Gait Analysis in Laboratory Animals: Studying Coordinated Movement and Associated Disorders

Sponsored by:

Martin HessInsideScientific

Tom Hampton, PhDMouse Specifics Inc.

Carol Milligan, PhDWake Forest School of

Medicine

Charles Meshul, PhDVA Medical Center/Portland & Oregon Health & Science

University

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DigiGait is a widely published ventral plane videography instrumentation available for gait analysis in laboratory animals. Voluntary and treadmill walking, DigiGait performs gait analysis of mice and rats over a range of walking and running speeds. Learn More >>>

Gait analysis in animal models of human diseases –measures of strength, balance, & coordination

Thomas Hampton, PhD

President and CSO

Mouse Specifics, Inc.

Copyright 2015 T. Hampton, Mouse Specifics, Inc. & InsideScientific. All Rights Reserved.

What is gait analysis?

Gait analysis is the quantitative assessment of the manner of movement, as it applies to ambulation [walking and running].

When is gait disturbed?• Arthritis

• Bone fractures

• Traumatic Brain Injury• Amyotrophic lateral sclerosis• Ataxia

• Medulloblastoma• Spinal cord injury

• Huntington’s disease• Nerve injury• Orthopedic injuries

• Parkinson’s disease• Multiple sclerosis• Stroke• Muscular dystrophy

Amyotrophic lateral sclerosisDr. Carol Milligan

Parkinson’s diseaseDr. Charles Meshul

Why gait analysis?

Patients want to walk!

Why gait analysis?

Why treadmill gait analysis?

1. rodents rarely follow instructions

2. walking speed significantly impacts posture & kinematics

3. higher repeatability and lower standard error

4. explore challenge conditions to highlight subtle problems

5. early detection

What does gait analysis measure?

How long is my stride?

How far apart are my feet?

Do my toes point inwards?

Is my swing exaggerated?

How steady am I on my feet?

The DigiGait™ Imaging System, is patented instrumentation for studying gait by examining the ventral view of subjects as they walk on a transparent treadmill belt.

A high speed camera images the ventral view of animals as they walk, run, limp, or hop on the motorized transparent treadmill belt.

AI examines each paw to determine its position relative to the treadmill belt, resulting in gait signals for each limb.

Braking

PropulsionStance

Stride

Swing

Pa

w a

rea

Time

Multiple strides

Voluntary and treadmill

Range of speeds (0-100 cm/s)

Horizontal, incline, & decline

How do my animals walk?

Stride length

Stance width

Cadence

Paw placement angle

Swing time

Step-to-step stability

Braking duration

Propulsion duration

Gait symmetry

Paw overlap

Paw area

Tau

Rate of loading

Sciatic Functional Index

……….

18 cm/s

36 cm/s

Guinea PigEven small differences in walking speed significantly impact gait metrics, including stride length and paw angles.

Ensemble averaged gait signals:

note good symmetry between left & right forelimbs (top) & hind limbs (bottom).

Sciatic nerve

injury

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11

13

15

17

19

32 41 52 63 76 97 110

Life Day

Hin

d p

aw

pla

cem

en

t an

gle

(d

eg

rees)

Wild-type

SOD1 G93A

P<0.05

ALS model

PD model

5

7

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13

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32 41 52 63 76 97 110

Life Day

Hin

d p

aw

pla

cem

en

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gle

(d

eg

rees)

Wild-type

SOD1 G93A

Stride length changes in

mouse ~0.5 cm.

“ we can’t just place a banana in front of a mouse to cause a disturbance”

Changing the properties of the walking surface primarily affected forelimb kinematics.

Oil applied to walking surface

Changing the properties of the walking surface primarily affected forelimb kinematics.

Oil applied to walking surface

How do lab animals manage obstacles in their walking path?

How are obstacles managed?

How might neurotoxins affect ability to detect and negotiate obstacles?

Baseline

Ethanol

Pnd 14 Pnd 25

Pnd 14

Study of developmental abnormalities

• Cerebral palsy

• Muscular dystrophy

• Spinal muscular atrophy

Huntington’s disease [3NP, R6/2]

Parkinson’s disease [MPTP, 6-hydroxydopamine]

Amyotrophic lateral sclerosis [TDP-43, SOD1 G93A]

MS

OA, RA, Pain

Stroke

Spinal Cord Injury

The DigiGait™ Imaging System is the most widely published treadmill gait analysis system available.

Recent Publications:

Sashindranath et al.....craniotomy and traumatic brain

injury. Behav Brain Res. 2015

Poulet et al. ...articular cartilage lesions.

Osteoarthritis Cartilage. 2015

Gadalla et al. Gait analysis in a Mecp2 knockout....

PLoS One. 2014

Benefits

In vivo

Easy-to-use

Turn-key solution

Scalable

Automated

Digital information

Relevant metrics of motion

Integrates strength, balance,

coordination

Replaces multiple motor

function tests

Visual record of study

Traumatic Brain Injury

ALS, HD, PD

Pain

Muscular dystrophy

Multiple sclerosis

Neuropathy

Drug screening

Features Benefits Applications

The DigiGait™ Imaging System has features that bring benefits to numerous disease applications.

Behavioral Deficits Correlate with Early Pathology in the SOD1 mouse model of ALS

Carol Milligan, Ph.D.

Professor, Department of

Neurobiology & AnatomyWake Forest School of Medicine

Copyright 2015 C. Milligan, Mouse Specifics Inc. & InsideScientific. All Rights Reserved.

a. Amyotrophic Lateral Sclerosis and the usefulness (or not) of the SOD1G93A mouse as an experimental model system

b. The importance of thorough, scientific characterization of experimental model systems

c. The importance of including behavioral assays in determining pathological processes

What are we going to discuss?

Ron Oppenheim

James Caress

Tom Hampton

David Gifondorwa

Mac RobinsonAnna Taylor

David Prevette

Thomas Gould

Ramon Jimenez-Moreno

Sherry Vinsant

Carol Mansfield

Jane Strupe

Phonepasong Arounleut

Masaaki Yoshikawa

Vickie Moore

Acknowledgements

Funding:

Wake Forest Brian White Funds

Blazeman Foundation for ALS

NIH/NINDS R01NS069212

NIH/NINDS R01NS036081

Robert Packard Center for ALS Research at Johns Hopkins

Collaborators and Colleagues:

350,000 individuals in the world have ALS/MND

120,000 diagnosed each year - 100,000 will die each year

30,000 individuals in US affected with 5000 new cases each year.

The ALS center at WFUBMC sees approximately 150 patients/year.

Adult onset (+ 55 years)

5-10% of cases are familial (fALS) with remaining 90-95% being sporadic (sALS).

Amyotrophic Lateral Sclerosis (ALS) Motor Neuron Disease (MND)

http://keribstill.com/

Amyotrophic Lateral Sclerosis (ALS) Motor Neuron Disease (MND)

Patients present with difficulties with:

• speech and swallowing

• muscle weakness and atrophy (loss of large motoneurons of brainstem and spinal cord)

• muscle fasciculations/twitching

• hyperreflexia and/or spasticity (lesions to upper motoneurons)

Intellect, cardiovascular and other body functions are not affected.

With no substantially effective treatment, patients die on average thee years after diagnosis.

http://keribstill.com/

90% sporadic

Variations in DCTN1 (dynactin 1), NEFH (neurofilament, heavy polypeptide), PRPH (peripherin) and SMN1 (survival motor neuron 1) increase chances of developing ALS.

ALS Patients and Genetics

ALS Patients and Genetics

10% familial

C9orf72 – 30-40% sALS- normal gene has a GGGGCC stretch, in ALS patients this can be repeated > 30 times

SOD1 – 20% - Superoxide Dismutase 1- mutation appears to be toxic gain of function

TARDBP (TDP-43) - 5% - TAR DNA binding protein, binds to RNA and ensures stability

FUS – 5% - fused in sarcoma – binds DNA and regulates transcription

ANG – 1% - angiogenin, ribonuclease involved in angiogenesis

ALS2, SeTX, VAPB

• Autosomal dominant missense point mutation in SOD1 identified in a subset of familial ALS patients (Rosen et al., 1993. Nature. 362(6415):59-62).

• 10-15% of familial ALS cases (1% of all cases) possess mutations in Cu+2/Zn+2 superoxide dismutase (SOD).

• Cu+2/Zn+2 SOD1 catalyzes the conversion of .O2 to O2 and H2O2.

• Mutation is toxic “gain of function”

• Cytoplasmic superoxide dismutase

• Mutation suggest a role for free radical damage in ALS.

Genetics and ALS?

• Gurney et al., 1994. Science 264(5166):1772-5

• Commercially available from Jackson Laboratory

• Females do not breed

• Autosomal dominant

• Develop “symptoms” at about 90 days

• Age of symptom onset is determined when mice can not fully extend legs.

• Die by about 120-140 days

G93AG93A mutant SOD1 mouse

Wild-Type

The SOD1G93A mouse model of ALS has been used in many pre-clinical studies.

a, Average age of symptom onset is significantly delayed in rhHsp70 injected animals (n = 7) compared with Riluzole treated (n = 12) and untreated mice (n = 11; ***p ≤ 0.001).

Gifondorwa DJ, et. al. Exogenous delivery of heat shock protein 70 increases lifespan in a mouse model of amyotrophic lateral sclerosis. J Neurosci. 2007 Nov 28;27(48):13173-80.

SOD1 mice exhibit denervation of the neuromuscular junction (NMJ).

a, Injection of rhHsp70 resulted in an increased percentage of innervated NMJs in the MG at P90.

Gifondorwa DJ, et. al. Exogenous delivery of heat shock protein 70 increases lifespan in a mouse model of amyotrophic lateral sclerosis. J Neurosci. 2007 Nov 28;27(48):13173-80.

Motoneurons die by endstage in the SOD1G93A mouse.

Vinsant S et al., (2013). Brain and Behavior 3 (4): 335–350. PMCID: PMC3869677 Vinsant S et al., (2013). Brain and Behavior 3 (4): 431–457. PMCID: PMC3869683 Modified from

Tradi onalcoun ngdoesnotreveallossofMNsun lendstage.

ButthenumberofvacuolatedMNspredictsMNsthatwilldegenerate.

• Charcot J-M (1874). De la sclérose latérale amyotrophique. Prog Med. 2: 325-327, 341-342, 453-455.

• Duchen LW, Strich SJ (1968). An hereditary motor neurone disease with progressive denervation of muscle in the mouse: the mutant ‘wobbler.’ J. Neurol Neurosurg Psychiatry 31 (6): 535-42)

• Messer, A., and Flaherty, L. (1986). Autosomal dominance in a late onset motor neuron disease in the mouse. J. Neurogenet 3: 345-355.

• Gurney ME, Pu H, Chiu AY, Dal Cnato MC et al., (1994). Motor neuron degeneration in mice that express a human Cu,Zn superoxide dismutase mutation. Science 264(5166):1772-5.

• Wegorzewska I, Bell S, Cairns NJ, Miller TM, Baloh RH (2009). TDP-43 mutant transgenic mice develop features of ALS and frontotemporal lobar degeneration. PNAS 106(44): 18809-14.

Landmark papers in ALS

• Charcot J-M (1874). De la sclérose latérale amyotrophique. Prog Med. 2: 325-327, 341-342, 453-455.

• Duchen LW, Strich SJ (1968). An hereditary motor neurone disease with progressive denervation of muscle in the mouse: the mutant ‘wobbler.’ J. Neurol Neurosurg Psychiatry 31 (6): 535-42)

• Messer, A., and Flaherty, L. (1986). Autosomal dominance in a late onset motor neuron disease in the mouse. J. Neurogenet 3: 345-355.

• Gurney ME, Pu H, Chiu AY, Dal Cnato MC et al., (1994). Motor neuron degeneration in mice that express a human Cu,Zn superoxide dismutase mutation. Science 264(5166):1772-5.

• Wegorzewska I, Bell S, Cairns NJ, Miller TM, Baloh RH (2009). TDP-43 mutant transgenic mice develop features of ALS and frontotemporal lobar degeneration. PNAS 106(44): 18809-14.

Title…

When and where does ALS pathology begin?

What cells and processes are involved?

SOD1G93A High Expression Chronology of Pathophysiology

• MNs are hyperexcitable (Pieri 2003; Kuo 2004; De Vos 2007)• Transient behavioral deficits (Van Zundert 2008; Saxena 2009)• Golgi fragmentation, mitochondrial vacuolization and damage

(Bendotti 2001; Gould 2006; Martin 2007)• ER stress (Saxena 2009)

• SOD1 aggregates (Johnston 2000; Turner 2003; Gould 2006)• Reduced motor units and muscle denervation (Frey 2000; Pun 2006; Gould 2006;

Hegedus 2007)• Axonal transport deficits (Ligon 2005)• Motor deficits (Open field test, grip strength (Barneoud 1997; Ligon 2005; Wooley

2005;Haywoth 2009)• Reduced numbers of spinal motoneurons, corticospinal and bulbar spinal neurons

(Zang 2002; Shin 2007; Martin 2007)• Disrupted BBB (Zhong 2008)

• Glial activation (Gould 2006)• VR and DR axon loss (Fischer 2004; Fischer 2005)• Hindlimb tremor (Chiu 1995)

• Rotorod deficits (Fischer 2005)• MN cell death (Chiu 1995; Gould 2006)

Progressive paralysis, loss of 50% MNs and death

P30

Birth

P60

P90

P120-endstage

Pre

-sym

pto

ma

tic

?

Pre

-sym

pto

ma

tic

rhHsp70 treatment delays symptom onset in G93A mice

Gifondorwa DJ, et. al. Exogenous delivery of heat shock protein 70 increases lifespan in a mouse model of amyotrophic lateral sclerosis. J Neurosci. 2007 Nov 28;27(48):13173-80.

• Treatment beginning at postnatal day (P) 50 with rhHsp70 significantly delayed symptom onset and extended survival

• Treatment beginning at P90 had no effect on symptom onset or survival.

• Treatment beginning at P30 had greatest effects on extending survival.

wt

Bax

KO

SOD

1

SOD

/ B

ax K

O1

P140 end‐ stage

Dissociation of Motoneuron Death from ALS

• Loss or pro-apoptotic protein Bax prevents loss of MN during normal development

• Loss of Bax in the SOD1 mouse prevents MN cell death

• However, while there was a slight extension of survival, the BAX deficient SOD1 mice still died.

• Denervation of NMJ still occurs and in SOD1 mice, denervation occurs quite early.

When and where is earliest pathology?

Vinsant S et al., (2013). Brain and Behavior 3 (4): 335–350. PMCID: PMC3869677 Vinsant S et al., (2013). Brain and Behavior 3 (4): 431–457. PMCID: PMC3869683

When and where is earliest pathology?

Tibialis Anterior (TA)

• Anterior (skin)- Type 2B muscle fibers• Posterior (bone)- Type 2A, B , x muscle fibers• Motoneurons that innervate type 2B fibers are

most susceptible in ALS/MND.

Soleus

• Type 1 muscle fibers• Motoneurons that innervate type 1

fibers are less susceptible in ALS/MND.

Initial denervation of TA NMJs begins after postnatal day 14 and before day 30

Vinsant S et al., (2013). Brain and Behavior 3 (4): 335–350. PMCID: PMC3869677 Vinsant S et al., (2013). Brain and Behavior 3 (4): 431–457. PMCID: PMC3869683

Abnormalities are observed in the MN soma in region of the TA motor pool at P30

Wild Type

Wild Type

SOD+

SOD+

• Enlarged and vacuolated mitochondria are observed

• Clear, empty cytoplastmicvacuoles are present

P30 distal dendrites show more profound changes.

• Large, vacuolated mitochondria are prominent

• Clear, empty cytoplasmic vacuoles are also present in distal dendrites

• Distal dendrites are where many excitatory synapses are found on MNs

Fewer but larger mitochondria are observed in motoneuron soma at postnatal day 30.

Vinsant S et al., (2013). Brain and Behavior 3 (4): 335–350. PMCID: PMC3869677 Vinsant S et al., (2013). Brain and Behavior 3 (4): 431–457. PMCID: PMC3869683

Mitochondria membrane potential, ATP content and generation are reduced in SODG93A at day 30.

Vinsant S et al., (2013). Brain and Behavior 3 (4): 335–350. PMCID: PMC3869677 Vinsant S et al., (2013). Brain and Behavior 3 (4): 431–457. PMCID: PMC3869683

Wild type

SODG93A SODG93A

Mitochondrial abnormali es are seen in axons in TA and occasionally in soleus at P30.

TA soleus

SOD1 SOD1

WT

Abnormal mitochondria are observed in axons at day 30.

Mitochondria morphological alterations are also observed in motoneuron terminals in NMJs of TA and soleus muscles.

SOD1 WT

Mitochondria morphological alterations are also observed in motoneuron terminals in NMJs of TA and soleus muscles.

SOD1 WT

Fewer but larger mitochondria are observed presynaptic terminals in both TA and soleus NMJs.

• Using ultrastuctural characteristics, the number and type of afferent synapses was determined at day 30.

• A C-type synapse that is usually excitatory is shown in A.

• A type 2 synapse that is usually inhibitory is shown in B.

• A type 1 synapse that is usually excitatory is shown in C.

• In the SOD1 animals, synaptic morphologies appeared normal.

Are there other indicators of pathology at day 30?

Wild Type

SOD1

• There is a decrease in the number of excitatory, Type 1 synapses on the MN cell body.

• There is an increase in the number of C-type synapses on the MN cell body.

• This is also a decrease in the number of excitatory, Type 1 synapses on distal dendrites.

The number and type of afferent synapses is altered at day 30.

Axo-somatic synapses

Axo-dendritic synapses

• Mitochondrial abnormalities are abundant in dendrites, soma and NMJ presynaptic terminal.

• Mitochondria membrane potential, ATP content and generation are reduced in lumbar spinal cord.

• Small, empty cytoplasmic vacuoles appear in motoneuron soma and dendrites.

• Decrease in total synapse and excitatory synapses in distal dendrites

• No change in total number of synapses, but decrease in excitatory and increase in C-terminals

• Denervation of tibialis anterior and medial gastrocnemius muscles

• No apparent change in retrograde transport.

By postnatal day 30 there are obvious pathological changes observed in the SOD1 mouse.

Symptom onset in the SOD1 mouse occurs much later than day 30.

Gifondorwa DJ, et. al. Exogenous delivery of heat shock protein 70 increases lifespan in a mouse model of amyotrophic lateral sclerosis. J Neurosci. 2007 Nov 28;27(48):13173-80.

G93A

Wild-Type

P90

Age of symptom onset was determined when mice can not fully extend legs.

Observed typically day 90

The initial symptoms of ALS can be quite varied in different people. One person may have trouble grasping a pen or lifting a coffee cup, while another person may experience a change in vocal pitch when speaking. ALS is typically a disease that involves a gradual onset.

http://www.alsa.org/about-als/symptoms

Jon “the Blazeman” Blais (www.waronals.org)

He noticed he was having a hard time holding things -- soap, toothbrush, etc. -- but he kept putting off seeing someone about it.

Digigait Imaging System Mouse Specific

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Mouse Specific

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Mouse Specific

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We wanted to determine of the pathological changes were associated with symptom onset.

Digigait Imaging System Mouse Specific

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Mouse Specific

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Mouse Specific

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Gait dynamics were recorded using ventral plane videography using the Digigait Imaging System.

Decreases in limb stance width and increases in variability of paw placement angle occur at the time of initial denervation

Forelimb stance width

Hindlimb stance width

• In mouse models, pathological changes occur much earlier than overt behavior changes.

• It is essential to characterize early pathology and utilize appropriate behavioral analysis.

• By understanding the earliest pathology, we will

- gain insight into potential causes of disease,

- identify biomarkers, and

- develop effective therapeutics

Conclusions…

Changes in DigiGait measures in a progressive animal model of Parkinson's disease

Charles K. Meshul, Ph.D

Research Biologist, VA Medical Center/Portland and Professor,

Department of Behavioral Neuroscience

Oregon Health & Science University

Copyright 2015 C.K.Meshul, Mouse Specifics Inc. & InsideScientific. All Rights Reserved.

Acknowledgments

The important contributions from the following individuals are greatly appreciated:

Michelle Sconce

Madeline Churchill

Rebecca Hood

Natalie Goldberg

This research was supported by the Department of Veterans Affairs Merit Review Program

The Parkinson’s disease (PD) animal model

• Most PD rodent models primarily have used acute/subacute toxin administration, resulting in >70-95% unilateral or bilateral loss of nigrostriatal dopamine. This results in significant motor dysfunction.

• We have used a progressive loss of dopamine over a 4-week time period to try and simulate the longer term loss of dopamine as seen in PD patients. This results in a 60-80% loss of dopamine. This slower loss of dopamine most likely results in the brain adapting to the new environment, making motor dysfunction more difficult to measure.

• Most treatment paradigms have used a neuroprotection strategy, which are not clinically relevant. We have tested treatments either during (intervention) or following (restoration) progressive MPTP administration.

Dopaminergic and Behavioral Correlations

• Increased dosing of MPTP over a 4-week time period results in a progressive loss of dopamine.

• Treatment can be initiated anytime during this 4-week time period, although the emphasis in terms of translation is more in restoration versus protection.

Goldberg et al: Dopaminergic and Behavioral Correlates of Progressive Lesioning of the Nigrostriatal Pathway with 1-Methyl-4-Phenyl-1,2,3,6-Tetrahydropyridine. Neuroscience 180:256-271 (2011).

Gait dynamics in vehicle and MPTP-treated (4mg/kg – 32 mg/kg) at a walking speed of 24 cm/s

Goldberg et al.: Profiling changes in gait dynamics resulting from progressive MPTP-induced nigrostriatal lesioning. J. Neuroscience Research 89:1698-1706 (2011).

Sconce et al: Intervention with 7,8-dihydroxyflavone blocks further striatal terminal loss and restores motor deficits in a progressive mouse model of Parkinson’s disease. Neuroscience 290:454-471 (2015).

Intervention with 7,8-dihydroxyflavone (DHF): Gait changes

With MPTP treatment, the forepaws exerted a greater

distance from the midline compared to the

hindpaws (ie negative values).

Correlation of dopamine, sprouting and second messengerbiomarkers on measures of motor function

• With a decrease in TH/dopamine terminals within the striatum following MPTP treatment, there was an increase in the time that the hind paws were on the belt during running. There was improvement following DHF treatment.

• Following DHF treatment, there was an increase in the levels of SCG 10 (sprouting factor) and the activated BDNF receptor (pTrkB), resulting in gait symmetry between the forepaws and hindpaws.

Sconce et al: Intervention with 7,8-dihydroxyflavone blocks further striatal terminal loss and restores motor deficits in a progressive mouse model of Parkinson’s disease. Neuroscience 290:454-471 (2015)..

Intervention with Exercise

• Progressive treatment with MPTP results in changes in several measures of gait, including paw area, stance width and shared stance, suggesting instability due to dopamine loss.

• Intervention with voluntary exercise, starting 2 weeks after the start of MPTP treatment, results in recovery of these gait measures.

Sconce et al: Intervention with exercise restores motor deficits but not nigrostriatal loss in a progressive MPTP mouse model of Parkinson’s disease. Neuroscience 299:156-174 (2015).

Maximal rate of change of paw

area in contact with belt during

breaking phase.

% of stance of hind paws in contact

with belt at same time.

• With MPTP treatment, levels of the glutamate transporter increased, which was positively correlated with an increase in paw area.

• Interestingly, as the levels of the vesicular dopamine transporter, VMAT2, decreased, the paw area increased.

Correlation of dopamine and glutamate biomarkers

Curcumin Treatment Improves Motor Behavior in ɑ-Synuclein Transgenic Mice

Spinelli et al: Curcumin treatment improves motor behavior in alpha-synulcein transgenic mice. Plos One, 10(6): e0128510 (2015).

MPTP: 4 weeks, followed by DHF treatment for 4 weeks (restoration). Most of the DigiGait measures were significantly different 4 weeks after MPTP treatment (MPTP group)compared to the 4wk MPTP only group.

Flavone-induced restoration of gait function following MPTP

Sconce et al: in preparation

• MPTP treatment resulted in increased stance width, decreased stance/swing, increased swing time, and increased paw angle.

• The changes in gait described above were reversed following DHF treatment and these were correlated with changes in second messenger and sprouting levels.

Correlation of sprouting and second messenger biomarkers with gait measures following flavone treatment.

Sconce et al: in preparation

Data courtesy of: Madeline Churchill (manuscript in preparation)

• 4 weeks of MPTP followed by 4 weeks of daily cyclosporin A treatment (restoration)• Greater stance width implies overcompensation for gait instability; connected with step angle variance.

Effect of Cyclosporin A (CsA) treatment following MPTP

Blue bars = CsA treatmentWhite bars = vehicle treatment

Summary & Conclusions

1. Progressive loss of dopamine in a mouse model of PD, followed by withdrawal of the toxin for 1-4 weeks, results in variable changes in several measures of gait. All the MPTP-induced gait alterations appear to be connected to gait instability. However, the slight differences in dopamine loss (60-75%) may contribute to which gait measures are affected.

2. Although the same strain of mouse (male, C57Bl/6J, 12-15 weeks old) and dose of MPTP are used for each study, the variability in the differences in gait measures may simply replicate what is seen in patients with PD. Not all PD patients develop exactly the identical motor disturbances. Our data may be reflective of those differences seen in the human population despite the fact that the same strain/sex/age of mouse is used.

Thank You!For additional information on Mouse Specifics equipment specially designed for gait analysis in rodents please visit:

https://mousespecifics.com/