title: Between-session progressive ratio performance in rats responding for cocaine and water reinforcers.
abstract: BACKGROUND
  A between-session progressive ratio (BtwPR) procedure was tested in rats responding for cocaine and water reinforcers.
  
  
  OBJECTIVE
  Experiment 1 evaluated the sensitivity of the BtwPR procedure to the magnitude of cocaine and water reinforcers. Experiment 2 compared BtwPR performance to within-session progressive ratio (WinPR) performance.
  
  
  METHODS
  In experiment 1, rats were tested on a BtwPR procedure with three doses of cocaine (0.1, 0.3, and 1.0 mg/kg/inf) or volumes of water (0.01, 0.03, and 0.1 mL/reinforcer). BtwPR test sessions began with a seeking phase, during which the animal is required to complete a fixed ratio in order to initiate a 2-h consumption phase, where the reinforcer was available according to a fixed ratio 1 (FR1) schedule. Failure to complete the seeking ratio, which was increased after each test session, determined the breakpoint (BP). In experiment 2, the same BtwPR procedure was used except that the consumption phase was a WinPR schedule of reinforcement for cocaine (1.0 mg/kg/inf) or water (0.1 mL) reinforcers.
  
  
  CONCLUSIONS
  BtwPR BPs increased as a function of the magnitude of both cocaine and water reinforcers. The BtwPR produced smaller BPs than the WinPR for cocaine reinforcers. In contrast, the BtwPR produced larger BPs than the WinPR for water reinforcers. One possible explanation is that priming and response activating effects of the cocaine reinforcer increased the WinPR BP. BtwPR and WinPR procedures may measure different aspects of drug-seeking.
authors.affiliation: Research Institute on Addictions, University at Buffalo, 1021 Main St, Buffalo, NY 14203, USA. agancarz@ria.buffalo.edu
authors.forename: Amy M
authors.initials: AM
authors.lastname: Gancarz
authors.forename: Michael A
authors.initials: MA
authors.lastname: Kausch
authors.forename: David R
authors.initials: DR
authors.lastname: Lloyd
authors.forename: Jerry B
authors.initials: JB
authors.lastname: Richards
mesh_terms: D000818:Animals; D003042:Cocaine / Q000008:administration & dosage*; D003216:Conditioning, Operant / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012055:Reinforcement Schedule; D012646:Self Administration; D014867:Water / Q000008:administration & dosage*
chemical_list: D014867:Water; D003042:Cocaine