Discriminative stimulus effects of diazepam, ketamine and their mixture: Ethanol substitution patterns

Y. E. Harrison, J. A. Jenkins, B. A. Rocha, D. A. Lytle, Eunsun Jung, Michael Oglesby

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

When ethanol is used as a training stimulus in drug discrimination experiments, benzodiazepines (such as diazepam) as well as non-competitive N-methyl-D-aspartate (NMDA) antagonists (such as ketamine) substitute for ethanol; in contrast, when a benzodiazepine or an NMDA antagonist is used as a training drug, ethanol does not substitute reliably. In the present experiments, we trained rats to discriminate a mixture of diazepam and ketamine, to test the hypothesis that ethanol would substitute for this drug combination. Using a two-lever choice procedure with food as a reinforcer, 22 rats were trained to discriminate a mixture of diazepam (5.6 mg/kg) and ketamine (10 mg/kg) from vehicle. When administered as a mixture, diazepam and ketamine substituted for the training mixture in a dose-dependent manner. When administered separately, diazepam or ketamine substituted for the mixture with full substitution occurring at 5.6 and 17.8 mg/kg, respectively. Ethanol almost completely substituted for the mixture at 1 g/kg. There was no cross-substitution between diazepam and ketamine in rats trained to discriminate diazepam (5.6 mg/kg, n = 10) or ketamine (10 mg/kg, n = 12) from vehicle. In addition, ethanol did not substitute for the training drug in either of these discriminations. These results suggest that the simultaneous action of GABA(A) agonist and NMDA antagonist mechanisms produce a greater ethanol-specific discriminative stimulus than activation of either component individually.

Original languageEnglish
Pages (from-to)31-40
Number of pages10
JournalBehavioural Pharmacology
Volume9
Issue number1
StatePublished - 18 Mar 1998

Fingerprint

Ketamine
Diazepam
Ethanol
N-Methylaspartate
Benzodiazepines
Pharmaceutical Preparations
GABA-A Receptor Agonists
Drug Combinations
Food

Keywords

  • Chloridazepoxide
  • Diazepam
  • Dizocilpine
  • Drug discrimination
  • Drug mixtures
  • Ethanol
  • Ketamine
  • Morphine
  • Pentobarbital
  • Rat

Cite this

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title = "Discriminative stimulus effects of diazepam, ketamine and their mixture: Ethanol substitution patterns",
abstract = "When ethanol is used as a training stimulus in drug discrimination experiments, benzodiazepines (such as diazepam) as well as non-competitive N-methyl-D-aspartate (NMDA) antagonists (such as ketamine) substitute for ethanol; in contrast, when a benzodiazepine or an NMDA antagonist is used as a training drug, ethanol does not substitute reliably. In the present experiments, we trained rats to discriminate a mixture of diazepam and ketamine, to test the hypothesis that ethanol would substitute for this drug combination. Using a two-lever choice procedure with food as a reinforcer, 22 rats were trained to discriminate a mixture of diazepam (5.6 mg/kg) and ketamine (10 mg/kg) from vehicle. When administered as a mixture, diazepam and ketamine substituted for the training mixture in a dose-dependent manner. When administered separately, diazepam or ketamine substituted for the mixture with full substitution occurring at 5.6 and 17.8 mg/kg, respectively. Ethanol almost completely substituted for the mixture at 1 g/kg. There was no cross-substitution between diazepam and ketamine in rats trained to discriminate diazepam (5.6 mg/kg, n = 10) or ketamine (10 mg/kg, n = 12) from vehicle. In addition, ethanol did not substitute for the training drug in either of these discriminations. These results suggest that the simultaneous action of GABA(A) agonist and NMDA antagonist mechanisms produce a greater ethanol-specific discriminative stimulus than activation of either component individually.",
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Discriminative stimulus effects of diazepam, ketamine and their mixture : Ethanol substitution patterns. / Harrison, Y. E.; Jenkins, J. A.; Rocha, B. A.; Lytle, D. A.; Jung, Eunsun; Oglesby, Michael.

In: Behavioural Pharmacology, Vol. 9, No. 1, 18.03.1998, p. 31-40.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Discriminative stimulus effects of diazepam, ketamine and their mixture

T2 - Ethanol substitution patterns

AU - Harrison, Y. E.

AU - Jenkins, J. A.

AU - Rocha, B. A.

AU - Lytle, D. A.

AU - Jung, Eunsun

AU - Oglesby, Michael

PY - 1998/3/18

Y1 - 1998/3/18

N2 - When ethanol is used as a training stimulus in drug discrimination experiments, benzodiazepines (such as diazepam) as well as non-competitive N-methyl-D-aspartate (NMDA) antagonists (such as ketamine) substitute for ethanol; in contrast, when a benzodiazepine or an NMDA antagonist is used as a training drug, ethanol does not substitute reliably. In the present experiments, we trained rats to discriminate a mixture of diazepam and ketamine, to test the hypothesis that ethanol would substitute for this drug combination. Using a two-lever choice procedure with food as a reinforcer, 22 rats were trained to discriminate a mixture of diazepam (5.6 mg/kg) and ketamine (10 mg/kg) from vehicle. When administered as a mixture, diazepam and ketamine substituted for the training mixture in a dose-dependent manner. When administered separately, diazepam or ketamine substituted for the mixture with full substitution occurring at 5.6 and 17.8 mg/kg, respectively. Ethanol almost completely substituted for the mixture at 1 g/kg. There was no cross-substitution between diazepam and ketamine in rats trained to discriminate diazepam (5.6 mg/kg, n = 10) or ketamine (10 mg/kg, n = 12) from vehicle. In addition, ethanol did not substitute for the training drug in either of these discriminations. These results suggest that the simultaneous action of GABA(A) agonist and NMDA antagonist mechanisms produce a greater ethanol-specific discriminative stimulus than activation of either component individually.

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KW - Dizocilpine

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KW - Ethanol

KW - Ketamine

KW - Morphine

KW - Pentobarbital

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