Interference by a nonpharmacological factor on the action of psychoactive drugs in rats. A comparative study

The interaction of 5 psychoactive drugs (ethanol, chlorpromazine, diazepam, pentobarbital and THC) with a nonpharmacological factor was studied in rats. The nonpharmacological variable studied was the level of motivation to overcome the depressant action of the drugs administered. Rats highly motivated to perform a learned escape response (high intensity footshocks during training) required significantly higher doses of ethanol to become impaired when compared to low motivated animals (low intensity footshocks during training). However, the level of motivation did not interact with the action of the other 4 drugs, as the doses required to impair the escape response were the same in the low and high motivated rats. The greater susceptibility of ethanol to a nonpharmacological factor when compared to the other psychoactive drugs is discussed.