title: Effects of delta 9-tetrahydrocannabinol on glucagon receptor coupling to adenylate cyclase in rat liver plasma membranes.
abstract: Delta-Tetrahydrocannabinol (delta 9-THC), the principal psychoactive constituent of Cannabis sativa, was found to increase glucagon activation of liver plasma membrane adenylate cyclase. In the presence of 30 microM delta 9-THC, the EC50 for glucagon was decreased by 60% from 7.6nM to 3.1 nM. 11-OH-delta 9-THC, a psychoactive metabolite of delta 9-THC, also increased glucagon activation of adenylate cyclase while two cannabinoids without marihuana-like psychoactive potency, cannabinol and cannabidiol, did not. At 30 microM, delta 9-THC either slightly decreased or had no effect on the activation of adenylate cyclase by GTP, Gpp(NH)p, fluoride ion, forskolin or ATP alone. Delta 9-THC had no effect on the binding of [125I] glucagon to liver plasma membranes. Arrhenius plots demonstrated that delta 9-THC and 11-OH-delta 9-THC, but not CBD, decreased the activation energy above the break temperature. Therefore, delta 9-THC increased the coupling of the glucagon receptor to adenylate cyclase apparently by removing a constraint on receptor-Ns coupling.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D002186:Cannabinoids / Q000494:pharmacology; D002462:Cell Membrane / Q000201:enzymology; D005576:Colforsin / Q000494:pharmacology; D013759:Dronabinol / Q000494:pharmacology*; D005934:Glucagon / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000494:pharmacology; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D007700:Kinetics; D008099:Liver / Q000166:cytology / Q000201:enzymology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018027:Receptors, Glucagon; D012969:Sodium Fluoride / Q000494:pharmacology
chemical_list: D002186:Cannabinoids; D011956:Receptors, Cell Surface; D018027:Receptors, Glucagon; D005576:Colforsin; D006165:Guanylyl Imidodiphosphate; D013759:Dronabinol; D006160:Guanosine Triphosphate; D012969:Sodium Fluoride; D005934:Glucagon; D000262:Adenylyl Cyclases