Mechanisms of the adrenal medulla stress response

描述（由申请人提供）：应激是交感神经系统对环境压力的生理反应。如果不加以控制，它可能导致病理生理学，如高血压和糖尿病。肾上腺髓质的嗜铬细胞是交感神经系统的主要内分泌输出，并通过致密核心分泌颗粒的融合分泌许多递质分子，包括儿茶酚胺和肽递质。在由交感神经张力设定的基础放电率下，儿茶酚胺输出调节稳态过程，例如肠功能、血管张力和胰岛素分泌。应激介导的交感神经激活导致升高的儿茶酚胺分泌，增加心输出量和胰高血糖素水平。压力也会引起肽递质的释放，包括脑啡肽，脑啡肽可以起到止痛的作用，使生物体专注于逃避和防御。我们的目标是了解嗜铬细胞如何在生理性基底放电和应激激活下调节儿茶酚胺和信号肽的释放。已经研究了儿茶酚胺释放的细胞机制，但在这些条件下肽递质释放的了解较少。在这个提议中，我们将测试，在基础射击，嗜铬颗粒进行限制性融合与细胞表面和选择性释放儿茶酚胺。我们将测试应激激活诱导颗粒的完全融合和塌陷，从而导致儿茶酚胺和肽货物的释放。我们将采用电生理，电化学，荧光成像，免疫细胞化学和生物化学的方法。我们将测试在基底放电和应激激活状态下嗜铬颗粒的儿茶酚胺和蛋白质货物的胞吐作用。我们将测试关键分子在外吞-内吞机制中的作用，并测量颗粒在外吞-内吞周期中塌陷到细胞表面的程度。这些数据将为嗜铬细胞内分泌应激反应的细胞和分子机制提供一个基本的理解。

DESCRIPTION (provided by applicant): Stress is a physiological response of the sympathetic nervous system to environmental pressures. If left unchecked it can lead to patho-physiologies such as hypertension and diabetes. Chromaffin cells of the adrenal medulla are a primary endocrine output of the sympathetic nervous system and secrete a host of transmitter molecules, including catecholamines and peptide transmitters, through the fusion of dense core secretory granules. At basal firing rates, set by the sympathetic tone, catecholamine output regulates homeostatic processes such as enteric function, vascular tone and insulin secretion. Stress-mediated sympathetic activation leads to elevated catecholamine secretion, increasing cardiac output and glucagon levels. Stress also evokes peptide transmitter release, including enkephalin which acts as an analgesic and allows the organism to focus on escape and defense. Our goal is to understand how chromaffin cells regulate the release of catecholamine and signaling peptides under physiological basal-firing and stress activation. Cellular mechanisms for catecholamine release have been studied, but peptide transmitter release is less well understood under these conditions. In this proposal we will test that, under basal firing, chromaffin granules undergo a restricted fusion with the cell surface and selectively release catecholamine. We will test that stress-activation induces a full fusion and collapse of the granule leading to release of both catecholamine and peptide cargos. We will employ electrophysiological, electrochemical, fluorescence imaging, immunocytochemical and biochemical approaches. We will test for exocytosis of catecholamine and protein cargo from chromaffin granules under basal-firing and stress-activated states. We will test the roles of key molecules in the exo-endocytic mechanism and we will measure the degree granule collapse into the cell surface during the exo-endocytic cycle. This data will provide a fundamental understanding of the cellular and molecular mechanisms for the endocrine stress response in chromaffin cells.