Glutamine Acts as a Neuroprotectant against DNA Damage, Beta-Amyloid and H2O2-Induced Stress

• Published in: PloS one Vol. 7; no. 3; p. e33177
• Main Authors: Chen, Jianmin, Herrup, Karl
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 08.03.2012; Public Library of Science (PLoS)
• Subjects: Activation; Age; Aging; Alzheimer Disease - genetics; Alzheimer Disease - metabolism; Alzheimer's disease; Alzheimers disease; Amino acids; Amyloid beta-Peptides - metabolism; Amyloid beta-Peptides - toxicity; Animal models; Animals; Artificial chromosomes; Autophagy; Biology; Brain; Brain research; Cell activation; Cell cycle; Cell Line; Cell Survival - drug effects; Chemistry; Chemotherapy; Deoxyribonucleic acid; Diet; Dietary supplements; Disease Models, Animal; DNA; DNA damage; DNA Damage - drug effects; DNA repair; Drug dosages; Gene Expression; Glutamate-ammonia ligase; Glutamate-Ammonia Ligase - genetics; Glutamate-Ammonia Ligase - metabolism; Glutamine; Glutamine - metabolism; Glutamine - pharmacology; Hippocampus; Hippocampus - metabolism; Humans; Hydrogen peroxide; Hydrogen Peroxide - metabolism; Hypotheses; Intracellular; Intracellular levels; Medicine; Metabolism; Metabolites; Mice; Mutation; Neurodegenerative diseases; Neurodegenerative Diseases - genetics; Neurodegenerative Diseases - metabolism; Neurological diseases; Neurons; Neurons - drug effects; Neurons - metabolism; Neuroprotection; Neuroprotective agents; Neuroprotective Agents - pharmacology; Neurosciences; Neurotoxicity; Oxidation; Phosphorylation; Proteins; Salts; Spectrum analysis; Stress, Physiological - drug effects; Supplementation; Synaptophysin; Tau protein; Zinc; Zinc salts; β-Amyloid; United States > US; New Jersey
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0033177

Glutamine is the most abundant free amino acid in the human blood stream and is 'conditionally essential' to cells. Its intracellular levels are regulated both by the uptake of extracellular glutamine via specific transport systems and by its intracellular synthesis by glutamine synthetase (GS). Adding to the regulatory complexity, when extracellular glutamine is reduced GS protein levels rise. Unfortunately, this excess GS can be maladaptive. GS overexpression is neurotoxic especially if the cells are in a low-glutamine medium. Similarly, in low glutamine, the levels of multiple stress response proteins are reduced rendering cells hypersensitive to H(2)O(2), zinc salts and DNA damage. These altered responses may have particular relevance to neurodegenerative diseases of aging. GS activity and glutamine levels are lower in the Alzheimer's disease (AD) brain, and a fraction of AD hippocampal neurons have dramatically increased GS levels compared with control subjects. We validated the importance of these observations by showing that raising glutamine levels in the medium protects cultured neuronal cells against the amyloid peptide, Aβ. Further, a 10-day course of dietary glutamine supplementation reduced inflammation-induced neuronal cell cycle activation, tau phosphorylation and ATM-activation in two different mouse models of familial AD while raising the levels of two synaptic proteins, VAMP2 and synaptophysin. Together, our observations suggest that healthy neuronal cells require both intracellular and extracellular glutamine, and that the neuroprotective effects of glutamine supplementation may prove beneficial in the treatment of AD.