Measuring ATP in axons with FRET

Abstract

Synaptic transmission is an energetically demanding process that consumes much of the brain’s energy. In many neurodegenerative diseases, such as Parkinson’s disease (PD), Alzheimer’s disease (AD), and Huntington’s disease (HD), synapses are lost at early stages, which may be caused by an inability to meet this high energy demand. Until recently, however, tools were unable to measure energy levels in synapses, which limited the understanding of the physiological and pathological requirements for ATP at the nerve terminal. Here described is an approach to measure ATP specifically in axons and at the synapse with a FRET-based ATP sensor. This approach involves imaging ATP levels in live cultures of primary neurons, specifically examining ATP production by respiration and glycolysis, based on the level of neural activity. This approach also allows assessment of different cell types for their relative and required levels of synaptic energy.