High Trait Impulsivity Predicts Food Addiction-Like Behavior in the Rat (2014)

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Neuropsychopharmacology. 2014 Apr 29. doi: 10.1038/npp.2014.98.

Velázquez-Sánchez C1, Ferragud A1, Moore CF1, Everitt BJ2, Sabino V1, Cottone P1.

Abstract

Impulsivity is a behavioral trait frequently seen in drug addicted individuals, but also in individuals who pathologically overeat. However, whether impulsivity predates the development of uncontrollable feeding is unknown. In this study we hypothesized that a high impulsivity trait precedes and confers vulnerability for food addiction-like behavior.

For this purpose we trained ad libitum fed male Wistar rats in a differential reinforcement of low rates of responding (DRL) task to select high- and low-impulsive rats. Then, we allowed Low- and High-impulsive rats to self-administer a highly palatable diet (Palatable group) or a regular chow diet (Chow group) in 1 h daily sessions, under fixed ratio (FR) 1, FR3, FR5, and under a progressive ratio (PR) schedules of reinforcement.

In addition, we tested the compulsiveness for food in Low- and High-impulsive rats 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.

Neuropsychopharmacology accepted article peview online, 29 April 2014. doi:10.1038/npp.2014.98.