title: Involvement of Raf-1 in chronic delta-opioid receptor agonist-mediated adenylyl cyclase superactivation.
abstract: Chronic delta-opioid receptor agonist treatment of Chinese hamster ovary (CHO) cells stably expressing the human delta-opioid receptor (hDOR/CHO) leads to increased cAMP formation after the removal of the agonist (adenylyl cyclase superactivation). We have previously found that at the same time, chronic delta-opioid receptor agonist treatment augments phosphorylation of the adenylyl cyclase VI isoenzyme. Since phosphorylation of adenylyl cyclase VI by Raf-1 protein kinase was recently shown, we tested the role of Raf-1 in adenylyl cyclase superactivation in hDOR/CHO cells. We found that pretreatment of the cells with the selective Raf-1 inhibitor GW5074 (3-(3,5-dibromo-4-hydroxybenzylidene-5-iodo-1,3-dihydro-indol-2-one) (10 microM, 30 min) attenuates chronic deltorphin II-mediated increase in forskolin-stimulated cAMP formation by 40% (n = 6, P < 0.05). Better understanding of the molecular mechanism of adenylyl cyclase superactivation should aid in the development of analgesics that act longer and have fewer side effects.
authors.affiliation: Department of Pharmacology and the Sarver Heart Center, College of Medicine, The University of Arizona Health Sciences Center, Tucson 85724, USA.
authors.forename: Eva V
authors.initials: EV
authors.lastname: Varga
authors.forename: Marc
authors.initials: M
authors.lastname: Rubenzik
authors.forename: Vanessa
authors.initials: V
authors.lastname: Grife
authors.forename: Masano
authors.initials: M
authors.lastname: Sugiyama
authors.forename: Dagmar
authors.initials: D
authors.lastname: Stropova
authors.forename: William R
authors.initials: WR
authors.lastname: Roeske
authors.forename: Henry I
authors.initials: HI
authors.lastname: Yamamura
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D016466:CHO Cells; D005576:Colforsin / Q000494:pharmacology*; D006224:Cricetinae; D004789:Enzyme Activation; D019908:Proto-Oncogene Proteins c-raf / Q000037:antagonists & inhibitors*; D017465:Receptors, Opioid, delta / Q000819:agonists*
chemical_list: D017465:Receptors, Opioid, delta; D005576:Colforsin; D019908:Proto-Oncogene Proteins c-raf; D000262:Adenylyl Cyclases