Rat insulin-like growth factor- Ⅰ and transforming growth factor-β1 mRNA expression in thyroid and placenta with different iodine intakes during pregnancy / 中国地方病学杂志

ABSTRACT

ObjectiveTo study the mRNA expression of rat Insulin-like growth factors- Ⅰ (IGF- Ⅰ ) and Transforming growth factor-β1 (TGF-β1) in thyroid and placenta with different iodine intakes during pregnancy.MethodsOne hundred and fifty female Wistar rats,weighting 80 - 100 g,were randomly divided into five groups according to body weight,30 rats in each group.Each group was given deionized water containing different concentrations of iodine,50 μg/L(control group,NI),0 μg/L(iodine deficiency 1 group,LI1 ),5 μg/L(iodine deficiency 2 group,LI2),3000 μg/L(iodine excess 1 group,HI1 ),and 10 000 μg/L(iodine excess 2 group,HI2),respectively.After feeding for 12 weeks,the female rats were mated with male rats.The female rats were sacrificed at first(6,7 days),trimester( 12,13 days),and third trimesters( 19,20 days),respectively,then their thyroid and placenta were collected.The mRNA expressions of IGF- Ⅰ and TGF-1 in thyroid and placenta were detected by real-time quantitative PCR.Results①The actual thyroid weights of LI1 and LI2 groups[ (12.17 ± 5.41 ) × 10-2 g,(3.54 ± 1.21) × 10-2 g] were significantly higher than that of NI group[ (2.05 ± 0.50) × 10-2 g,all P ＜ 0.05] ;actual weights of HI1 and HI 2 groups[ (1.64 ± 0.27) × 10-2 g,(1.66 ± 0.29) × 10-2 g] were compared with that of NI group,the difference was not statistically significant(all P ＞ 0.05).②The mRNA expression of IGF- Ⅰ at the first trimester,LI1 and LI2 groups(l.98 ± 0.35,1.47 ± 0.22) were all higher than that of NI group(1.01 ± 0.18,all P＜ 0.01 ),HI1 and HI2 groups(0.68 ± 0.16,0.75 ± 0.09) were lower than that of NI group(all P ＜ 0.01 );at the second trimester,HI2 group( 1.14 ± 0.17) was lower than that of NI group( 1.58 ± 0.33,P ＜ 0.01 ) ; at the third trimester,LI2 and HI2 groups(1.47 ± 0.20,1.45 ± 0.35) were lower than that of NI group(2.20 ± 0.37,all P＜0.01).The mRNA expression of IGF- I level in NI group at the first,second,and third trimesters(1.01 ±0.18,1.58 ±0.33,2.20 ± 0.37) was up regulated gradually,pairwise comparisons were statistically significant(all P ＜ 0,01 ).③The mRNA expression of TGF-β1 at the first trimester,LI1 group (1.37 ± 0.13) was higher than NI group (1.05 ±0.18,P ＜ 0.01 ),HI1 and HI2 groups(0.50 ± 0.09,0.44 ± 0.11) were lower than NI group(all P＜ 0.01); at the second trimester,LI1 and HI2 groups(1.39 ± 0.28,1.17 ± 0.12) were higher than NI group(0.63 ± 0.22,all P ＜0.01 ) ; at the third trimester,LI1 and LI2 groups ( 1.57 ± 0.30,1.23 ± 0.20) were higher than NI group ( 0.68 ± 0.17,all P＜ 0.01).TGF-β1 mRNA expressions of NI group at the second (0.63 ± 0.22) and third trimesters(0.68 ± 0.17) were lower than that of the first trimester (1.05 ± 0.18,all P ＜ 0.01).④ Rats' IGF-Ⅰ mRNA expression in placental at the second trimester HI1 group,HI2 group( 1.48 ± 0.16,1.45 ± 0.25) were all higher than the NI group ( 1.00 ± 0.10,all P ＜ 0.01 ) ; at third trimester,HI1 group ( 1.75 ± 0.15 ) were higher than the NI group ( 1.54 ± 0.29,P＜ 0.05),HI2 group(l.94 ± 0.31) were higher than the NI group(P ＜ 0.01 ).IGF- Ⅰ mRNA expression in placental of NI group at the third trimester was higher than the second trimester(P＜ 0.01).⑤ Rats' TGF-β1 mRNA expression in the placenta at the second trimester and the third trimester of pregnancy there were no significant difference between the five groups(all P ＞ 0.05) ; NI group at the third trimester(0.83 ± 0.16) was lower than the second trimester(0.98 ± 0.20,P ＜ 0.05).Conclusions During pregnancy,IGF- I mRNA expression increases in thyroid under the conditions of iodine deficiency,and this effect is particularly significant in the first trimester; at the same time,TGF-β1 mRNA expression is increased,and this inhibition becomes clear with the deepening of iodine deficiency.Under the condition of iodine excess,the functions of IGF- Ⅰ and TGF-β1 in thyroid above-mentioned were relatively weak.With the development of gestational period,promoting tissues growth and differentiation effect of placenta's IGF- Ⅰ was more significant gradually,but,inhibited effect of TGF-β1 was weaken.