title: Regulation of androgen receptors in Atlantic croaker brains by testosterone and estradiol.
abstract: A nuclear androgen receptor (AR1), distinctly different from the mammalian AR, has previously been identified in the brain of the Atlantic croaker, Micropogonias undulatus. Interestingly, brain AR1 levels were higher in gonadally recrudesced than in regressed fish. Therefore, the possible involvement of gonadal steroids in the regulation of brain AR1 levels was investigated in the present study. Saturation analysis of [3H]testosterone binding showed that brain AR1 levels were significantly reduced (2-3-fold) in either the nuclear or cytosolic fractions of both males and females three weeks after gonadectomy. Implantation of gonadectomized females with testosterone or estradiol-17beta one week prior to sampling resulted in physiological plasma steroid concentrations and restored brain AR1 levels to 60-105% of those in intact or sham-operated fish. These results suggest that gonadal factors, including both androgens and estrogens, are involved in the physiological regulation of brain androgen receptors in a teleost species during the reproductive cycle.
authors.affiliation: Marine Science Institute, University of Texas at Austin, 750 Channel View Drive, Port Aransas, TX 78373, USA. joakim.larson.@fysiologi.gu.se
authors.forename: D G
authors.initials: DG
authors.lastname: Joakim Larsson
authors.forename: Todd S
authors.initials: TS
authors.lastname: Sperry
authors.forename: Peter
authors.initials: P
authors.lastname: Thomas
mesh_terms: D000818:Animals; D001921:Brain / Q000502:physiology*; D004958:Estradiol / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism*; D005260:Female; D020249:Hormone Replacement Therapy; D008297:Male; D009919:Orchiectomy; D010052:Ovariectomy; D010473:Perciformes / Q000502:physiology*; D011944:Receptors, Androgen / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D012621:Seasons; D012727:Sex Characteristics; D013739:Testosterone / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D011944:Receptors, Androgen; D018160:Receptors, Cytoplasmic and Nuclear; D013739:Testosterone; D004958:Estradiol