title: Pharmacological activation of kappa opioid receptors: aversive effects in adolescent and adult male rats.
abstract: BACKGROUND
  The dynorphin (DYN)/kappa opioid receptor (KOR) system is involved in the dysphoric properties of drugs of abuse. Given that adolescents show reduced sensitivity to aversive effects of many drugs, alterations in the DYN/KOR system may contribute to the prevalence of drug use during adolescence.
  
  
  OBJECTIVE
  The present study was designed to assess dysphoric properties of a selective kappa agonist, U62,066, in adolescent and adult rats using both conditioned taste aversion (CTA) and conditioned place aversion (CPA) paradigms.
  
  
  METHODS
  For CTA, water-restricted rats were administered U62,066 following 30 min access to a saccharin solution, with subsequent saccharin consumption used to index aversion. For CPA, animals were allowed access to both compartments of a two-compartment chamber for a 15-min pre- and post-conditioning test. For conditioning, subjects were administered U62,066 prior to confinement to one side of the chamber and saline prior to confinement to the other side for a total of four pairings.
  
  
  RESULTS
  Overall, adolescents displayed reduced sensitivity to the kappa agonist relative to adults. Adults demonstrated taste aversions to the 0.2 and 0.3 mg/kg doses of U62,066, whereas adolescents did not display aversions to any tested doses. Adults demonstrated a place aversion to the 0.1 and 0.2 mg/kg dose of U62,066 when paired with the preferred side of the conditioning chamber. Adolescents did not display aversions to any of the doses tested.
  
  
  CONCLUSIONS
  Reduced sensitivity to DYN/KOR system activation during adolescence may be a contributing factor to the age-typical insensitivity to aversive properties of drugs commonly abused by adolescents.
authors.affiliation: Center for Development and Behavioral Neuroscience, Department of Psychology, Binghamton University, 4400 Vestal Parkway East, Binghamton, NY, 13902-6000, USA, randers1@binghamton.edu.
authors.forename: Rachel I
authors.initials: RI
authors.lastname: Anderson
authors.forename: Melissa
authors.initials: M
authors.lastname: Morales
authors.forename: Linda P
authors.initials: LP
authors.lastname: Spear
authors.forename: Elena I
authors.initials: EI
authors.lastname: Varlinskaya
mesh_terms: D000375:Aging; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects* / Q000502:physiology*; D003213:Conditioning, Psychological / Q000187:drug effects* / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D008297:Male; D009294:Narcotics / Q000494:pharmacology; D011759:Pyrrolidines / Q000494:pharmacology*; D017207:Rats, Sprague-Dawley; D017473:Receptors, Opioid, kappa / Q000819:agonists* / Q000378:metabolism; D012439:Saccharin / Q000008:administration & dosage; D013028:Space Perception / Q000187:drug effects / Q000502:physiology; D055697:Taste Perception / Q000187:drug effects / Q000502:physiology
chemical_list: D009294:Narcotics; D011759:Pyrrolidines; D017473:Receptors, Opioid, kappa; D012439:Saccharin; C051272:spiradoline