[ effect of dorsal hippocampal alpha2-adrenegic receptors on WIN55,212-2 state-dependent memory of passive avoidance]

ABSTRACT

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-CA1 injections of an alpha2-adrenergic receptor agents, on WIN55, 212-2 state-dependent learning were examined in adult male Wistar rats. 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 24h after training to measure step-down latency. Post-training intra-CA1 injection of WIN55, 212-2 [0.25 and 0.5microg/rat] induced impairment of memory retention. Amnesia produced by post-training WIN55, 212-2 [0.5microg/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-CA1 injection of clonidine [0.5 and 0.75microg/rat, intra-CA1] improved post-training WIN55, 212-2 [0.5microg/rat, intra-CA1]-induced retrieval impairment, while pre-test intra-CA1 injection of yohimbine [1microg/rat, intra-CA1] 2min before the administration of WIN55, 212-2 [0.5microg/rat, intra-CA1] inhibited WIN55, 212-2 state-dependent memory. These results suggest that alpha2-adrenergic receptors of the dorsal hippocampal CA1 regions may play an important role in Win55, 212-2-induced amnesia and WIN55, 212-2 state-dependent memory