Zarrindast Mohammad-Reza, Farajzadeh Zahra, Rostami Parvin, Rezayof Ameneh, Nourjah Parvaneh
Department of Pharmacology and Iranian National Center for Addiction Studies, Tehran University of Medical Sciences, P.O. Box 13145-784, Tehran, Iran.
Behav Brain Res. 2005 Aug 30;163(1):100-6. doi: 10.1016/j.bbr.2005.04.006.
In the present study, the effects of intra-ventral tegmental area (VTA) injections of morphine on memory retention of a one-trial passive avoidance task have been investigated in morphine-sensitized rats. Retrieval was examined 24h after training and used as memory retention. Sensitization was obtained by subcutaneous (s.c.) injections of morphine, once daily for 3 and 5 days free of the opioid before training. Post-training administration of the both systemic (2.5, 5 and 7.5mg/kg, s.c.) and intra-VTA (5 and 7.5microg/rat) of morphine, dose-dependently decreased memory retention. The response induced by post-training administration of intra-VTA morphine (7.5microg/rat) was significantly reversed in morphine-sensitized rats. The inhibition of morphine-induced amnesia in morphine-sensitized rats was decreased by once daily injections of naloxone (0.5, 1 and 2mg/kg, s.c.), SCH 23390 (0.025, 0.05 and 0.1mg/kg, s.c.) or sulpiride (25, 50 and 100mg/kg, s.c.), during the sensitization. The results suggest that VTA has an important role in morphine-induced amnesia and morphine sensitization affects this process through opioid and dopamine receptors.
在本研究中，已在吗啡致敏大鼠中研究了腹侧被盖区（VTA）注射吗啡对单次被动回避任务记忆保持的影响。训练后24小时检查记忆提取情况，并将其用作记忆保持的指标。在训练前，通过皮下（s.c.）注射吗啡来诱导致敏，连续3天和5天每天注射一次，在这期间不使用阿片类药物。训练后全身给予吗啡（2.5、5和7.5mg/kg，皮下注射）以及VTA内给予吗啡（5和7.5μg/只大鼠），均剂量依赖性地降低了记忆保持。在吗啡致敏大鼠中，训练后给予VTA内吗啡（7.5μg/只大鼠）所诱导的反应被显著逆转。在致敏期间，每天注射一次纳洛酮（0.5、1和2mg/kg，皮下注射）、SCH 23390（0.025、0.05和0.1mg/kg，皮下注射）或舒必利（25、50和100mg/kg，皮下注射），可减轻吗啡致敏大鼠中吗啡诱导的遗忘。结果表明，VTA在吗啡诱导的遗忘中起重要作用，且吗啡致敏通过阿片类和多巴胺受体影响这一过程。
