SOMATOSTATIN BIOSYNTHESIS IN THE HYPOTHALMUS

本研究旨在研究生长抑素的体内生物合成。 下丘脑中的多肽家族。这条途径涉及最初的 从信使RNA合成ProSRIF分子，该分子 然后被蛋白水解酶裂解成各种更小的多肽， 包括生长抑素28(SRIF-28)和生长抑素-14； 下丘脑的原始生长激素抑制激素)。超过了 在过去的几年里，我们已经开发了一种测量SRIF-14和 SRIF-28在大鼠下丘脑的体内合成，并已用于研究 生长抑素生物合成的几个方面。该方法涉及 向第三脑室注射(35S)半胱氨酸，然后取出 几个小时后下丘脑和测量标记半胱氨酸 纳入SRIF 14和SRIF-28。这些多肽是通过以下方式分离的 在标记定量之前进行高效液相色谱(HPLC法)。 我们建议继续研究控制SRIF-14和SRIF-28的因素 下丘脑的生物合成。我们将调查对SRIF的影响 合成药物、激素和其他已知可改变的治疗方法 下丘脑中SRIF免疫反应性水平。我们将开发高效液相色谱方法 用于ProSRIF的分离和定量。然后我们计划研究标有 半胱氨酸掺入ProSRIF，以及生理、 药理和激素治疗对其生产和加工的影响 SRIF-14和SRIF-28。最后，我们将从以下方面开始研究SRIF合成 (35S)半胱氨酸在下丘脑的出生后发育过程中，也开始 为了研究SRIF在体内和体外的合成 含有SRIF免疫反应神经元的中枢神经系统 没有内分泌功能的：视网膜。后一个CNS区域 之所以被选中，特别是因为它很容易在体外 生化研究，对组织的破坏最小。结果是 这些调查应提供信息，说明 中枢神经系统中生长抑素多肽的合成，并帮助 了解SRIF神经元在整个中枢神经系统中的功能作用 功能。此外，他们应该帮助建立一个基础 有助于了解CNS病因的基本信息 与生长激素分泌异常有关的疾病，可能也与 与前脑相关的痴呆症和其他神经系统疾病 退化(和生长抑素神经元的丧失)。

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).