X-Irradiation at 0.5 Gy after the forced swim test reduces forced swimming-induced immobility in mice

Abstract

The forcedswimtest (FST)is a screeningmodel forantidepressantactivity; it causes immobilityand inducesoxidative stress. We previously reported that radon inhalation has antidepressant-like effects in mice potentially through the activation of antioxidative functions upon radon inhalation. This study aimed to investigate the effect of prior and post low-dose X-irradiation (0.1, 0.5, 1.0 and 2.0 Gy) on FST-induced immobility and oxidative stress in the mouse brain, and the differences, if any, between the two.Mice received X-irradiation before or after the FST repeatedly for 5 days. In the post-FST-irradiated group, an additional FST was conducted 4 h after the last irradiation.Consequently, animals receiving priorX-irradiation (0.1Gy) had better mobility outcomes than sham-irradiatedmice; however, their levels of lipid peroxide (LPO), an oxidative stressmarker, remained unchanged.However, animals that received post- FST X-irradiation (0.5 Gy) had better mobility outcomes and their LPO levels were significantly lower than those of the sham-irradiated mice. The present results indicate that 0.5 Gy X-irradiation after FST inhibits FST-induced immobility and oxidative stress in mice.