D2/D3 RECEPTOR AGONIST, QUINPIROLE, AND HIGH FAT DIET DECREASE FAT PREFERENCE IN RATS

Abstract

Long term exposure to a high fat diet can cause a persistent preference for a high fat diet even after a switch to a low fat diet (Teegarden, Scott, & Bale, 2009). High fat foods stimulate the release of the neurotransmitter dopamine, which activates the reinforcing areas in the brain (Martel, & Fantino, 1996). Long term exposure to a high fat diet will decrease dopamine levels and also significantly reduce the dopamine response to a low fat food, but will still elicit a significant dopamine increase to high fat foods (Geiger et al., 2009). However, rats will significantly prefer more low than high fat foods after administration of the dopamine D2/D3 agonist quinpirole (Cooper, & Al-Naser, 2006). The aim of the current research was to investigate how long term exposure to a high fat diet could cause an enduring preference for high fat foods and if quinpirole could dose-dependently decrease high fat food preference. High versus low fat food preference and total energy intake were assessed at a drug free baseline and four doses of quinpirole (0, 0.01, 0.05, 0.1 mg/kg s.c.) at two different test periods, and in each, intake was measured at 30, 60, 120 and 180 minutes. Thirteen male Sprague-Dawley rats were maintained on a high fat (HF) diet for 8 weeks (test #1) and then changed to a low fat diet for 6 weeks (test #2). Twelve rats were maintained on a low fat (LF) diet throughout the study. At test time #1 baseline, overall energy intake was lower in the HF group there were no diet group differences in fat preference. The 0.05 and 0.1 mg/kg doses decreased energy intake and fat preference in both groups. At test time #2 baseline, energy intake was similar in both groups, but the HF group had lower fat preference at 30-60 and 60-120 intervals. The 0.01, 0.05, and 0.1 mg/kg doses decreased energy intake and fat preference at test time #2 in both groups. These results support the role of a D2/D3 agonist in decreasing high fat preference and have implications for the impact food preference, dietary exposure and diet maintenance on long-term eating-related health issues.