NEUROTOXICOLOGY OF TRIALKYL-TIN AND LEAD COMPOUNDS

这项工作的目的是阐明致病的分子机制。 某些有机锡化合物的神经生理和神经毒理作用 具有选择性结构相关的有机先导化合物 神经毒性。它的目的是确定细胞信号转导 由这种化合物触发的机制(S)，并将它们与 神经组织中的特定生化和生理反应。 一个特定的目标1)是检验这样一个假设，即选择性 三乙基锡(Tet)、三甲基锡(TMT)的神经毒理作用 三乙基铅(TEL)和三甲基铅(TML)是通过在 目标的磷酸化状态，从而功能的状态 大脑特定区域中的蛋白质。亚细胞组分来自 大鼠大脑的不同部分将暴露在这些化合物中，在 (伽玛-32P)三磷酸腺苷的存在，以分析它们对心率和 钠对内源蛋白质的磷酸化程度 十二烷基硫酸酯聚丙烯酰胺凝胶电泳法(SDS-PAGE) 放射自显影。显示有机金属诱导的改变的蛋白质 将分离磷酸化状态以确定 产生这些变化的机制。经济衰退带来的影响 有机金属对脑内这些蛋白磷酸化状态的影响 切片、培养的脑细胞和完整的动物体内将被分析 确定它们在生理上是否相关。另一个目标2)， 是为了确定，尤其是 初步实验表明，脑线粒体的磷酸化 丙酮酸脱氢酶被Tet选择性地激活。这种酶会 以确定刺激的分子机制。 此外，在体内，这种Tet诱导的修饰的意义， 将通过研究PDH磷酸化对 组织细胞内钙流通量与神经递质(乙酰胆碱)释放 切片和细胞培养。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TET和TEL的影响。磷酸化AS的作用机制 以及这些修改的生理相关性将同样是 调查过了。另一个目标是确定 有机金属作为影响脑膜的信号 磷脂酰肌醇周转率。这将通过测量 从预先标记的脑细胞释放肌醇磷酸盐 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.