title: Repeated stress exposure causes strain-dependent shifts in the behavioral economics of cocaine in rats.
abstract: Cocaine-experienced Wistar and Wistar Kyoto (WKY) rats received four daily repeated forced swim stress sessions (R-FSS), each of which preceded 4-hour cocaine self-administration sessions. Twenty-four hours after the last swim stress, cocaine valuation was assessed during a single-session threshold procedure. Prior exposure to R-FSS significantly altered cocaine responding in Wistar, but not WKY, rats. Behavioral economic analysis of responding revealed that the Wistar rats that had received R-FSS exhibited an increase in the maximum price that they were willing to pay for cocaine (Pmax ). Pre-treatment with the long-lasting kappa opioid receptor (KOR) antagonist norbinaltorphimine prevented the stress-induced increase in Pmax . Thus, R-FSS exposure had strain-dependent effects on cocaine responding during the threshold procedure, and the stress effects on cocaine valuation exhibited by Wistar, but not WKY, required intact KOR signaling.
authors.affiliation: Department of Pharmacology, University of Washington, Seattle, WA, USA.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Groblewski
authors.forename: Chad
authors.initials: C
authors.lastname: Zietz
authors.forename: Ingo
authors.initials: I
authors.lastname: Willuhn
authors.forename: Paul E M
authors.initials: PE
authors.lastname: Phillips
authors.forename: Charles
authors.initials: C
authors.lastname: Chavkin
mesh_terms: D000818:Animals; D003042:Cocaine / Q000008:administration & dosage*; D018765:Dopamine Uptake Inhibitors / Q000008:administration & dosage*; D058999:Drug-Seeking Behavior / Q000187:drug effects / Q000502:physiology*; D060909:Economics, Behavioral; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D051381:Rats; D011921:Rats, Inbred WKY; D017208:Rats, Wistar; D012646:Self Administration; D013315:Stress, Psychological / Q000503:physiopathology*; D013550:Swimming
chemical_list: D018765:Dopamine Uptake Inhibitors; D009292:Narcotic Antagonists; C051844:norbinaltorphimine; D009271:Naltrexone; D003042:Cocaine
keywords: Addiction; cocaine; kappa opioid receptor; self-administration; stress