INTRODUCTION: The interplay between aging and environmental factors such as light pollution is critical in understanding retinal health, as they can alter neuronal and glial function. The presynaptic protein Bruchpilot (BRP) is vital for synaptic integrity and neurotransmitter release, and alpha subunit of ATP synthase (αATP) is a component of glial metabolism. It was previously shown that the expression level of BRP changes daily in the photoreceptor terminals, which affects not only photoreception but also coordination between the visual system and clock neurons. On the other hand, αATP expression is rhythmic in epithelial glia in the first optic neuropile, lamina. Aging retina shows many changes, possibly also in daily rhythmicity. Light pollution worsens these effects, potentially accelerating neurodegenerative processes.

AIM(S): We investigated the effects of aging and light pollution on daily changes in the expression of BRP in R1-R6 photoreceptor terminals and αATP in epithelial glia in the lamina, as well as effects on visual processing.

METHOD(S): Flies were kept in normal or dim light at night lighting conditions. 7-, 30-, or 60-day old flies were decapitated, cryosectioned, and immunostained against BRP or αATP; fluorescence intensity from confocal images was analyzed. Optomotor response in 30-day old flies was tested using an apparatus with moving visual stimuli.

RESULTS: Rhythm of BRP expression observed in young flies declines with age, while αATP rhythm changes its pattern. Light pollution caused disruptions in the rhythms observed in the visual system. Optomotor responses also declined with both age and artificial light exposure.

CONCLUSIONS: Aging and light pollution are key elements disrupting the circadian rhythms in the Drosophila visual system. Loss of rhythmic optomotor responses highlights the behavioral consequences of molecular changes detected in this study. These findings provide insight into the cellular and behavioral consequences of clock disruptions, with implications for retinal degeneration.

FINANCIAL SUPPORT: This work was supported by the NCN OPUS grant 2022/47/B/NZ3/00250