Objective: 

Recent evidence suggests that glucocorticoids can impair memory reconsolidation, but the underlying mechanism(s) are not clear. The aim of this study was to determine the role of cholinergic system in glucocorticoid-induced impairment of memory reconsolidation in mice.

Methods: 

Experiments were performed on 120 male albino mice (about 30 gr). The animals were trained in an inhibitory avoidance task (1 mA shock for 3 seconds). In experiment 1, effects of corticosterone were determined. Immediately after reactivation test, the animals received of vehicle or corticosterone (0.5, 1 and 3 mg/kg). In experiments 2 and 3, effects of corticosterone were examined in the presence or 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 2, 5, 7 and 9 days after reactivation.

Results: 

Results from experiment 1 indicated that corticosterone impaired memory reconsolidation in a dose-dependent manner (P<0.01). Blockade of muscarinic cholinergic, but not nicotinic receptors suppressed corticosterone-induced impairment of memory reconsolidation. Both blockers alone did not change memory reconsolidation as compared with control group.

Conclusions: 

Findings above showed that the memory impairing effects of corticosterone on reconsolidation process, at least in part, may mediate via muscarinic cholinergic receptors.