Drug history overrides opioid reinforcement in a rat runway procedure.
To determine the effect of the drug history of rats on their subsequent operant behaviour in the rat runway procedure, we tested the mu opioid receptor agonists morphine and remifentanil and found a carryover of previous drug/saline experience that was not found for a food reinforcer. Previous exposure to saline significantly decreased the apparent reinforcing effect of subsequently offered morphine or remifentanil, while previous experience with morphine or remifentanil significantly increased responding for saline. This carryover of a previous learning experience on subsequent operant performance in the rat runway procedure cautions that the drug history should be considered and might even invalidate subsequent findings when testing drugs of abuse or other reinforcers.
Wakonigg
Gudrun
G
Division of Neurochemistry, Department of Psychiatry, Medical University of Innsbruck, Austria.
Sturm
Katja
K
Saria
Alois
A
Zernig
Gerald
G
D000818:Animals; D003216:Conditioning, Operant / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005283:Fentanyl / Q000494:pharmacology; D005502:Food; D007275:Injections, Intravenous; D008297:Male; D009020:Morphine / Q000494:pharmacology; D009294:Narcotics / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012054:Reinforcement, Psychology
D009294:Narcotics; D009020:Morphine; D005283:Fentanyl