Involvement of α-1-adrenergic receptors in central region of amygdala and the effects of cannabinoid agonist on inhibitory avoidance memory in male rats

Introduction: There are many similarities between memory impairment in patients suffering from Alzheimer and animals treated by Cannabinoids. The agonists of Cannabinoid receptors affect on a variety of memories and leanings. The present study aims to investigate the role of α-1-adrenergic receptors in central region of amygdala in state-dependent learning induced by WIN55,212-2 (cannabinoid agonist) in rats. Methods: Cannulae placement was performed bilaterally in the central amygdala region of male rats. The rats were trained in the avoidance learning apparatus (step-down model). 24 hours after training, the memory was tested by measuring the lag time for stepping down the platform. Results: Injection of WIN55, 212-2 intra central amygdala (dose-dependent, 0.25, 0.5 μg/rat) post-training reduced lag time/latency for stepping down. Injection induced amnesia was reversed by pre-test administration of the same dose of WIN55, 212-2. It is called state-dependent learning. Pre-test intra-central injection of α-1-adrenoceptor agonist, Phenylephrine (0.5, 0.25 μg/rat) improved post-training WIN55, 212-2 (0.5 μg/rat) intra central injection induced retrieval impairment. But intra injection of Prazosin (0.5 μg/rat) 2 minutes before injection of WIN55, 212-2 (0.5 μg/rat) on the testing day inhibited WIN55, 212-2 state-dependent learning. Conclusion: The results suggest that α-1-adrenergic receptors in central region of amygdala are involved in learning which dependent on the state induced by WIN55, 212-2.