Mitsuma T, Hirooka Y, Kimura M, Nogimori T
Fourth Department of Internal Medicine, Aichi Medical University, Nagakute, Japan.
Exp Clin Endocrinol. 1991 Mar;97(1):45-9. doi: 10.1055/s-0029-1211037.
The effects of hypophysectomy on pro-thyrotropin-releasing hormone (pro-TRH) and TRH concentrations in the rat hypothalamus, cerebrum, cerebellum and brain stem, stomach and eye were studied. The hypophysectomy was performed via ear route and the rats were used for experiments at seven days after the operation. The hypophysectomized rats were administered T4 (500 micrograms/kg), T3 (100 micrograms/kg), TRH (1.0 mg/kg), or bovine TSH (1.25 IU/kg) was injected ip, and five rats in each subgroup were decapitated at four hours after the injection. Pro-TRH, TRH, TSH and thyroid hormone were measured by their radioimmunoassays. Immunoreactive pro-TRH (ir-pro-TRH) concentrations in the hypothalamus increased significantly after hypophysectomy, while its concentrations in the other tissues showed no changes. The immunoreactive TRH (ir-TRH) concentrations in the hypothalamus decreased significantly after hypophysectomy, but its concentrations did not change in the other tissues. In the hypophysectomized rats, ir-pro-TRH concentrations in the hypothalamus decreased significantly after T4 or T3 injection and tended to decrease after TRH or TSH injection. The ir-TRH concentrations in the hypothalamus increased significantly after T4, T3, TSH or TRH injection in the hypophysectomized rats. However, ir-pro-TRH and ir-TRH concentrations in the other tissues did not change after these hormone injections. The findings suggest that hypophysectomy stimulates TRH synthesis and release in the hypothalamus, and that pro-TRH synthesis in the tissues except the hypothalamus may not be regulated with thyroid hormone.
研究了垂体切除对大鼠下丘脑、大脑、小脑、脑干、胃和眼中促甲状腺激素释放激素(pro-TRH)和TRH浓度的影响。通过耳部途径进行垂体切除,术后7天将大鼠用于实验。对垂体切除的大鼠腹腔注射T4(500微克/千克)、T3(100微克/千克)、TRH(1.0毫克/千克)或牛促甲状腺激素(1.25国际单位/千克),每个亚组的5只大鼠在注射后4小时断头。通过放射免疫分析法测定pro-TRH、TRH、促甲状腺激素(TSH)和甲状腺激素。垂体切除后,下丘脑免疫反应性pro-TRH(ir-pro-TRH)浓度显著升高,而其他组织中的浓度无变化。垂体切除后,下丘脑免疫反应性TRH(ir-TRH)浓度显著降低,但其他组织中的浓度未改变。在垂体切除的大鼠中,注射T4或T3后,下丘脑ir-pro-TRH浓度显著降低,注射TRH或TSH后有降低趋势。垂体切除的大鼠注射T4、T3、TSH或TRH后,下丘脑ir-TRH浓度显著升高。然而,这些激素注射后,其他组织中的ir-pro-TRH和ir-TRH浓度未改变。这些发现表明,垂体切除刺激下丘脑TRH的合成和释放,并且下丘脑以外组织中的pro-TRH合成可能不受甲状腺激素的调节。