title: Buprenorphine-elicited alteration of adenylate cyclase activity in human embryonic kidney 293 cells coexpressing κ-, μ-opioid and nociceptin receptors.
abstract: Buprenorphine, a maintenance drug for heroin addicts, exerts its pharmacological function via κ- (KOP), μ-opioid (MOP) and nociceptin/opioid receptor-like 1 (NOP) receptors. Previously, we investigated its effects in an in vitro model expressing human MOP and NOP receptors individually or simultaneously (MOP, NOP, and MOP+NOP) in human embryonic kidney 293 cells. Here, we expanded this cell model by expressing human KOP, MOP and NOP receptors individually or simultaneously (KOP, KOP+MOP, KOP+NOP and KOP+MOP+NOP). Radioligand binding with tritium-labelled diprenorphine confirmed the expression of KOP receptors. Immunoblotting and immunocytochemistry indicated that the expressed KOP, MOP and NOP receptors are N-linked glycoproteins and colocalized in cytoplasmic compartments. Acute application of the opioid receptor agonists- U-69593, DAMGO and nociceptin- inhibited adenylate cyclase (AC) activity in cells expressing KOP, MOP and NOP receptors respectively. Buprenorphine, when applied acutely, inhibited AC activity to ~90% in cells expressing KOP+MOP+NOP receptors. Chronic exposure to buprenorphine induced concentration-dependent AC superactivation in cells expressing KOP+NOP receptors, and the level of this superactivation was even higher in KOP+MOP+NOP-expressing cells. Our study demonstrated that MOP receptor could enhance AC regulation in the presence of coexpressed KOP and NOP receptors, and NOP receptor is essential for concentration-dependent AC superactivation elicited by chronic buprenorphine exposure.
authors.affiliation: Neuropsychiatric Center, National Health Research Institutes, Miaoli County, Taiwan.
authors.forename: Pei-Chen
authors.initials: PC
authors.lastname: Wang
authors.affiliation: Neuropsychiatric Center, National Health Research Institutes, Miaoli County, Taiwan.|Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan.|Center for Drug Abuse and Addiction, China Medical University Hospital, Taichung, Taiwan.
authors.forename: Ing-Kang
authors.initials: IK
authors.lastname: Ho
authors.affiliation: Center for Drug Abuse and Addiction, China Medical University Hospital, Taichung, Taiwan.|China Medical University, Taichung, Taiwan.
authors.forename: Cynthia Wei-Sheng
authors.initials: CW
authors.lastname: Lee
mesh_terms: D000067956:Adenylyl Cyclase Inhibitors / Q000494:pharmacology; D000262:Adenylyl Cyclases / Q000378:metabolism*; D000701:Analgesics, Opioid / Q000494:pharmacology*; D002047:Buprenorphine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D057809:HEK293 Cells; D006801:Humans; D007158:Immunologic Techniques; D017473:Receptors, Opioid, kappa / Q000096:biosynthesis*; D017450:Receptors, Opioid, mu / Q000096:biosynthesis*
chemical_list: D000067956:Adenylyl Cyclase Inhibitors; D000701:Analgesics, Opioid; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D002047:Buprenorphine; D000262:Adenylyl Cyclases
keywords: adenylate cyclase activity; buprenorphine; opioid receptors