.forename: Maria
authors.initials: M
authors.lastname: Freese
authors.forename: Dagmar
authors.initials: D
authors.lastname: Drexler
authors.forename: Irm
authors.initials: I
authors.lastname: Hermans-Borgmeyer
authors.forename: Annette
authors.initials: A
authors.lastname: Marquardt
authors.forename: Ulrich
authors.initials: U
authors.lastname: Boehm
mesh_terms: D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000196:embryology / Q000378:metabolism*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000096:biosynthesis*; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D009415:Nerve Net / Q000196:embryology / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D011247:Pregnancy; D043562:Receptors, G-Protein-Coupled / Q000096:biosynthesis*; D000074502:Receptors, Kisspeptin-1
chemical_list: C492248:Kiss1r protein, mouse; D043562:Receptors, G-Protein-Coupled; D000074502:Receptors, Kisspeptin-1; D007987:Gonadotropin-Releasing Hormone
keywords: Cre recombinase; GPR54; gene targeting; genetic transneuronal tracing; kisspeptin; puberty