Berelowitz M, Maeda K, Harris S, Frohman L A
Endocrinology. 1980 Jul;107(1):24-9. doi: 10.1210/endo-107-1-24.
The role of somatostatin (SRIF) in the regulation of thyroid homeostasis was studied by measuring hypothalamic SRIF-like immunoreactivity (SRIF-LI) content and in vitro release in hypothyroid (T3-treated and untreated), euthyroid, and T3-treated normal rats. Hypothalamic SRIF-LI content was decreased in hypothyroid rats and was restored to euthyroid levels by T3 treatment. SRIF-LI release from hypothalami of hypothyroid rats was decreased compared to that in euthyroid controls under basal and stimulated (60 mM K+ or 10(-6) M dopamine) in vitro conditions. The release of SRIF-LI from hypothalami of hypothyroid rats treated with T3 was restored to euthyroid levels. The release of SRIF-LI from normal rat hypothalami was unaffected by TRH or TSH but was stimulated by T3. These results suggest that T3 exerts its negative feedback effect on pituitary TSH release via stimulation of hypothalamic SRIF release as well as by a direct pituitary effect, and that the elevated TSH levels seen in primary hypothyroidism may result in part from a decrease in the tonic inhibitory effect of hypothalamic SRIF. Pancreatic, but not antral or colonic, SRIF-LI was increased in hypothyroid rats, and the levels were reduced by T3 treatment. The changes cannot be explained by alterations in food intake and may represent primary effects of the hypothyroid state.
通过测量甲状腺功能减退（经T3治疗和未治疗）、甲状腺功能正常以及经T3治疗的正常大鼠下丘脑生长抑素样免疫反应性（SRIF-LI）含量和体外释放，研究了生长抑素（SRIF）在调节甲状腺内环境稳定中的作用。甲状腺功能减退大鼠下丘脑SRIF-LI含量降低，经T3治疗后恢复到甲状腺功能正常水平。在基础和刺激（60 mM K+或10(-6) M多巴胺）体外条件下，甲状腺功能减退大鼠下丘脑SRIF-LI释放量与甲状腺功能正常对照组相比降低。经T3治疗的甲状腺功能减退大鼠下丘脑SRIF-LI释放量恢复到甲状腺功能正常水平。正常大鼠下丘脑SRIF-LI释放不受促甲状腺激素释放激素（TRH）或促甲状腺激素（TSH）影响，但受T3刺激。这些结果表明，T3通过刺激下丘脑SRIF释放以及对垂体的直接作用，对垂体TSH释放发挥负反馈作用，并且原发性甲状腺功能减退中所见的TSH水平升高可能部分源于下丘脑SRIF的紧张性抑制作用降低。甲状腺功能减退大鼠胰腺而非胃窦或结肠的SRIF-LI增加，经T3治疗后水平降低。这些变化无法用食物摄入量的改变来解释，可能代表甲状腺功能减退状态的原发性作用。
