Expression of thioredoxin reductase 1 in liver and peripheral blood of human and rats exposed to airborne arsenic through coal-burning / 中华地方病学杂志

ABSTRACT

Objective To study the expression and enzyme activity of thioredoxin reductase 1 (TrxR1) in liver and peripheral blood of human and rats exposed to airborne arsenic through coal-burning as well as its role in liver injury of coal-burning-borne arsenic poisoning.Methods This study was divided into 2 parts.Part 1 was a population study133 local residents exposed to airborne arsenic through coal-burning were selected as arsenic exposure groups including a non-patient group (25 cases),no obvious hepatopathy group (38 cases),mild (43 cases) and moderate to severe hepatopathy groups (27 cases) from areas affected by endemic arsenism in Guizhou Province.Thirty-four healthy residents from arsenic not affected areas were selected as controls.Peripheral blood samples were collected from all these people.The expression of TrxR1 mRNA was determined by real-time fluorescence quantitative PCR (qPCR),and enzyme activity of TrxR was tested by visible spectrophotometry.Part 2 was an animal experiment studyThirty Wistar rats,weighing about 80-100 g,were divided into control group,drinking-waterborne arsenic poisoning group and coal-burning-borne arsenic poisoning group (including low,medium and high arsenic contaminated grain groups) by means of a table of random number according to body mass,6 rats in each group.The control group was fed with normal diet for 3 months; drinking-water-borne arsenic poisoning group and coal-burning-borne arsenic poisoning group were fed with 10 mg/kg As2O3 solution and different concentrations(25,50,100 mg/kg) of arsenic-containing feed,respectively,for 3 months.The expression of TrxR1 mRNA was determined by qPCR; protein expression level of TrxR1 in liver tissue was detected by immunohistochemistry,and enzyme activity of TrxR in serum and liver tissue was tested by visible spectrophotometry.Results The mRNA expressions of TrxR1 in peripheral blood were 1.599 8 (1.128 9-2.156 8),1.469 3 (1.146 1-1.976 3),1.203 6 (0.463 1-1.816 2) and 0.912 3(0.631 8-1.535 0),respectively,among non-patient group,no obvious hepatopathy group,mild and moderate to severe hepatopathy groups.Compared to the control group[1.649 7(1.161 1-2.380 2)],the differences were significant statistically in mild and moderate to severe hepatopathy groups (all P ＜ 0.05).The enzyme activity of TrxR in peripheral blood was (3.12 ± 0.76),(2.81 ± 0.84),(2.52 ± 0.73),(2.42 ± 0.76)U/ml,respectively,in those corresponding groups.Compared to the control group [(3.02 ± 0.70)U/ml],the differences were significant statistically in mild and moderate to severe hepatopathy groups (all P ＜ 0.05).The mRNA expressions of TrxR1 in peripheral blood were 1.05 ± 0.14,1.18 ± 0.18,1.04 ± 0.10 and 0.97 ± 0.13,respectively,among drinking-water-borne arsenic poisoning group,low,medium and high arsenic contaminated grain groups; all of which were lower than that in the control group (1.23 ± 0.15,all P ＜ 0.05) except that of the low arsenic contaminated grain group.The mRNA expressions of TrxR1 in liver tissue were 0.78± 0.10,0.83 ± 0.10,0.79 ± 0.09 and 0.77 ± 0.11,respectively; all of which were lower than that in the control group (0.94 ± 0.12,all P ＜ 0.05).The protein expression of TrxR1 in liver tissue was 310.33 ± 38.81,312.50 ± 23.36,305.67 ± 20.57 and 298.17 ± 23.52,respectively,among the arsenic poisoning groups; all of which were lower than that in the control group (348.50 ± 32.35,all P ＜ 0.05).The enzyme activity of TrxR in serum was (4.22 ± 0.73),(4.86 ± 0.63),(4.04 ± 0.57),(3.73 ± 0.64)U/ml,respectively; all of which were lower than that in the control group [(9.52 ± 1.08)U/ml,all P ＜ 0.05].The enzyme activity of TrxR in liver tissue was (14.82 ± 1.67),(18.76 ± 2.76),(14.90 ± 2.17),(11.55 ± 1.74) U/mg,respectively; all of which were lower than that in the control group [(23.71 ± 3.05)U/mg,all P ＜ 0.05].Conclusion Arsenic aggravates liver injury of coal-burning arsenic poisoning through down-regulating the expressions of TrxR1 mRNA and protein and reducing its enzyme activity as well.