ROLE OF CALCIUM IN ACRYLAMIDE NEUROTOXICITY

钙在丙烯酰胺神经毒性中的作用

• 批准号: 3251555
• 负责人: Richard Michael Lopachin
• 金额: $ 18.67万
• 依托单位: STATE UNIVERSITY NEW YORK STONY BROOK
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-08-01 至 1994-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3251555
• 关键词: acrylamides; atomic absorption spectrometry; autoradiography; axon reaction; calcium; calcium channel; calcium channel blockers; cell osmotic pressure; cerebellum; chlorine; dorsal root; electron microscopy; electron probe spectrometry; elements; embryo /fetus; enzyme mechanism; laboratory rat; magnesium; mitochondria; myelin; neurotoxins; oxygen consumption; oxygen microelectrode; peripheral nervous system disorders; phosphatidylinositols; phospholipase C; phosphorylation; potassium; protein kinase; radiotracer; sciatic nerve; scintillation counter; sodium; sodium potassium exchanging ATPase; spinal cord; sulfur compounds; thin layer chromatography; tissue /cell culture

Despite 20 years of research, the mechanism by which acrylamide (ACR) produces central peripheral distal axonopathy remains poorly understood. Based on accumulating evidence, it is possible that perturbation of elemental homeostasis represents an important component of the mechanism of ACR neurotoxicity. The long-term goals of this research project are: (1) to determine whether subcellular elemental deregulation plays an important role in the manifestation of ACR nerve damage, and (2) to determine the biochemical lesion responsible for disruption of elemental homeostasis. Electron probe x-ray microanalysis (EPMA) used during the previous grant period showed that ACR disrupted elemental regulation and water content in several compartments of rat distal tibial nerve. Therefore, our first specific aim for the next grant period will be to expand our EPMA study of ACR neurotoxicity in rats. Concentrations of elements (NA, K, Cl, P, Ca, S, Mg) and water content will be determined in axoplasm, mitochondria and myelin of small, medium, and large diameter fibers and in, nodes of Ranvier, Schwann cell cytoplasm and extra-cellular space. To establish the spatio-temporal nature of altered elemental regulation in ACR neuropathy, the above morphological compartments will be analyzed in proximal and distal sciatic nerve and in tibial nerve. Such determinants will be made at several times during the development of neurotoxicity. The effects of ACR intoxication on the levels of elements and water in dorsal root ganglion and spinal cord will also be defined. Recently, we found that both protein phosphorylation and phosphoinositide turnover were increased in sciatic nerve of ACR-treated rats. To identify the mechanism by which ACR produces these effects three specific aims will be pursued. We will determine the site of altered phosphoinositide metabolism and protein phosphorylation in fractions of sciatic nerve. We will determine whether the activities of phospholipase C and protein kinase C (PKc) in sciatic nerve are affected by ACR administration. We will provide evidence for a biochemical link between increased phosphoinositide turnover and protein phosphorylation by comparing the levels of 1,2-diacylglycerol in sciatic nerves from control and ACR-treated rats. Several lines of evidence indicate that alterations in phosphoinositide turnover caused by ACR might be related to observed elemental disruption through altered modulation of membrane Na/K-ATPase activity. Accordingly, the activity of this enzyme will measured in sciatic nerve of ACR intoxicated rats and compared to that of control. The final specific aim is to conduct parallel studies with 2,5-hexanedione to determine whether biochemical and elemental changes associated with ACR are shared by other agents which cause a distal axonopathy. The proposed experiments should provide new information concerning the mechanism of experimental distal axonopathies and may have relevance to the pathogenesis and treatment of comparable acquired and inherited neuropathies in humans.

尽管经过 20 年的研究，丙烯酰胺 (ACR) 的作用机制 产生中枢外周远端轴突病变的情况仍知之甚少。 根据不断积累的证据，扰动可能是 元素稳态是机制的重要组成部分 ACR 神经毒性。 本研究项目的长期目标是：（1） 确定亚细胞元素失调是否发挥重要作用 在 ACR 神经损伤表现中的作用，以及 (2) 确定 导致元素稳态破坏的生化损伤。 上次资助期间使用的电子探针 X 射线微量分析 (EPMA) 期间表明，ACR 扰乱了元素调节和水含量 大鼠远端胫神经的几个室。 因此，我们的第一个 下一个资助期的具体目标将是扩大我们的 EPMA 研究 ACR 对大鼠的神经毒性。 元素浓度（NA、K、Cl、P、Ca、 S、Mg）和水含量将在轴浆、线粒体和 小、中、大直径纤维和结节中的髓磷脂 Ranvier，雪旺细胞的细胞质和细胞外空间。 建立 ACR 神经病中元素调节改变的时空性质， 上述形态区室将在近端和近端进行分析 远端坐骨神经和胫神经。 将做出这样的决定因素 在神经毒性的发展过程中多次发生。 的影响 ACR中毒对背根元素和水含量的影响 神经节和脊髓也将被定义。 最近，我们发现 蛋白质磷酸化和磷酸肌醇周转率均增加 在 ACR 处理的大鼠的坐骨神经中。 确定其机制 ACR 产生这些效果将追求三个具体目标。 我们将 确定改变磷酸肌醇代谢和蛋白质的位点 坐骨神经部分的磷酸化。 我们将确定是否 坐骨神经痛中磷脂酶 C 和蛋白激酶 C (PKc) 的活性 神经受到 ACR 给药的影响。 我们将提供证据 磷酸肌醇周转增加与蛋白质之间的生化联系 通过比较坐骨神经中 1,2-二酰甘油的水平来观察磷酸化 来自对照和 ACR 处理的大鼠的神经。 几行证据 表明 ACR 引起的磷酸肌醇周转的改变可能 通过改变调制与观察到的元素破坏有关 膜 Na/K-ATP 酶活性。 因此，该酶的活性 将在 ACR 中毒大鼠的坐骨神经中进行测量并与 的控制。 最终的具体目标是与 2,5-己二酮测定是否发生生化和元素变化 与 ACR 相关的其他因素共同导致远端 轴突病。 拟议的实验应该提供新的信息 关于实验性远端轴突病的机制，可能有 与可比较的获得性和治疗的发病机制和治疗的相关性 人类遗传性神经病。