Interaction of α2-adrenergic system and caffeine on passive avoidance learning in male wistar rats

There are numerous studies on the effects of caffeine on memory and learning. The activation of α2-adrenoreceptors has been reported to impair memory functions in both rats and humans. In this study, interaction of α2-adrenergic system and caffeine on memory and learning was evaluated. In this experimental study, 90 wistar rats assigned into six groups of fifteen. Rats received yohimbine (4, 6, 8, 10 μg), as a α2-adrenergic antagonist, clonidine (2, 4, 6 μg), as a α2-adrenergic agonist, and caffeine (10, 20, 30 μg). The cannula was implanted into the right lateral ventricle of all rats with steriotaxi method. Then, they were trained in shuttlebox. Post-training intracerebroventricular (ICV) injection was carried out in all experiments and optimum doses were identified. Caffeine and yohimbine fostered memory and learning (p<0.001), while clonidine diminished these abilities compared to saline injection (p<0.05). Co-administration of the optimum doses of clonidine and yohimbine showed statistically significant reduction in the time of step-through latency (p<0.05). Instead, co-administration of clonidine and caffeine revealed no significant increase in the time of step-through latency (NS). It is concluded that yohimbine and caffeine, unlike clonidine, increase memory.