Chemical Classification and Biological Activity of Fish Pituitary Glycoprotein Hormones

鱼类垂体糖蛋白激素的化学分类及生物活性

• 批准号: 61300014
• 负责人: KAWAUCHI Hiroshi
• 金额: $ 8万
• 依托单位: Kitasato University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Co-operative Research (A)
• 财政年份: 1986
• 资助国家: 日本
• 起止时间: 1986 至 1988
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-61300014/
• 关键词: gonadotropin; steroidogenesis; vitellogenesis; ovulation; spermatogenesis; spermiation; estradiol-17; 17 ,20 -diOHprog; 11-ketotestosterone; thyroid hormone; thyroxine, metamorphosis; silvering, salmon; subunits; cDNA; cAMP; GTH産生細胞; GTHの2

Duality of teleost gonadotropins (GTHs): Two chemically distinct GTHs homologous to mammalian GTHs were isolated form salmon, carp and bonito pituitary glands, designated GTH I and GTH II and their cDNAs were cloned. They are composed of and subunits. Sequence studies show that two -subunits have approximately 30% homology and suggest that the divergence of the GTH gene took place earlier than the time of divergence of teleosts from the mainline of evolution leading to tetrapods. Salmon GTH I and GTH II were equipotent in stimulating estradiol production, whereas GTH II appears to be more potent in stimulating 17 , 20 -diohprog synthesis. In salmonids, the ratio of plasma levels and pituitary contents of GTHs and the secretory control by a GnRH suggest that GTH I is the predominant GTH during vitellogenesis and early stages of spermatogenesis, whereas GTH II is predominant at the time of spermiation and ovulation. GTH I and GTH II are found in distinctly separate cells. In trout, GTH I … More is expressed first in ontogeny, whereas GTH II cells appear coincident with the onset of spermatogenesis and vitellogenesis, and increase dramatically at the time of final reproductive maturation.Mechanism of GTH actions: Two steroid hormones, estradiol-17 and 17 , 20 -diOHprog are involved in the regulation of vitellogenesis and ovulation, respectively. During vitellogenesis, GTH stimulates the thecal cells to produce testosterone, which are converted to estradiol-17 in granulosa cells by enhancing aromatase enzyme activity. A distinct steroidogenic shift occurs in follicles just prior to oocyte maturation. GTH stimulate thecal cells to produce 17 -OHprog, which is converted to 17 ,20 -diOHprog in granulosa cells by enhancing 20 -OHsteroid dehydrogenase activity. Two steroid hormones are involved in the regulation of two important processes of male germ cell development: 11-ketotestosterone for spermatogenesis and 17 ,20 -diOHprog for spermiation. Analysis of steroid biosynthetic pathways of the testis showed a shift in testicular steroid metabolic enzyme activity in response to GTH. During spermatogenesis, the testis synthesized 11-ketotestosterone, 17 ,20 -diOHprog production results from a change in the pathway, immediately prior to spermiation. GTH stimulates the production of these steroid hormones in ovary and testis via an adenylate cyclase-cAMP-dependent step.Thyroid hormones: A bioassay of salmon TSH was established based on the increase in plasma thyroxine levels in juvenile rainbow throut. Thyroid hormones are found in the yolk of unfertilized eggs of all teleost studied. Treatment of juvenile salmonids with thyroid hormones caused an increase in oxygen consumption and body silvering, but no consistent effect was seen in seawater adaptability. The tissue and plasma levels of the hormones of chum salmon fry increased just before downstream migration. A marked increase in the tissue levels of the hormones was also observed during metamorphic climax of the flounder larvae, and injection of thyroxine or ovine TSH into pelagic larvae of the flounder accelerated the metamorphosis to benthic larvae. Less

硬骨鱼促性腺激素（GTH）的双重性：从鲑鱼、鲤鱼和鲣鱼脑垂体中分离到两种与哺乳动物GTH同源的GTH，命名为GTH I和GTH II，并克隆了它们的cDNA。它们由和亚单位组成。序列研究表明，两个亚基有大约30%的同源性，并建议GTH基因的分歧发生早于时间的分化硬骨鱼从主线的进化，导致四足动物。鲑鱼GTH I和GTH II在刺激雌二醇产生方面是等效的，而GTH II似乎在刺激17，20 -diohprog合成方面更有效。在鲑鱼，GTH的血浆水平和垂体含量的比例和分泌控制的GnRH表明，GTH I是主要的GTH在卵黄发生和精子发生的早期阶段，而GTH II是主要的精子和排卵的时间。GTH I和GTH II存在于不同的细胞中。在鳟鱼中，GTH I ...更多信息 GTH Ⅱ细胞在精子发生和卵黄发生开始时表达，在最后的生殖成熟时表达量急剧增加，其作用机制：雌二醇（E2）和17，20 -二羟孕酮（17，20 -diOHprog）分别参与卵黄发生和排卵的调节。在卵黄发生过程中，GTH刺激卵泡膜细胞产生睾酮，睾酮在颗粒细胞中通过增强芳香酶活性转化为雌二醇-17。在卵母细胞成熟之前，卵泡中发生明显的类固醇生成转变。GTH刺激卵泡膜细胞产生17 -OHprog，17-OHprog在颗粒细胞中通过增强20 -OH类固醇脱氢酶活性转化为17，20-diOHprog。两种类固醇激素参与调节雄性生殖细胞发育的两个重要过程：11-酮睾酮用于精子发生和17，20-diOHprog用于精子形成。睾丸类固醇生物合成途径的分析表明，睾丸类固醇代谢酶的活性响应GTH的转变。在精子发生过程中，睾丸合成11-酮睾酮，17，20-diOHprog的产生是由于在精子形成之前途径的改变。促甲状腺激素通过腺苷酸环化酶-cAMP-依赖step.Thyroid hormones刺激卵巢和睾丸中这些类固醇激素的产生：鲑鱼TSH的生物测定建立在少年彩虹鱼血浆甲状腺素水平增加的基础上。甲状腺激素存在于所有被研究的硬骨鱼类未受精卵的蛋黄中。用甲状腺激素处理幼鲑引起耗氧量和身体镀银的增加，但在海水适应性方面没有一致的效果。鲑鱼鱼苗的激素的组织和血浆水平增加之前，下游迁移。组织中的激素水平显着增加，也观察到在变性高潮的比目鱼幼虫，和注射甲状腺素或羊TSH到浮游幼虫的比目鱼加速了底栖幼虫的变态。少

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