Stimulus properties of nicotine, amphetamine, and chlordiazepoxide as positive features in a pavlovian appetitive discrimination task in rats

Matthew I. Palmatier, Jamie L. Wilkinson, Dawn M. Metschke, Rick A Bevins

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33 Scopus citations

Abstract

Recent experiments from our laboratory have demonstrated that drug states can signal when environmental cues will be followed by rewarding outcomes (ie Pavlovian conditioning). However, little is known about the generality of this approach and whether it can be used for studying the pharmacological properties of drug states. Accordingly, the present experiments tested the pharmacological specificity of nicotine (0.4 mg/kg), amphetamine (1 mg/kg), and chlordiazepoxide (CDP, 5 mg/kg) in this Pavlovian drug discrimination procedure. Following drug administration, presentation of a conditional stimulus (CS) was followed by brief access to sucrose. When saline was administered, the same CS was presented but sucrose was withheld. In substitution tests, rats in each condition received varying doses of all training drugs and caffeine. Anticipatory food seeking developed during the CS on drug sessions but not on saline sessions for all drug features (ie drug state-specific conditional response (CR)). In generalization tests, this CR decreased as a function of decreases in the training dose. Median effective doses (ED50s) were calculated for nicotine (0.054 mg/kg), amphetamine (0.26 mg/kg), and CDP (2.48 mg/kg). No compound tested substituted for the CDP training drug. Partial substitution was evident between nicotine and amphetamine; CDP did not substitute for either of these drug features. Caffeine fully substituted for nicotine (ED50 = 15.45 mg/kg) and amphetamine (ED50 = 3.70 mg/kg), but not for CDP. These results are consistent with the hypothesis that drug states can occasion appetitive Pavlovian CRs in a pharmacologically specific manner.

Original languageEnglish (US)
Pages (from-to)731-741
Number of pages11
JournalNeuropsychopharmacology
Volume30
Issue number4
DOIs
StatePublished - Apr 1 2005

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Keywords

  • Abused drugs
  • Appetitive
  • Benzodiazepine
  • Drug discrimination
  • Generalization
  • Reward learning

ASJC Scopus subject areas

  • Pharmacology
  • Psychiatry and Mental health

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