Energy metabolism in the vertebrate retina

Abstract

The fundamental need for efficient and well-controlled energy metabolism in living organisms is ubiquitous. However, vertebrate retinas have many fascinating adaptations that give them the ability to regulate energy production and anabolic activity to meet a unique set of metabolic demands. Retinas have An extraordinarily high rate of ATP consumption in darkness A localized and highly specialized signal transduction apparatus that has an overwhelming and direct influence on energy demand Exposure to light and O 2 that create a high demand for membrane renewal A higher rate of aerobic glycolysis than most other tissues A laminated structure that facilitates localization of metabolic enzymes and metabolites Synaptic terminals with a unique structure that allows recovery of neurotransmitter into presynaptic neurons at very high efficiency Unusual mitochondrial morphology and distribution Distinctive localization of creatine kinase and a specialized mechanism for distributing metabolic energy within the cell An extensive database of genes linked to retinal degeneration: many of these may cause metabolic dysregulation and failure Unique sensitivity to loss of mitochondrial isocitrate dehydrogenase activity This review summarizes what is known about these extraordinary features in the context of the retina structure, its anabolic requirements, its metabolic requirements in light and darkness, the ways that it distributes metabolic energy, and, finally, the consequences of metabolic dysregulation.