17α-甲基睾酮对赤点石斑鱼性逆转的影响  

Effects of 17α-methyltestosterone on sex reversal in red-spotted grouper,Epinephelus akaara

作　　者：李广丽[1] 刘晓春[1] 林浩然[1] 

机构地区：[1]中山大学水生经济动物研究所暨广东省水生经济动物良种繁育重点实验室

出　　处：《水产学报》2006年第2期145-150,共6页Journal of Fisheries of China

基　　金：国家海洋863项目(2001AA621010);广东省科技计划项目(A3050201);教育部科学技术研究重点项目(02105);国家自然科学基金项目(39970586)

摘　　要：采用腹部埋植方式,用17α-甲基睾酮(17-αMT)以10mg.kg-1剂量处理2龄雌性赤点石斑鱼(每4周埋植1次,共埋植2次),检查埋植前后性腺结构、血清中性类固醇激素水平以及脑和性腺芳香化酶活性的变化。结果显示:一次埋植17-αMT即可诱导赤点石斑鱼发生不同程度的性逆转,性腺成熟系数(GSI)明显下降,性腺中卵细胞退化,精原细胞增殖,出现大量精母细胞和精子细胞,性逆转雄鱼精巢的组织结构与正常雄鱼精巢相似,部分鱼转变为功能性雄鱼,经轻微的腹部挤压可排精,精子活力与正常雄鱼相似。赤点石斑鱼埋植17-αMT后前脑、中脑的芳香化酶活性明显提高而后脑的芳香化酶活性降低,但性腺芳香化酶活性无显著变化。埋植17α-MT后第4周血清中11-酮基睾酮(11-ketotestosterone,11-KT)浓度显著升高,而睾酮(testosterone,T)和雌二醇(estradiol-17,βE2)浓度变化不显著。这些结果表明,脑部芳香化酶活性的显著升高与性逆转密切相关,17-αMT主要通过提高血清中11-KT水平诱导赤点石斑鱼发生性逆转。The objective of this study was to investigate the effects of 17α-methyltestosterone （17α-MT） on gonadal development, serum steroids and aromatase activities in 2-year-old female red-spotted grouper（ Epinephelus akaara ） during reproductive season. Groupers were divided into two groups, one implanted with 17α-MT （ 10 mg· kg^-1 body weight） and the other elastomer without 17α- MT into peritoneal cavity once every four weeks for 8 weeks. Blood samples were obtained from 6 fish of each group every 4 weeks for later analysis of sex steroids. After blood samples were collected, forebraln, midbrain, hindbrain, and gonads were collected and stored at - 70 ℃ for later aromatase activity measurement and gonadal histological study. Significantly lower gonadosomatic index （GSI） was observed in 17α-MT-treated group. Fish implanted with 17α-MT once showed complete degradation of oocytes and sex inversion with developing testicular tissues at the 4th week, while all fish in the control group were still female with developing ovaries. 17α-MT induced females to develop into functional males with authentic testes similar in structure to those in normal males, and no significant difference in sperm motility rate and concentration was observed between them. 17α-MT elevated the aromatase activities both in forebraln and midbrain but reduced that in hindbrain, with no difference in gonad before and after 17α-MT implantation. Serum 11-ketotestosterone （11-KT） levels increased significantly on the 4th week, while no differences of serum testosterone （T） and estradiol-17β （E2） levels were observed in control and 17α-MT-treated group. Present results suggested that the elevation of brain aromatase activities was associated closely with sex reversion, and the increasing 11-KT levels may be important for sex inversion induced by 17α-MT in red-spotted grouper.

关 键 词：赤点石斑鱼 17α-甲基睾酮 性逆转 芳香化酶活性 性类固醇激素 

分 类 号：Q45[生物学—生理学] S917[农业科学—水产科学]