title: Identification of biosynthetic precursors for the endocannabinoid anandamide in the rat brain.
abstract: Anandamide is an endogenous signaling lipid that binds to and activates cannabinoid receptors in the brain and peripheral tissues. The endogenous precursors of anandamide, N-arachidonoyl phosphatidylethanolamines (NArPEs), are a family of complex glycerophospholipids that derive from the exchange reaction of an arachidonoyl group between the sn-1 position of phosphatidylcholine and the primary amine of phosphatidylethanolamine catalyzed by N-acyl transferase activity. A precise characterization of the molecular composition of NArPE species generating anandamide has not yet been reported. In the present study, using liquid chromatography coupled to electrospray ionization ion-trap mass spectrometry, we identified the major endogenous NArPE species, which mainly contained sn-1 alkenyl groups (C16:0, C18:0, C18:1) and monounsaturated (C18:1) or polyunsaturated (C20:4, C22:4, C22:6) acyl groups at the sn-2 position of the glycerol backbone. Using rat brain particulate fractions, we observed a calcium-dependent increase in both NArPEs and anandamide formation after incubation at 37 degrees C for 30 min. Furthermore, a targeted lipidomic analysis showed that Ca(2+) specifically stimulated the formation of PUFA-containing NArPE species. These results reveal a previously unrecognized preference of brain N-acyl transferase activity for polyunsaturated NArPE and provide new insights on the physiological regulation of anandamide biosynthesis.
authors.affiliation: Department of Pharmacology and Center for Drug Discovery, University of California, Irvine, CA 92967, USA.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Astarita
authors.forename: Faizy
authors.initials: F
authors.lastname: Ahmed
authors.forename: Daniele
authors.initials: D
authors.lastname: Piomelli
mesh_terms: D000818:Animals; D001095:Arachidonic Acids / Q000096:biosynthesis* / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D063385:Cannabinoid Receptor Modulators / Q000378:metabolism*; D063388:Endocannabinoids; D008297:Male; D010713:Phosphatidylcholines / Q000378:metabolism*; D010714:Phosphatidylethanolamines / Q000737:chemistry / Q000378:metabolism*; D053284:Polyunsaturated Alkamides / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
chemical_list: D001095:Arachidonic Acids; D063385:Cannabinoid Receptor Modulators; D063388:Endocannabinoids; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D053284:Polyunsaturated Alkamides; C078814:anandamide