title: Synaptosomal phospholipase D potential role in providing choline for acetylcholine synthesis.
abstract: The phospholipase D of the rat brain synaptic membrane possesses the highest activity of this enzyme of any mammalian tissue examined. The synaptic phospholipase D activity is latent and barely detectable in the absence of 4 mM sodium oleate. Several other fatty acids were either less effective or ineffective as stimulators of activity compared to this monounsaturated fatty acid. The activity was decreased by hemicholinium-3, an inhibitor of choline uptake and slightly activated by neostigmine, an acetylcholinesterase inhibitor. Incubation of synaptosomes in the presence of sodium oleate and acetyl-coenzyme A resulted in the formation of a product chromatographing with acetylcholine. Acetylcholine formation was nearly undetectable in the absence of sodium oleate or acetyl-coenzyme A. These results implicate synaptosomal phospholipase D in releasing choline from phosphatidylcholine for acetylcholine formation.
mesh_terms: D000109:Acetylcholine / Q000096:biosynthesis*; D000818:Animals; D002540:Cerebral Cortex / Q000201:enzymology*; D002794:Choline / Q000378:metabolism*; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D006426:Hemicholinium 3 / Q000494:pharmacology; D007700:Kinetics; D009388:Neostigmine / Q000494:pharmacology; D010713:Phosphatidylcholines / Q000096:biosynthesis; D010739:Phospholipase D / Q000378:metabolism*; D010740:Phospholipases / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013347:Subcellular Fractions / Q000201:enzymology; D013574:Synaptosomes / Q000201:enzymology*
chemical_list: D010713:Phosphatidylcholines; D006426:Hemicholinium 3; D009388:Neostigmine; D002795:Choline O-Acetyltransferase; D010740:Phospholipases; D010739:Phospholipase D; D002794:Choline; D000109:Acetylcholine