This research was supported by the Intramural Research Program of the NIH, The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), Grant 1Z01 DK011006. We wish to thank Michele Allen for providing technical assistance, Eleni Solomos for editorial assistance, and the NIH veterinary and animal care staff for providing care for the mice used in developing this method.

This procedure was approved by the National Institute of Diabetes and Digestive and Kidney Diseases Animal Care and Use Committee.
1. Preparation
<ol>
	<li>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.</li>
	<li>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&#176;, to be kept consistent throughout training and testing) and set the electric shock frequency and intensity appropriately (recommended: 2 Hz, 1.22 mA). 
	NOTE: The electric shock used should produce no more than a mild tingling sensation when touched by an ungloved finger and should be delivered in a pulsatile fashion (with each shock lasting 200 msec).</li>
	<li>Place a clean sheet of butcher&#39;s paper or an absorbent pad under the treadmill to collect fecal boli and urine during training and testing.</li>
	<li>Place a sheet of paper or an absorbent pad over the third of the treadmill housing (i.e., the clear plastic lid that covers the treadmill lanes) furthest from the shock grid. 
	NOTE: This step is optional, but will create a darker space and may provide additional encouragement to avoid the lower portion of the treadmill.</li>
	<li>If planning to use a wire brush to provide additional motivation during training, ensure that one is readily available prior to beginning training sessions.</li>
	<li>Ensure that any drug or method for inducing and/or alleviating fatigue is available and can be prepared or performed during Step 2.14.</li>
</ol>
2. Training Mice to Use the Treadmill
NOTE: Training is necessary to ensure that mice are familiar with the treadmill and task and can perform appropriately when tested. If the majority of mice being trained are receiving frequent shocks or otherwise performing poorly during any training session, additional training sessions should be performed. On the first day, most mice will be shocked several times. By the second day of training, mice should be rarely making contact with the grid. If a mouse displays consistently poor training performance, it should be removed from the study. For female C57BL/6NCr mice, this is a rare occurrence (less than 1% have been removed from studies due to poor training performance), but it should be noted that other strains may perform differently during training.
<ol>
	<li>With the treadmill off (and speed set to 0 m/min), individually lift the mice by the tail and place mice into separate lanes of a mouse treadmill. Promptly turn on the corresponding grid after placing each mouse on the treadmill. Ensure that mice are placed directly on the treadmill belt. 
	NOTE: The amount of time and distance each mouse is held by its tail should be minimized by placing the cage near the treadmill prior to transferring mice to the treadmill and/or allowing mice to stand on a solid platform (e.g., a wire cage lid) until they are near the treadmill and the experimenter is ready to place them in the treadmill.</li>
	<li>Allow mice to freely explore the treadmill for 1-3 min or until each mouse has explored its lane and/or received at least one shock from the grid.</li>
	<li>Turn on the treadmill and slowly increase the speed until it begins moving (approximately 1.5 to 3.0 m/min). Monitor all mice to ensure that they begin walking. If a mouse does not begin walking or walks toward the shock grid, be prepared to intervene by tapping the mouse with a wire brush or tail tickling.</li>
	<li>Slowly increase the treadmill speed to 8 m/min. Start a timer and continue monitoring behavior.</li>
	<li>Increase treadmill speed to 9 m/min at 5 min, 10 m/min at 7 min, and stop the treadmill at 10 min.</li>
	<li>Allow the mice to briefly explore the treadmill, then remove and return each to its cage.</li>
	<li>Clean the treadmill and grid with alcohol and replace the paper or absorbent pad beneath the treadmill.</li>
	<li>To train additional mice, repeat Steps 2.1 through 2.7. 
	NOTE: Allow alcohol to dry prior to placing new mice on the treadmill.</li>
	<li>On the second day of training, repeat Step 2.1. Turn on the treadmill and increase the speed to 10 m/min. Start a timer. 
	NOTE: Treadmill speed can be increased more rapidly than on the first day of training.</li>
	<li>Increase treadmill speed to 11 m/min at 5 min, 12 m/min at 10 min, and stop the treadmill at 15 min.</li>
	<li>Remove mice and return them to their cages.</li>
	<li>Clean the treadmill and grid with alcohol and replace the paper or absorbent pad beneath the treadmill. To train additional mice, repeat Steps 2.9 through 2.12.</li>
	<li>Perform additional days (3 days) of training in the same manner as the second day. 
	NOTE: This step is optional, but is strongly recommended if most or all mice (of the same sex and strain) being trained display difficulty with the task. Mice can generally perform well in Step 3 when they have been trained for 3 days (i.e., with one additional day of training), although additional or fewer days of training may be appropriate depending on their performance during the second training day and the duration of Step 2.14.</li>
	<li>Allow at least one full day to pass in which the mice have no exposure to the treadmill before proceeding to Step 3. 
	NOTE: Any drug(s) used to induce and/or alleviate fatigue should be administered during this step. 
	NOTE: This time period can be varied in length and used to induce fatigue and/or test interventions to reduce or eliminate fatigue. If testing mice more than 7 days after completing training, a pilot study is recommended to verify that the mice used will perform during testing.</li>
</ol>
3. Treadmill Fatigue Test
NOTE: In this test, fatigue-like behavior is defined as spending 5 consecutive seconds in the &#34;fatigue zone&#34;. The fatigue zone is defined as the region encompassing the portion of the treadmill belt within approximately 1 body length of the shock grid as well as the grid, itself. Prior to testing, ensure that the point delineating this zone is clear to the experimenter, such as by applying a mark to the top or side of the treadmill lanes.
<ol>
	<li>Set the treadmill speed to 12 m/min. Do not start the treadmill. Ensure that shock grids are turned off.</li>
	<li>Individually place mice into separate lanes of the treadmill. Turn on the corresponding grid immediately after placing each mouse on the treadmill.</li>
	<li>Simultaneously start the treadmill and a stopwatch. 
	NOTE: Do not intervene during testing except to remove mice that meet the criterion for removal (see Step 3.5).</li>
	<li>Increase treadmill speed as indicated in Table 1. Carefully observe all mice throughout the test. 
	NOTE: The treadmill speeds listed in Table 1 were selected based on observations from adult female C57BL/6NCr mice. Higher treadmill speeds may be appropriate for larger (e.g., outbred CD-1 mice) or more athletic mice.</li>
	<li>If a mouse remains in the fatigue zone for 5 continuous sec, promptly remove the mouse from the treadmill and record the duration and distance it ran.</li>
	<li>When no mice remain on the treadmill, stop the treadmill. Clean the treadmill and grid with alcohol and replace the paper or absorbent pad beneath the treadmill.</li>
	<li>To test additional mice, repeat Steps 3.1 through 3.6. 
	NOTE: This step is optional.</li>
</ol>

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</ol>

The authors have nothing to disclose.

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...

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 reduce CRF for some breast cancer patients2,3), but many individuals still lack effective treatment. Furthermore, existing drug treatments for CRF have not been found to be broadly, if at all, efficacious4-7.
Despite the therapeutic need and lack of drug treatment options, preclinical assays of fatigue to aid in the discovery and development of novel fatigue treatments are lacking, especially in animal models. One of the only preclinical assays of fatigue for rodent studies is voluntary wheel running activity (VWRA)9-15, in which mice or other rodents are given free access to a running wheel and their daily running activity is recorded. In many studies, VWRA is the only measure of fatigue-like behavior, with fatigue-like behavior defined (in either VWRA or the current protocol) as a decrease in the measured physical activity in the experimental group. Although VWRA can provide a useful longitudinal measure of fatigue-like behavior, it is a relatively low-throughput assay, running varies considerably between inbred mouse strains16, and it requires subjects to be individually housed, which may cause changes in behavior and test performance17-19. Other assays, such as home cage behavioral monitoring and analysis, can also provide continuous data collection and some systems may allow for subjects to be housed in pairs20. These assays have utility, but may be less sensitive as a means of detecting fatigue-like behavior and, like wheel running, are also low-throughput.
In contrast to VWRA, mouse treadmill tests do not rely upon voluntary activity and can be completed in a short time frame, allowing for higher throughput. In comparison to VWRA, these tests employ external motivators. Specifically, there is usually an electrified metal grid located to the rear of the moving belt to provide mice with an electric shock should they cease to run. In addition to this shock grid, mice may be motivated to run on the treadmill via several other methods, including prodding, poking, or touching them with a hand, brush, or other tool and directing short puffs of air at them. Instead of fatigue, mouse treadmill tests are often used to measure aerobic and/or anaerobic exercise capacity21-25. Mice are motivated to run until they are incapable of or unwilling to continue running on the treadmill as a means of escaping further electric shocks. Testing then ends when mice meet the criterion for exhaustion. In these protocols, to ensure that mice reach true physiologic exhaustion, the criterion for exhaustion is often defined as spending five continuous seconds laying on top of the shock grid and failing to continue running in the face of repeated aversive stimuli. Thus, fatigue-like behavior may be masked in typical treadmill tests due to the strong aversive nature of the external motivation and criterion for ending the test. Interestingly, and in contrast to many other studies using rodent treadmills, a recent publication describes another version of a treadmill fatigue test, which was used as part of an examination of the effects of social stress in mice26. Although the method used by this group markedly differed from the current protocol (i.e., they employed a single-lane treadmill and required 10 sec of electric shock as the criterion for ending their test), their study highlights the utility of and interest in developing a quick, simple fatigue test using the mouse treadmill.
Fatigue is likely to be detectable by means other than wheel running and alterations in routine behaviors. CRF makes patients feel exhausted by a lesser amount of muscle fatigue, as determined by electromyographic analysis, than people without CRF27. Additionally, reduced motivation has been noted in and is measured by several scales measuring human fatigue28,29. Thus, a useful preclinical assay of fatigue-like behavior should distinguish between healthy and fatigued mice on the basis of a measure other than physiological capability and should not obscure decreases in motivation. To achieve that end while avoiding limitations of VWRA and other assays, the current method was developed by adapting the mouse treadmill test. This method uses a shock grid as the sole external motivator to make mice run on the treadmill. Mice quickly learn that the grid provides an aversive stimulus and will promptly move away from it when placed on the treadmill and maintain some distance from it when running.
When mice fatigue, they spend progressively more time toward the back of the treadmill instead of maintaining speed toward the front end. Therefore, the criterion for test completion in this protocol is spending five continuous seconds in the designated fatigue zone (i.e., the rear of the treadmill, ranging from approximately one body length from the shock grid to, and including, the shock grid). This takes advantage of the aversive nature of the grid without requiring mice to receive many or any actual shocks after training. By allowing mice to complete testing using the current criterion rather than exhaustion (as defined above), this method provides a means of using the treadmill to measure fatigue-like behavior rather than its maximal (or near-maximal) physiological capability. Thus, this method can provide a simple, high-throughput assay of fatigue-like behavior in mice and can serve either as an independent or complementary measure to other assays of fatigue-like behavior.

<table><tbody><tr><td>Exer 3/6 Animal Treadmill</td><td>Columbus Instruments</td><td>1050-RM Exer-3/6</td><td></td></tr><tr><td>Stopwatch</td><td>Daigger</td><td>EF24490M&amp;nbsp;</td><td></td></tr><tr><td>Wire brush</td><td>Fisher Scientific</td><td>03-572-5</td><td></td></tr><tr><td>Compressed air</td><td>Dust-Off</td><td>FALDSXLPW</td><td></td></tr><tr><td>Absorbent pads</td><td>Daigger</td><td>EF2175CX&amp;nbsp;</td><td></td></tr><tr><td>Butcher paper</td><td>Newell Paper Company</td><td>4620510</td><td></td></tr><tr><td>Alcohol (70%)</td><td>Fisher Scientific</td><td>BP82011</td><td></td></tr></tbody></table>

the treadmill fatigue test: a simple, high-throughput assay of fatigue-like behavior for the mouse

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.

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 mice10,13, was administered.&#160;All data presented are from...

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

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.

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 ...

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Research

JoVE Journal

Behavior

18.6K Views.  National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health. 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.

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

A Mouse Model of Fatigue Induced by Peripheral Irradiation

Cancer-related fatigue (CRF) is a distressing and costly condition that often affects patients receiving cancer treatments, including radiation therapy. Here we describe a method using targeted peripheral irradiation to induce fatigue-like behavior in mice. With appropriate shielding, the irradiation targets the lower abdominal/pelvic region of the mouse, sparing the brain, in an effort to model radiation treatment received by individuals with pelvic cancers. We deliver an irradiation dose that is sufficient to induce fatigue-like behavior in mice, measured by voluntary wheel-running activity (VWRA), without causing obvious morbidity. Since wheel running is a normal, voluntary behavior in mice, its use should have little confounding effect on other behavioral tests or biological measures. Hence, wheel running can be used as a feasible outcome measure in understanding the behavioral and biological correlates of fatigue. CRF is a complex condition with frequent comorbidities, and likely has causes related both to cancer and its various treatments. The methods described in this paper are useful for investigating radiation-induced changes that contribute to the development of CRF and, more generally, to explore the biological networks that can explain the development and persistence of a peripherally-triggered but centrally-driven behavior like fatigue.

We describe a method using targeted peripheral irradiation to induce fatigue-like behavior in mice. The selected non-lethal irradiation dose leads to a week-long reduction in voluntary wheel-running activity.

Cancer-related fatigue (CRF) is a distressing and costly condition that often affects patients receiving cancer treatments, including radiation therapy. ...

Cancer Research

Assessing Functional Performance in the Mdx Mouse Model

Duchenne muscular dystrophy (DMD) is a severe and progressive muscle wasting disorder for which no cure is available. Nevertheless, several potential pharmaceutical compounds and gene therapy approaches have progressed into clinical trials. With improvement in muscle function being the most important end point in these trials, a lot of emphasis has been placed on setting up reliable, reproducible, and easy to perform functional tests to pre clinically assess muscle function, strength, condition, and coordination in the mdx mouse model for DMD. Both invasive and noninvasive tests are available. Tests that do not exacerbate the disease can be used to determine the natural history of the disease and the effects of therapeutic interventions (e.g. forelimb grip strength test, two different hanging tests using either a wire or a grid and rotarod running). Alternatively, forced treadmill running can be used to enhance disease progression and/or assess protective effects of therapeutic interventions on disease pathology. We here describe how to perform these most commonly used functional tests in a reliable and reproducible manner. Using these protocols based on standard operating procedures enables comparison of data between different laboratories.

Assessing Functional Performance in the Mdx Mouse Model

The primary outcome measure in clinical trials for neuromuscular disorders is generally improved muscle function. Therefore, assessing the effect of potential therapeutic compounds on muscle performance pre clinically in mouse models is of great importance. We here describe several functional tests to address this.

Duchenne muscular dystrophy (DMD) is a severe and progressive muscle wasting disorder for which no cure is available. Nevertheless, several potential ...

Getting to Compliance in Forced Exercise in Rodents: A Critical Standard to Evaluate Exercise Impact in Aging-related Disorders and Disease

There is a major increase in the awareness of the positive impact of exercise on improving several disease states with neurobiological basis; these include improving cognitive function and physical performance. As a result, there is an increase in the number of animal studies employing exercise. It is argued that one intrinsic value of forced exercise is that the investigator has control over the factors that can influence the impact of exercise on behavioral outcomes, notably exercise frequency, duration, and intensity of the exercise regimen. However, compliance in forced exercise regimens may be an issue, particularly if potential confounds of employing foot-shock are to be avoided. It is also important to consider that since most cognitive and locomotor impairments strike in the aged individual, determining impact of exercise on these impairments should consider using aged rodents with a highest possible level of compliance to ensure minimal need for test subjects. Here, the pertinent steps and considerations necessary to achieve nearly 100% compliance to treadmill exercise in an aged rodent model will be presented and discussed. Notwithstanding the particular exercise regimen being employed by the investigator, our protocol should be of use to investigators that are particularly interested in the potential impact of forced exercise on aging-related impairments, including aging-related Parkinsonism and Parkinson&#8217;s disease.

Exercise may alleviate behavioral impairments associated with neurodegenerative diseases. Studies of the mechanisms underlying exercise-mediated effects have increased in disease models, but the neurobiological background accompanying these diseases, specifically aging, is likely not considered. Here, we illustrate measures to increase the likelihood of a successful exercise paradigm in aged rats.

There is a major increase in the awareness of the positive impact of exercise on improving several disease states with neurobiological basis; these ...

Assessment of Murine Exercise Endurance Without the Use of a Shock Grid: An Alternative to Forced Exercise

Using laboratory mouse models, the molecular pathways responsible for the metabolic benefits of endurance exercise are beginning to be defined. The most common method for assessing exercise endurance in mice utilizes forced running on a motorized treadmill equipped with a shock grid. Animals who quit running are pushed by the moving treadmill belt onto a grid that delivers an electric foot shock; to escape the negative stimulus, the mice return to running on the belt. However, avoidance behavior and psychological stress due to use of a shock apparatus can interfere with quantitation of running endurance, as well as confound measurements of postexercise serum hormone and cytokine levels. Here, we demonstrate and validate a refined method to measure running endurance in na&#239;ve C57BL/6 laboratory mice on a motorized treadmill without utilizing a shock grid. When mice are preacclimated to the treadmill, they run voluntarily with gait speeds specific to each mouse. Use of the shock grid is replaced by gentle encouragement by a human operator using a tongue depressor, coupled with sensitivity to the voluntary willingness to run on the part of the mouse. Clear endpoints for quantifying running time-to-exhaustion for each mouse are defined and reflected in behavioral signs of exhaustion such as splayed posture and labored breathing. This method is a humane refinement which also decreases the confounding effects of stress on experimental parameters.

A method to assess exercise endurance in laboratory mice without the use of a shock grid is demonstrated. This method is a humane refinement that can decrease the confounding effects of stress on experimental parameters.

Using laboratory mouse models, the molecular pathways responsible for the metabolic benefits of endurance exercise are beginning to be defined. The most ...

Short Session High Intensity Interval Training and Treadmill Assessment in Aged Mice

High intensity interval training (HIIT) is emerging as a therapeutic approach to prevent, delay, or ameliorate frailty. In particular short session HIIT, with regimens less than or equal to 10 min is of particular interest as several human studies feature routines as short as a few minutes a couple times a week. However, there is a paucity of animal studies that model the impacts of short session HIIT. Here, we describe a methodology for an individually tailored and progressive short session HIIT regimen of 10 min given 3 days a week for aged mice using an inclined treadmill. Our methodology also includes protocols for treadmill assessment. Mice are initially acclimatized to the treadmill and then given baseline flat and uphill treadmill assessments. Exercise sessions begin with a 3 min warm-up, then three intervals of 1 min at a fast pace, followed by 1 min at an active recovery pace. Following these intervals, the mice are given a final segment that starts at the fast pace and accelerates for 1 min. The HIIT protocol is individually tailored as the speed and intensity for each mouse are determined based upon initial anaerobic assessment scores. Additionally, we detail the conditions for increasing or decreasing the intensity for individual mice depending on performance. Finally, intensity is increased for all mice every two weeks. We previously reported in this protocol enhanced physical performance in aged male mice and here show it also increases treadmill performance in aged female mice. Advantages of our protocol include low administration time (about 15 min per 6 mice, 3 days a week), strategy for individualizing for mice to better model prescribed exercise, and a modular design that allows for the addition or removal of the number and length of intervals to titrate exercise benefits.

Short session (&#8804;10 min) high intensity interval training (HIIT) is emerging as an alternative to longer exercise modalities, yet the shorter variants are rarely modeled in animal studies. Here, we describe a 10 min, 3 day a week, uphill treadmill HIIT protocol that enhances physical performance in male and female aged mice.

High intensity interval training (HIIT) is emerging as a therapeutic approach to prevent, delay, or ameliorate frailty. In particular short session HIIT, ...

A Method to Study the Impact of Chemically-induced Ovarian Failure on Exercise Capacity and Cardiac Adaptation in Mice

The risk of cardiovascular disease (CVD) increases in post-menopausal women, yet, the role of exercise, as a preventative measure for CVD risk in post-menopausal women has not been adequately studied. Accordingly, we investigated the impact of voluntary cage-wheel exercise and forced treadmill exercise on cardiac adaptation in menopausal mice. The most commonly used inducible model for mimicking menopause in women is the ovariectomized (OVX) rodent. However, the OVX model has a few dissimilarities from menopause in humans. In this study, we administered 4-vinylcyclohexene diepoxide (VCD) to female mice, which accelerates ovarian failure as an alternative menopause model to study the impact of exercise in menopausal mice. VCD selectively accelerates the loss of primary and primordial follicles resulting in an endocrine state that closely mimics the natural progression from pre- to peri- to post-menopause in humans. To determine the impact of exercise on exercise capacity and cardiac adaptation in VCD-treated female mice, two methods were used. First, we exposed a group of VCD-treated and untreated mice to a voluntary cage wheel. Second, we used forced treadmill exercise to determine exercise capacity in a separate group VCD-treated and untreated mice measured as a tolerance to exercise intensity and endurance.

Two exercise paradigms were tested on a newly developed chemically induced menopausal mouse model to examine the impact of menopause on exercise capacity and cardiac adaption to exercise.

The risk of cardiovascular disease (CVD) increases in post-menopausal women, yet, the role of exercise, as a preventative measure for CVD risk in ...

Medicine

Measuring Skeletal Muscle Thermogenesis in Mice and Rats

Skeletal muscle thermogenesis provides a potential avenue for better understanding metabolic homeostasis and the mechanisms underlying energy expenditure. Surprisingly little evidence is available to link the neural, myocellular, and molecular mechanisms of thermogenesis directly to measurable changes in muscle temperature. This paper describes a method in which temperature transponders are utilized to retrieve direct measurements of mouse and rat skeletal muscle temperature.
Remote transponders are surgically implanted within the muscle of mice and rats, and the animals are given time to recover. Mice and rats must then be repeatedly habituated to the testing environment and procedure. Changes in muscle temperature are measured in response to pharmacological or contextual stimuli in the home cage. Muscle temperature can also be measured during prescribed physical activity (i.e., treadmill walking at a constant speed) to factor out changes in activity as contributors to the changes in muscle temperature induced by these stimuli.
This method has been successfully used to elucidate mechanisms underlying muscle thermogenic control at the level of the brain, sympathetic nervous system, and skeletal muscle. Provided are demonstrations of this success using predator odor (PO; ferret odor) as a contextual stimulus and injections of oxytocin (Oxt) as a pharmacological stimulus, where predator odor induces muscle thermogenesis, and Oxt suppresses muscle temperature. Thus, these datasets display the efficacy of this method in detecting rapid changes in muscle temperature.

Mice and rats are surgically implanted with remote temperature transponders and then habituated to the testing environment and procedure. Changes in muscle temperature are measured in response to pharmacological or contextual stimuli in the home cage or during prescribed physical activity (i.e., treadmill walking at a constant speed).

Skeletal muscle thermogenesis provides a potential avenue for better understanding metabolic homeostasis and the mechanisms underlying energy expenditure. ...

Visualization of MG53-mediated Cell Membrane Repair Using in vivo and in vitro Systems

Repair of acute injury to the cell membrane is an elemental process of normal cellular physiology, and defective membrane repair has been linked to many degenerative human diseases. The recent discovery of MG53 as a key component of the membrane resealing machinery allows for a better molecular understanding of the basic biology of tissue repair, as well as for potential translational applications in regenerative medicine. Here we detail the experimental protocols for exploring the in vivo function of MG53 in repair of muscle injury using treadmill exercise protocols on mouse models, for testing the ex vivo membrane repair capacity by measuring dye entry into isolated muscle fibers, and for monitoring the dynamic process of MG53-mediated vesicle trafficking and cell membrane repair in cultured cells using live cell confocal microscopy.

Visualization of MG53-mediated Cell Membrane Repair Using in vivo and in vitro Systems

Described here are protocols used to visualize the dynamic process of MG53-mediated cell membrane repair in whole animals and at the cellular level. These methods can be applied to investigate the cell biology of plasma membrane resealing and regenerative medicine.

Repair of acute injury to the cell membrane is an elemental process of normal cellular physiology, and defective membrane repair has been linked to many ...

Biology

A Rat Model of Central Fatigue Using a Modified Multiple Platform Method

In this article, we introduced a rat model of central fatigue using the modified multiple platform method (MMPM). The Multiple Platform box was designed as a water tank with narrow platforms on the bottom. The model rats were put into the tank and stood on the platforms for 14 h (18:00 - 8:00) per day for a consecutive 21 days, with a blank control group set for contrast. At the end of modeling, rats in the model group showed an obvious fatigued appearance. To assess the model, we performed several behavioral tests, including the open field test (OFT), the elevated plus maze (EPM) test, and the exhaustive swimming (ES) test. The results showed that anxiety, spatial cognition impairment, poor muscle performance, and declined voluntary activity presented in model rats confirm the diagnosis of&#160;central fatigue. Changes of the central neurotransmitters also verified the result. In conclusion, the model successfully simulated central fatigue, and future study with the model may help reveal the pathological mechanism of the disease.

Here, we present a protocol to introduce a rat model of central fatigue using the modified multiple platform method (MMPM).

In this article, we introduced a rat model of central fatigue using the modified multiple platform method (MMPM). The Multiple Platform box was designed ...

Neuroscience

Real-Time Electrocardiogram Monitoring During Treadmill Training in Mice

Regular physical exercise is a major contributor to cardiovascular health, influencing various metabolic as well as electrophysiological processes. However, in certain cardiac diseases such as inherited arrhythmia syndromes, e.g., arrhythmogenic cardiomyopathy (ACM) or myocarditis, physical exercise may have negative effects on the heart leading to a proarrhythmogenic substrate production. Currently, the underlying molecular mechanisms of exercise-related proarrhythmogenic remodeling are largely unknown, thus it remains unclear which frequency, duration, and intensity of exercise can be considered safe in the context of disease(s).
The proposed method allows to study proarrhythmic/antiarrhythmic effects of physical exercise by combining treadmill training with real-time monitoring of the ECG. Implantable telemetry devices are used to continuously record the ECG of freely moving mice over a period of up to 3 months both at rest and during treadmill training. Data acquisition software with its analysis modules is used to analyze basic ECG parameters such as heart rate, P wave duration, PR interval, QRS interval, or QT duration at rest, during and after training. Furthermore, heart rate variability (HRV) parameters and occurrence of arrhythmias are evaluated. In brief, this manuscript describes a step-by-step approach to experimentally explore exercise induced effects on cardiac electrophysiology, including potential proarrhythmogenic remodeling in mouse models.

Electrocardiogram (ECG) is the key variable to understanding cardiac electrophysiology. Physical exercise has beneficial effects but may also be harmful in the context of cardiovascular diseases. This manuscript provides a method of recording real-time ECG during exercise, which can serve to investigate its effects on cardiac electrophysiology in mice.

Regular physical exercise is a major contributor to cardiovascular health, influencing various metabolic as well as electrophysiological processes. ...

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

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