Amphetamine and some relate compounds were compared in rats trained to discriminate (+)-amphetamine (0.4, 1.0 or 1.6 mg/kg) or cocaine (10.0 mg/kg) from the non drug condition in a standard, two-bar procedure with food reinforcement (n=5-6). Amphetamine and cocaine were generalized completely with each other, in most cases at dose levels which did not greatly reduce the overall numbers of responses. The ED50 values for amphetamine and cocaine varied with the drug and dose used for training, and it was concluded that the stimuli produced by the two drugs were similar but may not be identical. There was an excellent correlation between ED50 values derived from indices of bar selection and percentage-responding on the drug-appropriate bar. Apomorphine was generalized with amphetamine only in the rats trained with the higher doses of amphetamine, and only when administered in doses which greatly reduced the overall number of responses. Para-hydroxyamphetamine increased responding on the drug-appropriate bar only when administered in high doses to the rats trained with the lowest dose of amphetamine (0.4 mg/kg). The results strengthen the evidence that the particular drug and dose level used for training can significantly affect the outcome of generalization tests, and challenge the notion that the discriminability of drugs is an immutable property that is amenable to absolute measurement.

Two antiemetic drugs were tested on the expression of taste aversions previously conditioned in rats with lithium, amphetamine or morphine. Neither prochlorperazine nor scopolamine administered prior to testing attenuated established aversions, although both drugs are known to have antiemetic effects in other species. Negative findings were obtained with a range of dose of prochlorperazine and scopolamine, with strong and weak aversions, with one- and two-stimulus tests, in a repeated one-stimulus extinction procedure, with between- and within-group designs and with hooded, albino, male and female rats. The results do not support the widely accepted hypothesis that conditioned nausea mediates conditioned taste aversion.

No abstract

No abstract

Rats failed to drink a flavoured solution when its consumption had been followed by injection of amphetamine (conditioned taste aversion). There was very little difference between the potencies of (+)‐ and (‐)‐amphetamine. p‐Chloromethamphetamine was a more potent aversive agent than methamphetamine. Strong taste aversions were also conditioned with other congeners of amphetamine. The rank order of potency was: fenfluramine > chlorphentermine >p‐hydroxyamphetamine. Cocaine induced only moderate taste aversions, even at high doses. Aversive potency did not appear to be correlated with known neurochemical actions of the drugs or with behavioural stimulation, but appeared to be a central action which may have been linked to anorexigenic potency or time course of action.