Institute of Toxicology, Shandong University, 44 West Wenhua Road, Jinan 250012, PR China; Department of Toxicology, Shandong Center for Disease Control and Prevention, 72 Jingshi Road, Jinan 250014, PR China.
Environ Toxicol Pharmacol. 2005 Jul;20(1):92-8. doi: 10.1016/j.etap.2004.11.003. Epub 2005 Jan 7.
Exposure chronically to n-hexane produces central-peripheral axonopathy mediated by 2,5-hexanedione (HD). Studies have shown neurofilament (NF) subunit proteins are decreased substantially in cerebral cortices, optic axons, spinal cords, and sciatic nerves from HD-exposed rats. To deeply investigate the alterations in NF contents in HD neuropathy, the relative levels of NF-L, NF-M, and NF-H in rat cerebral cortex were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. HD was administrated to Wistar rats by intraperitoneal injection at dosage of 200 or 400mg/kg. Rats were sacrificed after 6 weeks of treatment, and cerebral cortices were dissected, homogenized, and used for the determination of NF subunit proteins. The results, except for supernatant NF-L and NF-M that could not be assayed, showed HD intoxication resulted in significant decreases by 32-67% (P<0.01) in NF subunits in both of the pellet and supernatant fractions of cerebral cortex homogenate. As an initial investigation to determine how such changes in NF proteins might occur, the gene expression of NF-L, NF-M, and NF-H subunit mRNA was quantified using reverse transcription-polymerase chain reaction (RT-PCR). Statistical analysis revealed that HD exposure caused a significant reduction in the expression of NF-L and NF-H gene (P<0.05 or P<0.01), while the levels of NF-M mRNA kept unaffected (P>0.05). These suggest that the observed reduction in NF gene expression might be related to diminished levels of subunit proteins, while the actual contribution might be uncertain. The functional significance of the reduced protein contents and the regulation of gene expression remain to be determined.
长期接触正己烷会产生由 2,5-己二酮（HD）介导的中枢-周围轴索病。研究表明，暴露于 HD 的大鼠大脑皮质、视神经轴索、脊髓和坐骨神经中的神经丝（NF）亚单位蛋白显著减少。为了深入研究 HD 神经病中 NF 含量的变化，通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）和免疫印迹法测定大鼠大脑皮质中 NF-L、NF-M 和 NF-H 的相对水平。HD 通过腹腔注射以 200 或 400mg/kg 的剂量给予 Wistar 大鼠。治疗 6 周后处死大鼠，取大脑皮质进行解剖、匀浆，并用于测定 NF 亚单位蛋白。结果表明，除上清液中 NF-L 和 NF-M 无法测定外，HD 中毒导致大脑皮质匀浆沉淀和上清部分的 NF 亚单位显著减少 32-67%（P<0.01）。作为初步研究以确定 NF 蛋白的这种变化如何发生，使用逆转录-聚合酶链反应（RT-PCR）定量测定 NF-L、NF-M 和 NF-H 亚基 mRNA 的基因表达。统计分析显示，HD 暴露导致 NF-L 和 NF-H 基因表达显著降低（P<0.05 或 P<0.01），而 NF-M mRNA 水平保持不变（P>0.05）。这表明观察到的 NF 基因表达减少可能与亚基蛋白水平降低有关，而实际贡献可能不确定。减少的蛋白质含量的功能意义和基因表达的调节仍有待确定。
