title: Alteration of amino acid metabolism in neuronal aggregate cultures exposed to hypoglycaemic conditions.
abstract: The neuronal effects of glucose deficiency on amino acid metabolism was studied on three-dimensional cultures of rat telencephalon neurones. Transient (6 h) exposure of differentiated cultures to low glucose (0.25 mm instead of 25 mm) caused irreversible damage, as judged by the marked decrease in the activities of two neurone-specific enzymes and lactate dehydrogenase, 1 week after the hypoglycemic insult. Quantification of amino acids and ammonia in the culture media supernatants indicated increased amino acid utilization and ammonia production during glucose-deficiency. Measurement of intracellular amino acids showed decreased levels of alanine, glutamine, glutamate and GABA, while aspartate was increased. Added lactate (11 mm) during glucose deficiency largely prevented the changes in amino acid metabolism and ammonia production, and attenuated irreversible damage. Higher media levels of glutamine (4 mm instead of 0.25 mm) during glucose deprivation prevented the decrease of intracellular glutamate and GABA, while it further increased intracellular aspartate, ammonia production and neuronal damage. Both lactate and glutamine were readily oxidized in these neuronal cultures. The present results suggest that in neurones, glucose deficiency enhances amino acid deamination at the expense of transamination reactions. This results in increased ammonia production and neuronal damage.
authors.affiliation: Institute of Physiology, University of Lausanne, CH-1005 Lausanne, Switzerland. Paul.Honegger@iphysiol.unil.ch
authors.forename: Paul
authors.initials: P
authors.lastname: Honegger
authors.forename: Olivier
authors.initials: O
authors.lastname: Braissant
authors.forename: Hugues
authors.initials: H
authors.lastname: Henry
authors.forename: Olivier
authors.initials: O
authors.lastname: Boulat
authors.forename: Claude
authors.initials: C
authors.lastname: Bachmann
authors.forename: Marie-Gabrielle
authors.initials: MG
authors.lastname: Zurich
authors.forename: Beatriz
authors.initials: B
authors.lastname: Pardo
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D002449:Cell Aggregation; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004734:Energy Metabolism; D005110:Extracellular Space / Q000378:metabolism; D005947:Glucose / Q000008:administration & dosage / Q000172:deficiency* / Q000494:pharmacology; D005973:Glutamine / Q000008:administration & dosage / Q000494:pharmacology; D007424:Intracellular Fluid / Q000378:metabolism; D019344:Lactic Acid / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D010084:Oxidation-Reduction; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013687:Telencephalon / Q000166:cytology
chemical_list: D000596:Amino Acids; D000644:Quaternary Ammonium Compounds; D005973:Glutamine; D019344:Lactic Acid; D005947:Glucose