Effects of d-amphetamine and of diazepam on non-punished and punished schedule-induced drinking in rats

Drinking induced in food-deprived rats by a Fixed-Time 1min schedule of food presentation was measured by the amount of water consumed per session and the number of licks per inter-food interval. Subsequently each lick initiated a 10-sec signalled delay in the delivery of food, which led to a decrease in drinking (punishment). With three rats the effects of d-amphetamine (0.25, 0.5, 1.0, 2.0mg/kg) were assessed on non-punished and then on punished drinking. With another three rats, the effects of diazepam (0.5, 1.0, 2.0, 4.0mg/kg) were assessed. The smaller doses of d-amphetamine had no consistent effect on overall measures of non-punished schedule-induced drinking, but the largest dose decreased them. With the signalled delay d-amphetamine increased punished schedule-induced drinking. Non-punished drinking was increased by small doses of diazepam and decreased by the largest dose, but no dose of diazepam affected punished drinking.