Cannabinoid receptor stimulation of guanosine-5'-O-(3-[35S]thio)triphosphate binding in rat brain membranes.
Cannabinoid receptors belong to the class of G-protein-coupled receptors which inhibit adenylyl cyclase. Coupling of receptors to G-proteins can be assessed by the ability of agonists to stimulate guanosine-5'-O-(3-[35S]thio)triphosphate ([35S]GTP gamma S) binding in the presence of excess GDP. The present study examined the effect of cannabinoid agonists on [35S]GTP gamma S binding in rat brain membranes. Assays were conducted with 0.05 nM [35S]GTP gamma S, incubated with rat cerebellar membranes, 1-30 microM GDP and the cannabinoid agonist WIN 55212-2. Results showed that the ability of WIN 55212-2 to stimulate [35S]GTP gamma S binding increased with increasing concentrations of GDP, with 10-30 microM GDP providing approximately 150-200% stimulation by the cannabinoid agonist. The pharmacology of cannabinoid agonist stimulation of [35S]GTP gamma S binding paralleled that of previously reported receptor binding and adenylyl cyclase assays, and agonist stimulation of [35S]GTP gamma S binding was blocked by the cannabinoid antagonist SR141716A. Brain regional studies revealed widespread stimulation of [35S]GTP gamma S binding by WIN 55212-2 in a number of brain areas, consistent with in vitro [35S]GTP gamma S autoradiography. These results demonstrate that [35S]GTP gamma S binding in the presence of excess GDP is an effective measure of cannabinoid receptor coupling to G-proteins in brain membranes.
Selley
D E
DE
Department of Physiology and Pharmacology, Bowman Gray School of Medicine, Winston-Salem, NC 27157, USA.
Stark
S
S
Sim
L J
LJ
Childers
S R
SR
D000818:Animals; D001345:Autoradiography; D048588:Benzoxazines; D001665:Binding Sites; D002186:Cannabinoids / Q000819:agonists / Q000378:metabolism / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism; D002531:Cerebellum / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D009025:Morpholines / Q000494:pharmacology; D009281:Naphthalenes / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D043882:Receptors, Cannabinoid; D011955:Receptors, Drug / Q000187:drug effects / Q000502:physiology*; D013462:Sulfur Radioisotopes
D048588:Benzoxazines; D002186:Cannabinoids; D009025:Morpholines; D009281:Naphthalenes; D043882:Receptors, Cannabinoid; D011955:Receptors, Drug; D013462:Sulfur Radioisotopes; D006153:Guanosine Diphosphate; 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; D019204:GTP-Binding Proteins