تداخل گيرنده هاي آلفا-1- آدرنرژيك هيپوكامپ پشتي با اثرات WIN55 212-2 بر روي به خاطر آوري حافظه اجتنابي مهاري

Involvement of dorsal hippocampal al-adrenergic receptors in the effect of WIN55, 212-2 on memory retrieval in inhibitory avoidance task

Objective: The present study evaluated the possible role of al-adrenergic receptors of the dorsal hippocampus on WIN55, 212-2 induced amnesia and WIN55, 212-2 state-dependent memory in adult male Wistar rats. Methods: In this study Phenylephrine as agonist and prazosin as antagonist of al-adrenergic receptor, WIN55, 212-2 as agonist of cannabinoid receptor was used. The animals were bilaterally implanted with chronic cannulae in the CA1 regions of the dorsal hippocampus, trained in a step-down type inhibitory avoidance task, and tested 24 h after training to measure step-down latency. Results: post-training intra-CAl administration of WIN55, 212-2 (0.25 and 0.5 fig/rat) impaired the memory retrieval. Amnesia produced by post-training WIN55, 212-2 (0.5 fig/rat) was reversed by pre-test administration of the same dose of WIN55, 212-2 that is due to a state-dependent effect. Pre-test intra-CAl injection of phenylephrine (0.5 and 0.75 jig/rat) improved post-training WIN55, 212-2 (0.5 jig/rat)-induced retrieval impairment. On the other hand, pre-test injection of prazosin prevented the restoration of memory by pre-test WIN55, 212-2. It is important to note that pre-test intra-CAl administration of the same doses of prazosin or phenylephrine, alone did not affect memory retrieval. Conclusion: These results suggest that al-adrenergic receptors of the dorsal hippocampal CA1 regions may play an important role in WIN55, 212-2 state-dependent memory. Keywords: WIN55, 212-2; Phenylephrine; Prazosin; Dorsal hippocampus; State dependent learning.