title: Characterization of CB1 receptors on rat neuronal cell cultures: binding and functional studies using the selective receptor antagonist SR 141716A.
abstract: This study was undertaken to characterize further the central cannabinoid receptors in rat primary neuronal cell cultures from selected brain structures. By using [3H]SR 141716A, the specific CB1 receptor antagonist, we demonstrate in cortical neurons the presence of a high density of specific binding sites (Bmax = 139 +/- 9 fmol/mg of protein) displaying a high affinity (KD = 0.76 +/- 0.09 nM). The two cannabinoid receptor agonists, CP 55940 and WIN 55212-2, inhibited in a concentration-dependent manner cyclic AMP production induced by either 1 microM forskolin or isoproterenol with EC50 values in the nanomolar range (4.6 and 65 nM with forskolin and 1.0 and 5.1 nM with isoproterenol for CP 55940 and WIN 55212-2, respectively). Moreover, in striatal neurons and cerebellar granule cells, CP 55940 was also able to reduce the cyclic AMP accumulation induced by 1 microM forskolin with a potency similar to that observed in cortical neurons (EC50 values of 3.5 and 1.9 nM in striatum and cerebellum, respectively). SR 141716A antagonized the CP 55940- and WIN 55212-2-induced inhibition of cyclic AMP accumulation, suggesting CB1 receptor-specific mediation of these effects on all primary cultures tested. Furthermore, CP 55940 was unable to induce mitogen-activated protein kinase activation in either cortical or striatal neurons. In conclusion, our results show nanomolar efficiencies for CP 55940 and WIN 55212-2 on adenylyl cyclase activity and no effect on any other signal transduction pathway investigated in primary neuronal cultures.
authors.affiliation: Sanofi Recherche, Montepellier, France.
authors.forename: M
authors.initials: M
authors.lastname: Jung
authors.forename: R
authors.initials: R
authors.lastname: Calassi
authors.forename: M
authors.initials: M
authors.lastname: Rinaldi-Carmona
authors.forename: P
authors.initials: P
authors.lastname: Chardenot
authors.forename: G
authors.initials: G
authors.lastname: Le Fur
authors.forename: P
authors.initials: P
authors.lastname: Soubrié
authors.forename: F
authors.initials: F
authors.lastname: Oury-Donat
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D009474:Neurons / Q000378:metabolism*; D010880:Piperidines / Q000378:metabolism*; D011720:Pyrazoles / Q000378:metabolism*; D051381:Rats; D043882:Receptors, Cannabinoid; D011955:Receptors, Drug / Q000187:drug effects / Q000378:metabolism*; D000077285:Rimonabant
chemical_list: D010880:Piperidines; D011720:Pyrazoles; D043882:Receptors, Cannabinoid; D011955:Receptors, Drug; D005576:Colforsin; D000242:Cyclic AMP; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D000077285:Rimonabant