甲状腺激素对垂体生长激素释放因子受体基因表达的调节

Thyroid hormone regulation of gene expression of the pituitary growth hormone-releasing factor receptor.

作者信息

Miki N, Ono M, Murata Y, Ohsaki E, Tamitsu K, Ri T, Demura H, Yamada M

机构信息

Department of Medicine, Tokyo Women's Medical College, Japan.

出版信息

Biochem Biophys Res Commun. 1995 Dec 26;217(3):1087-93. doi: 10.1006/bbrc.1995.2880.

DOI:10.1006/bbrc.1995.2880

PMID:8554561

Abstract

To examine thyroid hormone regulation of the pituitary receptor for hypothalamic growth hormone (GH)-releasing factor (GRF), we studied effects of hypothyroidism on the pituitary GRF receptor (GRF-R) mRNA and its related parameters in rats. Thyroidectomy (Tx) induced a 61-65% reduction in GRF-R mRNA levels, which was significantly reversed with thyroxine (T4) replacement for 5 days at a dose of 1 microgram/100 g/day. Pituitary GH contents changed parallel to GRF-R mRNA levels following the Tx and T4 replacement. In contrast, Tx enhanced GRF release > 2 fold, which was not reversed with the regime of T4 replacement. These results indicate that thyroid hormone promotes pituitary GRF-R gene expression, not by modulating GRF secretion, but by acting on the pituitary directly. The decline in GRF receptor expression would contribute to somatotroph failure by rendering the pituitary refractory to the increased GRF signal in hypothyroidism.

摘要

为研究甲状腺激素对垂体中下丘脑生长激素（GH）释放因子（GRF）受体的调节作用，我们研究了甲状腺功能减退对大鼠垂体GRF受体（GRF-R）mRNA及其相关参数的影响。甲状腺切除术（Tx）导致GRF-R mRNA水平降低61%-65%，以1微克/100克/天的剂量给予甲状腺素（T4）替代治疗5天可显著逆转这一降低。垂体GH含量在Tx及T4替代治疗后与GRF-R mRNA水平平行变化。相反，Tx使GRF释放增加2倍以上，T4替代治疗方案不能逆转这一变化。这些结果表明，甲状腺激素促进垂体GRF-R基因表达，不是通过调节GRF分泌，而是直接作用于垂体。GRF受体表达的下降会使垂体对甲状腺功能减退时增加的GRF信号产生不应性，从而导致生长激素细胞功能衰竭。