ROLE OF CALCIUM IN ACRYLAMIDE NEUROTOXICITY

尽管经过了20年的研究，丙烯酰胺(ACR)的作用机制 产生中枢性外周远端轴索病变仍知之甚少。 根据不断积累的证据，有可能是 元素动态平衡是细胞免疫调节机制的重要组成部分 ACR神经毒性。这项研究项目的长期目标是：(1) 确定亚细胞要素去监管化是否起到重要作用 在ACR神经损害表现中的作用，以及(2)确定 导致元素动态平衡紊乱的生化损伤。 上一次拨款期间使用的电子探针X射线显微分析(EPMA) 期间表明，ACR扰乱了元素调节和水分含量 大鼠胫骨远端神经的几个亚室。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对大鼠的神经毒性作用。元素浓度(钠、钾、氯、磷、钙、 S、镁)和水分含量将在轴浆、线粒体和 小、中、大直径纤维和结节内的髓鞘 Ranvier、Schwann细胞质和胞外间隙。要建立 ACR神经病元素调节改变的时空性质， 上述形态间隔将在近端和 远端坐骨神经和胫神经。这样的决定因素将被做出 在发展过程中多次出现神经毒性。的影响 ACR中毒对背根元素和水分水平的影响 神经节和脊髓也将被定义。最近，我们发现， 蛋白质磷酸化和肌醇磷脂周转率均增加。 在ACR处理的大鼠坐骨神经中。以确定通过什么机制 ACR产生了这些效果，将追求三个具体目标。我们会 确定肌醇磷脂代谢和蛋白质改变的位置 坐骨神经部分的磷酸化。我们将确定是否 坐骨神经磷脂酶C和蛋白激酶C活性的研究 神经受到ACR给药的影响。我们将提供证据证明 肌醇磷脂周转率升高与蛋白质的生化联系 比较坐骨神经中1，2-二酰甘油水平的磷酸化 对照组和ACR处理组大鼠的神经。有几条证据 提示ACR引起的肌醇磷脂周转的改变可能 与观察到的元素分裂有关，通过改变调制 膜Na/K-ATPase活性。因此，这种酶的活性 ACR中毒大鼠坐骨神经Will的测定及比较 对控制权的控制。最终的具体目标是与 2，5-己二酮测定生化和元素变化 与ACR关联的是由其他代理共享的，这些代理导致远端 轴突病症。拟议中的实验应该提供新的信息 关于实验性远端轴索病变的机制，并可能 与获得性和可比性肺炎的发病机制和治疗的相关性 人类的遗传性神经病。

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.