2，5-己二酮诱导大鼠脊髓中神经丝含量变化的研究

Dynamic study of neurofilament contents in rat＇ s spinal cord induced by 2, 5-hexanedione

目的观察2，5-己二酮（2，5-HD）诱导大鼠脊髓中神经丝（NF）含量变化，以探讨正己烷中毒性神经病的分子机制。方法雄性Wistar大鼠70只随机分为0、2、4、8周对照组和2、4、8周染毒组，每组10只。经腹腔注射2，5-DH予染毒组动物，剂量为400mg／kg，建立正己烷中毒性神经病模型，对照组注射等量的盐水。利用步态评分评价大鼠周围神经病症状的进展，免疫印迹法（Western Blotting）检测脊髓组织高、中和低相对分子质量神经丝（NF-H、NF—M和NF—L）含量的变化。结果HD染毒2周后，大鼠逐渐出现肌力降低、步态异常、瘫痪等表现，至染毒8周结束时大鼠呈现典型的中毒性周围神经病特征。随着2，5．HD染毒的进行，大鼠脊髓NF含量呈进行性下降。与0周对照组相比，2、4和8周染毒组大鼠脊髓上清中NF—H含量分别下降15．7％、57．0％和58．0％，NF-M含量分别下降36．0％、61．3％和65．2％，NF-L含量分别下降20．8％、43．9％和44．3％，差异均有统计学意义（P〈0．01）；在脊髓沉淀中，与0周对照组比较，染毒4、8周组NF—H含量分别下降35．6％和43．2％，NF-L含量分别下降26．4％和42．1％，差异均有统计学意义（P〈0．01）；2、4和8周染毒组大鼠脊髓沉淀中NF—M含量分别下降23.3％、33．9％和63．7％，差异有统计学意义（P〈0．01）。大鼠脊髓组织中NF—H、NF-M和NF—L含量与步态评分的复相关系数分别为0．8912，0．9282和0．8981，差异均有统计学意义（P〈0．01）。结论2，5-HD染毒诱导的脊髓组织中NF亚单位含量下降，可能是正己烷神经毒性的机制之一。

Objective To investigate the dynamic changes of neurofilament contents in rat＇s spinal cord induced by 2,5-hexanedione （2,5-HD）,and explore the molecular mechanism of n-hexane neuropathy. Methods Male Wistar rats were administered at a dosage of 400 mg/kg/day 2,5-HD for 2,4 and 8 weeks respectively. HD-induded neurological defects were detected and quantified using gait score, and the relative levels of NF-H,NF-M, and NF-L in spinal cords of rats were determined by Western Blotting. Results Exposure to 2,5-HD produced progressive gait abnormalities,which suggested that the rat model of 2,5-HD-induced neurotoxicity was established successfully. Western-Blotting results showed that NFs content in spinal cord demonstrated a progressive decline as the intoxication continued. In the supernatant fraction, compared to the controls,NF-H con-tent decreased by 15.7%, 57.0%, and 58.0% respectively after 2,4, and 8-week treatment with 2,5-HD （P〈0.01） ; accordingly, NF-M decreased by 36.0%, 61.3%, and 65.2% respectively （P〈0.01） ; NF-L decreased by 20.8%, 43.9%, and 44.3% respectively （P〈0.01）. In the pellet fraction, the contents of NF- H in groups of 4 and 8 weeks＇ exposure to HD decreased by 35.6% and 43.2% ,respectively （P〈0.01）,and those of NF-L decreased by 26.4% and 42.1% ,respectively （P〈0.01） when compared to the control. Furthermore, NF-M contents in groups of 2,4 and 8 weeks＇ exposure decreased by 23.3%, 33.9%, and 63.7% respectively （P〈0.01）. The NFs level in spinal cords was highly correlated with gait abnormality of treated rats as the intoxication went on. Multiple correlation coefficients of NF-H, NF-M, and NF-L content with gait score of HDtreated rat were 0.8912,0.9282 and 0.8981 （P〈0.01） respectively. Conclusion The declines of NFs are high- ly related to neurobehavioral abnormality of 2,5-HD-treated animals, and involved in the development of nhexane neuropathy.