Renewal of sucrose-seeking behavior in rats: Role of D2 dopamine receptors

The present study characterized renewal of sucrose-seeking behavior in rats (Experiment 1). The role of the dopamine subtype-2 (D2) receptors in mediating renewal of sucrose-seeking behavior also was examined (Experiment 2). Rats were trained to respond for sucrose pellets (45 mg each) on a fixed-ratio 25 (Experiments 1 and 2) schedule of reinforcement in Context A. Following acquisition, rats underwent extinction and 4 renewal tests in Contexts B and A, respectively. In Experiment 2, rats were pretreated with vehicle or the D2 dopamine receptor antagonist eticlopride (5, 10, 20, or 40 μg/kg) 30 min prior to the first renewal test session. A follow-up experiment (Experiment 3) examined the effect of a high eticlopride dose (40 μg/kg) on locomotor activity. Renewal of sucrose-seeking behavior persisted for 3 sessions. Eticlopride dose-dependently blocked renewal of sucrose-seeking behavior without suppressing locomotor activity, implicating a role of D2 dopamine receptors in mediating renewal of sucrose-seeking behavior.

Research highlights
► Training on an FR 25 schedule produced robust renewal of sucrose-seeking behavior
► Renewal of sucrose-seeking behavior persisted for 3 sessions
► Response and latency measures differentially detected persistence of renewal
► Eticlopride dose-dependently blocked renewal of sucrose-seeking behavior
► The high eticlopride dose (40 μg/kg) did not reliably decrease locomotor activity