Seabrook G R, Kemp J A, Freedman S B, Patel S, Sinclair H A, McAllister G
Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Harlow, Essex.
Br J Pharmacol. 1994 Feb;111(2):391-3. doi: 10.1111/j.1476-5381.1994.tb14746.x.
This study describes the depression of calcium currents caused by activation of human D3 dopamine receptors which have been stably expressed in the neuroblastoma x glioma NG108-15 cell line. Transfected cells, which had been differentiated with prostaglandin E1 and isobutylmethylxanthine, exclusively expressed D3 receptor mRNA, which was demonstrated by reverse transcription polymerase chain reaction techniques. Transfected cells had high affinity binding sites for iodosulpiride, with a Kd of 0.8 nM and receptor density of 240 fmol mg-1 protein. Calcium currents were recorded using nystatin-perforated patch clamp techniques. In contrast to untransfected cells that had been differentiated, high-threshold calcium currents in differentiated hD3-NG108-15 cells were depressed by application of dopamine and quinpirole. These responses were abolished by the dopamine receptor antagonist S-(-)-sulpiride (1 microM), demonstrating that they were caused by the activation of the transfected dopamine receptors. Coupling of human D3 receptors to calcium currents was sensitive to the action of pertussis toxin, suggesting the involvement of G-proteins of the Gi and/or G(o) subtype. These results demonstrate that human D3 receptors represent a functional class of dopamine receptor.
本研究描述了在神经母细胞瘤x胶质瘤NG108 - 15细胞系中稳定表达的人D3多巴胺受体激活所引起的钙电流抑制。用前列腺素E1和异丁基甲基黄嘌呤分化后的转染细胞，特异性表达D3受体mRNA，这通过逆转录聚合酶链反应技术得以证实。转染细胞对碘舒必利有高亲和力结合位点，解离常数Kd为0.8 nM，受体密度为240 fmol mg-1蛋白质。使用制霉菌素穿孔膜片钳技术记录钙电流。与已分化的未转染细胞相比，多巴胺和喹吡罗可使分化的hD3 - NG108 - 15细胞中的高阈值钙电流受到抑制。多巴胺受体拮抗剂S - (-)-舒必利（1 microM）可消除这些反应，表明这些反应是由转染的多巴胺受体激活所致。人D3受体与钙电流的偶联对百日咳毒素的作用敏感，提示Gi和/或Go亚型的G蛋白参与其中。这些结果表明人D3受体代表了一类功能性多巴胺受体。
