Effect of Paraquat and Amyloid- -Peptide on the Metabolism in Primary Astrocytes

Amyloid -peptide (A ) and Paraquat PQ induce oxidative stress in astrocytes by formation of reactive oxygen species (ROS). The present study determines the cellular response to oxidative stress by use of proton nuclear magnetic resonance ( 1 H-NMR) spectroscopy. The cellular response was studied in cultured primary astrocytes exposed directly to 5 mM PQ or 40 M A (1-40) in the NMR tube (directly) or after a pre-incubation with either 60 M PQ for 48 hours, 10 M A (25-35) or A (1-40) for 44 hours. The ROS-mediated modifications in the metabolic profile were followed for at least 2 hours in the NMR spectrometer. Pre-incubation with PQ or A demonstrated increases in the end-products of glycolysis such as pyruvate and lactate. In addition, the concentrations of other metabolites, such as alanine, acetate, methionine, choline, glycine and formate were also increased, whereas the level of glutamate was decreased. These ROSmediated alterations in the metabolic profile are most likely due to disturbances of the enzymes of the tricarboxylic acid (TCA) cycle. The direct effect of PQ led to an increase of succinate among other metabolites. The rate of glycolysis was influenced both by the direct addition of PQ or after pre-incubation with A which clearly indicates an increased consumption of glucose. Thus, both PQ and A -inducible changes of the metabolic profile were detectable by the use of 1 HNMR-spectroscopy.