Improving mitochondrial function significantly reduces the rate of age related photoreceptor loss

Declining mitochondrial function drives ageing. With age, mitochondrial membrane potential declines, reducing ATP production and elevating pro-inflammatory reactive oxygen species production leading to cell death. In the retina mitochondrial density is high and there is a 30% photoreceptor loss with normal ageing. But aged mitochondrial membrane potential and ATP can be improved by long wavelengths absorbed in mitochondrial respiration. Hence, we ask if exposure to such wavelengths for 8 months in 12 month old mice can reduce aged photoreceptor loss. We expose aged mice daily for 10mins to 670 nm light then counted their photoreceptors. Exposure significantly retarded aged photoreceptor loss. Control mice suffered an approximate 30% decrease in photoreceptor outer segments and in the thickness of the retinal layer containing their nuclei compared to 2 month old mice. But in aged mice exposed to 670 nm over 8 month, reductions in outer segments were only <15% and reductions in their nuclear layer were only <10%. Hence, improving mitochndrial function reduces the impact of aged cell loss.