Ranaldi R, Pantalony D, Beninger R J
Department of Psychology, Queen's University, Kingston, Ontario, Canada.
Pharmacol Biochem Behav. 1995 Sep;52(1):131-7. doi: 10.1016/0091-3057(95)00065-5.
The present study investigated the hypothesis that the D1 subtype of DA receptors is critically involved in reward-related learning. The effects of SKF 38393, a D1-specific agonist, on amphetamine-produced enhancement of responding for conditioned reward were tested. We exposed 69 male Wistar rats to an experimental design consisting of three phases. The preexposure phase consisted of five sessions during which the rats were exposed to an operant chamber containing two levers. One lever produced a lights-off stimulus (3 s) and the other a tone stimulus (3 s). This was followed by four conditioning sessions during which the levers were removed and the rats were exposed to pairings of the lights-off stimulus with food. This phase was followed by two test sessions during which the levers were present and the number of responses made on each lever was calculated as a ratio of the number of responses made during the preexposure phase. A group receiving saline during the test sessions showed a higher ratio of responding for the lights off stimulus than the tone stimulus, demonstrating that the lights-off stimulus had become a conditioned reward. Amphetamine [2.0 mg/kg, intraperitoneally (i.p.), 5 min before the test] enhanced responding specifically on the lever producing the conditioned reward. Groups receiving SKF 38393 (5.0, 10.0, and 20.0 mg/kg, i.p., 5 min before the test) failed to show significantly greater responding for the lights-off stimulus than the tone, indicating a reduction or elimination of the conditioned reward effect. Moreover, SKF 38393 dose dependently reduced the amphetamine-produced enhancement of responding for conditioned reward.(ABSTRACT TRUNCATED AT 250 WORDS)
多巴胺（DA）受体的D1亚型在与奖励相关的学习中起关键作用。测试了D1特异性激动剂SKF 38393对苯丙胺引起的条件性奖励反应增强的影响。我们将69只雄性Wistar大鼠暴露于一个由三个阶段组成的实验设计中。预暴露阶段包括五个实验环节，在此期间大鼠被置于一个装有两个杠杆的操作箱中。一个杠杆产生熄灯刺激（3秒），另一个产生音调刺激（3秒）。接下来是四个条件化实验环节，在此期间移除杠杆，大鼠接受熄灯刺激与食物的配对。此阶段之后是两个测试环节，期间杠杆存在，每个杠杆上的反应次数计算为预暴露阶段反应次数的比率。在测试环节接受生理盐水的一组对熄灯刺激的反应比率高于对音调刺激的反应比率，表明熄灯刺激已成为条件性奖励。苯丙胺[2.0毫克/千克，腹腔注射（i.p.），在测试前5分钟]特异性增强了对产生条件性奖励的杠杆的反应。接受SKF 38393（5.0、10.0和20.0毫克/千克，腹腔注射，在测试前5分钟）的组对熄灯刺激的反应没有比音调刺激显著增强，表明条件性奖励效应减弱或消除。此外，SKF 38393剂量依赖性地降低了苯丙胺引起的条件性奖励反应增强。（摘要截断于250字）
