Non-cell autonomous processes involving astrocytes have been shown to contribute to motor neuron degeneration in amyotrophic lateral sclerosis. Mutant superoxide dismutase 1 (SOD1 G93A ) expression in astrocytes is selectively toxic to motor neurons in co-culture, even when mutant protein is expressed only in astrocytes and not in neurons. To examine metabolic changes in astrocyte-spinal neuron cocultures, we carried out metabolomic analysis by 1 H NMR spectroscopy of media from astrocyte-spinal neuron co-cultures and astrocyte-only cultures. We observed increased glucose uptake with SOD1 G93A expression in all co-cultures, but while co-cultures with only SOD1 G93A neurons had lower extracellular lactate, those with only SOD1 G93A astrocytes exhibited the reverse. Reduced branched-chain amino acid uptake and increased accumulation of 3-methyl-2-oxovalerate were observed in co-culture with only SOD1 G93A neurons while glutamate was reduced in all co-cultures expressing SOD1 G93A . The shifts in these coupled processes suggest a potential block in glutamate processing that may impact motor neuron survival. We also observed metabolic alterations which may relate to oxidative stress responses. Overall, the different metabolite changes observed with the two SOD1 G93A cell types highlight the role of the astrocyte-motor neuron interaction in the resulting metabolic phenotype, requiring further examination of altered met abolic pathways and their impact on motor neuron survival.Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the loss of motor neurons, leading to progressive neuromuscular impairment and death, usually within 2-3 years after diagnosis. Around 10% of ALS cases are due to inherited genetic mutations, with those in the Cu-Zn superoxide dismutase gene (SOD1) first to be associated with the disease. Rodents expressing SOD1 mutations invariably develop a motor syndrome with pathological and symptomatic features of the human disease, therefore representing the best experimental models of ALS available. To date, the process by which mutant SOD1 leads to toxicity has not yet been fully resolved, although oxidative stress, excitotoxicity, dysregulation of energy metabolism, and mitochondrial dysfunction have been extensively studied as potential pathogenic mechanisms, based on studies of patient tissues and experimental models of the disease 1-3 . A complex multifactorial pathogenesis would be compatible with a key toxic role for global derangements in metabolism.Metabolomic and proteomic analysis of biofluids from ALS patients have revealed altered profiles and are being applied in search of biomarkers for diagnosis [4][5][6] . However, there is still limited information available on the effect of mutant SOD1 expression on metabolism in the different cell types of the nervous system. Our group has previously shown that while expression of wild type human SOD1 in the NSC-34 cell line reinforced metabolic responses to stress, this process was dysregulated with expression of mutan...