Self administration of intravenous amphetamine is predicted by individual differences in sucrose feeding in rats

Rationale: Previous studies have shown that individual differences in oral sucrose consumption are predictive of the psychomotor and dopamine (DA) stimulant properties of amphetamine in rats. Objectives: The present experiment was designed to examine the relationship between sucrose feeding and the reinforcing properties of amphetamine using the intravenous (i.v.) drug self-administration paradigm, Methods: Based on a median split of sucrose intake during a final 1-h feeding test session, male Wistar rats were designated as either low (LSF) or high sucrose feeders (HSE). Acquisition of i.v.-amphetamine self-administration across ten daily 30-min sessions was then assessed. Following acquisition, i.v. self-administration of several doses of amphetamine was similarly tested across daily 30-min sessions. Results: Data from this experiment revealed augmented responding in HSF compared with LSF during acquisition of amphetamine self-administration. Correspondingly, when given access to different doses of amphetamine, responding was greater in HSF than in LSF across several doses (3 mu g and 10 mu g per infusion). Conclusions: These data support the notion that individual differences in oral sucrose consumption are predictive of the reinforcing properties of psychostimulant drugs.