title: Accumulation of docosahexaenoic acid in phosphatidylserine is selectively inhibited by chronic ethanol exposure in C-6 glioma cells.
abstract: Neuronal membranes are highly enriched with docosahexaenoic acid (22:6n-3), and its content can be altered by ethanol consumption. We have previously reported that the 22:6n-3 status in membrane affects the biosynthesis of phosphatidylserine (PS), a phospholipid class which contains an exceptionally high proportion of 22:6n-3. The aim of the present study is to investigate the effect of chronic ethanol exposure on PS accumulation in relation to the 22:6n-3 status. C-6 glioma cells were enriched with 25 microM 22:6n-3 for 48 h and the PS accumulation was first evaluated in comparison to nonenriched cells as well as cells enriched with arachidonic acid (20:4n-6). Electrospray liquid chromatography-mass spectrometry analysis revealed that cells treated with 22:6n-3 showed significantly higher accumulation of PS in comparison to nonenriched or 20:4n-6-enriched cells, primarily due to an increase of 1-stearoyl-2-docosahexaenoyl-glycerophosphoserine (18:0,22:6-PS). Chronic ethanol exposure selectively affected the accumulation of PS in 22:6n-3-enriched cells. After cells were exposed to 20 or 50 mM ethanol for 4 wk, accumulation of 18:0,22:6-PS upon 22:6n-3 supplementation was significantly lower, resulting in a drastic reduction of total PS. Concomitantly, ethanol-treated cells showed lower incorporation of serine in comparison to control cells. From these data, it was concluded that supplementation of cells with 22:6n-3 promotes the accumulation of PS and chronic ethanol treatment diminishes this effect at least in part through impaired serine incorporation processes. Attenuated accumulation of 22:6n-3 in PS and the reduction of PS thus may have significant implications in pathophysiological effects of ethanol, especially in tissues with abundant 22:6n-3.
authors.affiliation: Section of Mass Spectrometry, Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, Maryland 20852, USA. hykim@nih.gov
authors.forename: H Y
authors.initials: HY
authors.lastname: Kim
authors.forename: J
authors.initials: J
authors.lastname: Hamilton
mesh_terms: D000818:Animals; D016543:Central Nervous System Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D002853:Chromatography, Liquid / Q000379:methods; D004281:Docosahexaenoic Acids / Q000378:metabolism*; D000431:Ethanol / Q000494:pharmacology*; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D005910:Glioma / Q000188:drug therapy / Q000378:metabolism*; D010718:Phosphatidylserines / Q000378:metabolism*; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism; D051381:Rats; D012694:Serine / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D005231:Fatty Acids, Unsaturated; D010718:Phosphatidylserines; D010743:Phospholipids; D004281:Docosahexaenoic Acids; D000431:Ethanol; D012694:Serine