Effect of transcranial low-level laser therapy in chronic restraint stress induced depressive-like behaviour in mice

Abstract

In current study, we used three different doses of near-infrared (NIR) laser to find the optimum anti-anxiety and anti-depressive dose in this approach. Materials and Methods: In this study, sixty male BALB/c mice average weighing 20-25g were randomly divided into 5 equal groups. There was no intervention on the control group. Animals in four other groups went under chronic restraint stress (CRS) for 3 weeks (3 hours per day). Laser therapy was initiated simultaneously with stress induction and the animals were exposed to 0, 4, 8, and 16 J/cm2 doses of 810 nm laser with a pulse mode of 10 Hz. At the end of the treatment period, behavioral experiments including open field test, elevated plus maze test, and tail suspension test were done to investigate the anti-anxiety and anti-depressive effects of TLLLT. Also, serotonin (5-HT) and nitric oxide (NO) concentrations were measured in the prefrontal cortex (PFC) and hippocampus (Hipp) areas of mice brain. Results: CRS induced anti-anxiety and anti-depressive like behaviors in mice and also increased serum cortisol concentration. Molecular measurements also showed a decrease in 5-HT level and an increase in NO level in both PFC and Hipp areas. Laser therapy decreased anxiety-like and depression-like behaviors and also serum cortisol concentration. It also led to an increase in 5-HT level and a decrease in NO level in the PFC and Hipp areas. Therapeutic effects were observed for all three different doses, however the irradiation dose of 8 J/cm2 resulted the best effect.