Evaluation the role of cholinergic system in glucocorticoids-induced enhancement of emory consolidation in mice

Many evidence indicated that glucocorticoids enhanced memory consolidation n a variety of tasks, but the underlying mechanism(s) are not clear. The aim of this study was to determine the role of cholinergic system in glucocorticoids-induced enhancement of memory consolidation in mice. In this experimental study were performed on 100 male albino mice (about 30 g). The animals were trained in an inhibitory avoidance task (0.5 mA shock for 3 seconds). In Experiment 1, effects of corticosterone were determined. Immediately after training, the animals received of vehicle or corticosterone (0.3 mg/kg). In Experiments 2 and 3, effects of corticosterone were examined in the presence of absence of atropine, a blocker of muscarinic cholinergic receptors, (0.5 and 2 mg/kg) or Mecamylamine, a blocker of nicotinic cholinergic receptors, (0.5 and 2 mg/kg), respectively. In all experiments, memory retention tested 48 hr later. Results indicated that Corticosterone enhanced memory consolidation significantly (P<0.01). Blockade of muscarinic cholinergic receptors by atropine suppressed the glucocorticoids response dose-dependently. Blockade of nicotinic cholinergic receptors by Mecamylamine did not change the glucocorticoids response. Also both blockers alone did not change memory consolidation as compared with control group. Finding above showed that the memory enhancing effects of corticosterone, at least in part; may mediate via muscarinic cholinergic receptors.