Dobryakova Yulia V, Gurskaya Olga, Markevich Vladimir A
Neurophysiology of Learning Lab, Institute for Higher Nervous Activity and Neurophysiology Russian Academy of Science, Moscow, Russia,
Acta Neurobiol Exp (Wars). 2014;74(2):211-7. doi: 10.55782/ane-2014-1986.
It is well-known that the cholinergic system and the muscarinic cholinergic receptors are associated with cognitive functions. Here we examined whether a non-selective muscarinic receptor antagonist scopolamine affects learning performance and/or synaptic plasticity during the memory consolidation period. Adult male Wistar rats (250-300 g) were injected with scopolamine (2 mg/kg) or saline immediately after training in a "passive avoidance" task. Memory retention test was conducted 24 h after training. The changes in the latency of the first entry into a dark compartment of a test chamber was chosen as a criterion of learning. The efficacy of synaptic transmission was estimated by the changes in the basal level of focal potentials (fEPSP amplitude and slope ratio) before training (baseline), 90 min after the training (consolidation period), and 24 hour after the training (retention period). We found that foot-shock presentation by itself had no effect on fEPSP within the first 90 min after training, but in 24 hour fEPSPs were decreased. In untrained rats administration of scopolamine had no effect on the fEPSP amplitude within the first 90 min after the injection, but in 24 h we observed an increase in the fEPSP amplitude. In trained animals, scopolamine decreased the fEPSP amplitude in the hippocampal CA1 area during first 1.5 h after the injection. However, the drug had no effect on the memory retention in the passive avoidance task. Taken together our data suggest that scopolamine modifies the synaptic placticity of the hippocampal network but does not induce significant changes in the retention of the passive avoidance skill.
众所周知，胆碱能系统和毒蕈碱型胆碱能受体与认知功能相关。在此，我们研究了一种非选择性毒蕈碱受体拮抗剂东莨菪碱在记忆巩固期是否会影响学习表现和/或突触可塑性。成年雄性Wistar大鼠（250 - 300克）在“被动回避”任务训练后立即注射东莨菪碱（2毫克/千克）或生理盐水。训练后24小时进行记忆保持测试。将首次进入测试箱黑暗隔室的潜伏期变化作为学习的标准。通过训练前（基线）、训练后90分钟（巩固期）和训练后24小时（保持期）局部电位的基础水平变化（场兴奋性突触后电位幅度和斜率比）来评估突触传递的功效。我们发现，足部电击刺激本身在训练后的前90分钟内对场兴奋性突触后电位没有影响，但在24小时时场兴奋性突触后电位降低。在未训练的大鼠中，注射东莨菪碱后前90分钟内对场兴奋性突触后电位幅度没有影响，但在24小时时我们观察到场兴奋性突触后电位幅度增加。在受过训练的动物中，注射东莨菪碱后最初1.5小时内海马CA1区的场兴奋性突触后电位幅度降低。然而，该药物对被动回避任务中的记忆保持没有影响。综合我们的数据表明，东莨菪碱改变了海马网络的突触可塑性，但并未引起被动回避技能保持的显著变化。
