Molecular and Functional Investigations of Gonadotropin and Gonadotropin Releasing Hormone in Lamprey Reproduction

9722765康登这项提议将研究大脑和脑下垂体对七鳃鳗这一古老鱼类生殖的控制。七鳃鳗很重要，因为它们是最古老的脊椎动物血统的成员，Agnathan或无颌鱼，并提出了关于进化的有趣问题。这个实验室的重点是两种脑激素的结构和功能，这两种激素涉及七鳃鳗的脑垂体性腺轴。两种脑激素促性腺激素释放激素(GnRH-I和GnRH-III)在七鳃鳗中的一级结构已被确定。这一信息与免疫细胞化学和生理学研究相结合，提供了强有力的证据，证明大脑对七鳃鳗垂体-性腺轴的调节影响。此外，七鳃鳗是第一个清楚地证明GnRH分子作为神经激素调节垂体-性腺轴的双重角色的脊椎动物。然而，GnRH在生殖过程中作用的研究一直受到阻碍，因为缺乏一种可用于测定脑下垂体对GnRH反应的促性腺激素。七鳃鳗垂体促性腺激素(GTH)的纯化和鉴定是研究七鳃鳗下丘脑-垂体-性腺关系的关键。因此，确定GTH和验证下丘脑影响垂体性腺轴的方式对七鳗鱼来说是必要的，这也是该项目的一部分。这些实验将结合各种方法来进一步确定阿格纳坦人的大脑和脑下垂体之间的关系。正在进行的和拟议的研究主要集中在七鳃鳗促性腺激素释放激素的分子、生化和功能研究，以验证大脑释放的多种形式的促性腺激素释放激素影响促性腺素样分子的合成和分泌的假说，促性腺激素样分子调节性腺的功能。结果通过对七鳃鳗的这些研究，可以更好地理解从无脊椎动物到后来进化的脊椎动物的分子进化。这项研究旨在了解七鳃鳗是否存在从下丘脑到脑下垂体和性腺的调节。七鳃鳗属于脊椎动物中最古老的一种，被用来观察各种脊椎动物信号系统的起源。这个实验室已经确定了七鳃鳗下丘脑的促性腺激素释放激素并进行了测序，现在想要确定垂体释放的激素是对促性腺激素释放激素的反应。此外，还将确定环境因素对这一荷尔蒙途径的影响。这项研究将对生殖系统的分子进化提供更好的理解。***

9722765 Condon This proposal will investigate the control of reproduction by the brain and pituitary in an ancient fish, the lamprey. Lampreys are important because they are members of the oldest lineage of vertebrates, the Agnathans or jawless fish, and raise interesting questions on evolution. This laboratory has focused on the structure and function of two brain hormones involved in the brain- pituitary gonadal axis in lampreys. The primary structures of two brain hormones, gonadotropin-releasing hormone (GnRH- I and GnRH-III) have been determined in lampreys. This information combined with immunocytochemical and physiological studies provides strong evidence for the regulatory influence of the brain on the pituitary-gonadal axis in lampreys. In addition, lampreys are the first vertebrates to clearly demonstrate a dual role for GnRH molecules as neurohormones mediating the pituitary-gonadal axis. However, the investigations on the role of GnRHs in reproductive processes have been impeded by the lack of an identified gonadotropin that could be used in assays as a measure of pituitary responsiveness to GnRH. The purification and identification of lamprey pituitary gonadotropin, GTH, is critical to examine the hypothalamic- pituitary-gonadal relations in lampreys. Thus identification of GTH and verification of the ways in which the hypothalamus affects the pituitary gonadal axis are needed in the lamprey, and are part of this project. The experiments will incorporate a variety of approaches to further define the relationship of the brain and pituitary in Agnathans. The ongoing and proposed studies are focused on molecular, biochemical and functional studies of GnRHs in lampreys to test the hypothesis that multiple forms of GnRH released from the brain influence the synthesis and secretion of a gonadotropin-like molecule which regulated the function of the gonads. Results fsrom these studies in lampreys will provide better understanding of the molecular evolution from invertebrates to later evolved vertebrates. %%% This research is looking to see if there is regulation from the hypothalamus to the pituitary and the gonads in the lamprey. The lamprey belongs to one of the oldest lineage's of vertebrates and is used to look at the origin of various vertebrate signaling systems. This laboratory has identified and sequenced the gonadotropin releasing hormone from the hypothalamus of the lamprey, and now wants to identify the hormone released from the pituitary in response to GnRH. Also the effects of environmental factors on this hormonal pathway will be determined. This research will provide a better understanding of molecular evolution of the reproductive system. ***