Targeting Age-Related Metabolic Shifts in the Brain
Published in Brain/Neurology.
To perform various maintenance and protective tasks, the brain contains a large population of microglia alongside its neurons. These glia include astrocytes, which, among their many other tasks, are responsible for aiding neurons with metabolism. For example, after a neuron fires, the glutamate used in that firing is taken up by an astrocyte, processed into glutamine, and then given back to the neuron for re-conversion into glutamate.
Another part of this metabolic symbiosis involves how astrocytes use glucose. An astrocyte can either use aerobic glycolysis to convert pyruvate into lactate, which neurons use for fuel, or it can perform oxidative phosphorylation to use that energy for itself.
With aging, the astrocytes take more of this energy for themselves. In 76-year-olds, astrocyte mitochondria become about 30% more active, and neural mitochondria become about 30% less active, compared to 24-year-olds. That discovery led this research team to determine the genetic and biochemical reasons behind this metabolic shift.