Effects of Transcranial Photobiomodulation and Enriched Environment on Depressive- and Anxiety-Like Behaviors in a Mice Model of Noise Stress

Abstract

Noise as environmental stressor, is one of the serious health impairment in the world which is responsible for cognitive and psychiatric disorders including anxiety and depressive relevant behaviors. Due to long-term risks and side effects of current antidepressant such as pharmacological treatment, we sorely require to safe novel non-invasive therapies such as transcranial Photobiomodulation (tPBM) and Enriched Environment (EE). Despite the studies suggesting the neuroenhancement effects of tPBM and EE, the combined effects of these treatments have not been elucidated yet. The purpose of this paper is to assess therapeutic effects of the application of the tPBM and EE (alone or in combination) on depressive- and anxiety-like behaviors in a mice model of noise stress. Materials and methods: Animals were assigned to five groups: (1) Control (without any noise exposure and treatment), (2) Noise (exposed to noise without treatment), (3) Noise + EE (stress treated with EE), (4) Noise + tPBM (stress treated with 810 nm laser), Noise + EE + tPBM (stress treated with combined therapy with tPBM and EE). To develop a depression model, animals subjected to 110 dB SPL white noise for 4h/day for 14 consecutive days and also were initiated concurrently with tPBM treatment and EE (alone or in combination). After the experiment procedures, behavioral tests including Open Field Test, Elevated Plus Maze and Forced Swimming Test, as well as serum corticosterone levels, Brain-Derived Neurotrophic Factor (BDNF), Tyrosine receptor kinase B (TrkB), and cAMP Response Element-Binding (CREB) protein levels in hippocampus were assessed to evaluate the anti-anxiety and anti-depressive effects of tPBM and EE. Results: Exposure to noise stress significantly elevated serum corticosterone level, down-regulated hippocampal BDNF, TrkB, and CREB protein expressions, and resulted in depressive- and anxiety-like behaviors. While, the application of tPBM (810 nm wavelength, 8 J/cm2 fluence, 10 Hz pulsed wave mode), housing in EE, and their combination lowered corticosterone levels, up-regulated BDNF/TrkB/CREB signaling pathway in the hippocampus, and improved behavioral outcomes in noise stress-subjected mice.