Elevation of gene expression for salmon gonadotropin-releasing hormone in discrete brain loci of prespawning chum salmon during upstream migration
Elevation of gene expression for salmon gonadotropin-releasing hormone in discrete brain loci of prespawning chum salmon during upstream migration
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DOI：
10.1002/neu.20125
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发表时间：
2005-05-01
期刊：
影响因子：
--
通讯作者：
Urano, A
中科院分区：
文献类型：
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作者：
Onuma, T;Higa, M;Urano, A
我们以前的研究表明，鲑鱼促性腺激素释放激素（sGnRH）神经元调节最终成熟和迁移行为的鲑鱼归巢。sGnRH神经元的激活可在上游迁移期间发生。因此，我们研究了编码sGnRH，sGnRH-I，和sGnRH-II的前体基因的表达，在离散前脑位点的prepawning鲑鱼，虹鳟鱼。从1997年到1999年，沿着它们的归巢路径捕获了鱼：沿海地区、河的中途、纳塔尔孵化场下游4公里处和孵化场。通过实时定量聚合酶链反应测定新鲜冷冻切片（包括嗅球（OB）、终末神经（TN）、端脑腹侧（VT）、视前小细胞前核（PPa）和视前大细胞核（PM））中sGnRH mRNA的量。sGnRH-II mRNA的含量高于sGnRH-I mRNA的含量，但在上游迁移过程中两者表现出相似的变化。在OB和TN中，sGnRH mRNA的量从海岸到纳塔尔孵化场升高。VT和PPa随成熟度的增加而沿着升高。在PM的吻腹侧、中部和背尾侧部分也观察到这种升高。垂体中促性腺激素II β和生长激素肌动蛋白mRNA的量也随着sGnRH基因表达的升高而增加。这些结果，结合线的先前的证据表明，sGnRH神经元被激活，在几乎所有的前脑位点在产卵迁移的最后阶段，导致最终的性腺成熟和迁移行为的产卵场的协调。(c)2005 Wiley Periodicals，Inc.
Our previous studies suggested that salmon gonadotropin-releasing hormone (sGnRH) neurons regulate both final maturation and migratory behavior in homing salmonids. Activation of sGnRH neurons can occur during upstream migration. We therefore examined expression of genes encoding the precursors of sGnRH, sGnRH-I, and sGnRH-II, in discrete forebrain loci of prespawning chum salmon, Oncorhynchus keta. Fish were captured from 1997 through 1999 along their homing pathway: coastal areas, a midway of the river, 4 km downstream of the natal hatchery, and the hatchery. Amounts of sGnRH mRNAs in fresh frozen sections including the olfactory bulb (OB), terminal nerve (TN), ventral telencephalon (VT), nucleus preopticus parvocellularis anterioris (PPa), and nucleus preopticus magnocellularis (PM) were determined by quantitative real-time polymerase chain reactions. The amounts of sGnRH-II mRNA were higher than those of sGnRH-I mRNA, while they showed similar changes during upstream migration. In the OB and TN, the amounts of sGnRH mRNAs elevated from the coast to the natal hatchery. In the VT and PPa, they elevated along with the progress of final maturation. Such elevation was also observed in the rostroventral, middle, and dorsocaudal parts of the PM. The amounts of gonadotropin II beta and somatolactin mRNAs in the pituitary also increased consistently with the elevation of gene expression for sGnRH. These results, in combination with lines of previous evidence, indicate that sGnRH neurons are activated in almost all the forebrain loci during the last phases of spawning migration, resulting in coordination of final gonadal maturation and migratory behavior to the spawning ground. (c) 2005 Wiley Periodicals, Inc.