Binding of aminoalkylindoles to noncannabinoid binding sites in NG108-15 cells.
1. Aminoalkylindoles, typified by WIN 55212-2, bind to G protein-coupled cannabinoid receptors in brain. Although cannabinoids inhibit adenylyl cyclase in NG108-15 neuroblastoma x glioma hybrid cells, cannabinoid receptor binding in these cells has not been described previously. This study compares pharmacological characteristics of [3H]WIN 55212-2 binding sites in rat cerebellar membranes and in NG108-15 membranes. 2. Although the KD of specified [3H]WIN 55212-2 binding was similar in brain and NG108-15 membranes, the Bmax was 10 times lower in NG108-15 than in cerebellar membranes. In both brain and NG108-15 membranes, aminoalkylindole analogues were relatively potent in displacing [3H]WIN 55212-2 binding. However, IC50 values for more traditional cannabinoids were significantly higher in NG108-15 membranes than in brain, e.g., the Ki values for CP55,940 were 1.2 nM in brain and > 5000nM in NG108-15 membranes. Moreover, sodium and GTP-gamma-S decreased [3H]WIN 55212-2 binding in brain but not in NG108-15 membranes. 3. These data suggest that WIN 55212-2 does not label traditional cannabinoid receptors in NG108-15 cells and that these novel aminoalkylindole binding sites are not coupled to G proteins.
Stark
S
S
Neuroscience Program, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, North Carolina 27157, USA.
Pacheco
M A
MA
Childers
S R
SR
D000700:Analgesics / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D001095:Arachidonic Acids / Q000378:metabolism / Q000494:pharmacology; D048588:Benzoxazines; D001667:Binding, Competitive; D002121:Calcium Channel Blockers / Q000378:metabolism / Q000494:pharmacology; D002186:Cannabinoids / Q000819:agonists / Q000378:metabolism; D002531:Cerebellum / Q000166:cytology; D003511:Cyclohexanols / Q000378:metabolism / Q000494:pharmacology; D063388:Endocannabinoids; D005910:Glioma; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006822:Hybrid Cells / Q000737:chemistry* / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D009025:Morpholines / Q000378:metabolism* / Q000494:pharmacology; D009281:Naphthalenes / Q000378:metabolism* / Q000494:pharmacology; D009447:Neuroblastoma; D053284:Polyunsaturated Alkamides; D011869:Radioligand Assay; D051381:Rats; D017207:Rats, Sprague-Dawley; D043882:Receptors, Cannabinoid; D011955:Receptors, Drug / Q000819:agonists / Q000378:metabolism*; D012680:Sensitivity and Specificity; D014316:Tritium
D000700:Analgesics; D001095:Arachidonic Acids; D048588:Benzoxazines; D002121:Calcium Channel Blockers; D002186:Cannabinoids; D003511:Cyclohexanols; D063388:Endocannabinoids; D008565:Membrane Proteins; D009025:Morpholines; D009281:Naphthalenes; D053284:Polyunsaturated Alkamides; D043882:Receptors, Cannabinoid; D011955:Receptors, Drug; D014316:Tritium; D016244:Guanosine 5'-O-(3-Thiotriphosphate); 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; C078814:anandamide