SOMATOSTATIN BIOSYNTHESIS IN THE HYPOTHALMUS

本申请旨在研究生长抑素的体内生物合成 下丘脑中的肽家族。 该途径涉及初始 从促生长素抑制素原（proSRIF）分子的信使RNA合成， 然后被蛋白水解酶切割成各种更小的肽， 包括生长抑素-28（SRIF-28）和生长抑素-14（SRIF-14; 下丘脑的原始生长激素抑制激素）。 来 在过去的几年里，我们开发了一种测量SRIF-14的方法， SRIF-28在大鼠下丘脑中体内合成，并将其用于研究 生长抑素生物合成的几个方面。 该方法涉及 将（35S）半胱氨酸施用到第三脑室中，然后去除第三脑室中的半胱氨酸。 几小时后下丘脑和测量标记的半胱氨酸 纳入SRIF 14和SRIF-28。 通过以下方法分离肽： 在标记定量之前进行高效液相色谱（HPLC）。 我们建议继续研究影响SRIF-14和SRIF-28的因素 下丘脑的生物合成。 我们将研究对SRIF的影响 合成药物、激素和其他已知能改变 免疫反应性SRIF水平。 我们将开发HPLC方法 用于分离和定量proSRIF。 然后我们计划研究标记 半胱氨酸掺入proSRIF，以及生理， 药理学和激素治疗对其生产和加工， SRIF-14和SRIF-28。 最后，我们将开始研究SRIF的合成， （35 S）半胱氨酸在出生后发育过程中在下丘脑，也开始 研究SRIF在体内和体外合成的另一部分， 含有SRIF免疫反应神经元的中枢神经系统（CNS） 没有内分泌功能的：视网膜。 后一个CNS区域具有 特别是因为它很容易在体外 对组织破坏最小的生化研究。 的结果 这些调查应提供有关决定因素的信息， 中枢神经系统中生长抑素肽的合成， 了解SRIF神经元在整个CNS中的功能作用 功能 此外，他们还应帮助建立一个基础， 有助于了解CNS病因的基本信息 与GH分泌异常相关的疾病，也许还与 痴呆和其他与前脑有关的神经系统疾病 生长抑素神经元（Somatostatin neurons）

This application is to study the in vivo biosynthesis of the somatostatin family of peptides in the hypothalamus. The pathway involves initial synthesis from messenger RNA of a prosomatostatin (proSRIF) molecule, which is then cleaved by proteolytic enzymes into a variety of smaller peptides, including somatostatin-28 (SRIF-28) and somatostatin-14; (SRIF-14; the original growth hormone inhibiting hormone of the hypothalamus). Over the past few years, we have developed a method for measuring SRIF-14 and SRIF-28 synthesis in vivo in rat hypothalamus, and have used it to study several aspects of somatostatin biosynthesis. The method involves administering (35S)cysteine into the third ventricle, and then removing the hypothalamus several hours later and measuring labeled cysteine incorporation into SRIF 14 and SRIF-28. The peptides are isolated by high-performance liquid chromatography (HPLC) prior to label quantitation. We propose to continue to study factors governing SRIF-14 and SRIF-28 biosynthesis in hypothalamus. We will investigate the effects on SRIF synthesis of drugs, hormones, and other treatments known to modify immunoreactive SRIF levels in hypothalamus. We will develop HPLC methods for isolating and quantitating proSRIF. We then plan to study labeled cysteine incorporation into proSRIF, and the effects of physiologic, pharmacologic, and hormonal treatments on its production and processing to SRIF-14 and SRIF-28. Finally, we will begin to study SRIF synthesis from (35S)cysteine during postnatal development in hypothalamus, and also begin to investigate SRIF synthesis in vivo and in vitro in another portion of the central nervous system (CNS) that contains SRIF-immunoreactive neurons having no endocrine functions: the retina. This latter CNS region has been chosen in particular because it readily lends itself to in vitro biochemical study with minimal disruption to the tissue. The results of these investigations should provide information on the factors governing the synthesis of the somatostatin peptides in the CNS, and help in understanding the functional roles of SRIF neurons in overall CNS function. In addition, they should help in building of a foundation of basic information that will help in understanding the etiologies of CNS diseases associated with abnormal GH secretion, and perhaps also with dementias and other neurological diseases associated with forebrain deterioration (and loss of somatostatin neurons).