title: Oxycodone dose-dependently imparts conditioned reinforcing properties to discrete sensory stimuli in rats.
abstract: The aim of this study was to explore the psychopharmacological characteristics of opioid-induced conditioned reinforcement using oxycodone, a potent mu-opioid receptor agonist with known abuse potential. In differed groups of rats, passive intravenous infusions of oxycodone (100 infusions/3 h×6 sessions in total; 0, 0.01, 0.05 and 0.1 mg/kg/inf) were paired with an audio-visual stimulus and, subsequently, operant responding maintained by this conditioned stimulus was tested in extinction conditions. It was found that the oxycodone-paired stimulus maintained operant responding and that this effect was dependent on the number of conditioning sessions and on the conditioning dose. Responding maintained the oxycodone-paired stimulus could also be reinstated by both foot-shock stress and by oxycodone priming (0.25 mg/kg, SC). A conditioned place preference experiment (3 drug and 3 vehicle injections over 6 days; oxycodone: 0, 0.25, 2 and 5 mg/kg, SC) confirmed that stimuli associated with lower doses of oxycodone induce conditioned approach. Finally, two control experiments performed with chlordiazepoxide ruled out an interpretation of the oxycodone data based on drug-induced amnesia, and confirmed that operant responding for a drug-conditioned stimulus is observed only when the drug possesses unconditioned reinforcing properties. Therefore, the intravenous conditioned reinforcement procedure appears a useful method to study how opioid drugs impart reinforcing value to discrete environmental stimuli.
authors: Department of Psychology, University of Guelph, 50 Stone Rd. E., Guelph, ON, N1W 2G1, Canada.
authors: Stephanie L
authors: SL
authors: Grella
authors: AnneMarie
authors: A
authors: Levy
authors: Amanda
authors: A
authors: Campbell
authors: Shabdis
authors: S
authors: Djazayeri
authors: Craig P
authors: CP
authors: Allen
authors: Benjamin
authors: B
authors: Goddard
authors: Francesco
authors: F
authors: Leri
mesh_terms: D000818:Animals; D003216:Conditioning, Operant / Q000187:drug effects*; D008297:Male; D009294:Narcotics / Q000008:administration & dosage* / Q000494:pharmacology; D010098:Oxycodone / Q000008:administration & dosage* / Q000494:pharmacology; D011600:Psychopharmacology / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D012055:Reinforcement Schedule; D012054:Reinforcement, Psychology
chemical_list: D009294:Narcotics; D010098:Oxycodone