不同碘营养水平对妊娠期大鼠胎盘激素分泌的影响

目的 探讨不同碘营养水平对妊娠期大鼠胎盘激素分泌的影响.方法 Wistar大鼠225只(雌鼠165只,雄鼠60只),体质量约80～ 100g.将雌鼠按体质量随机分为5组:低碘1组、低碘2组、适碘(对照)组、高碘1组、高碘2组,每组33只.2个低碘组大鼠食用病区粮食,含碘量为13.46 μg/kg,分别饮用含0、5μg/L碘酸钾的去离子水；对照组和2个高碘组大鼠食用普通粮食,含碘量为22.00 μg/kg,分别饮用含50、3000、10000 μg/L碘酸钾的去离子水.饲养3个月,雌鼠与雄鼠合笼交配,于孕早期(5±2)d、孕中期(12±2)d、孕晚期(17±2)d处死母鼠,取血清.采用酶联免疫吸附测定法(ELISA)测血清绒毛膜促性腺激素(HCG)、绒毛膜促甲状腺激素(HCT)、孕激素.结果 孕晚期大鼠血清HCG组间比较差异有统计学意义(F=4.16,P＜ 0.05)；孕晚期低碘1组(16.08±4.45)U/L]、低碘2组(17.43±2.70)U/L]较对照组(13.68±3.52)U/L]显著升高(P均＜ 0.01).孕中、孕晚期大鼠血清HCT组间比较差异有统计学意义(F值分别为3.59、3.40,P均＜0.05)；孕中期高碘1组(70.11±10.97 )μU/L]、孕晚期高碘2组(74.93±13.22)μU/L]较对照组(57.14±12.56)、(58.17±8.54) μU/L]显著升高(P均＜0.01).低碘1组、对照组大鼠血清孕激素组内比较差异有统计学意义(F值分别为4.06、4.43,P均＜0.05)；低碘1组孕晚期(1462.80±286.48)pmol/L]低于孕旱(1929.93±158.37)pmol/L,P＜0.05]、孕中期(1856.44±542.08)pmol/L,P＜0.05]；对照组孕中期(2046.45±475.67)pmol/L]高于孕早期(1714.39±461.71 )pmol/L,P＜ 0.05].结论 妊娠期母体胎盘HCG分泌在缺碘条件下增加,HCT分泌在碘过量条件下增加.孕激素在重度低碘情况下,随孕期增加而分泌下降,与HCG在孕期的变化趋势相反,易造成不良妊娠结果.

Effect of different levels of iodine nutrition on secretion of placental hormone in pregnant rats

Objective To study the effect of different levels of iodine nutrition on secretion of placental hormone in pregnant rats.Methods Two hundred and twenty five Wistar rats (165 female,60 male),weighing about 80 - 100 g were used in the study.Female rats were randomly divided into five groups according to their body weights:low iodine group Ⅰ(LⅠ),low iodine group Ⅱ (LⅡ),adequate iodine(control) group(Al),high iodine group Ⅰ ( HⅠ ),and high iodine group Ⅱ (H Ⅱ ),and 33 rats in each group.Animals in the low iodine groups were fed low-iodine diet,the iodine content was 13.46 μg/kg,in addition,these rats drank deionized water which containing potassium iodated,the dose was 0 and 5 μg/L,respectively.The rats of adequate and the two high iodine groups were fed normal diet,the iodine content was 22.00 μg/kg,they also drank deionized water,containing potassium iodated 50,3000,and 10000 μg/L,respectively.The rats mated after 3 months of feeding,and were respectively sacrificed at early pregnancy(5 ± 2)d,second trimester( 12 ± 2)d,and third trimester of pregnancy(17 ± 2)d,and then their serum was taken.Serum human chorionic gonadotropin(HCG),human chorionic thyrotropin(HCT),and progesterone were measured by enzyme-linked immunosorbent assay (ELISA).Results In the third trimester,the serum levels of rat HCG were significantly different between groups(F =4.16,P ＜ 0.05).The means of rats serum HCG of the two low iodine groups (16.08 ± 4.45),(17.43 ± 2.70)U/L] were significantly higher compared with that of AI group (13.68 ± 3.52)U/L] in the third trimester(all P ＜ 0.01 ).In the second and third trimester,the levels of rats serum HCT were significantly different between groups(F =3.59,3.40,all P ＜ 0.05).The means of rats serum HCT of HI group (70.11 ± 10.97)μU/L] in the second trimester and HII group(74.93 ± 13.22)μU/L] in the third trimester were higher than those of AI group (57.14 ± 12.56),(58.17 ± 8.54)μU/L] significantly(all P ＜ 0.01 ).There were statistical differences of the means of serum progesterone among trimester of pregnancy(F =4.06,4.43,all P ＜ 0.05).The level of serum progesterone of the third trimester ( 1462.80 ± 286.48 )pmoL/L] compared to those of the first (1929.93 ± 158.37) pmol/L] and the second trimester (1856.44 ± 542.08)pmol/L] was decreased significantly(all P ＜ 0.05) in LI group.In the control group,the level of serum progesterone of the second trimester (2046.45 ± 475.67)pmol/L ] was significantly higher than the first trimester (1714.39 ± 461.71 )pmol/L,P ＜ 0.05 ].Conclusions During pregnancy,placenta could promote HCG secretion under iodine-deficient conditions.In addition,the placenta increases the secretion of HCT under conditions of excess iodine.In the condition of severe iodine deficiency,the secretion of serum progesterone decreases,and further decreases with prolongation of pregnancy,but it is opposite to the change of HCG during pregnancy.This phenomenon could lead to harmful pregnant outcomes easily.