Interaction of alpha[2]-adrenergic system and caffeine on passive avoidance learning in male Wistar rats

ABSTRACT

There are numerous studies on the effects of caffeine on memory and learning. The activation of alpha[2]-adrenoreceptors has been reported to impair memory functions in both rats and humans. In this study, interaction of alpha[2]-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 micro g]. 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