Induction of male-type gonadotropin secretion by implantation of 11-ketotestosterone in female goldfish.
In goldfish, plasma gonadotropin levels increase during spawning in both males and females (GTH surge). A female-typical GTH surge induces ovulation (ovulatory surge), and a male-typical surge triggers milt production in response to sex pheromones released from ovulatory females. This study examined whether the male-typical GTH surge occurs in adult females that are implanted with 11-ketotestosterone (KT), which induces male-typical sexual behavior in adult female goldfish. When KT-implanted females were exposed to ovulatory females, a GTH surge occurred without ovulation. No GTH surge was observed when KT-females were exposed to nonovulatory females. The GTH secretion in KT-females was further characterized by exposure to 17alpha,20beta-dihydroxy-4-pregnen-3-one (17,20-P), a female sex pheromone that induces the GTH surge in males. Exposure to waterborne 17,20-P caused an elevation of GTH levels in KT-females as well as in males. The elevation of GTH levels induced by 17,20-P exposure was abolished when the KT-females were rendered anosmic. Unlike the female-typical ovulatory GTH surge that occurs in synchrony with photoperiod and peaks in the dark phase of the day, the 17,20-P-induced surge did not show a peak in the dark phase. These results indicate that the GTH surge in KT-females is a male-typical surge. Together with a previous study showing KT-induced behavioral masculinization (N. E. Stacey and M. Kobayashi, 1996, Horm. Behav. 30, 434-445), this adult gonochoristic species was shown to possess sexual plasticity of brain function in behavior and GTH secretion in response to sex steroid.
Kobayashi
M
M
Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo, 113, Japan.
Furukawa
K
K
Kim
M H
MH
Aida
K
K
D000818:Animals; D005260:Female; D006054:Goldfish / Q000502:physiology*; D006065:Gonadotropins, Pituitary / Q000097:blood*; D006908:Hydroxyprogesterones / Q000494:pharmacology; D008297:Male; D010060:Ovulation / Q000502:physiology; D017440:Photoperiod; D012724:Sex Attractants / Q000494:pharmacology; D012726:Sexual Behavior, Animal / Q000187:drug effects* / Q000502:physiology; D013739:Testosterone / Q000031:analogs & derivatives* / Q000494:pharmacology
D006065:Gonadotropins, Pituitary; D006908:Hydroxyprogesterones; D012724:Sex Attractants; C007433:17,20-dihydroxy-4-pregnen-3-one; D013739:Testosterone; C003600:11-ketotestosterone