Molecular neuroendocrine basis of spawning migration in salmon

产卵迁移是鲑鱼成功繁殖所必需的一种先天行为。来实现这种行为的遗传程序。我们研究了鲑鱼迁徙的神经内分泌机制的分子基础。我们的研究主要集中在以下三个方面：1)产卵迁移过程中下丘脑和垂体激素基因表达水平的变化；2)神经激素基因的结构分析。3)促性腺激素释放激素(GnRH)在产卵行为控制中的作用本项目取得的成果总结如下：1.产卵前雌鱼的神经垂体激素(NH)mRNAs水平下降。NH基因的性别二态表达表明NH可能参与了归巢鲑鱼的生殖行为和渗透调节。结论：1.性腺激素和肾上腺皮质激素可能参与了NH基因表达的调控。鲑鱼促性腺激素释放激素(SGnRH)基因在视前区的表达在最终成熟过程中增加。两个sGnRH基因(sGnRH-I和-II)的5‘上游区域存在明显的分化。促性腺激素α和IIbeta基因的表达。在最终成熟过程中会暂时增加，并受到基因治疗的刺激。GnRH的加入缩短了寻的迁移持续时间。GnRH不仅在刺激性腺成熟中发挥作用，而且在迁移行为中也发挥作用。目前，产卵迁移的分子神经内分泌基础被认为是基本确立的。在特别促进研究助学金资助的新项目《鲑鱼产卵迁移的分子神经内分泌调控》中，将进一步研究神经激素在控制鲑鱼产卵迁移中的分子机制。

The spawning migration is a kind of innate behavior which is essential for successful reproduction in salmon. To realize a genetic program of the behavior. we have examined molecular basis of neuro-endocrine mechanisms of salmon migration. Our research has been focused mainly on the following three points ; 1)Changes in expression levels of hypothalamic and pituitary hormone genes during spawning migration, 2)Structural analysis of the neurohormone genes. 3)Roles of gonadotropin-releasing hormone (GnRH) in the control of spawning behavior. The results of this project are summarized as follows.1. The levels in neurohypophysial hormone (NH) mRNAs decrease in the pre-spawning females. The sexual dimorphic expression of the NH genes suggests that the NH may be involved in reproductive behavior as well as osmotic regulation in the homing salmon. The gonadal and adrenocortical stroid hormones may be concerned in the control of the NH gene expression.2. The expression of salmon GnRH (sGnRH) gene in the preoptic area increases during final maturation. The 5' upstream regions of the two sGnRH genes (sGnRH-I and-II) are distinctively divergent. The expression of gonadotropin alpha and IIbeta genes also. increases temporally in the final maturation, and is stimulated by the administration of genre.3. The adminiatration of GnRH shortens duration of the homing migration. The GnRH may play roles in the stimulation of not only gonadal maturation but also migratory behavior.The molecular neuroendocrine basis of spawning migration is considered to be mostly established at present. In the new project ''Moleclular neuroendocrine regulation of spawning migration in salmon", which is supported by the Grant-in-Aid for Specially Promoted Research, further investigations on the molecular mechanisms of neurohormone action in the control of salmon spawning migration will be progressively done.