We would like to thank Margriet Hulsker for her photographic assistance and help in obtaining images of mice and the reviewers for their very constructive comments. This work was supported by ZonMw, TREAT-NMD (contract number LSHM-CT-2006-036825) and the Duchenne Parent Project.

The experiments described here were approved by the Animal Ethics Committee (DEC) of the Leiden University Medical Center (LUMC). Mice were bred by the animal facility of the LUMC and kept in individually ventilated cages with 12 hr light dark cycles. They had ad libitum access to water and standard chow.
When performing any of the functional tests described below, experimental conditions have to be strictly controlled to reduce variation. Preferably, age and gender matched mice shoul...

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The authors have nothing to disclose.

The&#160;functional tests presented here are reproducible, easy to perform and applicable to wild type and dystrophic mice independent of their age. The tests provide useful tools to pre clinically assess muscle function, strength, condition, and coordination. When testing the effects of a compound on the natural history of the disease, the noninvasive tests described here (forelimb grip strength, both hanging tests and the rotarod test) can be nicely combined in a functional test regime where these tests are performed o...

Duchenne muscular dystrophy (DMD) is the most common neuromuscular disorder affecting 1:5,000 newborn boys. This severe and progressive muscle wasting disease is caused by mutations in the DMD gene that disrupt the open reading frame and prevent the synthesis of functional dystrophin protein. Muscle fibers lacking dystrophin are vulnerable to exercise induced damage. Upon exhaustion of the muscle&#39;s regenerative capacity, and due to chronic inflammation of damaged muscle, fibers are replaced by connective tissue and fat, subsequently leading to a loss of function. Generally, DMD patients lose ambulation of the lower limbs early in the second decade. Later, also the muscles of the arms and shoulder girdle are affected and patients often develop thoracolumbar scoliosis due to asymmetric weakening of the muscles supporting the spinal cord. Assisted ventilation is generally required in the late teens or early twenties. Respiratory and heart failure lead to death in the third or fourth decade1.
Although the causative gene has been discovered over 25 years ago2, there is no cure available for DMD. However, improved health care and the use of corticosteroids have increased life expectancy in the Western world3. With the use of animal models like the mdx mouse, major steps forward into the discovery of potential therapeutic strategies have been made. The mdx mouse is the most commonly used DMD mouse model. It has a point mutation in exon 23 of the murine Dmd gene and consequently lacks dystrophin4. Over the last couple of years, many proposed strategies have progressed into clinical trials5-9. In these trials, improvement of muscle function is the primary endpoint, underlying the importance of testing the benefit of compounds on muscle function in mice during the pre clinical stage of testing.
Like DMD patients, also the dystrophin negative muscle fibers of mdx mice are vulnerable to exercise induced damage and their muscle function is impaired compared to C57BL/10ScSnJ wild type mice. This impairment can be assessed with a variety of functional tests. Some of these tests are noninvasive and do not interfere with muscle pathology (e.g. forelimb grip strength, hanging tests and rotarod running). Therefore they can be used to monitor the natural history of the disease or determine the effects of compounds on disease progression. To get an in depth picture of the influence of compounds on muscle function in mdx mice, a functional test regime that does not interfere with disease progression consisting of all of these tests can be used10.
Alternatively, forced treadmill running can be used to intentionally exacerbate disease progression and test the protective capacities of compounds11. The treadmill can also be used as outcome measure in which running time till exhaustion is measured12, or as a tool to fatigue mdx mice so that they perform less well in a subsequent functional test ensuring larger differences in performance between treatment groups13. When choosing functional tests, their effect on disease progression should be kept in mind especially when testing dystrophic mice like the mdx mouse14.
We here describe in detail how to perform the most commonly used functional tests in a reliable and reproducible manner based on available standard operating procedures from the TREAT-NMD network. <a href="http://www.treat-nmd.eu/resources/research-resources/dmd-sops/" target="_blank">Click here to visit TREAT-NMD</a>.

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			<td height="21" style="height:21px;width:216px;">Mouse grip strength meter</td>
			<td style="width:331px;">Chatillon DFE (re-sold by Columbus Instruments)</td>
			<td style="width:119px;"># 80529</td>
			<td style="width:167px;"></td>
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			<td height="21" style="height:21px;width:216px;">Hanging wire 2 limbs device</td>
			<td style="width:331px;">Cloth hanger or custom made device</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Hanging wire 4 limbs device</td>
			<td style="width:331px;">Lid of rat cage or custom made device</td>
			<td style="width:119px;"></td>
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			<td height="21" style="height:21px;width:216px;">Rotarod</td>
			<td style="width:331px;">Ugo Basil</td>
			<td style="width:119px;"># 47600</td>
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			<td height="21" style="height:21px;width:216px;">Treadmill for mice Exer 3/6</td>
			<td style="width:331px;">Columbus Instruments</td>
			<td style="width:119px;"># 1055SRM</td>
			<td></td>
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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.

The forelimb grip strength of wild type and mdx mice increases between the age of 4-12 weeks and reduces again in older mice. Impairments in force can already be observed in young&#160;mdx mice. Representative data of 9 week old female mice are shown in Figures 1A and 1B. Although fatigue does not differ between the strains yet at this age, mdx mice are weaker than wild type mice. We do not have data yet on fatigability in older mdx and wild type mice....

Watch this Scientific Journal Video about Assessing Functional Performance in the Mdx Mouse Model at JoVE.com

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.

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 ...

assessing-functional-performance-in-the-mdx-mouse-model

Research

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Behavior

31.8K visualizações.  Leiden University Medical Center.  O desfecho primário em ensaios clínicos para doenças neuromusculares é geralmente melhora da função muscular. Portanto, avaliar o efeito de potenciais compostos terapêuticos sobre o desempenho muscular pré clinicamente em modelos do rato é de grande importância. Nós aqui descrever vários testes funcionais para resolver esta questão. 