NERVE TERMINAL AS A SITE OF ACRYLAMIDE ACTION

暴露于丙烯酰胺（ACR）会导致神经损伤，其特征在于远端 轴突肿胀和变性。我们调查了（08-11年） 变性可能是由反向Na+/Ca 2+交换引起的- 介导的Ca/2+内流继发于降低的Na+/K+ ATP酶活性。 大鼠亚慢性口服ACR中毒致胫神经损伤 轴突变性和Na/+泵活性降低，而两者都没有 PNS轴突的酶或结构扰动与 亚急性腹膜内给药，尽管发生了典型的神经毒性。到 确定生物转化中的途径特异性差异是否可能 参与轴突病的差异表达，具体目标#1 本竞争性续约申请的研究将描述ACR 腹膜内和口服暴露后的处置和动力学。提供 结论性证据表明，轴突变性不会发生在 亚急性腹膜内中毒，特异性目标#2研究将评估轴突 未检查神经组织（CNS，肌内神经）的形态 08-11年间。总的来说，我们的结果（08-11年）表明， 非轴突部位可能介导ACR的神经毒性作用。神经 终末是介导ACR诱导的功能障碍的基本位点 （骨骼肌无力，感觉性共济失调），并已发现， 由于暴露的早期后果而受损。我们假设ACR的作用是 在CNS和PNS中的突触前位点，以减少 神经传递素因此，具体目标#3-#5中提出的研究 将评估神经末梢损伤在ACR诱导的 神经毒性并确定相应的分子机制。具体 目标#3研究将定义突触损伤的发生和程度， ACR处理的大鼠。在特定目标4实验中，大鼠后肢 神经肌肉接头将被用作模型系统来研究 ACR作用的潜在前和后连接位点。具体目标#5 建议进行研究以定量ACR诱导的结合 突触囊泡与突触前质膜。此外，ACR 半胱氨酸串蛋白和SNAP-25的加合将在 大脑突触体中发现的。探索受损神经 在ACR中毒期间的末端功能和鉴定相应的 分子作用机制代表了一个新的研究领域， 中毒性轴突病结果可以让我们更好地了解 获得性和遗传性人类神经病以及 有效的药物治疗。

Exposure to acrylamide (ACR) causes nerve damage characterized by distal axon swelling and degeneration. We investigated (years 08-11) the possibility that degeneration is caused by reverse Na+/Ca2+ exchanger- mediated Ca/2+ entry secondary to reduced Na+/K+ ATPase activity. Subchronic oral ACR intoxication of rats produced distal tibial nerve axon degeneration and decreased Na/+ pump activity whereas neither enzymatic nor structural perturbation of PNS axons was associated with subacute i.p. treatment despite development of classic neurotoxicity. To determine whether route-specific differences in biotransformation might be involved in differential expression of axonopathy, Specific Aim #1 studies of this competitive renewal application will characterize ACR disposition and kinetics following i.p. and oral exposure. To provide conclusive evidence that axon degenerations does not occur during subacute i.p. intoxication, Specific Aim #2 studies will assess axon morphology in nervous tissue (CNS, intramuscular nerves) not examined during years 08-11. Overall, our results (years 08-11) suggest other non-axonal sites might mediate the neurotoxic actions of ACR. Nerve terminals are rationale sites for mediation of ACR-induce dysfunction (skeletal muscle weakness, sensory ataxia) and have been found to be damaged as an early consequence of exposure. We hypothesize ACR acts at presynaptic sites in CNS and PNS to reduce quantal release of neurotransmitter. Therefore, research proposed in Specific Aims #3-#5 will evaluate the role of nerve terminal injury in ACR-induced neurotoxicity and identify corresponding molecular mechanisms. Specific Aim #3 studies will define the onset and magnitude of synaptic damage in ACR-treated rats. In Specific Aim #4 experiments, the rat hindlimb neuromuscular junction will be used a model system to investigate potential pre- and post-junctional sites of ACR action. Specific Aim #5 studies are proposed to quantitate ACR-induced changes in binding of synaptic vesicles with presynaptic plasma membrane. In addition, ACR adduction of cysteine string protein and SNAP-25 will be determined in brain synaptosomes from intoxicated rats. Exploring compromised nerve terminal function during ACR intoxication and identifying corresponding molecular mechanism of action represents a new area of investigation in toxic axonopathies. Results could lead to a better understanding of acquired and inherited human neuropathies and the development of efficacious pharmacotherapies.