Roles of Thyroid and Adrenal glands in the regulation of hypothalamo-hypophysial-ovarian axis in the rat.

研究了成年雄性大鼠甲状腺、肾上腺和性腺激素之间的功能关系。在饮水中给予4-甲基-2-硫脲嘧啶（硫脲嘧啶）2周后产生甲状腺功能减退。与正常甲状腺大鼠相比，经硫脲嘧啶治疗的大鼠血浆TSH浓度显著升高，而三碘甲状腺原氨酸和甲状腺素浓度降低。甲状腺功能减退增加血浆ACTH基础水平和垂体ACTH含量。垂体对促肾上腺皮质激素释放的促肾上腺皮质激素反应性降低，而对促肾上腺皮质激素释放的促肾上腺皮质激素反应性明显升高。提示甲状腺功能减退可引起成年雄性大鼠肾上腺功能障碍。与甲状腺功能正常的大鼠相比，甲状腺功能减退大鼠垂体LH和催乳素含量降低。此外，甲状腺功能减退降低垂体LH对LHRH的反应性。然而，睾丸对人绒毛膜促性腺激素释放睾酮的反应性在甲状腺功能正常和甲状腺功能低下的动物之间没有差异。这些结果表明，甲状腺功能减退症引起肾上腺功能障碍，导致垂体促肾上腺皮质激素分泌过多。肾上腺功能障碍可能有助于抑制下丘脑的LHRH分泌，可能是由过量的CRH介导的。

The functional relationship between thyroid, adrenal and gonadal hormones was investigated using adult male rats. Hypothyroidism was produced by the administration of 4-methy1-2-thiouracil (thiouracil) in the drinking water for 2 weeks. Plasma concentrations of TSH dramatically increased, whereas plasma concentrations of tri-iodothyronine and thyroxine decreased in thiouracil-treated rats as compared with euthyroid rats.Hypothyroidism increased basal levels of plasma ACTH and pituitary content of ACTH.The pituitary responsiveness to CRH for ACTH release markedly increased, whereas the adrenal responsiveness to ACTH for corticosterone release decreased. These results indicated that hypothyroidism causes adrenal dysfunction in adult male rats. Pituitary contents of LH and prolactin decreased in hypothyroid rats as compared with euthyroid rats. In addition, hypothyroidism lowered pituitary LH responsiveness to LHRH.Testicular responsiveness to human chorionic gonadotrophin for testosterone release, however, was not different between euthyroid and hypothyroid animals. These results indicated that hypothyroidism causes adrenal dysfunction and results in hypersecretion of ACTH from the pituitary gland. Adrenal dysfunction may contribute to the inhibition of LHRH secretion from the hypothalamus, possibly mediated by excess CRH.