Influence of Intracerebral Administration of L-Arginine in Dorsal Hippocampus (CA۱) on WIN۵۵, ۲۱۲-۲ Induced State-Dependent Memory

Background and Objective: Cannabinoids are a class of psychoactive compounds that produce a wide array of effects in a large number of species. In the present study, the effects of bilateral intra-CA۱ injections of L-arginine on WIN۵۵, ۲۱۲-۲ induced state-dependent memory of passive avoidance task was examined in mice. Materials and Methods: One-trial step-down paradigm was used for the assessment of memory retention in adult male NMRI mice. Results: Post-training intra-CA۱ administration of cannabinoid receptor agonist, WIN۵۵, ۲۱۲-۲ (۰.۵ and ۱ µg/mouse), decreased the memory retrieval. The memory impairment induced by post-training administration of WIN۵۵, ۲۱۲-۲ (۱µg/mouse) was restored by pre-test administration of the same dose of the drug, showing the state-dependent memory of WIN۵۵, ۲۱۲-۲. Single intra-CA۱ administration of L-arginine (۰.۳, ۱ and ۳ µg/mouse) ۵ min pre-test could not alter the memory retrieval. On the other hand, in the animals in which retrieval was impaired due to post-training administration of WIN۵۵, ۲۱۲-۲ (۱µg/mouse), pre-test intra-CA۱ administration of L-arginine (۱ and ۳ µg/mouse), ۲۴ hr after training restored memory retrieval. Furthermore, in the animals under influence of post-training administration of WIN۵۵, ۲۱۲-۲ (۱µg/mouse), pre-test co-administration of non-effective doses of WIN۵۵, ۲۱۲-۲ and L-arginine, increased the restoration of memory by the pre-test WIN۵۵, ۲۱۲-۲. Conclusion: The findings of the present study suggest that NO system of dorsal hippocampus may play an important role in Win۵۵,۲۱۲-۲-induced amnesia and WIN۵۵,۲۱۲-۲ state-dependent memory.

Keywords:

Key words: WIN۵۵ , ۲۱۲-۲ , State-dependent memory , Step-down passive avoidance task , L-arginine , NO , Mice