权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

CYTOCHROME P450 DEPENDENT METABOLISM OF DRUGS IN BRAIN

大脑中细胞色素 P450 依赖性药物代谢

基本信息

批准号：
6186508
负责人：
HENRY W STROBEL
金额：
$ 25.9万
依托单位：
UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON
依托单位国家：
美国
项目类别：
财政年份：
1998
资助国家：
美国
起止时间：
1998-04-01 至 2003-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/6186508
关键词：
brain metabolism chlorpromazine cytochrome P450 drug metabolism enzyme activity enzyme substrate haloperidol imipramine immunocytochemistry in situ hybridization laboratory rat microdialysis phenytoin protein isoforms pyrrolidinediones recombinant proteins

项目摘要

DESCRIPTION (adapted from applicant's abstract): A role for brain cytochromes P450 in metabolism of therapeutic drugs has been suspected since brain microsomes were first shown to be able to activate carcinogens and neurotoxic agents. The low rate of clearance of xenobiotics by brain microsomes, however, diminished enthusiasm for brain as an organ of detoxification. Our laboratory has cloned 6 novel cytochrome P450 isoforms from a brain cDNA expression library namely CYP2D18, CYP3A9, CYP4F1, CYP4F4, CYP4F5 and CYP4F6. Using 2 of these newly cloned isoforms, CYP2D18 and CYP4F6, expressed in COS M6 cell lysates reconstituted with P450 reductase and lipid, we were able to provide direct evidence that these brain isoforms were able to catalyze the demethylation and 10-hydroxylation of an antidepressant, imipramine. This grant application requests support to define the catalytic activity toward drugs used as therapeutic agents for brain diseases - chlorpromazine, haloperidol, ethosuximide, phenytoin and imipramine - exhibited by expressed recombinant proteins of the newly cloned brain P450 isoforms CYP2D18, CYP3A9, CYP4FJ, CYP4F4, CYP4FS and CYP4F6. We will determine the catalytic ability of these isoforms by defining the Km and Vmax values for each substrate with each form. Moreover, we will define the catalytic ability of the isoforms with 2 substrates, that is the primary substrate and the product which is also a substrate such as is the case for imipramine to desipramine to didesmethyl imipramine. We will obtain rate constants for this A - to B - to C sequence and determine the true product turnover for the full reaction sequence by defining which is the best substrate and which compound is the true product. We will also define the regional localization in the brain of the new P450 isoforms. We will then use this information to place probes for microdialysis in specific locations in the brain and define local in situ metabolism of these therapeutic drugs. This combination of in vitro and in vivo determinations will establish a clear basis for evaluating the potential of brain cytochrome P450 isoforms to metabolize in situ drugs used to treat brain diseases.

描述（改编自申请人的摘要）：大脑的作用细胞色素 P450 在治疗药物代谢中的作用一直被怀疑脑微粒体首次被证明能够激活致癌物质神经毒剂。大脑对外源物质的清除率低然而，微粒体降低了人们对大脑作为大脑器官的热情。排毒。我们实验室克隆了6种新型细胞色素P450亚型来自大脑 cDNA 表达文库，即 CYP2D18、CYP3A9、CYP4F1、CYP4F4， CYP4F5 和 CYP4F6。使用其中 2 个新克隆的亚型，CYP2D18 和 CYP4F6，在用 P450 还原酶重建的 COS M6 细胞裂解物中表达和脂质，我们能够提供直接证据表明这些大脑亚型能够催化去甲基化和10-羟基化抗抑郁药，丙咪嗪。此拨款申请请求支持定义对用作治疗剂的药物的催化活性脑部疾病 - 氯丙嗪、氟哌啶醇、乙舒酰亚胺、苯妥英和丙咪嗪 - 通过新克隆的表达重组蛋白表现出来脑 P450 亚型 CYP2D18、CYP3A9、CYP4FJ、CYP4F4、CYP4FS 和 CYP4F6。我们将通过定义 Km 来确定这些亚型的催化能力每种形式的每种基质的 Vmax 值和 Vmax 值。此外，我们将定义具有 2 个底物的异构体的催化能力，即主要基材和产品也是基材，例如丙咪嗪至地昔帕明至双去甲基丙咪嗪。我们将获得费率该 A - 到 B - 到 C 序列的常数并确定真实的乘积通过定义最佳反应序列来实现整个反应序列的周转底物以及哪种化合物是真正的产物。我们还将定义新的 P450 异构体在大脑中的区域定位。我们随后将使用此信息将微透析探针放置在特定位置在大脑中并定义这些治疗药物的局部原位代谢。这种体外和体内测定的结合将建立一个评估脑细胞色素 P450 亚型潜力的明确基础代谢用于治疗脑部疾病的原位药物。