Neural Actions of Toluene

甲苯的神经作用

基本信息

批准号：
7024517
负责人：
JOHN J. WOODWARD
金额：
$ 28.06万
依托单位：
MEDICAL UNIVERSITY OF SOUTH CAROLINA
依托单位国家：
美国
项目类别：
财政年份：
2002
资助国家：
美国
起止时间：
2002-04-15 至 2009-02-28
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): Volatile solvents such as toluene, benzene and trichloroethane are widely distributed in a variety of products encountered in both industrial and home settings. These include glues, thinners, rubber cements, aerosol sprays, nail polish removers, correction fluid and dry cleaning solvents. Although the occupational hazards of exposure to these solvents have been previously examined in a variety of toxicological studies, the cellular and molecular sites of action that account for their intoxicating effects are virtually unknown. Surveys of drug use show that a significant percentage of the population has used volatile solvents for their intoxicating properties and such use is especially prevalent among adolescents and teens who may have easy access to these products. Previous behavioral studies show that toluene and other abused volatile solvents display actions similar to that observed for CNS depressants such as ethanol, barbiturates, benzodiazepines, and anesthetics. Thus, we hypothesize that abused solvents, like other CNS depressants, may exert some of its neurobehavioral effects by altering the function of specific ion channels that are involved in mediating and modulating neuronal transmission. We have generated data to support this hypothesis and have demonstrated that toluene and other volatile solvents inhibit the function of recombinant and native NMDA and acetylcholine receptors expressed in oocytes and cultured neurons. This inhibition was dose-dependent and was influenced by the subunit composition expressed. In contrast to ethanol, toluene had negligible effects on currents mediated by non-NMDA receptors or on G-protein coupled potassium channels. These results suggest that abused solvents may show greater selectivity than alcohol with respect to their ability to modulate the activity of neuronal ion channels. Studies outlined in this proposal will test this hypothesis by determining the sensitivity of recombinant and native ion channels to toluene and other volatile solvents that are subject to abuse. Two-electrode voltage-clamp and patch-clamp electrophysiology will be used to analyze the solvent sensitivity of recombinant ionotropic receptors expressed in oocytes and HEK cells. The molecular sites of action for toluene will be explored by testing whether sites known to regulate the alcohol/anesthetic sensitivity of these channels also regulate solvent sensitivity. Finally, the relevance of the findings obtained in recombinant receptor systems will be assessed by measuring the effects of toluene and other abused solvents on ion channels expressed in cultured brain neurons using whole-cell patch clamp and calcium imaging. Results obtained from these studies outlined are expected to greatly expand our knowledge of the cellular and molecular targets of these important drugs of abuse.

描述（申请人提供）：甲苯、苯等挥发性溶剂和三氯乙烷广泛分布在遇到的各种产品中在工业和家庭环境中。其中包括胶水、稀释剂、橡胶水泥、气溶胶喷雾剂、指甲油去除剂、涂改液和干粉清洁溶剂。虽然接触这些职业危害溶剂之前已在各种毒理学研究中进行过检查，导致其令人陶醉的细胞和分子作用位点影响几乎是未知的。对吸毒情况的调查显示，人口中使用挥发性溶剂的百分比财产和此类使用在青少年和青少年中尤其普遍可能可以轻松获得这些产品。之前的行为研究表明甲苯和其他滥用的挥发性溶剂表现出类似的作用观察到中枢神经系统抑制剂，如乙醇、巴比妥酸盐、苯二氮卓类药物，和麻醉剂。因此，我们假设滥用溶剂，就像其他中枢神经系统一样抑制剂，可能通过改变神经行为来发挥一些作用参与介导和调节的特定离子通道的功能神经元传递。我们生成了数据来支持这一假设，并且已证明甲苯和其他挥发性溶剂会抑制该功能卵母细胞中表达的重组和天然 NMDA 和乙酰胆碱受体和培养的神经元。这种抑制是剂量依赖性的，并受到以下因素的影响：表达的亚基组成。与乙醇相比，甲苯对非 NMDA 受体介导的电流或 G 蛋白的影响可忽略不计耦合钾通道。这些结果表明，滥用溶剂可能会显示在调节能力方面比酒精具有更大的选择性神经元离子通道的活性。本提案中概述的研究将测试通过确定重组离子和天然离子的敏感性来实现这一假设甲苯和其他易被滥用的挥发性溶剂的渠道。两电极电压钳和膜片钳电生理学将用于分析表达的重组离子型受体的溶剂敏感性在卵母细胞和 HEK 细胞中。甲苯的分子作用位点是通过测试是否已知调节酒精/麻醉剂的位点来探索这些通道的敏感性也调节溶剂敏感性。最后，在重组受体系统中获得的研究结果的相关性将是通过测量甲苯和其他滥用溶剂对离子的影响来评估使用全细胞膜片钳在培养的脑神经元中表达通道钙成像。从这些研究中获得的结果预计将极大地扩展了我们对这些细胞和分子靶点的了解重要的滥用药物。