Chronic 40-Hz Light-Emitting Diode (LED) Therapy Attenuates Cognitive and Behavioral Deficits and Modulates BDNF and Caspase-3 Expression in a D-galactose/Aluminum Chloride-Induced Sporadic Alzheimer’s-Like Rat Model

Introduction Alzheimer’s disease (AD) is a progressive neurodegenerative condition marked by gradual deterioration of cognition, synaptic integrity, and neuronal viability. Experimental exposure to D-galactose (D-gal) combined with aluminum chloride (AlCl3) produces oxidative and inflammatory damage within the brain, closely resembling AD-related neuropathology. Photobiomodulation therapy (PBMT) has recently gained attention as a safe, non-pharmacological approach with neuroprotective potential; however, the impact of sustained 40-Hz light-emitting diode (LED) stimulation in this context remains insufficiently explored.Methods In the present study, rats received D-gal (60 mg/kg, i.p.) and AlCl3 (200 mg/kg, oral) for six weeks to induce AD-like changes. The treatment group was exposed to 40-Hz pulsed LED light (425–550 nm, 15 min/session, three times weekly). Behavioral analyses were performed using the elevated plus maze (EPM), novel object recognition (NOR), and passive avoidance (PA) paradigms. Western blotting quantified brain-derived neurotrophic factor (BDNF) and cleaved-caspase-3 expression in whole brain tissue.Results D-gal/AlCl3 administration produced anxiety-like behavior, recognition deficits, and impaired memory retention, accompanied by decreased BDNF and elevated caspase-3. Remarkably, 40-Hz LED exposure reversed these alterations, up-regulating BDNF and suppressing caspase-3, in parallel with improvements in cognitive and emotional outcomes.Conclusion These data suggest that 40-Hz LED stimulation confers neuroprotection in the D-gal/AlCl3-induced AD model, potentially through enhancement of neurotropic signaling and inhibition of apoptosis, supporting its promise as a non-invasive strategy against neurodegenerative decline.