Okubo K, Amano M, Yoshiura Y, Suetake H, Aida K
Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo, Tokyo, 113-8657, Japan.
Biochem Biophys Res Commun. 2000 Sep 16;276(1):298-303. doi: 10.1006/bbrc.2000.3476.
The present study has identified three molecular forms of gonadotropin-releasing hormone (GnRH) in the brain of a teleost, the medaka, by isolation of their cDNAs. This species has a novel GnRH, which is here named medaka-type GnRH (mdGnRH), in addition to two characterized forms, chicken-II-type GnRH (cGnRH-II) and salmon-type GnRH (sGnRH). Phylogenetic analysis showed that mdGnRH is a medaka homolog of and seabream-type GnRH (sbGnRH) and mammalian-type GnRH (mGnRH) in other species, and suggested that all vertebrates have three distinct GnRHs. Furthermore, in situ hybridization revealed that the mdGnRH gene is expressed only in neurons clustered within the preoptic area as sbGnRH and mGnRH genes in other species are, while the genes for cGnRH-II and sGnRH are only in the midbrain tegmentum and nucleus olfactoretinalis, respectively. This result suggested that mdGnRH is a hypophysiotropic factor and the other two forms are involved in other physiological events as neuromodulators or neurotransmitters.
本研究通过分离cDNA，在硬骨鱼青鳉的大脑中鉴定出三种促性腺激素释放激素（GnRH）分子形式。除了两种已鉴定的形式，即鸡II型GnRH（cGnRH-II）和鲑鱼型GnRH（sGnRH）外，该物种还有一种新的GnRH，在此命名为青鳉型GnRH（mdGnRH）。系统发育分析表明，mdGnRH是其他物种中黑鲷型GnRH（sbGnRH）和哺乳动物型GnRH（mGnRH）的青鳉同源物，并表明所有脊椎动物都有三种不同的GnRH。此外，原位杂交显示，mdGnRH基因仅在视前区内聚集的神经元中表达，就像其他物种中的sbGnRH和mGnRH基因一样，而cGnRH-II和sGnRH基因分别仅在中脑被盖和嗅视网膜核中表达。这一结果表明，mdGnRH是一种促垂体激素因子，而其他两种形式作为神经调节剂或神经递质参与其他生理事件。
