Modulation of Corticotropin Releasing Hormone Action

本研究将探讨垂体细胞对促肾上腺皮质激素释放激素（CRH）和CRH作用的特异性调节剂的细胞和亚细胞反应的基本机制。它的重点是前叶促皮质物，并将研究CRH的结合和内化（通过定量电镜细胞化学分析）和激素储存（通过免疫细胞化学）。该研究将确定促肾上腺皮质激素释放的抑制剂（糖皮质激素）或增强剂（抗利尿激素）是否会改变促肾上腺皮质激素处理CRH的速率或途径。在增强剂抗利尿激素存在的情况下，被激活结合CRH的储备细胞群将被识别。该研究将验证CRH作用的增强依赖于具有产生ACTH潜力的独特抗利尿激素敏感细胞的激活这一假设。另一个有待验证的假设是，糖皮质激素对CRH作用的抑制，在其早期阶段，包括阻断CRH受体向质膜的运输，或将CRH受体复合物重新输送到溶酶体以进行快速降解。CRH结合的变化将通过生物素化的CRH配体和标记亲和素染色来识别。所有细胞化学染色将使用Bioquant System IV和图像分析系统进行分析。这项研究的结果将加强对一种垂体细胞调节激素释放的基本机制的理解，即促肾上腺皮质激素。

This study will investigate basic mechanisms underlying cellular and subcellular responses of pituitary cells to corticotropin releasing hormone (CRH) and specific modulators of CRH action. It is focused on anterior lobe corticotropes and will study CRH binding and internalization (with quantitative electron microscopic cytochemical analyses) and hormone storage (with immunocytochemistry). The study will determine if inhibitors (glucocorticoids) or potentiators (vasopressin) of ACTH release alter the rate or route of CRH processing by corticotropes. The reserve cell population that is activated to bind CRH in the presence of the potentiator, vasopressin, will be identified. The study will test the hypothesis that potentiation of CRH action is dependent upon the activation of unique vasopressin sensitive cells that have the potential to produce ACTH. Another hypothesis that will be tested is that glucocorticoid inhibition of CRH action, in its early stages, includes either a block in the transport of CRH receptors to the plasma membrane or a rerouting of CRH-receptor complexes to lysosomes for rapid degradation. Changes in CRH binding will be identified with a biotinylated CRH ligand and labelled avidin stains. All cytochemical stains will be analyzed with the Bioquant System IV and image analysis system. The results of this research will enhance the understanding of basic mechanisms regulating the release of hormone by one type of pituitary cell, the corticotrope.