The Treadmill Fatigue Test: A Simple, High-throughput Assay of Fatigue-like Behavior for the Mouse

Summary

Fatigue is a common, undertreated and frequently poorly-understood symptom in many diseases and disorders. New preclinical assays of fatigue may help to improve current understanding and future treatment of fatigue. To that end, the current protocol provides a novel means of measuring fatigue-like behavior in the mouse.

Abstract

Fatigue is a prominent symptom in many diseases and disorders and reduces quality of life for many people. The lack of clear pathogenesis and failure of current interventions to adequately treat fatigue in all patients leaves a need for new treatment options. Despite the therapeutic need and importance of preclinical research in helping identify promising novel treatments, few preclinical assays of fatigue are available. Moreover, the most common preclinical assay used to assess fatigue-like behavior, voluntary wheel running, is not suitable for use with some strains of mice, may not be sensitive to drugs that reduce fatigue, and has relatively low throughput. The current protocol describes a novel, non-voluntary preclinical assay of fatigue-like behavior, the treadmill fatigue test, and provides evidence of its efficacy in detecting fatigue-like behavior in mice treated with a chemotherapy drug known to cause fatigue in humans and fatigue-like behavior in animals. This assay may be a beneficial alternative to wheel running, as fatigue-like behavior and potential interventions can be assessed in a greater number of mice over a shorter time frame, thus permitting faster discovery of new therapeutic options.

Introduction

Fatigue affects a wide range of people, can markedly reduce quality of life, and frequently has an unclear or unknown pathogenesis. Cancer-related fatigue (CRF), for example, is experienced by the majority of cancer patients undergoing treatment and can persist long after cancer treatment has been completed and in the absence of detectable cancer¹. Moreover, fatigue is also a prominent symptom in numerous other diseases and disorders, including chronic fatigue syndrome, depression, diabetes, and fibromyalgia. Fortunately, there are non-pharmacological interventions that are capable of helping some people experiencing fatigue (e.g., exercise can red....

Protocol

This procedure was approved by the National Institute of Diabetes and Digestive and Kidney Diseases Animal Care and Use Committee.

1. Preparation

1. To allow for rapid identification of each mouse prior to testing, tattoo the tails of all mice to be trained and tested with identifying marks.
   NOTE: This step is optional. Permanent marker or other methods of identification can be used as an alternative to tattooing.
2. Prior to training and testing mice, ensure that the treadmill is on a flat surface and set to the treadmill to desired angle of inclination (recommended angle of inclination: 10°, to be kept consiste....

Results

This protocol allows fatigue-like behavior to be measured in mice using a treadmill. The data presented in this section was obtained by training and testing 3 separate groups of mice using the current protocol (excluding Figure 1A and 1C). To induce fatigue, 5-fluorouracil (5-FU), a cytotoxic chemotherapy drug known to cause fatigue in humans³⁰ and fatigue-like behavior in mice^10,13, was administered. All data presented are from.......

Discussion

The current protocol describes how to use a mouse treadmill to measure fatigue-like behavior. This method has several advantages over VWRA, a common preclinical assay of fatigue-like behavior. VWRA requires that mice choose to interact with the test apparatus. As a result, some inbred strains of mice rarely interact with the wheel¹⁶ and run so little that it may be difficult or impossible to identify a fatigue-induced decrease in activity. In contrast, the treadmill fatigue test eliminates that choice and ther.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Exer 3/6 Animal Treadmill	Columbus Instruments	1050-RM Exer-3/6
Stopwatch	Daigger	EF24490M
Wire brush	Fisher Scientific	03-572-5
Compressed air	Dust-Off	FALDSXLPW
Absorbent pads	Daigger	EF2175CX
Butcher paper	Newell Paper Company	4620510
Alcohol (70%)	Fisher Scientific	BP82011