EFFECTS OF NICOTINE ON THE ADRENAL MEDULLA

摄入尼古丁会导致血儿茶酚胺升高 水平，这与心率和血压的增加有关 在人类和实验动物身上。血儿茶酚胺的增加 部分原因是尼古丁介导的儿茶酚胺增加 肾上腺髓质的分泌物。为了防止资源枯竭， 儿茶酚胺在这些增强期的细胞储存 分泌，儿茶酚胺的生物合成通过激活和 酪氨酸羟化酶(TH)的诱导。这篇文章中概述的研究 提案旨在研究药理和细胞内 尼古丁调节大鼠肾上腺TH的分子机制 延髓。建议的具体目的如下：(一) 尼古丁介导的TH和TH激活的药理学特征 大鼠肾上腺髓质中TH-mRNA的表达 尼古丁；(2)确定尼古丁介导的诱导 肾上腺TH-mRNA是由于刺激转录速率而产生的 TH基因；(3)鉴定相互作用的大鼠肾上腺髓质核蛋白 与TH基因的5‘侧翼区连接，这可能参与了 尼古丁对基因的激活；以及(4)确定耐受性 发展为尼古丁介导的肾上腺TH激活 治疗过的老鼠。TH-mRNA水平将通过与克隆的 Cdna探针。TH基因的转录速率将使用 本实验室研制出了特异、灵敏的核连续分析方法。 与TH基因启动子区域结合的核蛋白将是 通过使用末端标记的限制性片段的凝胶位移分析进行测量 从编码TH基因的基因组克隆中分离出来。这些 测量将使用生理盐水处理的对照大鼠或 大鼠急性或慢性治疗不同的时间段和 尼古丁的不同给药途径。这些研究将 增进我们对监管机制的理解 尼古丁对肾上腺TH的影响，因此，将通过 哪种尼古丁会升高血儿茶酚胺并引发相应的 药物对心血管的影响。

The intake of nicotine results in the elevation of blood catecholamine levels, which is associated with increases in heart rate and blood pressure in humans and experimental animals. This increase in blood catecholamines is due partially to the nicotine-mediated increase in catecholamine secretion from the adrenal medulla. In order to prevent the depletion of the cellular stores of catecholamines during these periods of enhanced secretion, catecholamine biosynthesis is enhanced via the activation and induction of tyrosine hydroxylase (TH). The studies outlined in this proposal are designed to investigate the pharmacological and intracellular molecular mechanisms by which nicotine regulates TH in the rat adrenal medulla. The specific aims of the proposal are as follow: (1) to characterize pharmacologically the nicotine-mediated activation of TH and induction of TH-mRNA that occur in the adrenal medulla of rats treated with nicotine; (2) to determine whether the nicotine-mediated induction of adrenal TH-mRNA is due to the stimulation of the transcription rate of the TH gene; (3) to identify rat adrenomedullary nuclear proteins that interact with the 5'flanking region of the TH gene and that may be involved in the activation of the gene by nicotine; and (4) to determine whether tolerance develops to the nicotine-mediated activation of adrenal TH in chronically- treated rats. TH-mRNA levels will be measured by hybridization to a cloned cDNA probe. The transcription rate of the TH gene will be measured using a specific and sensitive nuclear run-on assay developed in my laboratory. Nuclear proteins that bind to he promoter regions of the TH gene will be measured by a gel shift assay using end-labeled restriction fragments isolated from a genomic clone that codes for the TH gene. THese measurements will be made using either control rats treated with saline or rats treated acutely or chronically for different periods of time and by different routes of administration with nicotine. These studies will increase our understanding of the mechanisms responsible for the regulation of adrenal TH by nicotine and thus, will shed light on the mechanisms by which nicotine elevates blood catecholamines and elicits the consequent cardiovascular effects of the drug.