The authors wish to thank A.M. for animal identification assistance. This work was supported by grants from the US National Institutes of Health (R01 7 RF1 AG057264 to A.R.L.S. and C.J.C. and R01 NS100023 to A.R.L.S) and the Muscular Dystrophy Association (Basic Research Grant to A.R.L.S., Development Grant to C.J.C.).

All testing conducted with mice was reviewed and approved by the Institutional Animal Care and Use Committee (IACUC) of Duke University. Personnel responsible for testing and scoring must be blinded to animal genotype or experimental condition until gait analysis and scoring of papers has been completed for the entire cohort.
1. Testing material preparation
<ol>
	<li>Conduct testing with a tunnel built from 3 pre-cut clear acrylic panels that are 0.375 inches thick. Assemble tunnel by gluing panels together with a sealant that specifically bonds acrylic and will not emit odors when dried.
	<ol>
		<li>For standard C57BL/6 mice, use the following tunnel measurements: 2.5 in. wide, 3 in. high, and 13 in. long. Mice must be able to comfortably walk through the tunnel and take enough steps (&#62;4) so that gait can be measured.</li>
	</ol>
	</li>
	<li>Construct the goal chamber with pre-cut gray acrylic panels 0.375 inches thick, glued together with the same sealant as used on the tunnel. The interior measurements of the chamber are 4 in. wide, 4 in. long, and 3 in. tall. Match the opening of this chamber to the opening of the tunnel (2.5 in. wide x 3.0 in. tall). Because the mice naturally prefer darkened spaces to well-lit spaces, use material that is opaque and dark in color.</li>
	<li>Use paper for tracking steps that is thick and smooth (watercolor paper works well). Cut individual papers strips to be slightly wider and longer than the width and length of the tunnel. If using the tunnel dimensions described here, cut papers to 15 in. long by 3.5 in. wide.</li>
	<li>Use two contrasting colors (e.g., green and purple) of non-toxic washable water-based paint. Assign one color for hind-limbs, the second one for forelimbs. Mice will lick the remaining paint from their feet after testing, so the selected paint must be completely non-toxic.</li>
	<li>Use two round barrel paintbrushes, one for each paint color (~0.5 cm in diameter, tapered/pointed brush tip).</li>
	<li>Select a ruler with markings down to millimeters, and a caliper with measurements down to 0.1 mm. Pencil is recommended to write on the scoring papers.</li>
	<li>Optional: For animals with high anxiety or low motivation, provide a behavioral incentive in the goal chamber. This can include small amounts of sterilized sunflower seeds (placed in the home cage 2 days prior to testing to allow habituation). On the day of testing, place sunflower seeds inside the goal chamber to encourage mice to walk through without stopping.</li>
</ol>
2. Data collection
<ol>
	<li>If testing is performed in a separate room, acclimate the mice to the new room for 30 minutes and then start the behavioral assays. Additionally, because mice are naturally nocturnal, ensure all mice are fully awake and alert for at least 5 minutes before testing.</li>
	<li>Prepare the testing setup by positioning the tunnel over the paper and marking the paper with mouse ID and testing date. Position the goal chamber at the end of the tunnel, connecting both open ends. Add sunflower seeds at the end of the tunnel (inside the goal chamber) for motivation if needed.</li>
	<li>Remove the mouse to be tested from its cage and grip it firmly by its scruff, making sure to grip the tail to stabilize movement of its hind limbs.</li>
	<li>Paint forepaws so the entire underside of all toes and the center of the foot are fully covered in paint. Repeat this with a contrasting color of paint on its hind paws. Wipe off any paint that the mouse gets on other parts of its body with a clean damp cloth to prevent smudges that may interfere with data collection. 
	NOTE: Mouse handling must be performed by experienced researchers to minimize animal stress.</li>
	<li>Place the mouse at the start of the tunnel and allow it to walk all the way into the goal chamber, and then retrieve the mouse, gently wipe off its feet with a water-dampened cloth, and return it to its home cage.</li>
	<li>Allow paper with footprints to dry fully before scoring. Wipe down the testing area and tunnel with ethanol or an equivalent cleaning solution in between each animal.</li>
</ol>
3. Scoring criteria
<ol>
	<li>Use steps that are consistently spaced with clear, non-smudged footprints for scoring. Figure 1B is a good example of a footprint sequence that can be scored. In order to generate sufficient scoring data, there must be at least 2 consecutive steps from each foot, but 4-6 steps per foot is recommended. Do not include the first and last footprints on the paper, as they are unlikely to represent normal gait because the mouse is changing its walking speed.</li>
	<li>Use stride length, stride width, and toe spread as three different measures of gait that can be analyzed using this method. 
	NOTE: Stride length and width require clear sequential prints where the forefoot region is well defined in paint. Toe spread does not require sequential prints for scoring, only clear prints of the first and last toes on a single foot. However, if a given footprint is not included in measurements of stride length or width, it cannot not be scored for toe spread. All three measures are assessed in centimeters.
	<ol>
		<li>Define stride length as the distance between two sequential footprints created by the same foot (i.e., one stride) (Figure 1A, 1B).
		<ol>
			<li>With a pencil, draw a 2-4 mm circle around the fore-foot region of both forelimb footprints (identified by assigned color above) in a single stride and draw a line between them using a ruler.</li>
			<li>Record the distance between two prints from the middle of each circle (i.e. center of each foot pad) as Right-Fore 1 (RF1) or Left-Fore 1 (LF1).</li>
			<li>Repeat for all steps that can be scored (RF2, LF2, RF3, LF3 and so on).</li>
			<li>Repeat for right and left hind-limb footprints.</li>
			<li>Average all individual recorded stride distances for each limb. For statistical analysis, individual cohort members can be averaged together.</li>
		</ol>
		</li>
		<li>Define stride width as the measure of distance between left and right forelimbs or hind-limbs (Figure 1A, 1B).
		<ol>
			<li>To assess this distance, draw and measure a line from the circled forefoot region of one hind-limb that intersects perpendicularly with the line for stride length on the contralateral hind-limb.</li>
			<li>Repeat this for all hind-limb prints that can be scored, and then average the measurements. The method of calculation for stride width is the same for fore- and hind-limbs.</li>
		</ol>
		</li>
		<li>Define toe spread as the distance between the first and last toes on a single fore- or hind-limb footprint (Figure 1A, 1B).
		<ol>
			<li>Use calipers to measure the distance between the tip of the first toe print and the tip of the last toe print.</li>
			<li>Repeat for all hind-limb prints that can be scored and average the measurements. The method of calculation for toe spread is the same for fore- and hind-limbs.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>If the paper cannot be scored, allow the animal to rest for 10 minutes before trying again.</li>
</ol>

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The authors have nothing to disclose.

Using the low-cost gait analysis method described above, we show successful identification of several parameters of gait dysfunction at post-symptomatic ages in the BAC fxAR121 mouse model of SBMA. Decreases in stride length are consistent with prior SBMA studies of mouse models and human patients9. We also show for the first time that there are significant differences in hind-limb toe spread in symptomatic SBMA mice compared to non-transgenic littermate controls. Interestingly, decreases in hind ...

Locomotion requires complex neurological and musculoskeletal coordination, and deficits in a single aspect of motor pathways can produce observable gait abnormalities1,2. Gait analysis is a critical tool for researchers testing mouse models because it provides quantifiable behavioral data on how a given disease, injury, or drug impacts an animal&#8217;s movement3. However, digitized gait analysis requires the purchase of a treadmill, a camera, and associated software, which can be prohibitively expensive for researchers. Gait analysis is often used intermittently to track longitudinal changes in motor function, hence it may be difficult to justify the expenditure if sporadically used4. Although digitized analyses may provide more detailed gait metrics than simple footprint analysis, these more complex measures are not always necessary or relevant for the characterization of a behavioral phenotype5.
Here we present a low-cost manual footprint analysis method as a quick and sensitive alternative to digitized gait analysis programs6,7. Manual footprint analysis has been demonstrated to detect significant gait differences in a multitude of murine disease models4,7,8,9,10,11,12,13,14,15,16,17, and in at least one case, this low-cost method identified changes in gait that were not detected by a common digitized gait analysis program12. The total cost of materials is nominal, and it can be easily adapted to other rodent research models.
While there are many different gait metrics from which data can be drawn, the method we describe focuses on three specific metrics: stride length, stride width (a.k.a. &#8220;track width&#8221;), and toe spread. It is important to note that the parameters to be assessed should be determined on a model-by-model basis. This method of gait analysis is not designed to measure cognitive function, and it is not recommended for studies that require complex biomechanical measurements of gait16.
We present behavioral data from a cohort of pre- and post-symptomatic mice modeling X-linked Spinal and Bulbar Muscular Atrophy (SBMA), a neuromuscular disease characterized by motor neuron degeneration and muscle atrophy. These mice develop progressive deficits in gait that coincide with the onset of other disease-specific phenotypes. This demonstrates the validity and specificity of this method, and confirms that it can reliably discriminate between affected and non-affected animals.
The experimental mice in this study were 2.5 (pre-symptomatic) and 9-month-old (post-symptomatic) BAC fxAR121 transgenic mice on a C57BL/6 background (nexpt=12). This model was generated in our lab and has been fully characterized as a powerful mouse model of SBMA9. Non-transgenic littermates were used as controls (nctrl=8). SBMA is a sex-limited disease which fully manifests in males only, so male mice were used exclusively for this study. During planning stages, researchers must take into account the National Institutes of Health&#8217;s considerations of sex as a biological variable to determine group sizes and composition18.

<table><tbody><tr><td>Caliper</td><td>n/a</td><td>n/a</td><td>must have markings down to 0.1 mm</td></tr><tr><td>Craft Glue</td><td>E6000</td><td>n/a</td><td></td></tr><tr><td>Footprint Paint (Tempera Paint)</td><td>Artmind</td><td>n/a</td><td>must be non-toxic</td></tr><tr><td>Round Barrel Paintbrushes</td><td>Symply Simmons</td><td>n/a</td><td>0.5 cm diameter</td></tr><tr><td>Ruler</td><td>n/a</td><td>n/a</td><td>must have markings down to millimeters</td></tr><tr><td>Scoring Paper (Watercolor Pads)</td><td>Canson</td><td>n/a</td><td>cut to size</td></tr><tr><td>Tunnel and Goal Chamber</td><td>Interstate Plastics</td><td>n/a</td><td>cut to size</td></tr></tbody></table>

low-cost gait analysis for behavioral phenotyping of mouse models of neuromuscular disease

Measurement of animal locomotion is a common behavioral tool used to describe the phenotype of a given disease, injury, or drug model. The low-cost method of gait analysis demonstrated here is a simple but effective measure of gait abnormalities in murine models. Footprints are analyzed by painting a mouse&#8217;s feet with non-toxic washable paint and allowing the subject to walk through a tunnel on a sheet of paper. The design of the testing tunnel takes advantage of natural mouse behavior and their affinity for small dark places. The stride length, stride width, and toe spread of each mouse is easily measured using a ruler and a pencil. This is a well-established and reliable method, and it generates several metrics that are analogous to digital systems. This approach is sensitive enough to detect changes in stride early in phenotype presentation, and due to its non-invasive approach, it allows for testing of groups across life-span or phenotypic presentation.

With sufficient numbers of animals, this procedure is capable of detecting gait differences between mouse genotypes, within the same strain over time. Figure 1B shows representative traces of footprint images collected in our lab, using a mouse model of X-linked Spinal and Bulbar Muscular Atrophy (SBMA), a neurodegenerative disorder affecting lower motor neurons and skeletal muscle. We have previously reported that male BAC fxAR121 transgenic mice develop significant weight loss, impairments...

Watch this Scientific Journal Video about Low-Cost Gait Analysis for Behavioral Phenotyping of Mouse Models of Neuromuscular Disease at JoVE.com

Low-Cost Gait Analysis for Behavioral Phenotyping of Mouse Models of Neuromuscular Disease

Footprint analysis is a low-cost alternative to digitized gait analysis programs for researchers quantifying movement abnormalities in mice. Because of its speed, simplicity, and longitudinal potential, it is ideal for behavioral phenotyping of mouse models.

Measurement of animal locomotion is a common behavioral tool used to describe the phenotype of a given disease, injury, or drug model. The low-cost method ...

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JoVE Journal

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16.2K Views.  Duke University School of Medicine. Footprint analysis is a low-cost alternative to digitized gait analysis programs for researchers quantifying movement abnormalities in mice. Because of its speed, simplicity, and longitudinal potential, it is ideal for behavioral phenotyping of mouse models.

Video: Low-Cost Gait Analysis for Behavioral Phenotyping of Mouse Models of Neuromuscular Disease

A Simple and Low-cost Assay for Measuring Ambulation in Mouse Models of Muscular Dystrophy

Measuring functional outcomes in the treatment of muscular dystrophy is an essential aspect of preclinical testing. The assessment of voluntary ambulation in mouse models is a non-invasive and reproducible activity assay that is directly analogous to measures of patient ambulation such as the 6-minute walk test and related mobility scores. Many common methods for testing mouse ambulation speed and distance are based on the open field test, where an animal&#39;s free movement within an arena is measured over time. One major downside to this approach is that commercial software and equipment for high-resolution motion tracking is expensive and may require transferring mice to specialized facilities for testing. Here, we describe a low-cost, video-based system for measuring mouse ambulation that utilizes free and open-source software. Using this protocol, we demonstrate that voluntary ambulation in the dystrophin-null mdx mouse model for Duchenne muscular dystrophy (DMD) is decreased relative to wild-type mouse activity. In mdx mice expressing the utrophin transgene, these activity deficits are not observed and the total distance traveled is indistinguishable from wild-type mice. This method is effective for measuring changes in voluntary ambulation associated with dystrophic pathology, and provides a versatile platform that can be readily adapted to diverse research settings.

This protocol describes a flexible, low-cost system for measuring mouse ambulation in an open field activity assay. We show that a 6-minute ambulation assay based on this system detects a decrease in voluntary movement in mdx mice, and accurately distinguishes improvement in a muscle-specific rescue of these animals.

Measuring functional outcomes in the treatment of muscular dystrophy is an essential aspect of preclinical testing. The assessment of voluntary ambulation ...

Low-cost Protocol of Footprint Analysis and Hanging Box Test for Mice Applied the Chronic Restraint Stress

Gait disturbance is frequently observed in patients with movement disorders. In mouse models used for movement disorders, gait analysis is important behavioral test to determine whether the mice mimic the symptoms of patients. Motor deficits are often induced by stress when no spontaneous motor phenotype is observed in the mouse models. Therefore, gait analysis followed by stress loading would be a sensitive method for evaluating the motor phenotype in mouse models. However, researchers face the requirement of an expensive apparatus to obtain quantitative results automatically from gait analysis. For stress, stress loading by simple methods without expensive apparatuses required for electric shock and forced running is desirable. Therefore, we introduce a simple and low-cost protocol consisting of footprint analysis with paper and ink, hanging box test to evaluate motor function, and stress loading defined by restraint with a conical tube. The motor deficits of mice were successfully detected by this protocol.

The low-cost protocol consisting of footprint analysis and hanging box test after restraint stress is useful for evaluating the movement disorders of mouse model.

Gait disturbance is frequently observed in patients with movement disorders. In mouse models used for movement disorders, gait analysis is important ...

Paw-Print Analysis of Contrast-Enhanced Recordings (PrAnCER): A Low-Cost, Open-Access Automated Gait Analysis System for Assessing Motor Deficits

Gait analysis is used to quantify changes in motor function in many rodent models of disease. Despite the importance of assessing gait and motor function in many areas of research, the available commercial options have several limitations such as high cost and lack of accessible, open code. To address these issues, we developed PrAnCER, Paw-Print Analysis of Contrast-Enhanced Recordings, for automated quantification of gait. The contrast-enhanced recordings are produced by using a translucent floor that obscures objects not in contact with the surface, effectively isolating the rat&#8217;s paw prints as it walks. Using these videos, our simple software program reliably measures a variety of spatiotemporal gait parameters. To demonstrate that PrAnCER can accurately detect changes in motor function, we employed a haloperidol model of Parkinson&#8217;s disease (PD). We tested rats at two doses of haloperidol: high dose (0.30 mg/kg) and low dose (0.15 mg/kg). Haloperidol significantly increased stance duration and hind paw contact area in the low dose condition, as might be expected in a PD model. In the high dose condition, we found a similar increase in contact area but also an unexpected increase in stride length. With further research, we found that this increased stride length is consistent with the bracing-escape phenomenon commonly observed at higher doses of haloperidol. Thus, PrAnCER was able to detect both expected and unexpected changes in rodent gait patterns. Additionally, we confirmed that PrAnCER is consistent and accurate when compared with manual scoring of gait parameters.

Paw-Print Analysis of Contrast-Enhanced Recordings PrAnCER: A Low-Cost, Open-Access Automated Gait Analysis System for Assessing Motor Deficits

We describe a novel gait analysis system, Paw-Print Analysis of Contrast-Enhanced Recordings (PrAnCER), an open-access automated system for the quantification of gait characteristics in rats that utilizes a novel semitransparent floor to automatically quantify gait. This system was validated using the haloperidol model of Parkinson&#8217;s Disease.

Gait analysis is used to quantify changes in motor function in many rodent models of disease. Despite the importance of assessing gait and motor function ...

3D Kinematic Gait Analysis for Preclinical Studies in Rodents

The utility of three-dimensional (3D) kinematic motion analysis systems is limited in rodents. Part of the reason for this inadequacy is the use of complex algorithms and mathematical modeling that accompany 3D data collection and analysis procedures. This work provides a simple, user-friendly, step-by-step detailed methodology for 3D kinematic gait analysis during treadmill locomotion in healthy and neurotraumatic rats using a six-camera motion capture system. Also provided are details on 1) calibration of the system in an experimental set-up customized for quadrupedal locomotion, 2) data collection for treadmill locomotion in adult rats using markers positioned on all four limbs, 3) options available for video tracking and processing, and 4) basic 3D kinematic data generation and visualization and quantification of data using the built-in data collection software. Finally, it is suggested that the utility of this motion capture system be expanded to studying a variety of motor behaviors before and after neurotrauma.

Presented here is a protocol to collect and analyze three-dimensional kinematics of quadrupedal locomotion in rodents for preclinical studies.

The utility of three-dimensional (3D) kinematic motion analysis systems is limited in rodents. Part of the reason for this inadequacy is the use of ...

Gait Analysis of Age-dependent Motor Impairments in Mice with Neurodegeneration

Motor behavior tests are commonly used to determine the functional relevance of a rodent model and to test newly developed treatments in these animals. Specifically, gait analysis allows recapturing disease relevant phenotypes that are observed in human patients, especially in neurodegenerative diseases that affect motor abilities such as Parkinson&#39;s disease (PD), Alzheimer&#39;s disease (AD), amyotrophic lateral sclerosis (ALS), and others. In early studies along this line, the measurement of gait parameters was laborious and depended on factors that were hard to control (e.g., running speed, continuous running). The development of ventral plane imaging (VPI) systems made it feasible to perform gait analysis at a large scale, making this method a useful tool for the assessment of motor behavior in rodents. Here, we present an in-depth protocol of how to use kinematic gait analysis to examine the age-dependent progression of motor deficits in mouse models of neurodegeneration; mouse lines with decreased levels of endophilin, in which neurodegenerative damage progressively increases with age, are used as an example.

In this study, we demonstrate the use of kinematic gait analysis based on ventral plane imaging to monitor the subtle changes in motor coordination as well as the progression of neurodegeneration with advancing age in mouse models (e.g., endophilin mutant mouse lines).

Motor behavior tests are commonly used to determine the functional relevance of a rodent model and to test newly developed treatments in these animals. ...

Developmental Biology

Validating a Murine Model of Angelman Syndrome Using Behavioral Tests

Behavioral Characterization of an Angelman Syndrome Mouse Model

This manuscript describes a battery of behavioral tests available to characterize Angelman syndrome (AS)-like phenotypes in an established murine model of AS. We use the rotarod learning paradigm, detailed gait analysis, and nest building test to detect and characterize animal motor impairments. We test animal emotionality in the open field and elevated plus maze tests, as well as the affect in the tail suspension test. When AS mice are tested in the open field test, the results should be interpreted with care, since motor dysfunctions influence mouse behavior in the maze and alter activity scores.
The reproducibility and effectiveness of the presented behavioral tests has already been validated in several independent Uba3a mouse lines with different knockout variants, establishing this set of tests as an excellent validation tool in AS research. Models with the relevant construct and face validity will warrant further investigations to elucidate the pathophysiology of the disease and grant the development of causal treatments.

Author Spotlight: A Battery of Highly Reproducible Behavioral Tests to Validate an Angelman Syndrome Murine Model 

This manuscript presents a set of highly reproducible behavioral tests to validate an Angelman syndrome mouse model.

This manuscript describes a battery of behavioral tests available to characterize Angelman syndrome (AS)-like phenotypes in an established murine model of ...

Home-Based Monitor for Gait and Activity Analysis

Current outcomes in neuromuscular disorder clinical trials include motor function scales, timed tests, and strength measures performed by trained clinical evaluators. These measures are slightly subjective and are performed during a visit to a clinic or hospital and constitute therefore a point assessment. Point assessments can be influenced by daily patient condition or factors such as fatigue, motivation, and intercurrent illness. To enable home-based monitoring of gait and activity, a wearable magneto-inertial sensor (WMIS) has been developed. This device is a movement monitor composed of two very light watch-like sensors and a docking station. Each sensor contains a tri-axial accelerometer, gyroscope, magnetometer, and a barometer that record linear acceleration, angular velocity, the magnetic field of the movement in all directions, and barometric altitude, respectively. The sensors can be worn on the wrist, ankle, or wheelchair to record the subject&#8217;s movements during the day. The docking station enables data uploading and recharging of sensor batteries during the night. Data are analyzed using proprietary algorithms to compute parameters representative of the type and intensity of the performed movement. This WMIS can record a set of digital biomarkers, including cumulative variables, such as total number of meters walked, and descriptive gait variables, such as the percentage of the most rapid or longest stride that represents the top performance of patient over a predefined period of time.

This innovative device uses magneto-inertial sensors to permit gait and activity analysis in uncontrolled environments. Currently in the qualification process as an outcome measure in the European Medical Agency, one of the applications will be to serve as a clinical endpoint in clinical trials in neuromuscular diseases.

Current outcomes in neuromuscular disorder clinical trials include motor function scales, timed tests, and strength measures performed by trained clinical ...

Bioengineering

Sagittal Plane Kinematic Gait Analysis in C57BL/6 Mice Subjected to MOG35-55 Induced Experimental Autoimmune Encephalomyelitis

Kinematic gait analysis in the sagittal plane has frequently been used to characterize motor deficits in multiple sclerosis (MS). We describe the application of these techniques to identify gait deficits in a mouse model of MS, known as experimental autoimmune encephalomyelitis (EAE). Paralysis and motor deficits in mice subjected to EAE are typically assessed using a clinical scoring scale. However, this scale yields only ordinal data that provides little information about the precise nature of the motor deficits. EAE disease severity has also been assessed by rotarod performance, which provides a measure of general motor coordination. By contrast, kinematic gait analysis of the hind limb in the sagittal plane generates highly precise information about how movement is impaired. To perform this procedure, reflective markers are placed on a hind limb to detect joint movement while a mouse is walking on a treadmill. Motion analysis software is used to measure movement of the markers during walking. Kinematic gait parameters are then derived from the resultant data. We show how these gait parameters can be used to quantify impaired movements of the hip, knee, and ankle joints in EAE. These techniques may be used to better understand disease mechanisms and identify potential treatments for MS and other neurodegenerative disorders that impair mobility.

Kinematic gait analysis in the sagittal plane yields highly precise information about how movement is executed. We describe the application of these techniques to identify gait deficits for mice subjected to autoimmune-mediated demyelination. These methods may also be used to characterize gait deficits for other mouse models featuring impaired locomotion.

Kinematic gait analysis in the sagittal plane has frequently been used to characterize motor deficits in multiple sclerosis (MS). We describe the ...

Neuroscience

Automated Gait Analysis in Mice with Chronic Constriction Injury

The von Frey test is a classical method that has been widely used to examine the sensory function of neuropathic pain animals. However, it has some disadvantages such as subjective data and the requirement of a skilled, experienced experimenter. To date, a variety of modifications have improved the von Frey method, but it still has a few limitations. Recent reports have suggested that gait analysis produces more accurate and objective data from the neuropathic animals. This protocol demonstrates how to perform the automated gait analysis to determine the degree of neuropathic pain in mice. After several days of acclimation, the mice were allowed to walk freely on the glass floor to illuminate footprints. Then, quantification of the footprints and gait were performed through video clips with automatic analysis of various walking parameters, such as area of paw print, swing time, angle of paw, etc.
The main purpose of this study is to describe the methodology of automated gait analysis and briefly compare it with data from the classical sensory test using von Frey filament.

The precise assessment of pain response in a neuropathic animal model is critical to investigate the pathophysiology of pain diseases and develop new analgesics. We present a sensitive and objective method to determine the sensory function of the rodent hind paw by an automated gait analysis system.

The von Frey test is a classical method that has been widely used to examine the sensory function of neuropathic pain animals. However, it has some ...

Applying the RatWalker System for Gait Analysis in a Genetic Rat Model of Parkinson's Disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder caused by the loss of dopaminergic (DA) neurons in the substantia nigra pars compacta. Gait abnormalities, including decreased arm swing, slower walking speed, and shorter steps are common in PD patients and appear early in the course of disease. Thus, the quantification of motor patterns in animal models of PD will be important for phenotypic characterization during disease course and upon therapeutic treatment. Most cases of PD are idiopathic; however, the identification of hereditary forms of PD uncovered gene mutations and variants, such as loss-of-function mutations in Pink1 and Parkin, two proteins involved in mitochondrial quality control that could be harnessed to create animal models. While mice are resistant to neurodegeneration upon loss of Pink1 and Parkin (single and combined deletion), in rats, Pink1 but not Parkin deficiency leads to nigral DA neuron loss and motor impairment. Here, we report the utility of FTIR imaging to uncover gait changes in freely walking young (2 months of age) male rats with combined loss of Pink1 and Parkin prior to the development of gross visually apparent motor abnormality as these rats age (observed at 4-6 months), characterized by hindlimb dragging as previously reported in Pink1 knockout (KO) rats.

Here we describe the RatWalker system, built by redesigning the MouseWalker apparatus to accommodate for the increased size and weight of rats. This system uses frustrated total internal reflection (FTIR), high-speed video capture, and open-access analysis software to track and quantify gait parameters.