Davies B, Bromage N, Swanson P
Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, United Kingdom.
Gen Comp Endocrinol. 1999 Jul;115(1):155-66. doi: 10.1006/gcen.1999.7301.
Two groups of post-spawned female rainbow trout were exposed to two different photoperiods, an ambient photoperiod (56 degrees N) and a combination of long and short photoperiods (a constant 18L:6D from February 1 until May 10, then a constant 6L:18D), which acted to advance maturation and spawning. The stimulatory long-short photoperiod advanced spawning by 3-4 months and correspondingly advanced peaks in serum levels of 17beta-estradiol, testosterone, calcium (an index of vitellogenin), and GTH II. Earlier events in gonadal recrudescence appeared to be less affected by the photoperiod. The initiation of exogenous vitellogenesis coincided with high levels of both pituitary salmon gonadotropin-releasing hormone (sGnRH) content and serum follicle-stimulating hormone (FSH, GTH I) levels. High levels of serum FSH were associated with rapid gonadal growth in the fish exposed to the stimulatory long-short photoperiod. In contrast, the fish exposed to the ambient photoperiod showed gonadal steroid production, formation of vitellogenin, and secondary oocyte growth without any detectable increase in serum FSH levels. The possible roles and interactions of sGnRH, gonadotropins, and steroids with respect to normal and artificially stimulated ovarian maturation are discussed.
两组产后雌性虹鳟鱼被暴露于两种不同的光照周期下，一种是环境光照周期（北纬56度），另一种是长短光照周期的组合（从2月1日至5月10日为恒定的18小时光照：6小时黑暗，然后从5月11日至实验结束为恒定的6小时光照：18小时黑暗），这种光照周期组合促使成熟和产卵提前。刺激性的长短光照周期使产卵提前了3 - 4个月，相应地也使血清中17β - 雌二醇、睾酮、钙（卵黄蛋白原的一个指标）和促性腺激素II（GTH II）的水平峰值提前。性腺再发育的早期事件似乎受光照周期的影响较小。外源性卵黄发生的开始与垂体鲑鱼促性腺激素释放激素（sGnRH）含量和血清促卵泡激素（FSH，GTH I）水平的升高同时发生。在暴露于刺激性长短光照周期的鱼中，高水平的血清FSH与性腺的快速生长相关。相比之下，暴露于环境光照周期的鱼显示出性腺类固醇的产生、卵黄蛋白原的形成和次级卵母细胞的生长，而血清FSH水平没有任何可检测到的增加。本文讨论了sGnRH、促性腺激素和类固醇在正常和人工刺激的卵巢成熟过程中的可能作用及相互作用。
