Fragner P, Quette J, Aratan-Spire S
INSERM U.30, Mécanisme d'action cellulaire des hormones, Paris, France.
Biochem Biophys Res Commun. 1998 Jun 29;247(3):564-8. doi: 10.1006/bbrc.1998.8830.
Thyrotropin-releasing hormone (TRH), originally characterized as the first hypothalamic hormone, is also synthesized in the insulin-containing cells. TRH stimulates the glucagon secretion and attenuates exocrine pancreatic secretions. We have previously reported, using whole pancreatic homogenates, that TRH content increased in hypothyroid rats, associated to a loss of TRH-degrading activity. The present study was undertaken on purified islets, an appropriate model to examine thyroid status-dependent regulation of two islet hormones, TRH and insulin. The islets from hypothyroid rat pancreas had increased TRH content (4x) without any change in insulin content. Likewise, the Northern blot analysis revealed that the steady-state concentrations of TRH mRNA increased (4x) while those of insulin remain unchanged. These data therefore suggest that TRH gene transcription is under the negative control of T3. This study also provides insight into islet response to impaired thyroid function.
促甲状腺激素释放激素（TRH）最初被鉴定为第一种下丘脑激素，也在含胰岛素的细胞中合成。TRH刺激胰高血糖素分泌并减弱胰腺外分泌。我们之前使用全胰腺匀浆报道过，甲状腺功能减退大鼠的TRH含量增加，这与TRH降解活性丧失有关。本研究是在纯化的胰岛上进行的，这是一个用于研究甲状腺状态依赖性调节两种胰岛激素（TRH和胰岛素）的合适模型。甲状腺功能减退大鼠胰腺的胰岛TRH含量增加（4倍），而胰岛素含量没有任何变化。同样，Northern印迹分析显示TRH mRNA的稳态浓度增加（4倍），而胰岛素的稳态浓度保持不变。因此，这些数据表明TRH基因转录受T3的负调控。本研究还为胰岛对甲状腺功能受损的反应提供了见解。
