Mitsuma T, Nogimori T, Sun D H, Chaya M
Exp Clin Endocrinol. 1986 Jul;87(2):162-8. doi: 10.1055/s-0029-1210538.
The effects of the peripheral administration of litorin on thyrotropin-releasing hormone (TRH) and thyrotropin (TSH) secretion were studied in rats. Litorin (400 micrograms/kg) was injected iv, and the rats were serially decapitated. TRH, TSH and thyroid hormone were measured by radioimmunoassay. The hypothalamic immunoreactive TRH (ir-TRH) content increased significantly after litorin injection, whereas its plasma concentration tended to decrease, but not significantly. The plasma TSH levels decreased significantly in a dose-related manner with a nadir at 20 min. after the injection. The plasma thyroid hormone levels showed no changes. The plasma ir-TRH and TSH responses to cold were inhibited by litorin, but the plasma TSH response to TRH was not affected. In the pimozide- or para-chlorophenylalanine-pretreated group, the inhibitory effect of litorin on TSH levels was prevented, but not in the L-DOPA- or 5-hydroxytryptophan-pretreated group. These drugs alone did not affect plasma TSH levels in terms of the dose used. The inactivation of TRH immunoreactivity by hypothalamus or plasma in vitro after litorin injection did not differ from that of the saline-treated group. These findings suggest that litorin acts on the hypothalamus to inhibit TRH release, and that its effects are modified by amines of the central nervous system.
研究了在大鼠体内外周给予利托林对促甲状腺激素释放激素（TRH）和促甲状腺激素（TSH）分泌的影响。静脉注射利托林（400微克/千克），然后将大鼠依次断头。采用放射免疫分析法测定TRH、TSH和甲状腺激素。注射利托林后，下丘脑免疫反应性TRH（ir-TRH）含量显著增加，而其血浆浓度有下降趋势，但不显著。注射后20分钟时，血浆TSH水平以剂量相关方式显著下降至最低点。血浆甲状腺激素水平无变化。利托林抑制了血浆ir-TRH和TSH对寒冷的反应，但不影响血浆TSH对TRH的反应。在预先用匹莫齐特或对氯苯丙氨酸处理的组中，利托林对TSH水平的抑制作用被阻止，但在预先用左旋多巴或5-羟色氨酸处理的组中则未被阻止。就所用剂量而言，这些药物单独使用时不影响血浆TSH水平。注射利托林后，下丘脑或血浆在体外对TRH免疫反应性的失活与生理盐水处理组无差异。这些发现表明，利托林作用于下丘脑以抑制TRH释放，并且其作用受到中枢神经系统胺类物质的调节。
