TOXICOLOGICAL ASPECTS OF HEMOPROTEIN REGULATION

血蛋白调节的毒理学方面

• 批准号: 6178460
• 负责人: YOICHI OSAWA
• 金额: $ 18.38万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-08-01 至 2001-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6178460
• 关键词: T lymphocyte; antihypertensive agents; cell line; drug adverse effect; enzyme activity; enzyme induction /repression; hemoprotein metabolism; impotence; molecular pathology; nitric oxide synthase; toxin metabolism

DESCRIPTION: (Adapted from the Investigator's Abstract) The objective of the proposed research is to elucidate the mechanisms of inactivation, degradation, and turnover of neuronal nitric oxide synthase (NOS), a cytochrome P450-like hemoprotein, caused by exposure to xenobiotics, including drugs and environmental toxicants. The central hypothesis is that such effects diminish the ability to form NO, an important bioregulatory molecule involved in many physiological functions, and cause some forms of chemically-induced toxicities. They has been shown that certain xenobiotics, such as CBrCl3, can irreversibly inactivate the neuronal isoform of NOS in a time- and metabolism-dependent manner, similar to that found for this compound with liver microsomal cytochrome P450. Protection of NOS from inactivation is afforded by the L-, but not the D-, isomer of arginine suggesting an active site directed event. More recently it was shown that guanabenz (WytesinTM), an antihypertensive agent, inactivates penile neuronal NOS in vitro in a similar metabolism dependent manner and causes a loss of penile NOS protein and activity in vivo at pharmacologically relevant doses. This may be important since NO plays a key role in penile erection and since many antihypertensive agents, including guanabenz, are known to cause impotence as a toxic side effect. Thus, the aims of the current proposal are to understand how neuronal NOS is inactivated and how the steady state levels of NOS are subsequently affected. Guanabenz will be used as a model agent to develop methods for further study of other similarly toxic agents. The specific aims are: (1) To determine the molecular mechanism of the inactivation caused by guanabenz with the use of purified recombinantly expressed neuronal NOS. (2) To characterize the decrease in the steady state levels of neuronal NOS caused by guanabenz in the T cell hybridoma 2B4 line. (3) To more fully characterize the effects of long term administration of guanabenz on NOS in vivo. (4) To utilize the in vitro, in vivo, and T cell line as they are developed to test other biomedically important chemicals, based on a computer based structure search as well as incidence of impotence, such as debrisoquin and bethanidine. These studies should lead to a better understanding of how drugs inactivate and regulate neuronal NOS, as well as the nature of the active site of the enzyme, and thereby lead to the design of safer drugs without undesired toxicological side effects, such as impotence. Conversely, the same knowledge could be used to design more effective inhibitors of NOS for pharmacological use in a variety of neurological diseases.

描述：(改编自《调查员摘要》)目标 这项拟议的研究旨在阐明失活的机制， 神经元型一氧化氮合酶(NOS)的降解和周转 细胞色素P450样血素蛋白，由接触外源物质引起， 包括毒品和环境毒物。中心假设是 这种效应削弱了形成一氧化氮的能力，一氧化氮是一种重要的生物调节物质 参与许多生理功能的分子，并导致某些形式的 化学诱导的毒性。 他们已经证明，某些外来生物，如CBrCl3，可以 在一段时间内不可逆转地使一氧化氮合酶神经元亚型失活 依赖新陈代谢的方式，类似于对这种化合物的发现 肝微粒体细胞色素P450。保护一氧化氮合酶免于失活是 由精氨酸的L异构体提供，而不是D-异构体提供，暗示有活性 现场指导的活动。最近有研究表明，鸟粪(WytesinTM)， 一种抗高血压药物在体外灭活阴茎神经元型一氧化氮合酶 相似的代谢依赖方式并导致阴茎一氧化氮合酶蛋白丢失 以及体内药理上相关剂量的活性。这可能是 很重要，因为NO在阴茎勃起中起着关键作用，而且由于许多 已知的抗高血压药物，包括吧那苯肼，会导致阳萎 作为一种毒副作用。因此，当前提案的目的是 了解神经元一氧化氮合酶是如何失活的，以及稳态水平是如何 的一氧化氮合酶随后受到影响。Ganabenz将被用作模范代理 开发其他类似毒物的进一步研究方法。这个 具体目标是：(1)确定致病的分子机制 重组纯化的愈创木酚灭活效果的研究 神经元型一氧化氮合酶表达。(2)刻画稳健性的下降 愈创木酚对T细胞杂交瘤2B4细胞神经元型一氧化氮合酶水平的影响 排队。(三)更充分地描述长期影响 在体给药对一氧化氮合酶的影响。(4)利用体外、体内 活体和T细胞系，因为它们是为了测试其他生物医学而开发的 重要化学品，基于计算机结构搜索以及 阳萎的发生率，如去氢异喹和贝他尼定。 这些研究应该有助于更好地理解药物是如何失活的 并调节神经元型一氧化氮合酶，以及活性部位的性质 酶，从而导致设计更安全的药物而不会产生不良影响 毒理副作用，如阳萎。相反，相同的 知识可以用来设计更有效的一氧化氮合酶抑制剂 在多种神经系统疾病中的药理作用。