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)的细胞和亚细胞反应的基本机制以及CRH作用的特定调节剂。它的重点是前叶皮质激素，并将研究CRH的结合和内化(用定量的电子显微镜细胞化学分析)和激素储存(用免疫细胞化学)。这项研究将确定ACTH释放的抑制剂(糖皮质激素)或增强剂(加压素)是否会改变促肾上腺皮质激素处理CRH的速度或途径。在后叶加压素存在的情况下被激活以结合CRH的储备细胞群将被识别出来。这项研究将检验CRH作用的增强依赖于有可能产生ACTH的独特的加压素敏感细胞的激活的假设。另一种将被检验的假说是，糖皮质激素抑制CRH的作用，在其早期阶段，包括阻止CRH受体到质膜的运输，或者将CRH受体复合体重新路由到溶酶体，以便快速降解。CRH结合的变化将通过生物素标记的CRH配体和标记的亲和素染色来鉴定。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深对调节一种类型的垂体细胞--促肾上腺皮质激素释放激素的基本机制的理解。

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.