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目的探讨甲状腺激素对胸腺的发育的影响及可能的机制。方法将12只怀孕4d的大鼠随机分成A组和B组,A组正常饮水,B组孕鼠供以含有0.02%甲巯咪唑的饮水制备仔鼠甲状腺功能低下动物模型,将A组的仔鼠随机分成对照组和甲状腺素钠组,将B组的仔鼠随机分成甲低组和甲低+甲状腺素钠组。甲状腺素钠组和甲低+甲状腺素钠组于出生后15d给予腹腔注射甲状腺素钠(0.5mg/kg体重,1次/d),连续给药25 d。所有动物于出生后40d麻醉处死,测定仔鼠的胸腺重量及脏器指数;采用放射免疫技术测定仔鼠血清中三碘甲状腺原氨酸(triiodothyronine,T3)、四碘甲状腺原氨酸(tetraiodothyronine,T4)、促甲状腺激素(thyroid-stimulatinghormone,TSH)水平,免疫组织化学技术检测胸腺上皮细胞细胞角蛋白19(cytokeratin19,CK19)蛋白的表达量。结果与对照组比较,甲状腺素钠组仔鼠血清中T3、T4显著升高,TSH减少,胸腺重量增大;甲低组仔鼠血清中T3、T4明显降低,TSH显著增高,胸腺重量降低,胸腺上皮细胞CK19蛋白表达减少。与甲低组比较,甲低+甲状腺素钠组仔鼠血清中T3、T4升高,TSH降低,胸腺指数增大,胸腺上皮细胞CK19蛋白的表达明显增多。结论甲状腺激素可以通过影响胸腺上皮细胞CK19的表达量,使胸腺发育或退化。
Objective To investigate the effects of thyroid hormones on the development of the thymus and possible mechanisms. Methods Twelve pregnant rats of 4 days pregnant were randomly divided into group A and group B. Rats in group A were fed with water containing 0.02% methimazole to prepare hypothyroid mice model. Rats were randomly divided into control group and sodium thyroxine group, the B group of offspring were randomly divided into hypothyroidism group and hypothyroidism + thyroxine sodium group. Thyroxine sodium group and hypothyroidism + sodium thyroxine sodium group were given intraperitoneal injection of sodium thyroxine (0.5mg / kg body weight, once a day) 15d after birth for 25 consecutive days. All animals were anesthetized and sacrificed 40 days after birth, and the thymus weight and organ index of offspring were measured. The serum levels of triiodothyronine (T3), tetraiodothyronine T4, thyroid-stimulating hormone (TSH) levels were detected by immunohistochemistry. The expression of cytokeratin 19 (CK19) protein in thymic epithelial cells was detected by immunohistochemistry. Results Compared with the control group, the levels of T3 and T4 in serum of thyroxine sodium group were significantly increased, the TSH was decreased and the thymus weight was increased. The serum T3 and T4 of hypothyroidism group were significantly decreased, the TSH was significantly increased, the thymus weight was decreased, Thymic epithelial cells CK19 protein expression decreased. Compared with hypothyroidism group, hypothyroidism + thyroxine sodium group increased serum T3, T4, decreased TSH, thymus index, thymus epithelial cells CK19 protein expression increased significantly. Conclusions Thyroid hormone can cause thymus to develop or degrade by affecting the expression of CK19 in thymic epithelial cells.