Amohashemi Elahe, Reisi Parham, Alaei Hojjat Allah
Department of Physiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
Adv Biomed Res. 2023 Jun 30;12:161. doi: 10.4103/abr.abr_126_22. eCollection 2023.
The involvement of lateral habenula and the ineffective dose of morphine on reward-related learning and memory is less well-known. This study looked into the effects of electrical stimulation, GABA receptor blockade, and a combination of both with morphine on conditioned place preference.
In this experiment, male rats were anesthetized with ketamine/xylazine (six rats in each group). A 5-day biased conditioned place preference paradigm was used for the behavioral test. The effects of electrical stimulation and phaclofen plus a low dose of morphine on the acquisition and expression phases were examined during conditioning sessions and before the test phase, respectively.
The conditioning scores were reduced by antagonist injection during the acquisition phase. Interestingly, different intensities exhibited opposite effects on the acquisition phase. Conditioned place preference scores during the acquisition phase were significantly induced by 25 μA electrical stimulation, while conditioning scores were suppressed by electrical stimulation at 150 μA. Phaclofen (2 μg/rat) combined with high intensity induced aversion during the acquisition phase, while inhibiting expression. In contrast, high intensity with phaclofen (1 μg/rat) inhibited only the acquisition session. However, low intensity during the acquisition phase had an additive effect that was prevented by pretreatment with phaclofen (2 μg/rat), but this response was modified by the antagonist's low dose.
A behavioral technique called conditioned place preference is frequently used to evaluate learning that is related to rewards. Therefore, lateral habenula electrical stimulation and phaclofen plus morphine could affect place preference through the involvement of the reward system.
外侧缰核的参与以及吗啡无效剂量对奖赏相关学习和记忆的影响鲜为人知。本研究探讨了电刺激、GABA受体阻断以及两者与吗啡联合应用对条件性位置偏爱（conditioned place preference）的影响。
在本实验中，雄性大鼠用氯胺酮/赛拉嗪麻醉（每组6只大鼠）。采用为期5天的偏倚条件性位置偏爱范式进行行为测试。分别在条件训练阶段和测试阶段前，检测电刺激和巴氯芬加低剂量吗啡对获得阶段和表达阶段的影响。
在获得阶段注射拮抗剂可降低条件训练得分。有趣的是，不同强度对获得阶段表现出相反的影响。在获得阶段，25 μA电刺激显著诱导条件性位置偏爱得分，而150 μA电刺激则抑制条件训练得分。巴氯芬（2 μg/只大鼠）与高强度联合应用在获得阶段诱导厌恶，同时抑制表达。相比之下，高强度与巴氯芬（1 μg/只大鼠）联合仅抑制获得阶段。然而，获得阶段的低强度有相加作用，预先用巴氯芬（2 μg/只大鼠）可阻止此作用，但该反应被拮抗剂低剂量所改变。
一种称为条件性位置偏爱的行为技术常用于评估与奖赏相关的学习。因此，外侧缰核电刺激以及巴氯芬加吗啡可能通过奖赏系统的参与影响位置偏爱。
