Miyoshi R, Kito S, Mizuno K
Jpn J Pharmacol. 1985 Jul;38(3):281-5. doi: 10.1254/jjp.38.281.
The technique of in vitro autoradiography which was developed by Kuhar and others was applied to the rat brain with use of 3H-flunitrazepam (flu) as a radioactive ligand. The cerebral cortex, hippocampus, substantia nigra and cerebellar cortex were rich in 3H-flu binding sites. To differentiate the benzodiazepine receptor (BZR) subtype, the authors used a type 1 specific ligand, either triazolopiridazine (CI 218872) or methyl-beta-carboline-carboxylate (beta-CCM), as an unlabeled displacer. The preparations were exposed on a 3H-sensitive film and then the film was developed. Computer-analysis of thus obtained autoradiographic pictures revealed that type 2 binding sites were distributed evenly within the rat brain, but with slight predominance in the hippocampus. After adding beta-CCM, no silver grains were noticed in the cerebellum and substantia nigra. These data meant that these two structures contained essentially type 1 BZR, while the hippocampus contained both type 1 and type 2 receptors. Autoradiographically, characteristic distribution of BZR represented by 3H-flu binding was considerably lost by adding a type 1 specific ligand, and this treatment caused the silver grains to be evenly distributed. These data suggest that the BZR which is directly associated with characteristic pharmacological actions such as anxiolytic and hypnotic effects is type 1, and type 2 binding sites have a less characteristic distribution pattern and might be pharmacologically less specific.
由库哈尔等人开发的体外放射自显影技术，使用³H-氟硝西泮（flu）作为放射性配体应用于大鼠脑。大脑皮层、海马体、黑质和小脑皮层富含³H-flu结合位点。为了区分苯二氮䓬受体（BZR）亚型，作者使用1型特异性配体，即三唑并吡啶（CI 218872）或甲基-β-咔啉-羧酸盐（β-CCM）作为未标记的置换剂。将制剂暴露于³H敏感胶片上，然后显影该胶片。对由此获得的放射自显影片进行计算机分析显示，2型结合位点在大鼠脑内分布均匀，但在海马体中略有优势。加入β-CCM后，在小脑和黑质中未观察到银粒。这些数据表明，这两个结构主要含有1型BZR，而海马体含有1型和2型受体。通过放射自显影，由³H-flu结合所代表的BZR特征性分布在加入1型特异性配体后显著消失，并且这种处理使银粒均匀分布。这些数据表明，与抗焦虑和催眠等特征性药理作用直接相关的BZR是1型，而2型结合位点具有较少特征性的分布模式，并且在药理上可能特异性较低。
