RESUMEN
Objective To observe the effects of insulin-like growth factor-Ⅰ (IGF-Ⅰ) and transforming growth factor-β1 (TGF-β1) on the expressions of sodium iodide symporter(NIS) and pendrin mRNA in a placental villous trophoblast cell line(HPT-8) exposed to different levels of iodine.Methods HPT-8 cells were cultured in vitro in the culture flask and divided into low iodine group-Ⅰ (LI-Ⅰ),low iodine group-Ⅱ (LI-Ⅱ),control group,high iodine group-Ⅰ (HI-Ⅰ) and high iodine group-Ⅱ (HI-Ⅱ) that exposed to different concentrations of iodine (0,5,50,500,5000 μg/L).After cell cultured for 24 h,the followings were added to the culture medium:iodine plus IGF-Ⅰ(0.050 mg/L),iodine plus TGF-β1 (0.001 mg/L).After cultured for another 24 h,total RNA was extracted,the expressions of NIS and pendrin mRNA of HPT-8 cells were determined by real-time quantitative PCR.Results The expression of NIS mRNA in HPT-8 cells:at different levels of iodine,the differences of NIS mRNA expression between groups were statistically significant in group with iodine alone(F =3.612,P ＜ 0.01).The expression of NIS mRNA in LI-Ⅰ group(0.44 ± 0.21) was significantly lower than that of control group(1.25 ± 0.77,P＜ 0.01).At the same level of iodine,in LI-Ⅰ group and HI-Ⅰ group,the differences of NIS mRNA expression within groups were statistically significant (F =13.632,6.900,all P ＜ 0.01).In LI-Ⅰ group,the expressions of NIS mRNA were higher in iodine plus IGF-Ⅰ(1.13 ± 0.38) and iodine plus TGF-β1 (0.81 ± 0.34) than that of pure iodine(0.44 ± 0.21,P ＜ 0.01 or ＜ 0.05);in HI-Ⅰ group,the expression of NIS mRNA was lower in iodine plus TGF-β1 (0.62 ± 0.30) than that of pure iodine(1.23 ± 0.91,P ＜ 0.01).The expression of pendrin mRNA in HPT-8 cells:at different levels of iodine,the differences of pendrin mRNA expression between groups were statistically significant in group with iodine alone(F =12.717,P ＜ 0.01).The expression of pendrin mRNA in LI-Ⅰ group(0.59 ± 0.15) was significantly lower than that of control group(1.03 ± 0.14,P ＜ 0.01) ; HI-Ⅰ group(1.29 ± 0.31) was higher than control group(P ＜ 0.05).At the same level of iodine,the differences of pendrin mRNA expression within groups were statistically significant in LI-Ⅰ,LI-Ⅱ,control and HI-Ⅰ groups (F=12.588,4.588,8.679,8.445,all P ＜ 0.01).In LI-Ⅰ,LI-Ⅱ and control groups,the expressions of pendrin mRNA were significantly higher in iodine plus IGF-Ⅰ(1.68 ± 0.82,1.51 ± 0.79,1.50 ± 0.51) than that of pure iodine(0.59 ± 0.15,0.89 ± 0.22,1.03 ± 0.14,all P ＜ 0.01); in HI-Ⅰ group,the expression of pendrin mRNA was significantly lower in iodine plus TGF-β1 (0.78 ± 0.20) than that of pure iodine(1.29 ± 0.31,P ＜ 0.01).Conclusions In the case of iodine deficiency,the mRNA expressions of NIS and pendrin in HPT-8 cells are decreased and the iodine uptake ability is decreased; the expression of pendrin mRNA in HPT-8 cells is increased and placental iodine uptake is increased under the conditions of mild iodine excessive.IGF-Ⅰ and TGF-β1 play a role in the placental iodine uptake through increasing iodine uptake under the conditions of iodine deficiency and decreasing iodine uptake under the conditions of iodine excessive.