In vivo and in vitro sex steroids stimulate seabream gonadotropin-releasing hormone content and release in the protandrous black porgy, Acanthopagrus schlegeli.
The objective of the present study was to investigate the regulation of seabream gonadotropin-releasing hormone (sbGnRH) release using in vivo and in vitro approaches in the protandrous black porgy, Acanthopagrus schlegeli. Estradiol-17beta (E2), testosterone (T), and 11-ketotestosterone (11-KT) were found to significantly stimulate the increase of sbGnRH levels in pituitary of black porgy after 5-96 h of injection. An in vitro culture system using dispersed brain neurons was also developed to investigate the effects of various steroids on sbGnRH release. Different doses (10(-6) - 10(-12) M) of E2, T, 11-KT, and cortisol were applied during 6 h experiment. KCl stimulated sbGnRH release at a dose- and time-dependent manner. The concentration of sbGnRH increased 2-fold in the highest dose of KCl treatment compared to the control. Treatments with E2, T, 11-KT and cortisol significantly stimulated the release of sbGnRH from the cultured brain neurons. The concentration of sbGnRH in medium was increased by 2-, 1.9-, 2.1-, and 4.9-fold when treated with E2, T, 11-KT, and cortisol, respectively, as compared to the respective control. Cholesterol did not have any stimulatory effects in the release of sbGnRH. The results showed that sex steroids and cortisol had direct effect on brain neuronal cells stimulating the release of sbGnRH.
Lee
Yan-Horn
YH
National Museum of Marine Biology and Aquarium, Pintung 944, Taiwan, ROC. lyh@nmmba.gov.tw
Du
Jin-Lien
JL
Shih
Yu-Su
YS
Jeng
Shan-Ru
SR
Sun
Lian-Tien
LT
Chang
Ching-Fong
CF
D000728:Androgens / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000166:cytology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000008:administration & dosage / Q000494:pharmacology; D012739:Gonadal Steroid Hormones / Q000494:pharmacology*; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D006854:Hydrocortisone / Q000008:administration & dosage / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D010902:Pituitary Gland / Q000378:metabolism; D011189:Potassium Chloride / Q000008:administration & dosage / Q000494:pharmacology; D021541:Sea Bream / Q000378:metabolism*; D013739:Testosterone / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology
D000728:Androgens; D012739:Gonadal Steroid Hormones; D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; D004958:Estradiol; D011189:Potassium Chloride; C003600:11-ketotestosterone; D006854:Hydrocortisone