Hiroi N, White N M
Department of Psychology, McGill University, Montreal, Que., Canada.
Brain Res. 1991 Jun 21;552(1):141-52. doi: 10.1016/0006-8993(91)90672-i.
We investigated involvement of dopamine receptor subtypes and two dopaminergic terminal areas in the acquisition and the expression of the amphetamine conditioned place preference (CPP). When injected systemically before conditioning, both D1 and D2 dopamine antagonists blocked acquisition in a dose-dependent manner. When injected systemically before testing, the effects of the same D1 and D2 antagonists differed. The selective D1 antagonist SCH23390 dose-dependently blocked expression of the previously established conditioned behavior within the dose range that also blocked acquisition. In contrast, D2 antagonists failed to block expression of the amphetamine CPP at doses which blocked acquisition. Expression was, however, blocked by higher doses of D2 antagonists, which may have lost their selectivity for the D2 dopamine receptor. The expression of the CPP was also blocked by microinjections of SCH23390 or sulpiride into nucleus accumbens, but not into striatum. In a control experiment, sodium pentobarbital, which significantly reduced spontaneous locomotor activity in a manner similar to the higher doses of the dopamine antagonists, had no effect on the expression of the amphetamine CPP when given before testing. Finally, electrolytic lesions of the dorsal striatum potentiated the amphetamine CPP. These findings indicate that the dopamine released by amphetamine interacts with both D1 and D2 dopamine receptors to establish a CPP, but that the expression of the CPP may involve activation of the D1 dopamine receptor in the nucleus accumbens.
我们研究了多巴胺受体亚型以及两个多巴胺能终末区域在苯丙胺条件性位置偏爱（CPP）的获得和表达过程中的作用。在条件化训练前全身注射时，D1和D2多巴胺拮抗剂均以剂量依赖性方式阻断CPP的获得。在测试前全身注射时，相同的D1和D2拮抗剂产生的效果有所不同。选择性D1拮抗剂SCH23390在阻断获得的剂量范围内，剂量依赖性地阻断先前建立的条件性行为的表达。相比之下，D2拮抗剂在阻断获得的剂量下未能阻断苯丙胺CPP的表达。然而，更高剂量的D2拮抗剂可阻断表达，这可能是因为它们对D2多巴胺受体失去了选择性。向伏隔核微量注射SCH23390或舒必利也可阻断CPP的表达，但向纹状体注射则无此作用。在一项对照实验中，戊巴比妥钠以类似于高剂量多巴胺拮抗剂的方式显著降低自发运动活性，但在测试前给予时对苯丙胺CPP的表达没有影响。最后，背侧纹状体的电解损伤增强了苯丙胺CPP。这些发现表明，苯丙胺释放的多巴胺与D1和D2多巴胺受体相互作用以建立CPP，但CPP的表达可能涉及伏隔核中D1多巴胺受体的激活。
