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Updated: May 20, 2026
Using the Activity-based Anorexia Rodent Model to Study the Neurobiological Basis of Anorexia Nervosa
Published on: October 22, 2015
Action of a serotonergic anorectic in meal-fed mice working for food
Neil E Rowland1, Kimberly L Robertson, Emilia M Cadiz
1Department of Psychology, University of Florida, Gainesville, Florida 32611-2250, USA. nrowland@ufl.edu
Abstract:
The aim of this study was to examine the effects of a serotonergic anorectic agent, dexnorfenfluramine (DNOR), on food intake in mice whose meals were constrained to specified periods each day and by effort. Mice were forced to adopt a human-like pattern of regular meals by making food available for four periods of 40 min/24-h period, mostly at night. They lived in behavior test chambers with a closed economy for food and were required to emit a fixed unit price (FUP) of either 2 or 25 nose pokes (FUP2, FUP25) to receive a 20 mg pellet of food. Once responding and intake were stable, mice were injected with a vehicle or DNOR (3 or 6 mg/kg) 1 h before a specified feeding opportunity. Food intake was dose-dependently suppressed at the next meal and to a greater extent when the cost of food was high (FUP25). Within a meal, the effect of the drug was the greatest in the first half of the available time. Therefore, the anorectic effect of DNOR was modified by the concurrent cost of food.
Insights
Dexnorfenfluramine (DNOR), a weight-loss drug, reduced food intake in mice. This appetite suppressant effect was stronger when obtaining food required more effort, demonstrating its interaction with food accessibility.
Area of Science:
- Neuroscience
- Pharmacology
- Behavioral Science
Background:
- Appetite regulation is complex, influenced by both neurochemical signals and environmental factors.
- Serotonergic agents, like dexnorfenfluramine (DNOR), are known for their effects on satiety and food intake.
- Understanding how drug efficacy is modulated by external variables is crucial for therapeutic applications.
Purpose of the Study:
- To investigate the anorectic effects of dexnorfenfluramine (DNOR) in mice.
- To determine if the cost of food (effort required to obtain it) influences DNOR's impact on food consumption.
- To analyze the temporal dynamics of DNOR's effect within a feeding period.
Main Methods:
- Mice were trained to obtain food pellets by performing a fixed unit price (FUP) of nose pokes (FUP2 or FUP25).
- Food availability was restricted to four 40-minute periods daily, mimicking human meal patterns.
- Mice received injections of DNOR (3 or 6 mg/kg) or vehicle before feeding opportunities.
Main Results:
- DNOR significantly suppressed food intake in a dose-dependent manner.
- The anorectic effect of DNOR was amplified when the effort required to obtain food was higher (FUP25).
- DNOR's impact was most pronounced during the initial phase of the feeding period.
Conclusions:
- The anorectic efficacy of dexnorfenfluramine is modulated by the cost of food, indicating an interaction between pharmacological and environmental factors.
- DNOR's effectiveness in reducing food intake is context-dependent.
- These findings contribute to understanding the behavioral pharmacology of appetite suppressants.
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