ROLE OF CALCIUM IN ACRYLAMIDE NEUROTOXICITY

尽管经过20年的研究，丙烯酰胺（ACR） 对中枢外周远端轴突病的发生仍知之甚少。 根据不断积累的证据，有可能 元素的体内平衡是一个重要的组成部分， ACR神经毒性。 本研究的远期目标是：（1） 以确定亚细胞元素失调是否在 在ACR神经损害的表现中的作用，以及（2）确定 造成元素平衡破坏的生化损伤。 电子探针X射线显微分析（EPMA）在上一次资助期间使用 结果表明，ACR破坏了土壤的元素调节和水分含量， 大鼠胫神经远端的几个隔室。 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， 大鼠ACR神经毒性。 元素（NA、K、Cl、P、Ca、Na、 S，Mg）和水含量将在轴质，线粒体和 小、中、大直径纤维的髓磷脂， Ranvier、Schwann细胞胞质和细胞外间隙。 建立 ACR神经病变中元素调节改变的时空性质， 将在近端分析上述形态学区室， 坐骨神经远端和胫神经。 这些决定因素将被 在神经毒性发展过程中的几次。 的影响 ACR中毒对大鼠背根元素和水分含量的影响 还将定义神经节和脊髓。 最近，我们发现， 蛋白质磷酸化和磷酸肌醇周转增加 在ACR处理的大鼠坐骨神经中。 为了确定 ACR产生这些效果将追求三个具体目标。 我们将 确定改变的磷酸肌醇代谢和蛋白质的位点 坐骨神经碎片中的磷酸化。 我们将决定 坐骨神经磷脂酶C和蛋白激酶C（PKC）活性 神经受到ACR给药的影响。 我们将提供证据， 磷脂酰肌醇周转增加与蛋白质之间的生物化学联系 通过比较坐骨神经中1，2-二酰基甘油的水平， 来自对照和ACR处理的大鼠的神经。 若干条证据 表明ACR引起的磷酸肌醇周转的改变可能 与通过改变的调制观察到的元素破坏有关， 膜Na/K-ATP酶活性。 因此，这种酶的活性 将ACR中毒大鼠坐骨神经测定与对照组比较， 控制力 最后的具体目标是进行平行研究， 2，5-己二酮，以确定是否生化和元素的变化 与ACR相关的是由引起远端 轴突病 拟议中的实验应该提供新的信息 关于实验性远端轴突病的机制， 相关的发病机制和治疗可比获得性和 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.