Safety of 810 nm photobiomodulation in the developing brain: no evidence of glial reactivity or pro-inflammatory cytokine expression in rats.

Photobiomodulation (PBM) is an innovative non-invasive light-based technique that uses wavelengths around red to infrared light to stimulate neural activity. Literature has addressed PBM's effectiveness in healthy adult subjects, in several neurological conditions, and also in younger populations. However, there is still a lack of both preclinical and clinical studies that evaluate its safety during early developmental stages, when the brain is still maturing. We explored safety of PBM (810 nm) in young male Wistar rats by examining astrocytes and microglia cells thought GFAP and Iba1 immunohistochemistry, as well as the expression of pro-inflammatory cytokines (Interleukin-6, interleukin-1β and tumour necrosis factor α) through quantitative PCR, both in prefrontal cortex and hippocampus. Under the tested parameters and time point, PBM did not induce detectable glial reactivity or pro-inflammatory cytokine expression. This research highlights the potential use of 810 nm-PBM in the developing brain, providing preliminary evidence that this technique does not induce a neuroinflammatory response, representing an important first step to verifying the beneficial use of this technique without risks in paediatric and adolescence populations. More research is necessary to confirm the safety of PBM for different conditions and employing diverse parameters.