title: Histamine acting on H2 receptors stimulates phospholipid methylation in synaptic membranes of rat brain.
abstract: Histamine stimulated [3H]methyl group incorporation into phospholipids in crude synaptic membranes of rat whole brain (without cerebellum) in modified Krebs-Ringer solution containing the methyl donor S-adenosyl-[methyl-3H]methionine. The transient increase of [3H]methyl incorporation into lipids peaked within 45 s after addition of histamine (5 or 10 microM) and decreased the basal level in 60 s. Histamine-stimulated [3H]methyl incorporation was increased linearly in a protein concentration-dependent manner. The stimulation was temperature and histamine concentration dependent. TLC analysis of a chloroform/methanol extract indicated that radioactive phospholipids (phosphatidylcholine, phosphatidyl-N,N-dimethylethanolamine, and phosphatidyl-N-monomethylethanolamine) accounted for 60-65% of the total radioactivity recovered. The synaptosomal fraction had the highest specific activity of all the subfractions of crude synaptic membranes (P2). Histamine-induced [3H]methyl incorporation was inhibited by addition of cimetidine (0.01-10 microM) or famotidine (0.01-1.0 microM) in a concentration-dependent manner but not by mepyramine (0.1-10 microM) or diphenhydramine (0.1-10 microM). The stimulation of [3H]methyl incorporation was also observed by addition of impromidine (0.01-10 microM) or dimaprit (1.0 microM-1.0 mM) in a concentration-dependent manner but not by 2-pyridylethylamine (1.0 microM-1.0 mM). These results indicate that phospholipid methylation is induced by histamine acting on H2 receptors in rat brain synaptosomes.
mesh_terms: D000818:Animals; D005591:Chemical Fractionation; D006632:Histamine / Q000378:metabolism* / Q000494:pharmacology; D050356:Lipid Metabolism; D008297:Male; D008745:Methylation; D010743:Phospholipids / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011969:Receptors, Histamine H1 / Q000378:metabolism; D011970:Receptors, Histamine H2 / Q000378:metabolism*; D013268:Stimulation, Chemical; D013574:Synaptosomes / Q000378:metabolism
chemical_list: D010743:Phospholipids; D011969:Receptors, Histamine H1; D011970:Receptors, Histamine H2; D006632:Histamine