Lee Y H, Du J L, Yueh W S, Lin B Y, Huang J D, Lee C Y, Lee M F, Lau E L, Lee F Y, Morrey C, Nagahama Y, Chang C F
Department of Aquaculture, National Taiwan Ocean University, Keelung 20224, Taiwan, Republic of China.
J Exp Zool. 2001 Dec 1;290(7):715-26. doi: 10.1002/jez.1122.
Black porgy, Acanthopagrus schlegeli Bleeker, a marine protandrous hermaphrodite, is functional male for the first two years of life but begins to sexually change to female after the third year. Testicular tissue and ovarian tissue was separated by connective tissue in the bisexual gonad. This sex pattern provides a very good model to study the endocrine mechanism of sex change in fish. The annual profiles of plasma estradiol, vitellogenin and 11-ketotestosterone concentrations in males were significantly different from those in the three-year-old females. Significantly high levels of plasma estradiol during the prespawning/spawning season and low levels of plasma 11-ketotestosterone during the spawning season were observed in the inversing females. No difference of plasma testosterone levels was observed in males and females. Oral administration of estradiol stimulated high levels of gonadal aromatase activity, plasma gonadotropin II levels and sex change in the two-year-old fish. Exogenous estradiol administered for 5-6 months induced a reversible sex change in one- and two-year-old fish. The sensitive period for estradiol treatment of sex change is from early prespawning to spawning season. Implantation with testosterone for more than a year could not block the natural sex change in three-year-old fish. Exogenous aromatase inhibitors (1,4,6-androstatriene-3,17-dione or fadrozole) suppressed aromatase activity in the brain. Oral administration with aromatase inhibitors for a year further inhibited the natural sex change in three-year-old black porgy and all fish became functional male with spermiation. Estrogen receptor alpha gene in the ovarian tissue of bisexual gonad is significantly less expressed than that in the vitellogenic ovary of female on the basis of reverse-transcription polymerase-chain reaction. There was no difference in the annual profiles of the plasma gonadotropin II levels in the males and natural inversing females. Plasma gonadotropin II levels were significantly higher in estradiol-treated group than those in the control. It is concluded that estradiol, aromatase activity and estrogen receptor in the ovarian tissue play an important role in the natural and controlled sex change in black porgy. The association of gonadotropin and sex change in black porgy is not clear.
黑鲷（Acanthopagrus schlegeli Bleeker）是一种海洋雄性先熟雌雄同体鱼类，在生命的头两年为功能性雄性，但在第三年后开始性转变为雌性。在两性性腺中，睾丸组织和卵巢组织被结缔组织分隔。这种性别模式为研究鱼类性转变的内分泌机制提供了一个很好的模型。雄性血浆雌二醇、卵黄蛋白原和11-酮睾酮浓度的年度变化与三岁雌性显著不同。在性逆转雌性中，产卵前/产卵季节血浆雌二醇水平显著升高，产卵季节血浆11-酮睾酮水平降低。雄性和雌性血浆睾酮水平没有差异。口服雌二醇可刺激两岁鱼性腺芳香化酶活性、血浆促性腺激素II水平升高并导致性转变。对一岁和两岁鱼施用外源雌二醇5-6个月可诱导可逆性性转变。雌二醇处理性转变的敏感期是从产卵前早期到产卵季节。对三岁鱼植入睾酮一年以上不能阻止其自然性转变。外源芳香化酶抑制剂（1,4,6-雄甾三烯-3,17-二酮或法倔唑）可抑制大脑中的芳香化酶活性。口服芳香化酶抑制剂一年可进一步抑制三岁黑鲷的自然性转变，所有鱼都变成了具有精子生成功能的雄性。基于逆转录聚合酶链反应，两性性腺卵巢组织中的雌激素受体α基因表达明显低于雌性卵黄生成卵巢中的表达。雄性和自然性逆转雌性血浆促性腺激素II水平的年度变化没有差异。雌二醇处理组的血浆促性腺激素II水平显著高于对照组。结论是，卵巢组织中的雌二醇、芳香化酶活性和雌激素受体在黑鲷自然和可控性转变中起重要作用。黑鲷中促性腺激素与性转变的关系尚不清楚。
