Factors influencing flavour aversions conditioned with amphetamine in rats.

Rats would not drink distinctively flavoured solutions after their previous ingestion had been followed by injection of amphetamine (1 mg/kg). In the same rats, intake of flavoured solutions followed by saline injections was not suppressed. Providing the rats with cues as to the location of flavoured solutions paired with amphetamine did not alter either the speed of development or the final severity of the aversion. Neither increasing the interval between presentation of the flavour and injection of amphetamine, nor decreasing baseline drinking levels, altered the final degree of aversion. The aversion became progressively weaker as the dose of amphetamine was reduced, but it was detectable at doses as low as 0.1 mg/kg. Further decreases in dose did not enhance intake of flavours paired with amphetamine, even when combined with reductions in baseline drinking brought about by reduced fluid deprivation and flavour palatability. The results are discussed in relation to the conditions in which amphetamine has been shown to exhibit either rewarding or aversive properties.