Peroutka S J
Department of Neurology, Stanford University School of Medicine, CA 94305.
Brain Res. 1991 Jul 12;553(2):206-10. doi: 10.1016/0006-8993(91)90826-h.
The ability of 5-hydroxytryptamine (5-HT), 5-carboxytryptamine (5-CT) and sumatriptan to compete for [3H]5-HT binding sites in various brain tissues was analyzed in bovine, guinea pig, pig and human cortex and caudate. Radioligand binding conditions were designed to allow for the selective labeling of putative 5-HT1D binding sites. 5-HT competed monophasically with putative 5-HT1D binding sites in each of the 8 tissues studied. By contrast, both 5-CT and sumatriptan competed with markedly shallow displacement curves in each of the 8 tissues. In the case of sumatriptan, complete displacement of [3H]5-HT could not be achieved even at concentrations as high as 2000 times its IC50 value. These data indicate that 10(-5) M 5-HT should not be used to define specific binding to 5-HT1D receptors in radioligand binding assays. Instead, 5-HT1D receptor binding sites should be redefined as [3H]5-HT-labeled binding sites displaced by 10(-5) M sumatriptan.
分析了5-羟色胺（5-HT）、5-羧基色胺（5-CT）和舒马曲坦在牛、豚鼠、猪和人类皮质及尾状核等不同脑组织中竞争[3H]5-HT结合位点的能力。设计放射性配体结合条件以实现对假定的5-HT1D结合位点的选择性标记。在所研究的8种组织中，5-HT与假定的5-HT1D结合位点呈单相竞争。相比之下，5-CT和舒马曲坦在所有8种组织中竞争时的置换曲线明显较浅。就舒马曲坦而言，即使浓度高达其IC50值的2000倍，也无法实现[3H]5-HT的完全置换。这些数据表明，在放射性配体结合试验中，不应使用10(-5)M 5-HT来定义与5-HT1D受体的特异性结合。相反，5-HT1D受体结合位点应重新定义为被10(-5)M舒马曲坦置换的[3H]5-HT标记结合位点。
