下垂体-甲状腺系negative feedback機構に及ぼす視床下部TRHの生理的役割

概要

論文の詳細を見る
To examine the physiological significance of TRH on the pituitary-thyroid axis, hypothalamic TRH contents and degradating activities in in vitro systems were measured in rats with various thyroid statuses. Furthermore, the influences of active and passive immunization with TRH were studied in normal and thyroid deficient rats. The hypothalamic TRH content was not significantly altered by thyroidectomy and T4 administration. The rate of TRH degradating activity determined in vitro was increased by the serum of T4-treated rats, while it was decreased by the serum of thyroidectomized rats, as compared with normal serum. On the other hand, the administration of anti-TRH rabbit serum significantly suppressed the elevation of serum TSH following thyroidectomy, although the decreased TSH level in passively immunized rats was still higher than in normal rats. No suppression of serum TSH levels was observed by the administration of normal rabbit serum (NRS) and anti-LH-RH serum. Moreover, the serum TSH rise following PTU treatment was blunted by active immunization with TRH. In addition, serum TSH levels of anti-TRH serum-injected rats was further decreased by T3 administration, and the rate of decline in serum TSH levels was facter than that of NRS-injected rats. The results of the present study suggest the physiological significance of endogenous TRH in the regulation of TSH secretion. In addition, TRH degradating activity may be influenced by various degrees of thyroid function ana thereby regulate the acting time of TRH on the pituitary level as the site of TSH secretion. Thus, it has been proposed that TRH may affect a "set-point" of the pituitary to induce TSH secretion in response to circulating thyroid hormone concentrations.

下垂体-甲状腺系negative feedback機構に及ぼす視床下部TRHの生理的役割

スポンサーリンク

概要

著者

関連論文

スポンサーリンク