Rodríguez L, Carrillo M, Sorbera L A, Soubrier M A, Mañanós E, Holland M C, Zohar Y, Zanuy S
Instituto de Acuicultura de Torre la Sal (CSIC), 12595 Ribera de Cabanes, Castellón, Spain.
Gen Comp Endocrinol. 2000 Oct;120(1):67-74. doi: 10.1006/gcen.2000.7533.
In the present study, levels of three GnRH forms [seabream GnRH (sbGnRH), chicken GnRH-II (cGnRH-II), and salmon GnRH (sGnRH)] were analyzed in the pituitary of male sea bass during sex differentiation and the first spawning season. Plasma levels of gonadotropin (GTH-2), testosterone (T), and 11-ketotestosterone (11-KT) were determined during the same periods. All GnRH forms were present in the pituitary. sbGnRH levels were 9-fold higher than cGnRH-II and 17-fold higher than sGnRH levels. The highest GnRHs levels were detected in November 1995, when fish were 9 months old and when the gonads started to differentiate. Levels of the three forms decreased and remained low during the first spawning season, with the exception of sbGnRH, which showed a significant increase in November 1996. Plasma GTH-2 levels were lowest in November 1995, later increasing 2.5 times during the next months. During the first spawning season, plasma GTH-2 levels peaked in December 1996, 1 month after the peak of sbGnRH. During sex differentiation, plasma T levels were high in November 1995 but decreased over the next months, while levels of 11-KT remained low and unchanged. During the first spawning season, both steroids peaked in January 1997. These results suggest a possible role for all three GnRH forms in achieving gonadal differentiation, while sbGnRH may be the most relevant form in the regulation of the first spawning season in male sea bass. Moreover, GTH-2 and 11-KT may play important roles in gonadal maturation, since plasma GTH-2 and 11-KT levels were high throughout the period of spermiation.
在本研究中，分析了雄性海鲈在性别分化和第一个产卵季节期间垂体中三种促性腺激素释放激素（GnRH）形式[鲷GnRH（sbGnRH）、鸡GnRH-II（cGnRH-II）和鲑鱼GnRH（sGnRH）]的水平。在同一时期测定了促性腺激素（GTH-2）、睾酮（T）和11-酮睾酮（11-KT）的血浆水平。所有GnRH形式均存在于垂体中。sbGnRH水平比cGnRH-II高9倍，比sGnRH水平高17倍。1995年11月检测到最高的GnRH水平，此时鱼9个月大，性腺开始分化。在第一个产卵季节，三种形式的水平下降并保持在低水平，但sbGnRH除外，它在1996年11月显著增加。血浆GTH-2水平在1995年11月最低，随后在接下来的几个月中增加了2.5倍。在第一个产卵季节，血浆GTH-2水平在1996年12月达到峰值，比sbGnRH峰值晚1个月。在性别分化期间，1995年11月血浆T水平较高，但在接下来的几个月中下降，而11-KT水平保持低且不变。在第一个产卵季节，两种类固醇在1997年1月达到峰值。这些结果表明，所有三种GnRH形式在性腺分化中可能发挥作用，而sbGnRH可能是雄性海鲈第一个产卵季节调节中最相关的形式。此外，GTH-2和11-KT可能在性腺成熟中发挥重要作用，因为在整个精子发生期血浆GTH-2和11-KT水平都很高。
