Ethanol induces glutamate secretion by Ca2+ mobilization and ROS generation in rat hippocampal astrocytes.
In this study we have investigated the effect of ethanol on [Ca2+]c by microfluorimetry and glutamate secretion using an enzyme-linked system, in rat hippocampal astrocytes in culture. Our results show that ethanol (1-200 mM) evoked a dose-dependent increase in glutamate secretion. 50 mM ethanol, a concentration within the range of blood alcohol levels in intoxicated humans, induced a release of Ca2+ from intracellular stores in the form of oscillations. Ca2+-mobilizing effect of ethanol was not prevented by preincubation of cells in the presence of 2 mM of the antioxidant dithiothreitol. Ethanol-evoked glutamate secretion was reduced when extracellular Ca2+ was omitted (medium containing 0.5 mM EGTA) and following preincubation of astrocytes in the presence of the intracellular Ca2+ chelator 1,2-bis-(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid tetraacetoxy-methyl ester (10 microM). Preincubation of astrocytes in the presence of 2 mM of the antioxidant dithiothreitol significantly reduced ethanol-evoked glutamate secretion. Finally, preincubation of astrocytes in the presence of bafilomycin (50 nM) significantly reduced ethanol-induced neurotransmitter release, indicating that exocytosis is involved in glutamate secretion. In conclusion, our results suggest that ethanol mobilizes Ca2+ from intracellular stores, and stimulates a Ca2+-dependent glutamate secretion, probably involving reactive oxygen species production, and therefore creating a situation potentially leading to neurotoxicity in the hippocampus.
Salazar
Miguel
M
Department of Physiology (Cell Physiology Research Group), University of Extremadura, Avenida Universidad s/n, E-10071, Cáceres, Spain.
Pariente
José A
JA
Salido
Ginés M
GM
González
Antonio
A
D020268:Alcohol-Induced Disorders, Nervous System / Q000378:metabolism / Q000503:physiopathology; D000818:Animals; D000831:Animals, Newborn; D000975:Antioxidants / Q000494:pharmacology; D001253:Astrocytes / Q000187:drug effects* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects* / Q000502:physiology; D002478:Cells, Cultured; D002492:Central Nervous System Depressants / Q000633:toxicity; D002614:Chelating Agents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000633:toxicity*; D018698:Glutamic Acid / Q000378:metabolism*; D006624:Hippocampus / Q000187:drug effects* / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism*
D000975:Antioxidants; D002492:Central Nervous System Depressants; D002614:Chelating Agents; D017382:Reactive Oxygen Species; D000431:Ethanol; D018698:Glutamic Acid; D002118:Calcium