ACS Chem. Neurosci., published online 22 April 2012, doi:10.1021/cn300003r

Credit: AMERICAN CHEMICAL SOCIETY

Under stressful conditions, such as when glucose is limited, neurons undergo a cytoprotective program where anaerobic biosynthesis of lactate leads to changes in neuronal membrane potential and cell signaling. Because suitable analytical tools to monitor dynamic stress responses are scarce, the identity of key metabolic mediators of this neuronal stress response remain unknown. To identify essential metabolic events that mediate injury, McKenzie et al. now use multianalyte microphysiometry to measure changes in lactate release, oxygen consumption and acidification rates after periods of glucose deprivation in neuronal cultures. Oxygen consumption was irreparably affected in pure neuronal cultures but was not affected when glia cells were mixed with the neurons, consistent with a supporting role of glia cells in the brain. Acidification decreased in both cultures, but the magnitude decrease was greater in the mixed cultures and the levels were not fully recovered upon readdition of glucose. Also, there was an increase in cell death in the neuronal but not the mixed cultures. Taken together and with subsequent experiments to measure oxidative modification of proteins and lipids during glucose deprivation, these findings suggest that extracellular acidification and oxygen consumption were the best predictors of neuronal survival in the presence of glia, correlating better than current clinical metrics of tissue damage, such as lactate concentrations and lipid oxidation.