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  • 1
    ISSN: 1432-2072
    Keywords: Fentanyl ; Morphine ; Narcotic cue ; Sensitivity ; Oscillation ; Drug discrimination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract With a discrete-trial, food-reward, two-lever procedure, rats were trained to discriminate 0.04 mg/kg fentanyl from saline. Individual threshold doses for seneralization of fentanyl and for cross-generalization of morphine were determined repeatedly during a 17-week posttraining period. Threshold doses of both drugs almost continuously shifted in both the up- and downward direction. Shifts of fentanyl threshold doses covaried with those of morphine threshold doses. These shifts can best be described by a sustained oscillation, the mean amplitude of which amounts to a factor 3.65 of the dose-range for fentanyl, and to a factor 1.85 for morphine. The upper and lower limits of oscillation were symmetrical with respect to baseline. The oscillation can be described by a function expressing that the more distant a point along the function is from the baseline, the more it is susceptible to (positive/negative) acceleration along the intensity (i.e., dose) axis.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2072
    Keywords: Fentanyl ; Narcotic cue ; Analgesia ; Drug discrimination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract By using a discrete-trial, two-lever, food-reinforced discrimination learning paradigm, rats were trained to discriminate the narcotic analgesic fentanyl (0.04 mg/kg) from saline. Stimulus generalization experiments with lower fentanyl doses (0.0025 to 0.02 mg/kg) were carried out to generate individual threshold doses. The latter were compared with the sensitivity of the same rats to the analgesic effect of fentanyl, and it was found that there is no correlation between these two sets of data. In a time-effect experiment, the duration of fentanyl's cuing effect was compared with that of its analgesic effect, and it was found that the time-effect characteristics of the narcotic cue are similar to those of analgesia. Again, however, there was no correlation between the duration of both effects within the same group of animals. The results further deliniate the associative and dissociative characteristics of the narcotic cue and narcotic analgesia.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2072
    Keywords: Haloperidol ; Fentanyl ; Drug discrimination ; Narcotic cue ; Discrimination index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Using a discrete-trial, two-lever, foodreward discrimination learning paradigm, we trained rats (n=6) to discriminate 0.04 mg/kg fentanyl (s.c. t-30′) from saline. Stimulus generalization experiments with an adequate dose range (0.01–0.04 mg/kg) of fentanyl revealed that the ED50 value for drug lever selection is 0.02 mg/kg, irrespective of whether the animals were pretreated (s.c., t-60′) with either saline or 0.08 mg/kg haloperidol. With increasing doses of the haloperidol-fentanyl combination, the percentage of total responding on the selected lever progressively decreased, and reached the 50% level at the highest drug combination. It is concluded that this percentage is heavily contaminated by factors unrelated to the discrimination condition being studied; these factors seem to invalidate this percentage as a discrimination index under experimental conditions (e.g., behaviorally toxic doses of drugs) where they are likely to operate. The use of response selection as a discrimination index in drug discrimination research is further argued.
    Type of Medium: Electronic Resource
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