Taste sensitivity to 6-n-propylthiouracil is associated with endocannabinoid plasma levels in normal-weight individuals

Objective: Reduced sensitivity to 6-n-propylthiouracil (PROP) has been shown to be associated with increased energy intake and therefore increased BMI, while other studies did not confirm this association, suggesting the involvement of other factors. We investigated whether the endocannabinoid system, which also modulates hunger/satiety and energy balance, plays a role in modulating eating behavior influenced by sensitivity to PROP. Methods: The plasma profile of the endocannabinoids 2-arachidonoylglycerol (2-AG), anandamide (AEA) and congeners of the latter, palmitoylethanolamide (PEA) and oleylethanolamide (OEA), was determined in normal-weight PROP super-tasters (ST) and PROP non-tasters (NT). Cognitive eating behavior disorder was assessed by the Three-Factor Eating Questionnaire (TFEQ), which estimates dietary restraint, disinhibition and perceived hunger. Results: Disinhibition score of NT was higher than those of ST (P = 0.02). Moreover, in NT, OEA was inversely correlated to the perceived hunger score (r = -0.7; P = 0.002), and AEA was positively correlated to restraint score (r = 0.5; P = 0.04) and negatively to perceived hunger score, although the latter correlation was at the limit of statistical significance (r = -0.47; P = 0.05). In addition, we found lower concentrations of AEA and 2-AG in the plasma of NT compared to ST subjects (AEA: P = 0.034; 2-AG: P = 0.003). Conclusions: Our data suggest that higher dishinibition behavior in NT may be partly compensated, in normal-weight subjects, by the reduction of peripheral endocannabinoids in order to downregulate the hunger-energy intake circuitry.