title: Effect of docosahexaenoic acid on the synthesis of phosphatidylserine in rat brain in microsomes and C6 glioma cells.
abstract: Docosahexaenoic acid (22:6n-3) is the major polyunsaturated fatty acid (PUFA) in the CNS and accumulates particularly in phosphatidylserine (PS). We have investigated the effect of the 22:6n-3 compositional status on the synthesis of PS. The fatty acid composition of brain microsomes from offspring of rats artificially reared on an n-3-deficient diet showed a dramatic reduction of 22:6n-3 content (1.7 +/- 0.1%) when compared with control animals (15.0 +/- 0.2%). The decrease was accompanied by an increase in docosapentaenoic acid (22:5n-6) content, which replaced the 22:6n-3 phospholipids with 22:5n-6 molecular species, as demonstrated using HPLC/electrospray mass spectrometry. The n-3 deficiency did not affect the total amount of polyunsaturated phospholipids in brain microsomes; however, it was associated with a decrease in the total polyunsaturated PS content and with increased levels of 1-stearoyl-2-docosapentanoyl (18:0/22:5n-6) species, particularly in phosphatidylcholine. Incorporation of [3H]serine into PS in rat brain microsomes from n-3-deficient animals was slightly but significantly less than that of the control animals. Similarly, C6 glioma cells cultured for 24 h in 22:6n-3-supplemented media (10-40 microM) showed a significant increase in the synthesis of [3H]PS when compared with unsupplemented cells. Our data show that neuronal and glial PS synthesis is sensitive to changes in the docosahexaenoate levels of phospholipids and suggest that 22:6n-3 may be a modulator of PS synthesis.
authors.affiliation: Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, Maryland 20852, USA.
authors.forename: M C
authors.initials: MC
authors.lastname: Garcia
authors.forename: G
authors.initials: G
authors.lastname: Ward
authors.forename: Y C
authors.initials: YC
authors.lastname: Ma
authors.forename: N
authors.initials: N
authors.lastname: Salem
authors.forename: H Y
authors.initials: HY
authors.lastname: Kim
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D001932:Brain Neoplasms / Q000378:metabolism* / Q000473:pathology; D004281:Docosahexaenoic Acids / Q000494:pharmacology*; D005260:Female; D005910:Glioma / Q000378:metabolism* / Q000473:pathology; D008861:Microsomes / Q000378:metabolism*; D010718:Phosphatidylserines / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012694:Serine / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D010718:Phosphatidylserines; D004281:Docosahexaenoic Acids; D012694:Serine