Shioda S, Nakai Y
Cell Tissue Res. 1983;228(3):475-87. doi: 10.1007/BF00211469.
Immunocytochemical and autoradiographic localization of thyrotropin-releasing hormone (TRH)- and 3H-TRH-binding sites was studied in the arcuate nucleus-median eminence region of the rat. TRH-like immunoreactivity was found in dense granular vesicles (90-140 nm in diameter) in TRH-like immunoreactive nerve fibers and terminals. In the median eminence, the immunoreactive terminals were observed to be in direct contact with the perivascular basal lamina of the portal vessel and to form synaptoid contacts with tanycytes. In the arcuate nucleus, the immunoreactive terminals were often found to form axosomatic and axo-axonic, and/or axo-dendritic synapses. The uptake of tritiated TRH into the nerve fibers and terminals of the median eminence was also observed by autoradiography and the distribution and localization of silver grains in them were analyzed quantitatively by circle analysis. Thirty minutes after intraventricular infusion of 3H-TRH, radioactive labeling occurred in type-2 and 3-nerve fibers and terminals containing dense granular vesicles in the median eminence. It is therefore suggested that the neurons labeled after 3H-TRH infusion possess certain functions as physiological recognition sites or receptors for TRH.
在大鼠的弓状核-正中隆起区域，研究了促甲状腺激素释放激素（TRH）和3H-TRH结合位点的免疫细胞化学及放射自显影定位。在TRH样免疫反应性神经纤维和终末的致密颗粒小泡（直径90-140nm）中发现了TRH样免疫反应性。在正中隆起，观察到免疫反应性终末与门脉血管的血管周围基膜直接接触，并与伸长细胞形成类突触接触。在弓状核，常发现免疫反应性终末形成轴-体、轴-轴和/或轴-树突触。通过放射自显影也观察到了氚化TRH被摄取到正中隆起的神经纤维和终末中，并通过圆形分析对其中银颗粒的分布和定位进行了定量分析。脑室内注入3H-TRH 30分钟后，正中隆起中含有致密颗粒小泡的2型和3型神经纤维及终末出现放射性标记。因此提示，注入3H-TRH后被标记的神经元作为TRH的生理识别位点或受体具有某些功能。
