Article ID Journal Published Year Pages File Type
2844518 Physiology & Behavior 2012 12 Pages PDF
Abstract

Positive reinforcement (e.g., appetitive, rewarding properties) has often been hypothesized to maintain excessive intake of palatable foods. Recently, rats receiving intermittent access to high sucrose diets showed binge-like intake with withdrawal-like signs upon cessation of access, suggesting negative reinforcement mechanisms contribute as well. Whether intermittent access to high fat diets also produces withdrawal-like syndromes is controversial. The present study therefore tested the hypothesis that binge-like eating and withdrawal-like anxiety would arise in a novel model of binge eating based on daily 10-min access to a sweet fat diet (35% fat kcal, 31% sucrose kcal). Within 2–3 weeks, female Wistar rats developed binge-like intake comparable to levels seen previously for high sucrose diets (~ 40% of daily caloric intake within 10 min) plus excess weight gain and adiposity, but absent increased anxiety-like behavior during elevated plus-maze or defensive withdrawal tests after diet withdrawal. Binge-like intake was unaffected by pretreatment with the corticotropin-releasing factor type 1 (CRF1) receptor antagonist R121919, and corticosterone responses to restraint stress did not differ between sweet-fat binge rats and chow-fed controls. In contrast, pretreatment with the cannabinoid type 1 (CB1) receptor antagonist SR147778 dose-dependently reduced binge-like intake, albeit less effectively than in ad lib chow or sweet fat controls. A priming dose of the sweet fat diet did not precipitate increased anxiety-like behavior, but rather increased plus-maze locomotor activity. The results suggest that CB1-dependent positive reinforcement rather than CRF1-dependent negative reinforcement mechanisms predominantly maintain excessive intake in this limited access model of sweet-fat diet binges.

► Binge-like eating develops in rats with 10-min daily access to a sweet fat diet. ► Sweet fat binging increases weight gain, adiposity, and feed efficiency. ► Binge magnitude is reduced by a CB1, but not CRF, receptor antagonist. ► Neither anxiety-like behavior nor HPA axis activity is altered by binge history. ► Unlike sugar diets, sweet fat diets maintain binge-like intake without withdrawal.

Related Topics
Life Sciences Biochemistry, Genetics and Molecular Biology Physiology
Authors
, , , , ,