The effect of sericin on anxiety, depressive-like behaviors, oxidative stress as well as apoptosis induced by chronic restraint stress in male mice

Abstract

Introduction: Stress, depression and anxiety are now considered as the most prevalent disease in the century. Long-term exposure to stress through different mechanisms causes complications and consequences. Prevention of destructive effects of stress and providing appropriate preventive and therapeutic methods are of illicit drug importance. Objective: Since years away in traditional Iranian medicine, the therapeutic uses of silk are especially common for the treatment of depression, memory and brain function enhancement. Considering the traditional medicine literatures on the insure of silk effect in a wide range of brain diseases, in this study, the protective effects of sericin as the main protein of silk is investigated in prevention of stress-induced brain complications. Methods: Animals were subjected to chronic inhibitory stress for 3 hours and within 21 days sericin were administrated at doses of 100, 150 and 200 mg/kg/day. At the end of the period, behavioral tests were used to evaluate depression and anxiety. Then, blood samples were obtained to measure serum corticosterone level and prefrontal cortical as well as hippocampal samples were used to evaluate the level of oxidative stress and apoptosis markers. Results: Sericin increased percentage of presence in the central area of the Open Field Test, percentage of frequencies and spent time in open arms of Elevated Plus Maze. Also it decreased the immobilization time in the Tail Suspension and Forced Swimming Tests. Sericin administration decreased lipid peroxidation levels and increased total antioxidant capacity (TAC) and GPx and SOD activities in the prefrontal cortex and hippocampus. Sericin modulates serum corticosterone concentration and inhibits apoptosis by decreasing Bax to Bcl-2 ratio and decreasing Caspase 3 levels in these regions. Results: The findings indicate the protective effect of sericin in the face of chronic restraint stress and prevention of behavioral, psycho-pathological and molecular changes.