Chronic exposure to LED lighting impairs prefrontal cortex-dependent cognitive functions in adolescent rats

The Light-emitting diodes (LEDs) have already replaced conventional lighting sources due to their energy efficiency and environmental benefits. Although previous studies suggest that chronic exposure to LED may affect human physiological health, its impact on cognitive functions remains unclear. To simulate typical human lighting conditions, we established an animal model which Sprague-Dawley (SD) rats exposed to LED light daily from 18:00 to 22:00 (ZT12-ZT16) for one month. Cognitive functions were assessed using social interaction, Morris water maze, and sound-location-association tasks. Results indicated that chronic LED exposure impaired social interaction ability, spatial learning and memory, and auditory-spatial associative learning. Immunohistochemical and Western blot analyses revealed a reduction in myelination levels and a decreased number of mature oligodendrocytes in the medial prefrontal cortex (mPFC). These findings suggest that chronic LED exposure impairs mPFC-dependent cognitive functions, possibly through downregulation of myelin integrity in the mPFC.