Far-Infrared Radiation Ameliorates the Cognitive Dysfunction in an Alzheimer’s Disease Transgenic Mouse via Modulating Jak-2/Stat3 and Nrf-2/HO-1 Pathways

Alzheimer's disease (AD) is the primary cause of dementia in the elderly. However, effective therapies that modify the disease process in AD remain elusive. Far-infrared radiation (FIR) is commonly utilized as a complementary treatment a range of disease, for example insomnia and rheumatoid arthritis. In this research, we explored how FIR light impacts the cognitive functions of TgCRND8 AD mice and elucidated its underlying molecular mechanism. The cognitive capabilities of TgCRND8 mice assessed by employing the Morris water maze. The concentrations of IL-1β, TNF-α, IL-4, Aβ40, and Aβ42 protein were assessed by enzyme-linked immunosorbent assay. Immunostaining was conducted to assess the Aβ deposits and microglial presence in the brains of TgCRND8 mice. Western blot was applied to detect the protein expressions of tau phosphorylation, amyloid-β (Aβ) production, Jak-2/Stat3, and Nrf-2/HO-1 pathways. The results indicated that FIR light notably ameliorated the cognitive impairments of the AD mice, reduced both Aβ deposition and tau protein hyperphosphorylation at sites of Thr205, Ser369, Ser404, and Thr181, suppressed the release of TNF-α and IL-1β, attenuated the ratios of p-Jak-2/Jak-2 and p-Stat3/Stat3, while increased the protein levels of IL-4, Nrf-2, and HO-1 in the brains of TgCRND8 mice. These findings amply demonstrated that FIR light ameliorated cognitive deficits of TgCRND8 mice via reducing both Aβ burden and tau protein hyperphosphorylation, suppressing the neuroinflammation, and restoring the levels of the oxidative-related proteins through modulating Jak-2/Stat3 and Nrf-2/HO-1 pathways. These experimental findings indicate that FIR light treatment is a promising treatment approach for AD.