Intermittent Binge-Intake Model in Mice

Summary

A binge-eating model was established in mice using intermittent access to M&M's (a highly palatable food made of fat and sugar). Mice with intermittent access to this high-fat, high-sugar food showed stress-like behaviors, increased caloric intake, and a preference for that food over standard chow compared to mice with continuous or no access to the food.

Abstract

Obesity affects one in eight individuals globally. Overeating, especially high-calorie foods, plays a significant role in obesity. Binge eating disorder (BED) is a complex condition caused by a combination of biological, psychological, and social factors. It involves excessive consumption of high-calorie foods in a short period and is often linked to anxiety and cravings.

Here, we present a protocol employing continuous and intermittent access to a new highly palatable food (HPF) -- M&M's -- to develop a mouse model for investigating binge eating disorder (BED). The HPF, chosen for its high fat and sugar content, represents an optimal food source to study due to its strong palatability, which makes it particularly suited for examining compulsive eating behaviors. Using C57BL/6 mice, we provided continuous or intermittent access to M&M's while allowing unrestricted access to standard chow and water. By the 8^th day, the mice in the intermittent access group exhibited pronounced binge-eating behaviors, which persisted through the 26^th day. These mice also consumed significantly more calories -- predominantly from the confectionary -- than those in the continuous access and control groups. The contrast between continuous and intermittent access underscores the critical role of feeding schedules in promoting the overconsumption of palatable foods.

Furthermore, behavioral assessments revealed intermittent access to the HPF-induced anxiety-like behaviors, highlighting the psychological impact of access patterns on both eating behavior and emotional states. By incorporating these two distinct feeding paradigms, this study offers valuable insights into how the availability of highly palatable foods can exacerbate binge-eating tendencies. This model provides a more realistic approach to studying binge-eating behaviors and their metabolic consequences. It highlights the importance of standardized models in biomedical research. Our findings offer insights into the physiological and neural mechanisms underlying BED, which could pave the way for developing effective therapeutic interventions for BED and obesity.

Introduction

According to data from the World Health Organization¹, one in eight people worldwide is obese. Although eating is a physiological necessity, overeating without a physiological need is known to be a factor associated with overweight and obesity². It is well known that humans prefer palatable foods high in calories, such as fats and sugars, over healthier foods³.

From the perspective of complexity science, eating disorders, particularly binge eating disorder (BED), are multifaceted phenomena that emerge from the interaction of various biological, psychological, and social....

Protocol

All experiments were conducted according to the Mexican Official Standard of Technical Specifications for the Production and Use of Laboratory Animals (NOM-062-ZOO-1999) and in full compliance with the guidelines set forth by the Internal Committee for the Care and Use of Laboratory Animals (CICUAL) at the National Autonomous University of Mexico (UNAM).

1. Animals

1. To follow this protocol, individually house 27 C57BLC/6 male mice, aged 1 month and weighing 16-20 g,.......

Discussion

We used the binge-eating model proposed by Corwin in 2006 as a basis for developing this protocol. However, the present study modified the variable of providing palatable food for 2 h for the CoG⁸. Instead, we offered palatable food ad libitum to CoG, as it better simulates a reality where we have 24 h access to any food. We also used M&M's as an HPF because they combine fats and sugars, unlike other binge-eating models that use either fat or sugar separately⁸

Materials

Name	Company	Catalog Number	Comments
ANY-maze Video Tracking Software	Stoelting Co.	4.73 version
C270 HD Webcam	Logitech	C270 HD	It is not necessary to use a specific video recorder; any webcam or camcorder with satisfactory image quality and resolution will suffice.
Gloves Ambiderm (black)	Ambiderm	7.50222E+12
GraphPad Prism 9	GraphPad
Laboratory Rodent Diet 5001	LabDiet	1320	https://di.facmed.unam.mx/comisiones/Composici%C3%B3n%20del%20alimento%20Laboratory%20Rodent%20Diet%205001.pdf
M&Ms 43.8g (Brown packaging)	M&M´s		Nutritional content per 100 : 480 kcal, 19g of fat, 70 g of carbohydrates, 5.1 g of protein, 0.13 g of saltIngredients: sugar, cocoa mass, skimmed milk powder, cocoa butter, lactose, starch, milk fat, palm fat, glucose syrup, shea fat, stabiliser (gum arabic), dextrin, glazing agents (beeswax, carnauba wax), colours (E100, carmine, E132, E133, E150a, E150c, E150d, E153, E160a, E160e, E162, E163, E170), beetroot concentrate, emulsifiers (soya lecithin, E445), salt, flavourings, palm kernel oil, antioxidant (E306). (May contain: peanut, hazelnut, almond). Milk chocolate contains milk solids 14% minimum. Milk chocolate contains vegetable fats in addition to cocoa butter.
Open Field maze
Polypropylene Mice Cage	Orchid Scientific	SMP 01
Rodent drinkers	Sunnypet	SP-3656
Uline Balanza-220 g x 0.01 g	unike.mx	H-9884
UniMask4	Uniseal
Plastic bottles	unike.mx	S-14487
Sanitary Bed, Sawdust for Animals	BIOINVERT	No number	10 kg