title: Effects of kappa opioid agonists on the discriminative stimulus effects of cocaine in rhesus monkeys.
abstract: This study examined the effects of the kappa opioid agonists U50,488 and ethylketocyclazocine (EKC) on cocaine discrimination in rhesus monkeys trained to discriminate cocaine (0.4 mg/kg) from saline. Administration of U50,488 and EKC alone produced primarily saline-appropriate responding. Kappa agonist pretreatments produced variable effects on cocaine discrimination across monkeys, attenuating the discriminative stimulus effects of cocaine in some monkeys, but either having no effect on cocaine discrimination or enhancing the discriminative stimulus effects of cocaine in other monkeys. The effects of kappa agonists on cocaine discrimination were reversed by pretreatment with the opioid antagonist naloxone (1.0 mg/kg). These results indicate that kappa agonists do not consistently block the discriminative stimulus effects of cocaine in rhesus monkeys.
authors.affiliation: McLean Hospital--Harvard Medical School, Belmont, Massachusetts 02178, USA.
authors.forename: S S
authors.initials: SS
authors.lastname: Negus
authors.forename: N K
authors.initials: NK
authors.lastname: Mello
mesh_terms: D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer / Q000494:pharmacology; D000701:Analgesics, Opioid / Q000494:pharmacology; D000818:Animals; D003042:Cocaine / Q000494:pharmacology*; D004193:Discrimination Learning / Q000187:drug effects; D004192:Discrimination, Psychological / Q000187:drug effects*; D018492:Dopamine Antagonists / Q000494:pharmacology; D065127:Dopamine D2 Receptor Antagonists; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D016314:Ethylketocyclazocine / Q000494:pharmacology; D008253:Macaca mulatta; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D017473:Receptors, Opioid, kappa / Q000819:agonists*; D012457:Salicylamides / Q000494:pharmacology
chemical_list: D000701:Analgesics, Opioid; D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; D018765:Dopamine Uptake Inhibitors; D009292:Narcotic Antagonists; D017473:Receptors, Opioid, kappa; D012457:Salicylamides; D009270:Naloxone; D016314:Ethylketocyclazocine; D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D003042:Cocaine; C045989:eticlopride