六溴环十二烷对斑马鱼的甲状腺激素干扰效应研究

Thyroid hormone-disrupting effects of hexabromocyclododecane in zebrafish(Danio rerio)

作为添加型阻燃剂,六溴环十二烷(HBCDs)广泛存在于环境介质及生物体内。为研究HBCDs饲料长期暴露对斑马鱼的甲状腺激素干扰效应,设计HBCDs饲料暴露剂量为0、10、100、400 ng·g-1,对斑马鱼成鱼进行为期56 d的长期暴露,以其肝脏组织中三碘甲腺原氨酸(T3)、四碘甲腺原氨酸(T4)、游离三碘甲腺原氨酸(FT3)和游离四碘甲腺原氨酸(FT4)含量及T3/T4比值作为生物标志物,评价HBCDs饲料长期暴露对斑马鱼肝脏组织甲状腺功能的影响。结果表明,HBCDs对斑马鱼体内T3和T4具有明显抑制作用(P<0.05),随着HBCDs暴露浓度的增加,T3和T4的含量水平呈现下降趋势;在中浓度组(100 ng·g-1)和高浓度组(400 ng·g-1),HBCDs对FT3和FT4具有显著性抑制作用(P<0.05);随着HBCDs暴露浓度增加,T3/T4的比值呈现升高的趋势,表明HBCDs可诱导T4转化为T3。研究表明,HBCDs对鱼类具有甲状腺激素干扰效应,从而影响鱼类的生长发育。

Hexabromocyclododecane （HBCD） is a brominated flame retardant, and has become a ubiquitous pollutant of the environment. To explore the thyroid hormone-disrupting effects of long-term dietary exposure to HBCD, adult zebrafish were exposed to different concentra- tions of the chemical（ 0, 10, 100 ng·g^-l, and 400 ng·g^-l） for 56 days to determine triiodothyronine （T3）, tetraiodothyronine （T4）, free tri- iodothyronine （FT3）, and free tetraiodothyronine （FT4） levels, and T3/T4 ratios in the liver tissues of zebrafish. The results showed that HBCD disrupted the action of the thyroid hormone in zebrafish. The levels of T3 and T4 in the liver tissues of the zebrafish decreased signif- icantly with increasing concentrations of HBCD. Significant inhibitory effects on FT3 and FT4 were observed in the 100 ng·g^-1 and 400 ng·g^-1 exposure groups（P〈0.01 ）. Moreover, the T3/T4 ratio in the liver tissues increased with increasing HBCD concentration. This result indi- cated that HBCD could transform T4 into T3. In summary, our findings showed that HBCD could affect thyroid function and homeostatic lev- els in zebrafish, and could further influence the growth and development of zebrafish.