Devaskar U P, Devaskar S U, Sadiq H F, Chechani V
Dev Pharmacol Ther. 1986;9(2):115-23. doi: 10.1159/000457083.
Although rabbit has been used as a convenient animal model in understanding the role of thyroid hormones during the perinatal development, ontogenetic changes in plasma-free thyroxine or triiodothyronine concentration has not been studied in this species. We delineated the ontogeny of immunoreactive plasma-free thyroxine and triiodothyronine concentration during the perinatal period. It is generally believed that thyroid hormones do not cross the placenta from the mother to the fetus in sufficient concentrations to exert biological effects in the fetus. We administered 250 micrograms/kg of thyroxine (T4) or 125 micrograms/kg of triiodothyronine (T3) intramuscularly to the rabbit doe on the 25th and 26th day of gestation. Maternal and fetal plasma-free T4, T3 and glucose concentration and fetal liver glycogen content were quantitated on the 27th day of gestation. Maternal and fetal plasma-free T4 and T3 concentration was significantly higher than the control in T4-treated animals. Maternal and fetal plasma T3 concentration was higher and free T4 concentration lower than the control in T3-treated animals. T3 or T4 treatment resulted in fetal hyperglycemia and depletion of fetal hepatic glycogen content. We conclude that T4 or T3 cross the rabbit placenta and exert thyromimetic effects in the fetus. A convenient animal model to investigate in utero effects of T4 or T3 in mammalian fetal development is proposed.
尽管兔子一直被用作一种方便的动物模型来理解甲状腺激素在围产期发育中的作用，但尚未对该物种血浆游离甲状腺素或三碘甲状腺原氨酸浓度的个体发生变化进行研究。我们描绘了围产期免疫反应性血浆游离甲状腺素和三碘甲状腺原氨酸浓度的个体发生情况。一般认为，甲状腺激素不会以足够的浓度从母体穿过胎盘到达胎儿，从而在胎儿体内发挥生物学作用。我们在妊娠第25天和第26天给兔母兽肌肉注射250微克/千克的甲状腺素（T4）或125微克/千克的三碘甲状腺原氨酸（T3）。在妊娠第27天对母体和胎儿的血浆游离T4、T3和葡萄糖浓度以及胎儿肝脏糖原含量进行定量。在接受T4治疗的动物中，母体和胎儿的血浆游离T4和T3浓度显著高于对照组。在接受T3治疗的动物中，母体和胎儿的血浆T3浓度较高，游离T4浓度低于对照组。T3或T4治疗导致胎儿高血糖和胎儿肝脏糖原含量减少。我们得出结论，T4或T3穿过兔胎盘并在胎儿体内发挥拟甲状腺作用。提出了一种方便的动物模型，用于研究T4或T3对哺乳动物胎儿发育的子宫内影响。
