ACTIONS OF CALCIUM REGULATING HORMONES IN THE GUT

在这项工作中提出的总体假设是，钙调节 激素肽，特别是甲状旁腺激素（PTH）和降钙素 基因相关肽（CGRP）在肠道调节中起重要作用 功能 PTH是一种高效的胃肠道平滑肌松弛剂。 这 该项目将详细研究胃肠道PTH受体的性质和 第二信使参与。 大鼠胃肠道平滑肌和粘膜将 研究使用标准配体结合技术，受体化学交叉- 连接和放射自显影，以比较GI受体与经典的 骨和肾脏中PTH受体的表达，并将受体定位于特定的 胃肠道细胞。 待检测的第二信使包括环核苷酸， 胞内Ca ++和肌醇磷酸。 还讨论了 假设PTH-related protein（PTHrP）是一种新发现肿瘤， 衍生肽参与恶性肿瘤的体液性高钙血症， 通常存在于GI粘膜或肌肉细胞中，并作为旁分泌或 自分泌因子调节胃肠道事件。 分子生物学技术 将被用来寻找PTHrP mRNA在肠道，并通过原位 杂交组织化学，将mRNA定位于特定的GI细胞。 同时采用免疫细胞化学定位PTHrP本身。 与妊娠、哺乳、衰老和 检查伤口愈合情况。 的生理意义 将通过研究来检查PTH样肽在肠道中的作用。 在大鼠肠道中体内不可吸收的标记物，以确定 这些肽对胃肠道运动的影响。 CGRP，也已知影响GI功能， 特别是收缩性，也将使用这些方法进行研究 PTHrP的概述。 大鼠和猪胃肠道组织中的受体将 第二信使将被识别， mRNA和肽本身的研究将使用杂交和 免疫细胞化学技术。 这些研究将有助于阐明 PTHrP是一种新的功能相关肽， 只存在于肿瘤组织中。 这项工作最终应该建立新的 钙相关肽在肠道中的作用，阐明所涉及的机制， 促进我们对它们在健康和疾病中的作用的理解，并使 我们希望使用这些肽或其类似物作为治疗剂。

The overall hypothesis addressed in this work is that Ca-regulatory hormonal peptides, especially parathyroid hormone (PTH) and calcitonin gene-related peptide (CGRP), play important roles in regulation of gut function. PTH is a highly effective relaxant of GI smooth muscle. This project will examine in detail the nature of the GI PTH receptors and the second messengers involved. Rat GI smooth muscle and mucosa will be studied using standard ligand binding techniques, receptor chemical cross- linking, and autoradiography in order to compare GI receptors to classical PTH receptors in bone and kidney and to localize the receptors to specific GI cells. Second messengers to be examined include cyclic nucleotides, intracellular Ca++, and inositol phosphates. Also addressed is the hypothesis that PTH-related protein (PTHrP), a newly discovered tumor- derived peptide involved in humoral hypercalcemia of malignancy, is present normally in GI mucosal or muscle cells and acts locally as a paracrine or autocrine factor to regulate GI events. Molecular biological technology will be used to search for PTHrP mRNA in the gut and, by in situ hybridization histochemistry, to localize the mRNA to specific GI cells. Immunocytochemistry will be employed concurrently to localize PTHrP itself. Developmental changes in association with gestation, lactation, aging, and wound healing will be examined. The physiological significance of the effect of PTH-like peptides in the gut will be examined by studying nonabsorbable markers in vivo in the rat gut to determine the influence of these peptides on GI motility. CGRP, also known to affect GI function, especially contractility, also will be studied using the approaches outlined for PTHrP. Receptors in rat and pig GI tissue will be characterized, second messengers will be identified, and the localization of mRNA and the peptide itself will be studied using hybridization and immunocytochemical techniques. The studies will help elucidate the physiological importance of PTHrP, a new peptide functionally associated at present only with tumor tissue. The work ultimately should establish new roles for Ca-related peptides in the gut, clarify the mechanisms involved, promote our understanding of their roles in health and disease, and enable us to employ these peptides or their analogs as therapeutic agents.