Modulation of muscimol state-dependent learning by α1-adrenergic receptors of the dorsal hippocampus

Adrenergic and GABAergic systems of the brain play important roles in learning and memory. Previous studies have shown that morphine, histamine and lithium can induce state dependent learning. In the present study we evaluated, the effects of α1-adrenergic receptor of CA1 on muscimol state-dependent learning in mice. In this experimental study adult male NMRI mice were used. The animals were anaesthetized and bilateral implantation of cannula in the CA1 regions of the dorsal hippocampus was performed by using stereotaxic method. Seven days after recovery, we used inhibitory avoidance task for behavioral testing. Data were analyzed by Kruskal–Wallis nonparametric one-way analysis of variance followed by Mann–Whitney test. Pre-training or pre-test intra-CA1 injection of muscimol impaired inhibitory avoidance memory on the test day (P<0.01). Pre-test injection of muscimol reversed the memory impairment induced by pre-training muscimol injection (P<0.001). Pre-test intra-CA1 injection of phenylephrine also reversed pre-training muscimol induced amnesia (P<0.01). Pre-test intra-CA1 injection of prazosin 2 min before administration of the effective dose of muscimol inhibited muscimol state dependent memory (P<0.01). It can be concluded that the α1-adrenergic receptors of the CA1 may play an important role in the muscimol state dependent learning, on the test day.