Extracellular lactate as an alternative energy source for retinal bipolar cells

Abstract

Retinal bipolar and amacrine cells receive visual information from photoreceptors and participate in the first steps of image processing in the retina. Several studies have suggested the operation of aerobic glycolysis and a lactate shuttle system in the retina due to the high production of this metabolite under aerobic conditions. However, whether bipolar cells form part of this metabolic circuit remains unclear. Here, we show that the lactate transporter MCT2 is functionally expressed in inner retinal neurons and demonstrate their ability to consume extracellular lactate as an alternative to glucose. In rod bipolar cells, lactate is used to maintain homeostasis of various ions and electrical responses. Overall, our data contribute to a better understanding of inner retinal metabolism.