氟对斑马鱼甲状腺内分泌功能的干扰效应

为探究氟对斑马鱼甲状腺内分泌功能的干扰效应,本研究以雌性斑马鱼成鱼为研究对象,分别以不同浓度氟(0、20、 40、80 mg·L~(-1))暴露45 d和90 d,对斑马鱼的生长发育指数进行测定,用组织学方法对斑马鱼甲状腺组织结构进行显微观察,用酶联免疫吸附法检测血浆中T3和T4激素水平,并用实时荧光定量PCR方法检测HPT轴上内分泌相关基因的表达.结果显示,与对照组相比,氟暴露组雌性斑马鱼的生长发育指数随着暴露浓度和时间的增加而呈下降趋势(p0.05);甲状腺组织病变程度随着氟暴露浓度的增大和时间的延长而加重;氟暴露45 d时,T3和T4水平呈升高趋势,90 d时,T4水平呈下降趋势且在80 mg·L~(-1)组下降显著(p0.05);氟暴露45 d时,40 mg·L~(-1)组除crh处,其他mRNA表达均显著下降(p0.05),80 mg·L~(-1)组除tg、nis、ttr外其他mRNA表达均显著下降(p0.05);暴露90 d时tg、dio1、dio2的mRNA表达水平在40 mg·L~(-1)和80 mg·L~(-1)组显著上升(p0.05),ugt1ab mRNA表达在80 mg·L~(-1)组显著下降(p0.05).综上,氟可通过影响雌性斑马鱼的生长发育、甲状腺组织结构、激素水平及HPT轴上内分泌相关基因的表达,从而对其甲状腺内分泌功能产生一定程度的干扰,进而影响机体的生长发育.本研究结果对水环境中氟的生态毒性效应及风险评估提供了理论资料.

Interference effects of fluoride on thyroid endocrine function in zebrafish

In order to investigate the interference effects of fluoride on thyroid endocrine function in female zebrafish, healthy female zebrafish were exposed to different concentrations of fluoride (0, 20, 40, 80 mg·L^-1) for 45 and 90 days to measure the growth and development index, the thyroid microstructure by histological method, the levels of T3 and T4 in plasma by enzyme-linked immunosorbent assay (ELISA), and the expressions of endocrine-related mRNA in hypothalamus-pituitary-thyroid (HPT) axis by Quantitative Real-time PCR. The results showed that the growth and development index had a decreasing trend in fluoride-exposed groups with the increase of exposure concentration and time compared with the control group (p<0.05). The lesion degree of thyroid tissue was aggravated with the increase of exposure dose and time. The levels of T3 and T4 had an increasing trend after exposure for 45 days, while the T4 level had a decreasing trend and was significantly reduced in 80 mg·L^-1 fluoride group after exposure for 90 days (p<0.05). After exposure for 45 days, all detected mRNA levels were significantly decreased in 40 mg·L^-1 fluoride group except crh mRNA (p<0.05), while the mRNA levels were remarkably reduced in 80 mg·L^-1 fluoride group except mRNA of tg, nis, ttr (p<0.05). After exposure for 90 days, the expressions of tg, dio1, dio2 mRNA were obviously elevated in 40 and 80 mg·L^-1 fluoride groups (p<0.05), while the ugt1ab mRNA levels were significantly decreased in 80 mg·L^-1 fluoride group (p<0.05). These results demonstrated that fluoride could disturb the thyroid endocrine function of female zebrafish by affecting the tissue structure of thyroid, the hormone levels, and the mRNA expressions in HPT axis, which inhibited the growth and development. All above provides the theoretical data for the ecotoxic effects and risk assessment of fluoride in aquatic environment.