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This Article Full Text Full Text (PDF) All Versions of this Article: 71/5/1491    most recent biolreprod.104.030627v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Vidal, B. Articles by Dufour, S. Search for Related Content PubMed PubMed Citation Articles by Vidal, B. Articles by Dufour, S. Agricola Articles by Vidal, B. Articles by Dufour, S.

Dopamine Inhibits Luteinizing Hormone Synthesis and Release in the Juvenile European Eel: A Neuroendocrine Lock for the Onset of Puberty¹

USM 0401,³ UMR 5178 CNRS/MNHN/UPMC Biologie des Organismes Marins et Ecosystèmes, DMPA, Muséum National d'Histoire Naturelle, 75231 Paris Cedex 05, France DEPSN,⁴ UPR CNRS 2197, Institut de Neurobiologie Alfred Fessard, CNRS, 91198 Gif-sur-Yvette Cedex, France Center of Marine Biotechnology,⁵ University of Maryland Biotechnology Institute, Baltimore, Maryland 21202

In various adult teleost fishes, LH ovulatory peak is under a dual neurohormonal control that is stimulatory by GnRH and inhibitory by dopamine (DA). We investigated whether DA could also be involved in the inhibitory control of LH at earlier steps of gametogenesis by studying the model of the European eel, Anguilla anguilla, which remains at a prepubertal stage until the oceanic reproductive migration. According to a protocol previously developed in the striped bass, eels received sustained treatments with GnRH agonist (GnRHa), DA-receptor antagonist (pimozide), and testosterone (T) either alone or in combination. Only the triple treatment with T, GnRHa, and pimozide could trigger dramatic increases in LH synthesis and release as well as in plasma vitellogenin levels and a stimulation of ovarian vitellogenesis. Thus, in the prepubertal eel, removal of DA inhibition is required for triggering GnRH-stimulated LH synthesis and release as well as ovarian development. To locate the anatomical support for DA inhibition, the distribution of tyrosine hydroxylase (TH) in the brain and pituitary was studied by immunocytochemistry. Numerous TH-immunoreactive cell bodies were observed in the preoptic anteroventral nucleus, with a dense tract of immunoreactive fibers reaching the pituitary proximal pars distalis, where the gonadotrophs are located. This pathway corresponds to that mediating the inhibition of LH and ovulation in adult teleosts. To our knowledge, this is the first demonstration of a pivotal role for DA in the control of LH and puberty in a juvenile teleost. These data support the view that DA inhibition on LH secretion is an ancient evolutionary component in the neuroendocrine regulation of reproduction that may have been partially maintained throughout vertebrate evolution.

¹ Supported in part by research grant 3900 from CNRS, France/NSF, USA (to S.D. and Y.Z.).

² Correspondence: Sylvie Dufour, USM 0401, UMR 5178 CNRS, DMPA, Muséum National d'Histoire Naturelle, 7 rue Cuvier, 75231 Paris Cedex 05, France. FAX: 33 1 40793618; dufour{at}mnhn.fr