Department of Endocrinology, Dr. ALM, Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani, Chennai, India.
Steroids. 2010 Dec 12;75(13-14):1058-66. doi: 10.1016/j.steroids.2010.06.009. Epub 2010 Jul 27.
Variations in sex steroids bioavailability were linked to the gender difference in the growth of thyroid glands of neonatal rats. In the present study we tested androgen receptor (AR) and estrogen receptor (ER) concentrations by ligand binding assay, and expression of their genes by RT-PCR and Western blot in the thyroid glands of neonatal rats. AR concentration remained elevated from postnatal day (PND) 10 onwards in males, whereas it decreased by PND 20 in females. AR mRNA and protein expressions were higher in males than females, which increased by PND 10, decreased after PND 15 and reached the nadir by PND 20. ER concentration increased by PND 10 and decreased thereafter in both sex. ERα mRNA expression diminished by PND 15 in both sex; while ERβ mRNA decreased by PND 15 to reach the nadir by PND 20 in males, it was augmented by PND 10 in females to reach the peak by PND 15 and diminished by PND 20. ERα protein expression increased by PND 10 and remained elevated till PND 20 in both sex. ERβ protein expression in males increased by PND 10 and decreased by PND 20, while it remained static up to PND 15 and decreased in females. Testosterone stimulated [(3)H]-thymidine uptake and the expression of IGF-1 and NIS genes in thyrocytes of both sex in vitro, while estradiol stimulated them in females but not in males. We conclude that androgens influence the growth and differentiation of thyrocytes through augmented expression of AR, IGF-1 and NIS in either sex, whereas estrogen imparts the gender difference, which may be at a level beyond the expression of ERs.
性类固醇生物利用度的变化与新生大鼠甲状腺生长的性别差异有关。在本研究中，我们通过配体结合测定法检测了雄激素受体 (AR) 和雌激素受体 (ER) 的浓度，并通过 RT-PCR 和 Western blot 检测了它们在新生大鼠甲状腺中的基因表达。雄性大鼠的 AR 浓度从出生后第 10 天 (PND) 开始升高，而雌性大鼠的 AR 浓度在 PND 20 时降低。AR mRNA 和蛋白表达在雄性大鼠中高于雌性大鼠，在 PND 10 时增加，PND 15 后减少，PND 20 时达到最低。ER 浓度在 PND 10 时增加，此后在两性中均降低。ERα mRNA 表达在两性中均在 PND 15 时减少；而 ERβ mRNA 在雄性大鼠中在 PND 15 时减少至最低点，在 PND 20 时增加，在雌性大鼠中在 PND 10 时增加至最高点，在 PND 20 时减少。ERα 蛋白表达在两性中均在 PND 10 时增加，并持续升高至 PND 20。雄性大鼠 ERβ 蛋白表达在 PND 10 时增加，在 PND 20 时减少，而在 PND 15 时保持不变，在雌性大鼠中减少。睾酮在体外刺激两性甲状腺细胞中的 [(3)H]-胸苷摄取和 IGF-1 和 NIS 基因的表达，而雌二醇仅在雌性大鼠中刺激它们，而不在雄性大鼠中刺激。我们得出结论，雄激素通过在两性中增加 AR、IGF-1 和 NIS 的表达来影响甲状腺细胞的生长和分化，而雌激素赋予性别差异，这可能在 ER 表达水平之上。
