赖燕, 何麒灿, 段燕英. 慢性砷染毒对大鼠周围神经机械痛觉的影响及甲钴胺的干预作用[J]. 环境与职业医学, 2020, 37(3): 260-266. DOI: 10.13213/j.cnki.jeom.2020.19741
引用本文: 赖燕, 何麒灿, 段燕英. 慢性砷染毒对大鼠周围神经机械痛觉的影响及甲钴胺的干预作用[J]. 环境与职业医学, 2020, 37(3): 260-266. DOI: 10.13213/j.cnki.jeom.2020.19741
LAI Yan, HE Qi-can, DUAN Yan-ying. Effect of chronic arsenic exposure on peripheral nerve mechanical algesthesia in rats and potential protection of mecobalamin[J]. Journal of Environmental and Occupational Medicine, 2020, 37(3): 260-266. DOI: 10.13213/j.cnki.jeom.2020.19741
Citation: LAI Yan, HE Qi-can, DUAN Yan-ying. Effect of chronic arsenic exposure on peripheral nerve mechanical algesthesia in rats and potential protection of mecobalamin[J]. Journal of Environmental and Occupational Medicine, 2020, 37(3): 260-266. DOI: 10.13213/j.cnki.jeom.2020.19741

慢性砷染毒对大鼠周围神经机械痛觉的影响及甲钴胺的干预作用

Effect of chronic arsenic exposure on peripheral nerve mechanical algesthesia in rats and potential protection of mecobalamin

  • 摘要: 背景

    砷是广泛存在于自然界的一种有毒类金属元素,经饮水摄入是其威胁人类健康的主要途径。慢性砷暴露造成多器官系统的损伤,周围神经病变引起的感觉异常是最常见症状之一。

    目的

    探究慢性砷染毒对大鼠周围神经机械痛觉的影响及甲钴胺的干预作用。

    方法

    28只SPF级SD雄性大鼠随机分为对照组、25 mg·L-1亚砷酸钠染毒组、100 mg·L-1亚砷酸钠染毒组、100 mg·L-1亚砷酸钠染毒+1 mg·kg-1甲钴胺干预组(简称为干预组),经饮水方式进行砷染毒。干预组在100 mg·L-1亚砷酸钠溶液染毒的同时给予1 mg·kg-1·d-1甲钴胺溶液灌胃处理,连续进行32周。在第10、20、30周时采用Von frey纤维丝测量大鼠后足机械痛阈值,染毒结束时收取24 h尿样及坐骨神经。采用Western blotting法检测神经纤维髓鞘碱性蛋白(MBP)的表达,免疫组化法检测炎症因子γ-干扰素(IFN-γ)、肿瘤坏死因子α(TNF-α)的表达,液相色谱-原子荧光联用法检测尿中砷代谢物浓度。

    结果

    染毒第20周时,相比于对照组(14.67 g),两个染毒组的机械痛阈值均值(9.14、6.80 g)分别下降了38%、54%(P < 0.05),干预组痛阈值(8.60 g)比100 mg·L-1染毒组上升了27%,但差异无统计学意义。两个染毒组坐骨神经中MBP表达水平(1.93±0.40、2.07±0.20)高于对照组(1.00±0.20)(P < 0.05),100 mg·L-1染毒组炎症因子IFN-γ(14 287.98±10 218.73)、TNF-α(54.87±7.86)的表达均高于对照组(分别为5 704.22±1 341.28、37.28±10.12)(P < 0.05)。相比于100 mg·L-1染毒组,干预组MBP表达(1.08±0.32)降低(P < 0.05),炎症因子IFN-γ(9 408.49±3 228.92)、TNF-α(41.64±7.68)的表达无明显变化。染毒组尿中无机砷的质量浓度随染毒质量浓度的增高而增高(P < 0.05),干预组(704.42±207.88)μg·L-1比100 mg·L-1染毒组(479.04±92.91)μg·L-1更高(P < 0.05);尿中二甲基砷也随染毒浓度的增高而增高(P < 0.05)。

    结论

    饮水慢性砷染毒引起大鼠机械痛阈值降低,MBP以及炎症因子IFN-γ、TNF-α表达升高。甲钴胺处理可降低MBP表达,但在缓解砷诱导的机械痛觉异常中效果尚不明显。

     

    Abstract: Background

    Arsenic is a toxic metalloid element widely distributed in natural environment, and a primary pathway for arsenic exposure is via drinking water. Chronic arsenic exposure may cause damage to multiple organs and systems, and sensory deficits caused by peripheral neuropathies are one of the most common complications.

    Objective

    This experiment aims to explore the effect of chronic arsenic exposure on peripheral nerve mechanical algesthesia in rats and the potential protection of mecobalamin.

    Methods

    A total of 28 SPF SD rats were randomly divided into four groups:control group, 25 mg·L-1 NaAsO2 group, 100 mg·L-1 NaAsO2 group, and intervention group (100 mg·L-1 NaAsO2+ 1 mg·kg-1 mecobalamin). The rats were exposed to arsenic by free drinking, and the rats in the intervention group was additionally given 1 mg·kg-1·d-1 mecobalamin solution by gavage; the experiment lasted for 32 weeks. The hind foot mechanical pain threshold was measured at the 10th, 20th, and 30th weeks with Von frey filament, and the 24 h urine samples and sciatic nerve samples were collected at the end of the exposure. The expression of myelin basic protein (MBP) was detected by Western blotting, the expressions of interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) were detected by immunohistochemistry, and the concentrations of arsenic metabolites in urine were detected by liquid chromatography-atomic fluorescence spectrometry.

    Results

    At the 20th week, compared with the control group (14.67 g), the mean mechanical pain thresholds of the 25 mg·L-1 NaAsO2 group (9.14 g) and the 100 mg·L-1 NaAsO2 group (6.80 g) decreased by 38% and 54% respectively (P < 0.05), and the threshold of the intervention group (8.60 g) was higher than that of the 100 mg·L-1 NaAsO2 group by 27% without statistical difference. The expression levels of MBP in the 25 mg·L-1 NaAsO2 group (1.93±0.40) and the 100 mg·L-1 NaAsO2 group (2.07±0.20) were higher than that in the control group (1.00±0.20) (P < 0.05), and the expressions levels of IFN-γ and TNF-α in the 100 mg·L-1 NaAsO2 group (respectively 14287.98±10218.73 and 54.87±7.86) were higher than those in the control group (respectively 5 704.22±1 341.28 and 37.28±10.12) (P < 0.05). The expression level of MBP was decreased in intervention group (1.08±0.32) compared to that in the 100 mg·L-1 NaAsO2 group (P < 0.05), and the expression levels of IFN-γ (9 408.49±3228.92) and TNF-α (41.64±7.68) did not significantly change. The concentrations of inorganic arsenic and dimethylarsinic acid in urine were increased with higher arsenic exposure dose (P < 0.05). Compared with the 100 mg·L-1 NaAsO2 group(479.04±92.91) μg·L-1, the intervention group showed a higher inorganic arsenic level(704.42±207.88) μg·L-1 (P < 0.05).

    Conclusion

    Chronic arsenic exposure of rats via drinking water can result in decreased mechanical pain threshold and increased expression levels of MBP and inflammatory factors (IFN-γ and TNF-α). The intervention of methylcobalamin can reduce the level of MBP, but its effect on alleviating the allodynia evoked by arsenic exposure is not obvious.

     

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