Figure 1.

Schematic representation of the timeline of the study. Briefly, rats were trained to nose-poke respond to obtain 45 mg pellets of a standard chow diet under a fixed-ratio 1 (FR1) schedule of reinforcement for 14 days. Upon stabilization of responding, rats were matched and subdivided into three experimental groups: one set (10 rats) was assigned to a chow group (Chow) and received the same 45 mg pellets received in the training phase; a second set (10 rats) was assigned to a high-sucrose diet (HSD) group and received high-sucrose 45 mg pellets; a third set (10 rats) was assigned to a high-fat diet (HFD) group and received high-fat 45 mg pellets. Testing lasted 21 days.