Involvement of dorsal hippocampal alpha 1-adrenergic receptors in the effect of WIN55,212-2 on memory retrieval in inhibitory avoidance task
In the present study, the possible role of alpha 1-adrenergic receptors of the dorsal hippocampus on WIN55,212-2-induced amnesia in male Wistar rats has been evaluated. As a model of learning, a step-down passive avoidance task was used. Results indicated that post-training or pre-test intra-CA1 administration of WIN55,212-2 (0.25 and 0.5 mu g/rat) reduced the step-down latency, showing an amnestic response. Amnesia produced by post-training WIN55,212-2 (0.5 mu g/rat) was reversed by pre-test administration of the same drug dose. Interestingly, pre-test intra-CA1 administration of alpha 1-noradrenergic agonists, phenylephrine alone or with an ineffective dose of WIN55,212-2 (0.25 mu g/rat) reversed post-training WIN55,212-2 (0.5 mu g/rat)-induced retrieval impairment. On the other hand, pre-test intra-CA1 microinjection of an alpha 1-adrenergic antagonist, prazosin (0.5 mu g/rat), 2 min before administration of WIN55,212-2 (0.5 mu g/rat) inhibited the pre-test WIN55,212-2 response. It may be concluded that alpha 1-adrenergic receptors of the dorsal hippocampal CA1 regions play an important role in WIN55,212-2-induced amnesia and restoration of memory by pre-test WIN55,212-2 administration. (C) 2010 Elsevier Ireland Ltd. All rights reserved.