The medio-basal hypothalamus as a dynamic and plastic reproduction-related kisspeptin-gnrh-pituitary center in fish.
Kisspeptin regulates reproductive events, including puberty and ovulation, primarily via GnRH neurons. Prolonged treatment of prepubertal striped bass females with kisspeptin (Kiss) 1 or Kiss2 peptides failed to enhance puberty but suggested a gnrh-independent pituitary control pathway. Kiss2 inhibited, but Kiss1 stimulated, FShβ expression and gonadal development, although hypophysiotropic gnrh1 and gnrh receptor expression remained unchanged. In situ hybridization and immunohistochemistry on brains and pituitaries revealed a differential plasticity between the 2 kisspeptin neurons. The differences were most pronounced at the prespawning phase in 2 regions along the path of gnrh1 axons: the nucleus lateralis tuberis (NLT) and the neurohypophysis. Kiss1 neurons appeared in the NLT and innervated the neurohypophysis of prespawning males and females, reaching Lh gonadotropes in the proximal pars distalis. Males, at all reproductive stages, had Kiss2 innervations in the NLT and the neurohypophysis, forming large axonal bundles in the former and intermingling with gnrh1 axons. Unlike in males, only preovulatory females had massive NLT-neurohypophysis staining of kiss2. Kiss2 neurons showed a distinct appearance in the NLT pars ventralis-equivalent region only in spawning zebrafish, indicating that this phenomenon is widespread. These results underscore the NLT as important nuclei for kisspeptin action in 2 facets: 1) kisspeptin-gnrh interaction, both kisspeptins are involved in the regulation of gnrh release, in a stage- and sex-dependent manner, especially at the prespawning phase; and 2) gnrh-independent effect of Kiss peptides on the pituitary, which together with the plastic nature of their neuronal projections to the pituitary implies that a direct gonadotropic regulation is plausible.
Department of Marine Biotechnology (N.Z., J.S., Y.Z.), University of Maryland Baltimore County and Institute of Marine and Environmental Technology, Baltimore, Maryland 21202; Faculty of Agriculture, Food and Environment (M.G., B.L.-S.), The Hebrew University, Rehobot, Israel 76100; and Ifremer (A.S.), Unité de Physiologie Fonctionnelle des Organismes Marins, Laboratoire des sciences de l'environnement marin Unité mixte de recherche 6539, Plouzané 29280, France.
Nilli
N
Zmora
John
J
Stubblefield
Matan
M
Golan
Arianna
A
Servili
Berta
B
Levavi-Sivan
Yonathan
Y
Zohar
D000818:Animals; D017756:Aquaculture; D001369:Axons / Q000187:drug effects / Q000378:metabolism; D001492:Bass / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004343:Drug Implants; D005260:Female; D005300:Fertility Agents, Female / Q000494:pharmacology; D029941:Fish Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D037201:Follicle Stimulating Hormone, beta Subunit / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D007987:Gonadotropin-Releasing Hormone / Q000235:genetics / Q000378:metabolism*; D007030:Hypothalamo-Hypophyseal System / Q000166:cytology / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D007033:Hypothalamus, Middle / Q000166:cytology / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D059648:Kisspeptins / Q000008:administration & dosage / Q000378:metabolism* / Q000494:pharmacology; D008396:Maryland; D010904:Pituitary Gland, Posterior / Q000166:cytology / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D012741:Sexual Maturation / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects; D029867:Xenopus Proteins / Q000008:administration & dosage / Q000378:metabolism* / Q000494:pharmacology
D004343:Drug Implants; D005300:Fertility Agents, Female; D029941:Fish Proteins; D037201:Follicle Stimulating Hormone, beta Subunit; C000588858:KISS1 peptide, Xenopus; D059648:Kisspeptins; D029867:Xenopus Proteins; D007987:Gonadotropin-Releasing Hormone