INTRODUCTION: Light pollution, the alteration of natural light levels by introducing excessive or misdirected artificial light at night (ALAN), has been regarded as a global environmental concern. ALAN can disrupt the organism's endogenous biological clock, affecting its physiological functions. The retina is the most susceptible to oxidative stress damage due to direct light exposure. The retina has protective mechanisms expressed in a circadian manner, shielding the photoreceptors against external factors such as UV light, particularly at the beginning of the day. The disruption of circadian clock function, which may occur with age and in light-polluted environments, may reduce the effectiveness of the protective mechanism.

AIM(S): Investigating the effects of aging and light pollution on retinal physiology.

METHOD(S): Wild-type flies were maintained under normal light conditions (LD 12:12; 12 h of light and 12 h of darkness) and under L-DIM conditions (12 h of light and 12 h of dimmed light). Young (7 days) and old (30 days) males were collected at specific time points of the day. Samples were used to check gene expression (qPCR), accumulation of DNA damages (immunostaining against 8-hydroxy-2'-deoxyguanosine), and lipofuscin accumulation.

RESULTS: The aging retina showed changes in the daily pattern of clock and clock-dependent gene expression and increased accumulation of lipofuscin. In addition, flies kept in light-polluted conditions showed higher levels of oxidative DNA damage.

CONCLUSIONS: Aging affects the peripheral clock located in the retina, which can disrupt the functioning of protective mechanisms and, consequently, increase oxidative DNA damage in photoreceptors. Light pollution disrupts the clock mechanism and accelerates the changes observed in the aged retina.

FINANCIAL SUPPORT: NCN; 2022/47/B/NZ3/00250; Project leader: PhD Milena Damulewicz.