High Trait Impulsivity Predicts Food Addiction‐Like Behavior in the Rat

Abstract

Impulsivity is a behavioral trait frequently seen in drug addicted individuals and individuals who pathologically overeat. In this study, we hypothesized that high impulsivity precedes and confers vulnerability for food addiction-like behavior. For this purpose we trained rats in a differential reinforcement of low rates of responding (DRL) task to select high- and low-impulsive rats. These rats then self-administered a highly palatable diet (Palatable group) or a regular chow diet (Chow group) in 1h daily sessions, under increasing fixed ratio (FR) and a progressive ratio (PR) schedule of reinforcement. In addition, we tested the compulsiveness for food by measuring the food eaten in the aversive, open compartment of a light/dark conflict test. Finally, we measured the expression of the transcription factor ΔFosB in the shell and the core of the nucleus accumbens which is a marker for neuroadaptive changes following addictive drug exposure. The data we obtained demonstrate that impulsivity is a trait which predicts the development of food addiction-like behaviors, including: i) excessive intake, ii) heightened motivation for food, and iii) compulsive-like eating, when rats are given access to highly palatable food. In addition, we show that the food addiction phenotype in high impulsive subjects is characterized by an increased expression of the transcription factor ΔFosB in the nucleus accumbens shell. These results prove that impulsivity confers an increased propensity to develop uncontrollable overeating of palatable food.