Effect of thyroid stimulating hormone, human chorionic gonadotrophin and estradiol with different levels of iodine on expression of pendrin mRNA in placental villous trophoblast cell line

Abstract

Objective To observe the expression of pendrin mRNA and ability of iodine uptake in a placental villous trophoblast cell line(HPT-8) cultured in vitro with different levels of iodine and the effects of thyroid stimulating hormone(TSH),human chorionic gonadotrophin(HCG) and estradiol(E2).Methods HPT-8 cells were cultured in six-well plates and divided into low iodine group 1 (LI-1),low iodine group 2(LI-2),adequate iodine group (AI),high iodine group 1 (HI-1) and high iodine group 2 (HI-2) based on iodine concentrations (0,5,50,500,5000 μg/L) added to the culture medium.After cultured for 24 h,the followings were added to the culture medium:pure iodine,iodine plus TSH(0.01 mg/L),iodine plus HCG(5000 U/L),iodine plus E2(0.1 mg/L) and iodine plus TSH,HCG,E2,respectively,then cultured for another 24 h.The expression of pendrin mRNA of HPT-8 cells was determined by real-time quantitative PCR.Results At different levels of iodine,the differences of pendrin mRNA expression between groups were statistically significant in groups with iodine alone,iodine plus TSH,iodine plus E2 and iodine plus TSH,HCG and E2(F =8.43,9.91,30.37,7.34,all P ＜ 0.01).In groups with iodine alone,the expression in LI-1 group(1.00 ± 0.11) was significantly lower than that in AI group(1.37 ± 0.19,P ＜ 0.01),and HI-2 group(1.67 ± 0.25) was higher than AI group(P ＜ 0.05).In groups with iodine plus E2,the expression of pendrin mRNA in HI-2 group (13.37 ± 6.48) was significantly higher than that of AI group(1.95 ± 0.61,P ＜ 0.01).In groups with iodine plus HCG,TSH and E2,the expression of pendrin mRNA in LI-2 group(2.26 ± 1.32) was significantly higher than that of AI group(1.06 ± 0.33,P ＜ 0.01).At the same level of iodine,the differences of pendrin mRNA expression within groups were statistically significant in LI-1,AI,HI-1,HI-2 groups(F=10.98,11.59,6.70,33.06,all P＜ 0.01).In HI-1 group,the expression was lower in iodine plus TSH,HCG and E2(1.10 ± 0.26) than pure iodine (1.49 ± 0.41,P ＜ 0.05).In HI-2 group,iodine plus E2(13.37 ± 6.48) was higher than the pure iodine(1.33 ± 0.28,P ＜ 0.01).Conclusions HPT-8 cells have increased expression of pendrin mRNA and promote iodine uptake under mild iodine deficiency conditions,but under severe iodine deficiency conditions,HPT-8 cells are in a decompensated state and have decreased expression of pendrin mRNA,the ability of iodine uptake is decreased.HCG and TSH play a week role in HPT-8 cells iodine uptake,whereas E2 promotes iodine uptake under severe iodine excess with significantly increased expression of pendrin mRNA obviously.When the three hormones are administrated together,the ability of iodine uptake is increased under mild iodine deficiency conditions and decreased under mild iodine excess. Key words: Iodine; Placental villous trophoblast cell; Pendrin; Thyroid stimulating hormone; Human chorionic gonadotropin; Estradiol