title: Interactions of gonadotropin-releasing hormone (GnRH) and gonadotropin-inhibitory hormone (GnIH) in birds and mammals.
abstract: Gonadotropin-releasing hormone (GnRH) regulates secretion of both of the gonadotropins, luteinizing hormone (LH) and follicle-stimulating hormone. Thus, it is a key hormone for vertebrate reproduction. GnRH was considered to be unusual among hypothalamic neuropeptides in that it appeared to have no direct antagonist, although some neurochemicals and peripheral hormones (opiates, GABA, gonadal steroids, inhibin) can modulate gonadotropin release to a degree. Five years ago, a vertebrate hypothalamic neuropeptide that inhibited pituitary gonadotropin release in a dose-dependent manner was discovered in quail by Tsutsui et al. (2000. Biochem Biophys Res Commun 275:661-667). We now know that this inhibitory peptide, named gonadotropin-inhibitory hormone, or GnIH, is a regulator of gonadotropin release in vitro and in vivo. Its discovery has opened the door to an entirely new line of research within the realm of reproductive biology. In our collaborative studies, we have begun to elucidate the manner in which GnIH interacts with GnRH to time release of gonadotropins and thus time reproductive activity in birds and mammals. This paper reviews the distribution of GnIH in songbirds relative to GnRHs, and our findings on its modes of action in vitro and in vivo, based on laboratory and field studies. These data are simultaneously compared with our findings in mammals, highlighting how the use of different model species within different vertebrate classes can be a useful approach to identify the conserved actions of this novel neuropeptide, along with its potential importance to vertebrate reproduction.
authors.affiliation: Department of Integrative Biology, University of California, Berkeley, California 94720, USA. gb7@berkely.edu
authors.forename: George E
authors.initials: GE
authors.lastname: Bentley
authors.forename: Lance J
authors.initials: LJ
authors.lastname: Kriegsfeld
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Osugi
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Ukena
authors.forename: Sara
authors.initials: S
authors.lastname: O'Brien
authors.forename: Nicole
authors.initials: N
authors.lastname: Perfito
authors.forename: Ignacio T
authors.initials: IT
authors.lastname: Moore
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Tsutsui
authors.forename: John C
authors.initials: JC
authors.lastname: Wingfield
mesh_terms: D000818:Animals; D030161:Avian Proteins / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D006224:Cricetinae / Q000502:physiology*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D007028:Hypothalamic Hormones / Q000378:metabolism; D008297:Male; D008322:Mammals / Q000378:metabolism* / Q000502:physiology; D012098:Reproduction / Q000502:physiology; D020308:Songbirds / Q000378:metabolism* / Q000502:physiology
chemical_list: D030161:Avian Proteins; D007028:Hypothalamic Hormones; C413752:gonadotropin-inhibitory hormone, Coturnix japonica; D007987:Gonadotropin-Releasing Hormone