Department of Legal Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan.
Toxicol Mech Methods. 2010 Mar;20(3):127-32. doi: 10.3109/15376511003621658.
The authors have previously shown that high alcohol preference rats (HAP) have a significantly higher sensitivity than low alcohol preference rats (LAP) for methamphetamine (MAP). In this study, changes in dopamine and serotonin release induced by MAP (1 mg/kg, intraperitoneally) after pre-treatment with D1 and D2 receptor antagonists were examined in the striatum of rats with different alcohol preferences to elucidate differences in receptor levels between the two rat strains. D1 receptor antagonist SCH23390 or D2 receptor antagonist haloperidol were administrated intracerebroventricularly 10 min before MAP stimulation. This study investigated the effect of methamphetamine-induced dopamine and serotonin release in striatum using microdialysis of freely moving rats coupled to ECD-HPLC. With haloperidol treatment both strains of rats showed a significantly greater maximum increase on MAP-induced dopamine release compared with respective control rats. However, after SCH23390 treatment only HAP rats showed a significantly greater increase in dopamine release compared with controls. SCH23390 blocks mainly D1 receptors only in the post-synaptic membrane, whereas haloperidol blocks D2 receptors in both the pre-synaptic and post-synaptic membranes. The MAP-induced increase in dopamine release following haloperidol pre-treatment was greater than SCH23390 pre-treatment in both strains. This result indicates that D2 receptors (autoreceptors) in the pre-synaptic membrane were blocked, leading to the elimination of the feedback function that regulates dopamine release. These data suggested that alcohol preference is associated with the action of MAP, and the dopaminergic mechanism, specifically the D1 system in the striatum, might have a different pathway dependent on alcohol preference.
作者先前已经表明,高酒精偏好大鼠(HAP)对甲基苯丙胺(MAP)的敏感性明显高于低酒精偏好大鼠(LAP)。在这项研究中,通过用 D1 和 D2 受体拮抗剂预处理,检查了不同酒精偏好大鼠纹状体中 MAP(1mg/kg,腹腔内)诱导的多巴胺和 5-羟色胺释放的变化,以阐明两种大鼠品系之间受体水平的差异。D1 受体拮抗剂 SCH23390 或 D2 受体拮抗剂氟哌啶醇在 MAP 刺激前 10 分钟通过脑室内给药。这项研究使用与 ECD-HPLC 耦合的自由移动大鼠的微透析研究了纹状体中 MAP 诱导的多巴胺和 5-羟色胺释放的影响。用氟哌啶醇处理后,与各自的对照大鼠相比,两种大鼠的 MAP 诱导的多巴胺释放的最大增加都显著增加。然而,在用 SCH23390 处理后,只有 HAP 大鼠显示出与对照相比多巴胺释放的显著增加。SCH23390 主要在突触后膜上阻断 D1 受体,而氟哌啶醇在突触前和突触后膜上都阻断 D2 受体。在用氟哌啶醇预处理后,MAP 诱导的多巴胺释放增加大于 SCH23390 预处理,这在两种品系中都是如此。该结果表明,突触前膜中的 D2 受体(自身受体)被阻断,导致调节多巴胺释放的反馈功能丧失。这些数据表明,酒精偏好与 MAP 的作用有关,多巴胺能机制,特别是纹状体中的 D1 系统,可能依赖于酒精偏好具有不同的途径。
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