Effects of Shortened Photoperiod on Gonadotropin-Releasing Hormone, Gonadotropin, and Vitellogenin Gene Expression Associated with Ovarian Maturation in Rainbow Trout
Effects of Shortened Photoperiod on Gonadotropin-Releasing Hormone, Gonadotropin, and Vitellogenin Gene Expression Associated with Ovarian Maturation in Rainbow Trout
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DOI：
10.2108/zsj.27.24
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发表时间：
2010-01-01
影响因子：
0.9
通讯作者：
Sohn, Young Chang
中科院分区：
文献类型：
--
作者：
Choi, Sungchang;Lee, Cheul Ho;Sohn, Young Chang
鲑科鱼类的生殖活动与光周期的变化同步，光周期通过脑-垂体-性腺轴控制内分泌系统。脑中的促性腺激素释放激素（GnRH）调节垂体促性腺激素（GTH; FSH和LH）的合成和释放。FSH和LH依次刺激雌鲑产生性类固醇激素，促进卵母细胞生长，并分别刺激雌鲑产生促成熟类固醇激素，促进卵母细胞成熟和排卵。为了阐明长期光周期操作对鲑鱼从早期复发到排卵的生殖活动的影响，我们研究了雌性虹鳟（Oncorhynchus mykiss）的GnRH，GTH和卵黄蛋白原（VTG）和血浆性类固醇的基因表达谱。此外，还测定了有眼胚胎和孵化卵的百分率以及排卵卵的数量，以评价光周期制度对卵质量的影响。在夏末，GnRHs，GTH α和LH β的mRNA水平，以及成熟类固醇（17 α，20 β-二羟基-4-异戊烯-3-酮; 17，20 β-P）的血浆水平显着升高，在恒温下逐渐缩短的光周期，根据加速性成熟。8月份排卵的鱼的眼睛胚胎和孵化的alevins的百分比与12月份观察到的对照鱼相当。这些结果清楚地表明，程序化的长短光周期方案可以有效地加速早期复发雌性虹鳟鱼的GnRHs、LH、VTG和17，20 β-P的合成，而不会显着降低卵子质量。
Reproductive activities of salmonids are synchronized by changes in photoperiod, which control the endocrine system via the brain-pituitary-gonadal axis. Gonadotropin-releasing hormone ( GnRH) in the brain regulates synthesis and release of the pituitary gonadotropins (GTHs; FSH and LH). FSH and LH in turn stimulate the production of sex steroids for oocyte growth and maturation-inducing steroid hormones for oocyte maturation and ovulation, respectively, in female salmonids. To clarify effects of long-term photoperiod manipulations on the reproductive activity of salmonids from early recrudescence to ovulation, we investigated the gene expression profiles of GnRH, GTHs, and vitellogenin (VTG), and plasma sex steroids in female rainbow trout (Oncorhynchus mykiss). In addition, the percentages of eyed embryos and hatched alevins were examined together with the number of ovulated eggs to evaluate the effects of photoperiod regimes on egg quality. During late summer, the mRNA levels of GnRHs, GTH alpha, and LH beta, and the plasma level of a maturational steroid (17 alpha,20 beta-dihydroxy-4-pregnen-3-one; 17,20 beta-P) were significantly elevated by a gradually shortened photoperiod under constant temperature, in accordance with accelerated sexual maturation. The percentages of eyed embryos and hatched alevins from fish ovulated in August were comparable to those of control fish observed in December. These results clearly indicate that syntheses of GnRHs, LH, VTG, and 17,20 beta-P are effectively accelerated by a programmed long-short photoperiod regime in early recrudescent female rainbow trout, without a marked deterioration in egg quality.