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目的观察不同价态、不同剂量砷染毒大鼠肝脏中DNA甲基转移酶和砷甲基转移酶mRNA的表达情况,寻找两者间的相关性及不同价态砷(iAs3+和iAs5+)体内甲基化间的差异。方法将35只健康清洁级Wistar雄性大鼠按体重随机分为7组,分别为正常对照(去离子水)组和低剂量(1/45 LD50,2.33 mg/kg)、中剂量(1/15 LD50,6.67 mg/kg)、高剂量(1/5LD50,20.00 mg/kg)砷酸氢钠(iAs5+)染毒组以及低剂量(2.33 mg/kg)、中剂量(6.67 mg/kg)、高剂量(20.00 mg/kg)亚砷酸钠(iAs3+)组,每组5只。采用自由饮水方式进行染毒,连续染毒90 d。采用实时荧光定量PCR法测定肝脏中DNA甲基转移酶(DNMT1、DNMT3A、DNMT3B)和砷甲基转移酶(As3MT)mRNA的表达情况。结果与对照组相比,各染毒组大鼠肝脏中As3MT mRNA的表达量较高,DNMT3A、DNMT3B mRNA的表达量较低,高、低剂量亚砷酸钠染毒组和高剂量砷酸氢钠染毒组DNMT1 mRNA的表达量均较高,中剂量亚砷酸钠染毒组和低剂量砷酸氢钠染毒组DNMT1 mRNA的表达量均较低,差异有统计学意义(P<0.05)。随着亚砷酸钠染毒剂量的升高,大鼠肝脏中As3MT mRNA的表达量呈上升趋势,DNMT3A、DNMT3B mRNA的表达量呈下降趋势;随着砷酸氢钠染毒剂量的升高,大鼠肝脏中As3MT mRNA的表达量呈下降趋势,DNMT3A、DNMT3B、DNMT1 mRNA的表达量呈上升趋势。As3MT的表达量与DNMT3A和DNMT3B表达量呈负相关(P<0.01);与DNMT1表达量无相关关系(P>0.01)。结论长期亚慢性暴露iAs3+和iAs5+均可促进As3MT的表达,抑制DNMT3A及DNMT3B的表达,但iAs3+和iAs5+间在剂量-效应关系上呈反向性;机体As3MT表达上调与DNMT3A和DNMT3B表达抑制间具有协同效应,并可导致基因低甲基化。
Objective To observe the expression of DNA methyltransferase and arsenomethylatransferase mRNA in the liver of arsenic-exposed rats with different valences and different doses of arsenic in order to find the correlation between them and the relationship between the expression of arsenic (iAs3 + and iAs5 +) in vivo Differences between the basis of. Methods 35 healthy male Wistar rats were randomly divided into 7 groups according to body weight: normal control (deionized water) group and low dose (1/45 LD50, 2.33 mg / kg), medium dose (1/15 LD50,6.67 mg / kg), high dose (1 / 5LD50, 20.00 mg / kg) iAs5 + and low dose (2.33 mg / kg) The dose (20.00 mg / kg) of sodium arsenite (iAs3 +) group, 5 in each group. Using free drinking water for exposure, continuous exposure 90 d. The mRNA expression of DNA methyltransferase (DNMT1, DNMT3A, DNMT3B) and arsenic methyl transferase (As3MT) in the liver were detected by real-time fluorescence quantitative PCR. Results Compared with the control group, the expression of As3MT mRNA in the liver of rats in each exposure group was higher than that in the control group. The expression of DNMT3A and DNMT3B mRNA was lower in high and low doses of sodium arsenite and high doses of arsate The expression level of DNMT1 mRNA in sodium exposure group was higher than that in the sodium arsenite exposure group and the low-dose sodium arsenate treatment group, and the difference was statistically significant (P <0.05 ). With the dose of sodium arsenite increased, the expression of As3MT mRNA in rat liver increased, the expression of DNMT3A and DNMT3B mRNA showed a decreasing trend. With the dose of sodium arsenite increased, The expression of As3MT mRNA in rat liver decreased. The expression of DNMT3A, DNMT3B and DNMT1 mRNA showed an increasing trend. The expression of As3MT was negatively correlated with the expression of DNMT3A and DNMT3B (P <0.01), but not with the expression of DNMT1 (P> 0.01). Conclusion Both long-term subchronic exposure of iAs3 + and iAs5 + can promote the expression of As3MT and inhibit the expression of DNMT3A and DNMT3B, but the reverse of the dose-response relationship between iAs3 + and iAs5 +. The up-regulation of As3MT and the inhibition of DNMT3A and DNMT3B expression Synergy and can lead to hypomethylation of genes.