Effects of glutamate on dehydroascorbate uptake and its enhanced vulnerability to the peroxidation in cerebral cortical slices.
Pro-oxidant properties of ascorbate have been studied with uses of brain tissues and neuronal cells. Here we address potential mechanism of ascorbate coupling with glutamate to generate oxidative stress, and the role which oxidized ascorbate (dehydroascorbate) transport plays in oxidative neuronal injury. Ascorbate in neurones can be depleted by adding glutamate in culture medium since endogenous ascorbate can be exchanged with glutamate, which enhances ascorbate/dehydroascorbate transport by depleting ascorbate in the neurons with the glutamate- heteroexchange. However, ascorbate is known readily being oxidized to dehydroascorbate in the medium. Glutamate enhanced the dehydroascorbate uptake by cells via a glucose transporter (GLUT) from extracellular region, and cytosolic dehydroascorbate enhanced lipid peroxide production and reduced glutathione (GSH) concentrations. Iso-ascorbate, the epimer of ascorbate was ineffective in generating the oxidative stress. These observations support the current concept that the high rates of dehydroascorbate transport via a GLUT after the release of ascorbate by glutamate leads to peroxidation, the role of glutamate on ascorbate/dehydroascorbate recycling being critical to induce neuronal death via an oxidative stress in the brain injury.
Song
Jin Hyang
JH
Department of Physiology, Queen's University, Kingston, Ontario, Canada, K7L 3N6.
Shin
Seon Ho
SH
Chung
Ill Min
IM
D000818:Animals; D001205:Ascorbic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D002540:Cerebral Cortex / Q000187:drug effects* / Q000378:metabolism*; D003571:Cytochalasin B / Q000494:pharmacology; D003683:Dehydroascorbic Acid / Q000378:metabolism*; D018698:Glutamic Acid / Q000494:pharmacology*; D005978:Glutathione / Q000378:metabolism; D066298:In Vitro Techniques; D015227:Lipid Peroxidation / Q000187:drug effects*; D008297:Male; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
D017392:Thiobarbituric Acid Reactive Substances; D003571:Cytochalasin B; D018698:Glutamic Acid; D005978:Glutathione; D001205:Ascorbic Acid; D003683:Dehydroascorbic Acid