title: Benzophenanthridine alkaloid, piperonyl butoxide and (S)-methoprene action at the cannabinoid-1 receptor (CB1-receptor) pathway of mouse brain: Interference with [(3)H]CP55940 and [(3)H]SR141716A binding and modification of WIN55212-2-dependent inhibition of synaptosomal l-glutamate release.
abstract: Benzophenanthridine alkaloids (chelerythrine and sanguinarine) inhibited binding of [(3)H]SR141716A to mouse brain membranes (IC50s: <1µM). Piperonyl butoxide and (S)-methoprene were less potent (IC50s: 21 and 63µM respectively). Benzophenanthridines and piperonyl butoxide were more selective towards brain CB1 receptors versus spleen CB2 receptors. All compounds reduced Bmax of [(3)H]SR141716A binding to CB1 receptors, but only methoprene and piperonyl butoxide increased Kd (3-5-fold). Benzophenanthridines increased the Kd of [(3)H]CP55940 binding (6-fold), but did not alter Bmax. (S)-methoprene increased the Kd of [(3)H]CP55940 binding (by almost 4-fold) and reduced Bmax by 60%. Piperonyl butoxide lowered the Bmax of [(3)H]CP55940 binding by 50%, but did not influence Kd. All compounds reduced [(3)H]SR141716A and [(3)H]CP55940 association with CB1 receptors. Combined with a saturating concentration of SR141716A, only piperonyl butoxide and (S)-methoprene increased dissociation of [(3)H]SR141716A above that of SR141716A alone. Only piperonyl butoxide increased dissociation of [(3)H]CP55940 to a level greater than CP55940 alone. Binding results indicate predominantly allosteric components to the study compounds action. 4-Aminopyridine-(4-AP-) evoked release of l-glutamate from synaptosomes was partially inhibited by WIN55212-2, an effect completely neutralized by AM251, (S)-methoprene and piperonyl butoxide. With WIN55212-2 present, benzophenanthridines enhanced 4-AP-evoked l-glutamate release above 4-AP alone. Modulatory patterns of l-glutamate release (with WIN-55212-2 present) align with previous antagonist/inverse agonist profiling based on [(35)S]GTPγS binding. Although these compounds exhibit lower potencies compared to many classical CB1 receptor inhibitors, they may have potential to modify CB1-receptor-dependent behavioral/physiological outcomes in the whole animal.
authors.affiliation: Simon Fraser University, Department of Biological Sciences, 8888 University drive, Burnaby, BC, Canada V5A 1S6. Electronic address: adhopesh@sfu.ca.
authors.forename: Amey Sadashiv
authors.initials: AS
authors.lastname: Dhopeshwarkar
authors.affiliation: Simon Fraser University, Department of Biological Sciences, 8888 University drive, Burnaby, BC, Canada V5A 1S6. Electronic address: russell_nicholson@sfu.ca.
authors.forename: Russell Alfred
authors.initials: RA
authors.lastname: Nicholson
mesh_terms: D000818:Animals; D053119:Benzophenanthridines / Q000494:pharmacology*; D048588:Benzoxazines / Q000494:pharmacology*; D001665:Binding Sites; D001921:Brain / Q000378:metabolism; D003511:Cyclohexanols / Q000494:pharmacology*; D018698:Glutamic Acid / Q000378:metabolism; D007546:Isoquinolines / Q000494:pharmacology*; D008297:Male; D008726:Methoprene / Q000494:pharmacology*; D051379:Mice; D009025:Morpholines / Q000494:pharmacology*; D009281:Naphthalenes / Q000494:pharmacology*; D010880:Piperidines / Q000494:pharmacology; D010882:Piperonyl Butoxide / Q000494:pharmacology*; D011720:Pyrazoles / Q000494:pharmacology; D011869:Radioligand Assay; D043884:Receptor, Cannabinoid, CB1 / Q000378:metabolism*; D043885:Receptor, Cannabinoid, CB2 / Q000378:metabolism; D000077285:Rimonabant; D013154:Spleen / Q000378:metabolism; D013574:Synaptosomes / Q000378:metabolism
chemical_list: D053119:Benzophenanthridines; D048588:Benzoxazines; D003511:Cyclohexanols; D007546:Isoquinolines; D009025:Morpholines; D009281:Naphthalenes; D010880:Piperidines; D011720:Pyrazoles; D043884:Receptor, Cannabinoid, CB1; D043885:Receptor, Cannabinoid, CB2; D018698:Glutamic Acid; C070417:(3R)-((2,3-dihydro-5-methyl-3-((4-morpholinyl)methyl)pyrrolo-(1,2,3-de)-1,4-benzoxazin-6-yl)(1-naphthalenyl))methanone; C054649:3-(2-hydroxy-4-(1,1-dimethylheptyl)phenyl)-4-(3-hydroxypropyl)cyclohexanol; D008726:Methoprene; C005705:sanguinarine; C016299:chelerythrine; D010882:Piperonyl Butoxide; D000077285:Rimonabant
keywords: (S)-methoprene; 4-AP; Benzophenanthridine alkaloid; CB1 receptor; Piperonyl butoxide; Synaptosome; [35S]GTPγS; [³H]CP55940; [³H]SR141716A; l-glutamate