Expression and significance of thyroid hormone receptors mRNA of residents exposed to arsenic via drinking water / 中华地方病学杂志

ABSTRACT

Objective To detect thyroid hormone receptors (TRs) mRNA expression of subjects exposed to different levels of arsenic,to further study the endocrine disturbing effect of arsenic.Methods Molecular epidemiological method was used,in drinking water type of endemic arsenic poisoning areas,which were divided into control (＜ 10 μg/L),low (10-＜ 100 μg/L),medium (100-＜ 200 μg/L) and high (≥200 μg/L) dose groups based on the drinking water arsenic concentrations.According to the gender stratification,a total of 273 (control,low,medium and high dose groups were 58,49,66,100,respectively) residents were chosen.To carry out the questionnaire,urine arsenic determination,electrocardiographic examination.Real-time PCR was used to detect blood TRs mRNA expression.Results TRα mRNA relative expression levels in the control,low,medium and high dose groups were (12.2 ± 5.7) × 10-4,(12.2 ± 5.0) × 10-4,(12.3 ± 5.4) × 10-4,(12.2 ± 4.3) × 10-4,respectively,the differences were not statistically significant (F =0.109,P ＞ 0.05).TRβ mRNA relative expression levels were all low,the control,low,medium and high dose groups were (5.7 ± 4.1) × 10-6,(8.6 ± 7.6) × 10-6,(6.3 ± 4.2) × 10-6 and (6.2 ± 3.8) ×10~,respectively,the differences were statistically significant (F =2.938,P ＜ 0.05).The levels of TRβ mRNA relative expression changed with increased content of arsenic in water and urine trends in inverse U-shaped curves (R2 =0.035,0.067,all P ＜ 0.05).TRβ mRNA relative expression in low dose group was higher than that in control group,the difference was statistically significant (P ＜ 0.05);TRβ mRNA relative expression in high dose group was lower than that in low dose group,the difference was statistically significant (P ＜ 0.05).Arsenic induced arrhythmia which most displayed sinus bradycardia;the prevalence of arrhythmia in the control,low,medium and high dose groups were 12.1％ (7/58),10.2％ (5/49),13.6％ (9/66),19.4％ (19/98),respectively,the differences were not statistically significant (x2 =2.877,P＞ 0.05).Heart rate was positively associated with the level of TRβ mRNA relative expression in lg value (r =0.218,P ＜ 0.05).Conclusion Chronic arsenic exposure can disturb TRβ mRNA expression;there is a possible relationship between TRβ mRNA abnormal expression and arrhythmia caused by arsenic.