Mechanisms of the adrenal medulla stress response.

描述（由申请人提供）：压力是交感神经系统对环境压力的生理反应。如果不加以控制，它会导致病理生理，如高血压和糖尿病。肾上腺髓质的染色质细胞是交感神经系统的主要内分泌输出物，通过致密的核心分泌颗粒融合分泌大量的递质分子，包括儿茶酚胺和肽递质。在由交感神经张力决定的基础放电速率下，儿茶酚胺的输出调节肠道功能、血管张力和胰岛素分泌等稳态过程。应激介导的交感神经激活导致儿茶酚胺分泌升高，心输出量和胰高血糖素水平增加。压力也会引起肽传递素的释放，包括脑啡肽，它可以作为止痛剂，让生物体专注于逃避和防御。我们的目标是了解染色质细胞在生理基底放电和应激激活下如何调节儿茶酚胺和信号肽的释放。儿茶酚胺释放的细胞机制已经被研究过，但在这些条件下肽递质的释放还不太清楚。在这个提议中，我们将测试在基底放电下，染色质颗粒与细胞表面进行有限的融合，并选择性地释放儿茶酚胺。我们将测试应激激活诱导颗粒的完全融合和崩溃导致儿茶酚胺和肽的释放。我们将采用电生理、电化学、荧光成像、免疫细胞化学和生化方法。我们将测试在基底放电和应激激活状态下染色质颗粒中儿茶酚胺和蛋白质的胞吐。我们将测试关键分子在外胞吞机制中的作用，我们将测量在外胞吞周期中颗粒塌陷到细胞表面的程度。这些数据将为染色质细胞内分泌应激反应的细胞和分子机制提供一个基本的认识。

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.