Interaction between 5-HT6 receptors and acute stress and corticosterone on fear memory reconsolidation in mice

Introduction: Rrecent studies indicated that serotonergic receptors can be mediate the glucocorticoids’ effects on behavioral procesess. The aim of this study was to determine the role of serotonergic receptor (5-HT6) in the effects of acute stress and corticosterone on fear memory reconsolidation in mice. Materials and Methods: Male adult mice were trained and tested in an inhibitory avoidance task (1mA, 3sec). For assessment memory reconsolidation, immediately after memory reactivation memory (48 hr. after training) animal received corticosterone or exposed to an acute restraint stress (10 min) and also received SC203575 as a 5-HT6 receptor agonist or SB271046 as an antagonist of 5-HT6 receptors simultaneously. Memory retention test was done 5, 8, 10 and 12 days after memory reactivation. Results: The results showed that corticosterone injection or acute stress application after memory reactivation impaired memory reconsolidation in subsequent tests. Co-treatment with both the 5-HT6 agonist SC203575 and antagonist SB271046 inhibited the effects of corticosterone or acute stress on memory reconsolidation. Conclusion: These findings indicated that the 5-HT6 receptors modulate the effects of glucocorticoids or acute stress on fear memory reconsolidation.