Chiang Ko-En, Hsiao Yi-Tse
Department of Veterinary Medicine, School of Veterinary Medicine, National Taiwan University, Taipei, 10617, Taiwan.
J Integr Neurosci. 2020 Mar 30;19(1):11-19. doi: 10.31083/j.jin.2020.01.1190.
The endocannabinoid system modulates many brain functions, including episodic memories, which contain memories of time and places. Most studies have focused on the involvement of the endocannabinoid system in spatial memory; however, its role in temporal memory is not well understood. Few studies have tested whether the unilateral endocannabinoid system is sufficient to modulate memory retrieval. Here, we tested whether type 1 cannabinoid receptors in the right hippocampal cornu ammonis area 1 region are enough to modulate the retrieval of episodic memories, specifically their spatial and temporal components. Because rats have innate preferences for displaced or old familiar objects, we changed the locations of "old familiar" and "recent familiar" objects in an open field and measured the rats' exploration times to evaluate spatial and temporal memory. To address the influence of the type 1 cannabinoid receptors on the retrieval of episodic-like memories, two doses of arachidonylcyclopropylamide, a selective type 1 cannabinoid receptor agonist, were infused into the cornu ammonis area 1 of rats ten minutes before the discrimination trials. We observed that rats injected with a low dose of arachidonylcyclopropylamide spent less time investigating displaced objects, suggesting spatial memory impairment, whereas those receiving a high dose explored old familiar objects less frequently, suggesting temporal memory impairment. This indicates that unilateral activation of type 1 cannabinoid receptors in the cornu ammonis area 1 impairs the spatial and temporal aspects of episodic memories. This research mimics the influence of marijuana intoxication effects in humans, such as spatial and temporal disintegration.
内源性大麻素系统调节许多大脑功能，包括情景记忆，情景记忆包含对时间和地点的记忆。大多数研究都集中在内源性大麻素系统在空间记忆中的作用；然而，其在时间记忆中的作用尚不清楚。很少有研究测试单侧内源性大麻素系统是否足以调节记忆提取。在这里，我们测试了右海马角回1区的1型大麻素受体是否足以调节情景记忆的提取，特别是其空间和时间成分。由于大鼠对移位或旧的熟悉物体有先天偏好，我们在开阔场地中改变了“旧熟悉”和“新熟悉”物体的位置，并测量大鼠的探索时间以评估空间和时间记忆。为了研究1型大麻素受体对类情景记忆提取的影响，在辨别试验前10分钟，将两剂花生四烯酰环丙酰胺（一种选择性1型大麻素受体激动剂）注入大鼠的角回1区。我们观察到，注射低剂量花生四烯酰环丙酰胺的大鼠花费较少时间探究移位物体，表明存在空间记忆损伤，而接受高剂量注射的大鼠较少频繁探索旧的熟悉物体，表明存在时间记忆损伤。这表明角回1区1型大麻素受体的单侧激活会损害情景记忆的空间和时间方面。这项研究模拟了大麻中毒对人类的影响，如空间和时间解体。
