Effects of transcranial photobiomodulation on peripheral biomarkers associated with oxidative stress and complex IV activity in the prefrontal cortex in rats subjected to chronic mild stress

BackgroundThis study addresses the urgent need for effective alternatives to treat major depressive disorder (MDD) in patients who do not respond to conventional therapies Transcranial photobiomodulation therapy (tPBM) shows promise by enhancing mitochondrial function and reducing oxidative stress, as demonstrated in the chronic mild stress (CMS) rat model. To analyze the impact of tPBM with two wavelengths (red and infrared) on behavioral and biological parameters related to MDD in a CMS model. MethodsMale Wistar rats were subjected to CMS for five weeks and categorized into resilient (CMS-R) and susceptible (CMS-S) groups using the sucrose consumption test (SCT). The CMS-S group received tPBM treatment (600nm and 840nm) for five weeks. Biological measures included lipid damage (TBARS), antioxidant defense (TEAC), mitochondrial complex IV activity (CCO), and nitric oxide (NO) concentration in the prefrontal cortex and blood were measured. ResultsAs expected, post-tPBM treatment (both red and infrared groups) exhibited increased sucrose consumption compared to the sham (Kruskal Wallis chi-squared=26.131; p<0.001). The red and infrared presented higher serum TEAC levels than the sham and control groups, but these effects did not reach statistical significance (p=0.306). In contrast, the red group showed lower peripheral TBARS levels (M = 9.50, SD = 2.87) than the sham group (M = 13.66, SD = 2.20) (p=0.0048); such effect was similar to the control non-stress group. The infrared group showed higher NO levels within the hippocampus than the sham group (Mean = 107.83; SD = 6.48, Dunn Test p = 0.0134) and higher prefrontal CCO activity levels than the red group (p=0.012), which was similar to the control non-stress group. ConclusionsOur study demonstrated that tPBM using both red and infrared wavelengths significantly improved behavioral and biological parameters in the chronic mild stress (CMS) rat model. In particular, tPBM may offer therapeutic benefits by ameliorating oxidative stress and enhancing mitochondrial function, thereby presenting a promising alternative for the management of MDD.