THE EFFECT OF CA1 DOPAMINERGIC SYSTEM IN HARMALINE-INDUCED AMNESIA

In the present study, the effects of bilateral injections of dopaminergic drugs into the hippocampal CA1 regions (intra-CA1) on harmaline-induced amnesia were examined in male mice. A one-trial step-down passive avoidance task was used for the assessment of memory retention in adult male mice. Pre-training intra-peritoneal (i.p.) administration of harmaline (1 mg/kg) induced impairment of memory retention. Moreover, intra-CA1 administration of dopamine D1 receptor antagonist, SCH23390 (0.02 mu g/mouse), dopamine D1 receptor agonist, SKF38393 (0.5 mu g/mouse), dopamine D2 receptor antagonist, sulpiride (1 mu g/mouse) and dopamine D2 receptor agonist, quinpirole (0.25 and 0.5 mu g/mouse) suppressed the learning of a single-trial passive avoidance task. Also, pre-training intra-CA1 injection of subthreshold doses of SCH23390 (0.001 mu g/mouse) or sulpiride (0.25 mu g/mouse) with the administration of harmaline (1 mg/kg, i.p.) reversed impairment of memory formation. However, pre-training intra-CA1 injection of SKF38393 (0.1 mu g/mouse) or quinpirole (0.1 mu g/mouse) increased pre-training harmaline (0.25 and 0.5 mg/kg, i.p.)induced retrieval impairment. Moreover, SKF Ca blocker (SKF) (0.01 mu g/mouse) decrease the amnesia induced by harmaline (1 mg/kg), while co-administration of SKF (0.01 mu g/mouse)/sulpiride (0.25 mu g/mouse) or SCH23390 (0.001 mu g/mouse)/sulpiride (0.25 mu g/mouse) potentiate amnesia caused by harmaline. These findings implicate the involvement of CA1 dopaminergic mechanism in harma-line-induced impairment of memory acquisition. (C) 2014 IBRO. Published by Elsevier Ltd. All rights reserved.