title: Does the hydrolysis of 2-arachidonoylglycerol regulate its cellular uptake?
abstract: Very little is known about the processes regulating the cellular uptake of the endogenous cannabinoid 2-arachidonoylglycerol (2-AG). In the present study, we investigated whether inhibition of 2-AG hydrolysis reduced its uptake, i.e. whether this compound behaves in a manner analogous to the related endocannabinoid anandamide. The selective fatty acid amide hydrolase inhibitor URB597 (3'-(aminocarbamoyl)[1,1'-biphenyl]-3-yl)-cyclohexylcarbamate) completely blocked the hydrolysis of anandamide and reduced its uptake by about half in RBL2H3 basophilic leukaemia cells. In contrast, in these cells, in PC3 and R3327AT-1 prostate cancer cells and in Neuro-2a neuroblastoma cells, the compound had more modest effects upon the hydrolysis of 2-AG and did not affect its cellular uptake at all, indicating that in these cells fatty acid amide hydrolase does not regulate the uptake of 2-AG. The serine hydrolase inhibitor methylarachidonoyl fluoronophosphonate behaved like URB597 with respect to anandamide uptake by RBL2H3 and Neuro-2a cells, and inhibited the hydrolysis of 2-AG with IC50 values of 0.014, 0.052, 0.41 and approximately 1 microM for RBL2H3, PC3, AT-1 and Neuro-2a cells, respectively. MAFP (1 microM) did not significantly reduce the uptake of 2-AG by RBL2H3, PC3 and AT-1 cells but did reduce the uptake of this endocannabinoid by Neuro-2a cells. Arachidonoyl trifluoromethyl ketone and URB602 ([1,1'-biphenyl]-3-yl-carbamic acid, cyclohexyl ester) reduced the uptake of 2-AG by both RBL2H3 and Neuro-2a cells, but at the high concentrations needed, the compound also blocked the retention of these ligands by wells. It is concluded that unlike the situation for anandamide, hydrolysis of 2-AG does not regulate its cellular uptake in RBL2H3, AT-1 and PC3 cells, but may gate the uptake in Neuro-2a cells.
authors.affiliation: Department of Pharmacology and Clinical Neuroscience, Umeå University, SE901 87 Umeå, Sweden. cf@pharm.umu.se
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Fowler
authors.forename: Nazdar
authors.initials: N
authors.lastname: Ghafouri
mesh_terms: D000581:Amidohydrolases / Q000037:antagonists & inhibitors; D000818:Animals; D001095:Arachidonic Acids / Q000378:metabolism*; D001549:Benzamides / Q000494:pharmacology; D001713:Biphenyl Compounds / Q000494:pharmacology; D063385:Cannabinoid Receptor Modulators / Q000378:metabolism*; D002219:Carbamates / Q000494:pharmacology; D045744:Cell Line, Tumor; D063388:Endocannabinoids; D005989:Glycerides / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D053284:Polyunsaturated Alkamides / Q000378:metabolism; D000099252:Fatty Acid Amide Hydrolases
chemical_list: D000581:Amidohydrolases; D001095:Arachidonic Acids; D001549:Benzamides; D001713:Biphenyl Compounds; D063385:Cannabinoid Receptor Modulators; D002219:Carbamates; D063388:Endocannabinoids; D005989:Glycerides; D053284:Polyunsaturated Alkamides; D000099252:Fatty Acid Amide Hydrolases; C501835:URB602; C500528:cyclohexyl carbamic acid 3'-carbamoylbiphenyl-3-yl ester; C094503:glyceryl 2-arachidonate; C078814:anandamide