TOXICOLOGICAL ASPECTS OF HEMOPROTEIN REGULATION

血蛋白调节的毒理学方面

• 批准号: 6043499
• 负责人: YOICHI OSAWA
• 金额: $ 18.25万
• 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/6043499
• 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：（改编自研究者摘要） 所提出的研究是为了阐明失活的机制， 神经元型一氧化氮合酶（NOS）的降解和周转， 细胞色素P450样血红素蛋白，由暴露于外源性物质引起， 包括毒品和环境毒物。 核心假设是， 这种作用降低了形成NO的能力，NO是一种重要的生物调节因子， 分子参与许多生理功能，并导致某些形式的 化学诱导的毒性。 他们已经证明，某些异生物质，如CBrCl 3， 在一定时间内不可逆地抑制NOS的神经元亚型， 代谢依赖性方式，与该化合物的代谢依赖性方式相似， 肝微粒体细胞色素P450。 保护NOS免于失活是 由精氨酸的L-异构体而不是D-异构体提供，这表明精氨酸的活性 现场指导活动。 最近显示胍那苄（WytesinTM）， 一种抗高血压药，在体外使阴茎神经元NOS失活， 类似的代谢依赖方式，并导致阴茎NOS蛋白的丢失 和在体内的活性。 这可能是 重要的是，因为NO在阴茎勃起中起关键作用， 抗高血压药物，包括胍那苄，已知会导致阳痿 作为一种毒副作用。 因此，本提案的目的是 了解神经元NOS如何失活以及稳态水平如何 NOS随后受到影响。 Guanabenz将被用作模型代理 为进一步研究其他类似的有毒物质开发方法。 的 具体目标是：（1）确定分子机制， 使用重组纯化的 表达神经元NOS。 (2)为了描述稳定的 T细胞杂交瘤2B 4中胍那苯引起的神经元NOS的状态水平 线 (3)为了更全面地描述长期 胍那苄给药对体内NOS的影响。 (4)为了利用体外、体内 体内，和T细胞系，因为它们被开发来测试其他生物医学 重要的化学品，基于计算机结构搜索以及 阳痿的发病率，如异喹胍和贝沙尼定。 这些研究将使我们更好地理解药物是如何通过 和调节神经元NOS，以及活性位点的性质， 酶，从而导致设计更安全的药物，而没有不希望的 毒性副作用，如阳痿。 相反，同样的 这些知识可以用来设计更有效的NOS抑制剂， 在多种神经系统疾病中的药理学用途。