The Potential Anti Stress-like Properties of Escitalopram on Improvement of Spatial Memory in Rats Subjected to Predictable and Unpredictable Chronic Mild Stress

Background: Chronic stress and chronic escitalopram usage affect memory. This research examined the potential anti-stress-like properties of escitalopram in improving spatial memory in rats subjected to predictable and unpredictable chronic mild stress (PCMS and UCMS). Materials and Methods: A total of forty-nine male rats were assigned to various groups: control (Co), sham (Sh), predictable stress (P.St; 2 h daily/21 days), unpredictable stress (UP.St; 2 h daily/21 days), escitalopram (Esc; 10 mg/kg/day for 21 days), and stress groups with escitalopram (P.St-Esc and UP.St-Esc). The Barnes maze test evaluated spatial learning and memory across all groups. Subsequently, the hippocampal weight was measured. Results: Both the P.St and UP.St groups showed significant ( P < 0.01 and P < 0.001, respectively) improvements in escape latency and traveled distance compared to the control group. It is important to note that only the P.St-Esc group showed decreases ( P < 0.05 in both) in these variables when compared to the P.St group, whereas no significant differences were found between the UP.St and UP.St-Esc groups. In the P.St and UP.St groups, the left hippocampal weight was significantly ( P < 0.05 and P < 0.01; respectively) lower than that of the control group. Conclusion: Both PCMS and UCMS adversely affected spatial learning and memory. Additionally, escitalopram improved spatial learning and memory only in rats subjected to PCMS conditions. Therefore, it seems that escitalopram improves learning and memory by different pathways in the PCMS and UCMS conditions. Consequently, it seems that different dosages of escitalopram are required to treat memory deficits due to various types of stress. Left hippocampal atrophy also confirmed the potential role of UCMS conditions in memory impairments.