Effect of ethanol on ATP-induced phospholipases C and D and serine base exchange in glioma C6 cells

The effect of extracellular ATP, a nucleotide receptor agonist in the centr al nervous system, was investigated in glioma C6 cells on the intracellular Ca2+ level and the formation of phosphatidylethanol and phosphatidic acid in the presence and absence of ethanol (150 mM). In the cells prelabeled wi th [C-14]palmitic acid, 100 mu M ATP induced both the hydrolysis and the tr ansphosphatidylation reactions leading to the formation of [C-14]phosphatid ic acid; addition of ethanol generated [C-14]phosphatidylethanol. However, ATP-mediated increase in the level of [C-14]phosphatidic acid was not inhib ited by ethanol. Furthermore, ethanol augmented ATP-induced transient and s ustained increase in the intracellular Ca2+ concentration, whereas ethanol alone did not produce any change in the intracellular Ca2+ level. These res ults indicate that in glioma C6 cells, ATP induces activation of polyphosph oinositide-specific phospholipase C and phospholipase D and that ethanol en hances this effect. In the present investigation we have also shown that lo ng-term (2 days) ethanol treatment, at concentration relevant to chronic al coholism (100 mM), decreased the incorporation of [C-14]serine into phospha tidylserine. Since the effect of ethanol on ATP-induced activities of phosp holipase C and phospholipase D and on serine base-exchange in glioma C6 cel ls differs significantly from that in cultured neuronal cells, these result s may contribute to a better understanding of the mechanisms of ethanol act ion in cells of glial origin. (C) 2000 Elsevier Science Ltd. All rights res erved.