Effects of Oleuropein on Depression Caused by Chronic Stress in Mice

Abstract

Background and Objectives: Depression is still one of challenging, and widely encountered disorders with complex etiology. Recently the role of healthy diet and olive oil in ameliorating depression has been claimed. This study was designed to explore the effects of oleuropein on depression induced by chronic stress in mice. Methods: To induce chronic stress Chronic Restraint Stress (CRS) mice immobilizated in restrainer 2 hours; for 2 weeks then an foot electric shock (2 minutes 0.5mA) were used. Mice under chronic stress were randomly divided into 5 groups; including control group (under chronic stress receiving normal saline), intervention groups (under acute stress receiving oleuropein at doses of 7.5, 15 and 30 mg/kg and positive control (under chronic stress receiving diazepam). Then the expression of 6-interleukin (6- IL) and Metabotropic Glutamate Receptor (mGluR1) were measured, Forced Swimming Test (FST) and Tail Suspension Test (TST) were recorded. Results: In CRS mice,at the dose of oleuropein at 15 mg/kg, the duration of immobility significantly reduced in tail suspension test and doses of 15 and 30 mg/kg of oleuropein significantly decreased the immobility time in forced swimming test (P<0.05) Oleuropein also decreased the expression of 6- IL and mGluR1. Conclusion: According to our results, it seems that reducing the expression of 6- IL and mGluR1 may induce the effect of oleuropein on depressive-like behaviors in mice under chronic stress disorder.