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目的探讨外源性蛋氨酸(methionine,Met)对饮水砷暴露小鼠体内不同组织器官砷形态分布的影响。方法将健康清洁级雌性昆明小鼠40只,随机分为对照组、单纯砷染毒组及低、中、高剂量Met与砷联合染毒组,每组8只。除对照组小鼠饮蒸馏水外,其余各组小鼠以自由饮水方式饮含50mg/L亚砷酸钠的水,连续染毒4周。在染毒的第4周,低、中、高剂量Met与砷联合染毒组小鼠分别被腹腔注射100、200、400mg/kg的Met溶液,对照组和单纯砷染毒组小鼠被腹腔注射生理盐水,连续注射7d。末次注射24h后,处死小鼠,快速取血,分离肝和脑组织,分别检测无机砷(iAs)、一甲基胂酸(MMA)和二甲基胂酸(DMA)含量,并计算各组织中总砷含量(TAs)及砷一甲基化率(primary methylation ratio,PMR)和二甲基化率(secondary methylation ratio,SMR)。结果单纯砷染毒组和高、中、低剂量Met与砷联合染毒组小鼠肝、脑组织及全血中iAs、MMA、DMA和TAs含量均高于对照组,差异有统计学意义(P<0.05)。与单纯砷染毒组比较,中、高剂量Met与砷联合染毒组小鼠肝组织中DMA含量和PMR较高,差异有统计学意义(P<0.05)。与单纯砷染毒组比较,各剂量Met与砷联合染毒组小鼠全血中iAs、MMA和TAs含量均下降,差异有统计学意义(P<0.05)。各剂量Met与砷联合染毒组小鼠脑组织中DMA和TAs含量低于单纯砷染毒组,差异有统计学意义(P<0.05)。结论外源性Met对小鼠体内砷甲基化代谢具有促进作用,并可加速体内砷化物的排泄,从而减少血液和脑组织中的砷负荷。
Objective To investigate the effect of exogenous methionine (Met) on the distribution of arsenic in different tissues and organs in mice exposed to arsenic drinking water. Methods Forty healthy female Kunming mice were randomly divided into control group, simple arsenic poisoning group and low, medium and high doses of Met and arsenic combined exposure group, with 8 mice in each group. In addition to the control group of mice drinking distilled water, the rest of the mice in free drinking water containing 50mg / L sodium arsenite water, continuous exposure for 4 weeks. At the 4th week of exposure, the mice in low, medium and high doses of Met and arsenic were injected intraperitoneally with 100, 200 and 400 mg / kg Met respectively. The mice in control group and arsenite-only group were intraperitoneally Saline injection, continuous injection of 7d. After the last injection, the mice were sacrificed and the blood samples were taken quickly to separate the liver and brain tissues. The content of inorganic arsenic (iAs), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) Total arsenic (TAs), amethylation rate (PMR) and secondary methylation ratio (SMR) in the samples. Results The contents of iAs, MMA, DMA and TAs in the liver, brain and whole blood of mice exposed to arsenic alone, combined with high, medium and low doses of Met and arsenic were significantly higher than those of the control group P <0.05). Compared with the arsenic-only group, the contents of DMA and PMR in the liver tissue of mice treated with medium and high doses of Met and arsenic were significantly higher than those of the arsenic-only group (P <0.05). Compared with the arsenic-only group, the contents of iAs, MMA and TAs in the whole blood of mice treated with Met and arsenic were significantly decreased (P <0.05). The contents of DMA and TAs in brain of mice exposed to Met and arsenic combined were lower than those of arsenic alone group (P <0.05). Conclusion Exogenous Met can promote methylation of arsenic in mice and accelerate the excretion of arsenic in the body, thus reducing the arsenic load in blood and brain.