SOMATOSTATIN BIOSYNTHESIS IN THE HYPOTHALAMUS

这一应用提出了一条研究体内 大鼠生长抑素(SRIF-14)生物合成的调控机制 下丘脑。SRIF-14被认为是一种下丘脑激素， 影响垂体生长激素(GH)的分泌；它还可能 在大脑的其他地方起神经递质的作用。虽然有些信息 有关SRIF-14可能来自的前体多肽的信息 对SRIF-14的合成动力学知之甚少 活着。最近，我们开发了一系列高性能液体 使我们能够分离SRIF-14及其 假定的即刻降压素，生长抑素-28(SRIF-28)，以及治疗技术 在体内获得35S-半胱氨酸掺入这些多肽 在将氨基酸注入他们的脑室后。再加上一个 放射免疫测定法，允许测量两者的内源性水平 SRIF-14和SRIF-28在高效液相分离后，这些方法将使我们能够 首次获得SRIF-14和SRIF-28生物合成的估计值 在活体中在大脑中。在本申请中，我们建议研究几个问题 与使用这些新开发的技术进行SRIF生物合成有关。 具体地说，我们希望确定[1]35S-半胱氨酸-SRIF-14(和-28)是否 通过神经元的蛋白质合成机制合成的，如果肽是 来自较大分子量前体(如SRIF-28和 拟议的12,000兆瓦前体)，如果从前体转换为SRIF-14 发生在从细胞体到神经末梢的运输过程中；[2]如果SRIF-14 合成受循环(或释放)生长激素或SRIF-14的控制 或SRIF-28；[3]如果SRIF生物合成在生理和生理条件下发生变化 先前显示的改变下丘脑SRIF的病理生理条件 含量和血液生长激素水平；以及[4]如果服用选定的 神经药理药物被认为通过作用于 下丘脑SRIF释放对下丘脑SRIF-14和SRIF-28合成的影响 (并可能发布)以这些先前预测的方式 调查结果。如果成功，这些研究将提供重要的 关于大脑合成的体内调节信息 神经肽被认为既是一种激素，也可能是一种 神经递质。

This application proposes a line of investigation into the in vivo mechanisms that control somatostatin (SRIF-14) biosynthesis in the rat hypothalamus. SRIF-14 is believed to be a hypothalamic hormone that influences the secretion of pituitary growth hormone (GH); it may also function as a neurotransmitter elsewhere in brain. While some information is available concerning possible precursor peptides from which SRIF-14 may be derived, very little is known about the dynamics of SRIF-14 synthesis in vivo. Recently, we have developed a series of high-performance liquid chromatographic (HPLC) separations that allow us to isolate SRIF-14 and its presumed immediate presursor, somatostatin-28 (SRIF-28), and techniques for obtaining incorporation of 35S-cysteine in vivo into these peptides following amino acid injection into the their ventricle. Coupled with a radioimmunoassay that allows measurement of endogenous levels of both SRIF-14 and SRIF-28 following HPLC separation, these methods will allow us to obtain estimates for the first time of SRIF-14 and SRIF-28 biosynthesis in vivo in brain. We propose in this application to study several issues relating to SRIF biosynthesis using thes newly-developed techniques. Specifically, we hope to determine [1] if 35S-cysteine-SRIF-14 (and -28) is synthesized via the neuron's protein sythetic machinery, if the peptide is derived from larger molecular weight precursors (like SRIF-28, and a proposed 12,000 mw precursor), and if conversion from precursors to SRIF-14 occurs during transit from cell body to nerve terminal; [2] if SRIF-14 synthesis is subject to control by circulating (or released) GH, or SRIF-14 or SRIF-28; [3] if SRIF biosynthesis changes under physiologic and pathophysiologic conditions shown previously to alter hypothalamic SRIF content and blood GH levels; and [4] if the administration of selected neuropharmacologic agents thought to influence GH secretion via effects on hypothalamic SRIF release modify hypothalamic SRIF-14 and SRIF-28 synthesis (and presumably release) in the manner predicted by these previous findings. If successful, these studies should provide important information about the in vivo regulation of the synthesis of a brain neuropeptide thought to function both as a hormone and possible also as a neurotransmitter.