Androgen-Dependent Stimulation of Brain Dopaminergic Systems in the Female European Eel (Anguilla anguilla)

• Published in: Endocrinology
• Main Authors: Weltzien, F.-A., Pasqualini, C., Sebert, M.-E., Vidal, B., Le Belle, N., Kah, Olivier, Vernier, P., Dufour, S.
• Other Authors: Biologie des organismes marins et écosystèmes (BOME), Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN), Développement, évolution et plasticité du système nerveux (DEPSN), Centre National de la Recherche Scientifique (CNRS), Interactions cellulaires et moléculaires (ICM), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), This work was supported by Muséum National d'Histoire Naturelle, Centre National de la Recherche Scientifique, and the European Commission (EELREP Project Q5RS-2001-01836 to S.D.; and Marie Curie Individual Fellowship MCFI-2002-01609 to F.A.W.)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2006
• Subjects: [SDV.BBM]Life Sciences [q-bio]/Biochemistry; Molecular Biology; [SDV.BDLR]Life Sciences [q-bio]/Reproductive Biology; Anguilla anguilla
• Online Access: https://hal.archives-ouvertes.fr/hal-00071117; https://doi.org/10.1210/en.2005-1477

International audience Dopamine (DA), a neurotransmitter present in all vertebrates, is involved in processes such as motor function, learning and behavior, sensory activities, and neuroendocrine control of pituitary hormone release. In the female eel, we analyzed how gonadal steroids regulate brain expression of tyrosine hydroxylase (TH), the rate-limiting enzyme in the biosynthesis of DA. TH mRNA levels were assayed by quantitative real-time RT-PCR. TH-positive nuclei were also localized by in situ hybridization (ISH) and immunohistochemistry, and the location of TH nuclei that project to the pituitary was determined using 1,1'-dioctadecyl-3,3,3',3'-tetramethylindicarbocyanine perchlorate retrograde tracing. Chronic in vivo treatment with testosterone increased TH mRNA specifically in the periglomerular area of the olfactory bulbs and in the nucleus preopticus anteroventralis (NPOav). NPOav was labeled with 1,1'-dioctadecyl-3,3,3',3'-tetramethylindicarbocyanine perchlorate, showing that this nucleus is hypophysiotropic in the eel. The nonaromatizable 5alpha-dihydrotestosterone gave identical results in both areas, whereas 17beta-estradiol had no stimulatory effect, showing that the observed stimulatory effects of testosterone were androgen dependent. In teleosts, DA neurons originating from the NPOav directly inhibit gonadotropic function, and our results indicate an androgen-dependent, positive feedback on this neuroendocrine control in the eel. In mammals, DA interneurons in the olfactory bulbs are involved in the enhancement of olfactory sensitivity and discrimination. Our results in the European eel suggest an androgen-dependent stimulation of olfactory processing, a sensory function believed to be important in eel navigation during its reproductive migration toward the oceanic spawning grounds. To our knowledge, this is the first evidence from any vertebrate of an androgen-dependent effect on DAergic activity in the olfactory bulbs, providing a new basis for understanding the regulation by gonadal ...