Rod photoreceptors have a dual dependency on both aerobic glycolysis and OXPHOS and diverge metabolically from other retinal neurons

The retina metabolizes glucose into lactate, a hallmark of aerobic glycolysis known as the Warburg effect. Although evidence points to rod photoreceptors as the primary source of aerobic glycolysis, a comparison of the energy metabolism in different retinal neurons has yet to be performed. We combined two-photon fluorescence lifetime imaging of biosensors with pharmacological protocols to analyze metabolic dynamics in healthy and diseased rod photoreceptors and RBPMS-positive ganglion and calretinin-positive amacrine cells. Our data reveal distinct metabolic profiles among retinal neurons, identify rods as the drivers of aerobic glycolysis, demonstrate that inner retinal neurons rely on oxidative phosphorylation, show that rods need both glycolysis and oxidative phosphorylation to maintain ATP levels, and suggest that rods can metabolize lactate. A mutation causing retinitis pigmentosa increases lactate production in rods but changes the energy metabolism only subtly otherwise. Our results improve the understanding of retinal physiology and are relevant for pathologies involving imbalanced energy metabolism.