De Keyser J, De Backer J P, Convents A, Ebinger G, Vauquelin G
J Neurochem. 1985 Sep;45(3):977-9. doi: 10.1111/j.1471-4159.1985.tb04091.x.
By use of the radioligand [3H]spiroperidol, D2 3,4-dihydroxyphenylethylamine (dopamine) receptor binding characteristics were studied in calf globus pallidus and compared with those of neostriatum. Antagonist competition curves were monophasic and revealed similar affinities for neostriatum and globus pallidus, suggesting a uniform receptor population with one affinity state for antagonists. In both regions, competition curves with the agonist dopamine were biphasic, distinguishing a high- and low-agonist-affinity state. In neostriatum and globus pallidus, respectively, 45% and 19% of [3H]spiroperidol binding was displaced with high affinity and the remainder with low affinity. In neostriatum, the addition of 0.4 mM GTP resulted in a partial conversion from high- to low-affinity state with a remaining high-affinity component of 15%. In globus pallidus, dopamine binding was not altered by GTP. The capability of GTP to modulate agonist binding to D2 receptors appears to be dependent on their neuroanatomical localization.
利用放射性配体[3H]螺哌啶醇，研究了小牛苍白球中D2 3,4-二羟基苯乙胺（多巴胺）受体的结合特性，并与新纹状体的进行了比较。拮抗剂竞争曲线呈单相，显示新纹状体和苍白球具有相似的亲和力，表明存在对拮抗剂具有单一亲和力状态的统一受体群体。在两个区域中，激动剂多巴胺的竞争曲线均为双相，区分出高激动剂亲和力状态和低激动剂亲和力状态。在新纹状体和苍白球中，分别有45%和19%的[3H]螺哌啶醇结合以高亲和力被置换，其余部分以低亲和力被置换。在新纹状体中，加入0.4 mM GTP导致从高亲和力状态部分转变为低亲和力状态，剩余的高亲和力成分占15%。在苍白球中，多巴胺结合不受GTP影响。GTP调节激动剂与D2受体结合的能力似乎取决于它们的神经解剖定位。
