The protective effects of escitalopram on chronic restraint stress-induced memory deficits in adult rats

Introduction: Stress influences brain functions adversely but escitalopram exhibits positive effects on cognitive processes.Therefore, this study investigated the protective effects of different escitalopram doses on cognitive functions in rats under chronic stress and normal conditions.Methods: Forty-nine rats were randomly allocated into seven groups: control, sham, stress, escitalopram (10, 20 mg/kg/day) and stress-escitalopram (both doses).Initial latency, latency after 1-day, dark stay (DS) time and the number of entrances to the dark compartment were evaluated by passive avoidance test.Results: There were significant latency differences in stress and escitalopram10 groups compared to control group.Additionally, latencies showed significant enhancements in both 10 and 20 mg/kg/day stress-escitalopram groups compared to stress group and significant decrease in escitalopram20 group with respect to escitalopram10 group.DS time was significantly higher in stressed group and significantly lower in escitalopram10 groups, both compared to control group.Also, it was significantly lower in both stress-escitalopram groups in comparison with stress group.Furthermore, escitalopram20 group had a significantly higher DS time compared to escitalopram10 group.Finally, the number of entrances to the dark compartment was significantly lower in stress, escitalopram10 and stress-escitalopram10 groups compared to control group.Conclusion: Different doses of escitalopram affected brain functions under chronic stress and normal conditions.Escitalopram10 presented the most beneficial effects on improving brain functions under normal conditions.Whereas, both escitalopram doses showed similar protective effects on memory under stress.Overall, escitalopram at a dose of 10 mg/kg/day improved learning, memory consolidation and locomotor activity better than its maximum dose of 20 mg/ kg/day. www.phypha.ir/ppjOriginal Article Physiology and Pharmacology 26 (2022) 39-48Stress is an internal response to harmful stimuli (internal and external) that affect cognitive functions (Rafdahmadi et al., 2017;Simoens et al., 2007).As such, it is reported that all kinds of stress, especially psychological stress, disrupt brain functions to a great extent (Patki et al., 2013;Tran et al., 2010).Even though stress is an inseparable mechanism of human life, it is rather chronic stress that activates the hypothalamic-pituitary-adrenal (HPA) axis and leads to the secretion of glucocorti- Escitalopram & cognitive function Physiology and Pharmacology 26 (2022) 39-48 | 40