Dipartimento di Scienze del Farmaco, Università di Sassari, Via Muroni, 23/A, 07100 Sassari, Italy.
Neuropharmacology. 2010 Jun;58(7):1085-96. doi: 10.1016/j.neuropharm.2010.01.017. Epub 2010 Feb 10.
The analysis of licking microstructure provides measures, such as duration and number of licking bouts, which might reveal the former an evaluation process and the latter an approach response. Dopamine D2-like receptor antagonists reduce the duration of licking bouts and mimic the effect of reducing sucrose concentration, while conflicting results are reported on the effects of dopamine D1-like receptor antagonists. The aim of this study is to examine the roles of dopamine D1-like and D2-like receptors in the activation of reward-associated responses and in reward evaluation, through the study of licking microstructure.
The effects of the dopamine D2-like receptor antagonists raclopride (0.025-0.25 mg/kg), the D1-like antagonist SCH 23390 (0.01-0.04 mg/kg) and the antipsychotic drug haloperidol (0.02-0.05 mg/kg), have been examined on the microstructure of licking for a 10% sucrose solution in rats.
The results confirm that dopamine D2-like receptor antagonists reduce the duration of licking bouts and reveal that while SCH 23390 reduced licking exclusively by reducing bout number, raclopride produced on this measure an extinction mimicry effect similar to that observed in instrumental responding for different rewards.
These results are consistent with the hypothesis that the level of activation of the responses to the reward-associated cues depends on dopamine D1-like receptor stimulation, and is updated, or "reboosted", on the basis of a dopamine D2-like receptor-mediated evaluation process occurring during the consummatory transaction with the reward.
舔舐微观结构的分析提供了一些指标，例如舔舐的持续时间和次数，这些指标可能揭示了前者是一种评价过程，后者是一种趋近反应。多巴胺 D2 样受体拮抗剂减少舔舐的持续时间，并模拟降低蔗糖浓度的效果，而多巴胺 D1 样受体拮抗剂的效果则存在冲突的报告。本研究旨在通过舔舐微观结构研究，检验多巴胺 D1 样和 D2 样受体在激活与奖励相关的反应和奖励评价中的作用。
研究了多巴胺 D2 样受体拮抗剂（raclopride，0.025-0.25mg/kg）、D1 样受体拮抗剂（SCH 23390，0.01-0.04mg/kg）和抗精神病药物（haloperidol，0.02-0.05mg/kg）对大鼠舔舐 10%蔗糖溶液的微观结构的影响。
结果证实，多巴胺 D2 样受体拮抗剂减少了舔舐的持续时间，并且表明，虽然 SCH 23390 通过减少次数来减少舔舐，但 raclopride 在这一措施上产生了类似于观察到的不同奖励工具性反应的消退模拟效应。
这些结果与以下假设一致，即对与奖励相关的线索的反应的激活水平取决于多巴胺 D1 样受体的刺激，并根据在与奖励的消耗性交易中发生的多巴胺 D2 样受体介导的评价过程进行更新或“再增强”。
