NEUROTOXICOLOGY OF TRIALKYL-TIN AND LEAD COMPOUNDS

本工作的目的是阐明的分子机制， 某些有机锡的神经生理学和神经毒理学影响， 显示出选择性结构相关的有机铅化合物 神经毒性 其目的是确定细胞信号转导 这些化合物触发的机制，并将它们与 神经组织中特异性生化和生理反应。 一个具体的目标1），是测试的假设，选择性 三乙基锡（泰特），三甲基锡（TMT）， 三乙基铅（TEL）和三甲基铅（TML）是通过改变 磷酸化的状态，因此，功能，目标 大脑特定区域的蛋白质。 亚细胞组分来自 大鼠大脑的各个部分将暴露于这些化合物， （γ-32 P）ATP的存在，以分析其对心率的影响， 内源性蛋白质通过钠的磷酸化程度 十二烷基硫酸盐聚丙烯酰胺凝胶电泳（SDS-PAGE）和 放射自显影 显示器官诱导的改变的蛋白质 磷酸化状态将被分离，以确定 产生这些变化的机制。 的影响 有机金属对脑中这些蛋白质磷酸化状态的影响 将分析切片、培养的脑细胞和完整动物中的细胞， 确定它们是否与生理相关。 另一个目标2）， 特别是，要确定观察结果的重要性， 初步实验表明，脑线粒体的磷酸化 丙酮酸脱氢酶被泰特选择性地刺激。 该酶将 分离以确定刺激的分子机制。 此外，这种TET诱导的修饰的意义，在体内， 将通过研究PDH磷酸化对 组织中细胞内Ca 2+流动和神经递质（乙酰胆碱）释放 切片和细胞培养物。 这项工作还将寻求3），以确定两个 其他蛋白质（Mr= 50，000和80，000），其磷酸化状态为 特别是受到泰特和TEL的影响。 磷酸化的机制， 以及这些修饰的生理相关性将同样被 研究了 另一个目标4）是确定 有机金属作为影响脑细胞膜的信号 磷脂酰肌醇周转 这将通过测量 肌醇磷酸从预先标记有 磷脂酰肌醇

The objective of this work is to elucidate the molecular mechanisms for the neurophysiological and neurotoxicological effects of certain organotin and organo-lead compounds that demonstrate selective structure-related neurotoxicity. It aims to determine the cellular signal transduction mechanism(s) that are triggered by such compounds and to relate them to the specific biochemical and physiological response in nervous tissue. A specific aim 1), is to test the hypothesis that the selective neurotoxicological effects of triethyltin (TET), trimethyltin (TMT), triethyllead (TEL and trimethyllead (TML) are produced by alterations in the states of phosphorylation, and thus, of the function, of target proteins in specific regions of the brain. Sub-cellular fractions from various sections of rat brain will be exposed to these compounds, in the presence of (Gamma-32P)ATP, to analyze their effects on the rates and extent of phosphorylation of endogenous proteins by means of sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) and autoradiography. Proteins that demonstrate organometal-induced altered states of phosphorylation will be isolated in order to determine the mechanisms by which these changes are produced. The effects of the organometals on the states of phosphorylation of these proteins in brain slices, cultured brain cells and in the intact animal will be analyzed to determine whether they could be physiologically relevant. Another aim 2), is to ascertain, in particular, the significance of observations made in preliminary experiments, that the phosphorylation of brain mitochondrial pyruvate dehydrogenase is selectively stimulated by TET. The enzyme will be isolated to determine the molecular mechanism of stimulation. Furthermore, the significance of this TET-induced modification, in vivo, will be examined by investigating the effects of PDH phosphorylation on cellular Ca2+ flux and neurotransmitter (acetylcholine) release in tissue slices and cell cultures. The work will also seek 3), to identify two other proteins, (Mr=50,000 and 80,000), whose states of phosphorylation are affected specifically by TET and TEL. The mechanisms of phosphorylation as well as the physiological relevance of these modifications will likewise be investigated. An additional aim 4), is to determine whether the organometals act as signals that influence brain membrane phosphatidylinositol turnover. This will be assessed by measuring the release of inositolphosphates from brain cells that are pre-labeled with phosphatidylinositol.