Automated quantitative gait analysis in animal models of movement disorders

<p>Abstract</p> <p>Background</p> <p>Accurate and reproducible behavioral tests in animal models are of major importance in the development and evaluation of new therapies for central nervous system disease. In this study we investigated for the first time gait parameters of rat models for Parkinson's disease (PD), Huntington's disease (HD) and stroke using the Catwalk method, a novel automated gait analysis test. Static and dynamic gait parameters were measured in all animal models, and these data were compared to readouts of established behavioral tests, such as the cylinder test in the PD and stroke rats and the rotarod tests for the HD group.</p> <p>Results</p> <p>Hemiparkinsonian rats were generated by unilateral injection of the neurotoxin 6-hydroxydopamine in the striatum or in the medial forebrain bundle. For Huntington's disease, a transgenic rat model expressing a truncated huntingtin fragment with multiple CAG repeats was used. Thirdly, a stroke model was generated by a photothrombotic induced infarct in the right sensorimotor cortex. We found that multiple gait parameters were significantly altered in all three disease models compared to their respective controls. Behavioural deficits could be efficiently measured using the cylinder test in the PD and stroke animals, and in the case of the PD model, the deficits in gait essentially confirmed results obtained by the cylinder test. However, in the HD model and the stroke model the Catwalk analysis proved more sensitive than the rotarod test and also added new and more detailed information on specific gait parameters.</p> <p>Conclusion</p> <p>The automated quantitative gait analysis test may be a useful tool to study both motor impairment and recovery associated with various neurological motor disorders.</p

Behavioural and Anatomical Effects of Unilateral Injection of Botulinum Neurotoxin A in the Entopeduncular Nucleus of a Parkinsonian Rat Model

Loss of dopamine in Parkinson’s disease is associated with glutamatergic hyperactivity of the subthalamic nucleus. Pharmacological and electrical therapies aimed to suppress this overactivity favourably alleviate parkinsonian motor symptoms. No study has explored the potential of botulinum neurotoxin A in the central nervous system beyond cholinergic blockage despite evidence of its ability to inhibit glutamate release. Thus, the present study investigates the effect of selective suppression of hyperactive glutamatergic input from the subthalamic nucleus to the entopeduncular nucleus by botulinum neurotoxin A in a parkinsonian model. Unilateral 6-hydroxydopamine lesioned rodents received microinfusions of botulinum neurotoxin A or vehicle into the ipsilateral entopeduncular nucleus, and their mobility was assessed using the CatWalk apparatus. Administration of a single dose of botulinum neurotoxin A (0.5 ng) significantly improved the rotational asymmetry and dynamic gait abnormalities, suggesting a potential use of intracerebral botulinum neurotoxin A to produce effective neuromodulation in the parkinsonian brain

Design of a gait acquisition and analysis system for assessing the recovery in a classical murine model of Parkinson's disease

Includes bibliographical references.2015 Fall.Gait deficits are important clinical symptoms of Parkinson's disease (PD). Data focusing on gait can be used to measure recovery of motor impairments in rodents with systemic dopamine depletion. This thesis presents a design for a gait acquisition and analysis system able to capture paw strikes of a mouse, extract their positions and timing data, and report quantitative gait metrics to the operator. These metrics can then be used to evaluate the gait changes in mice. This work presents the design evaluation of the system, from initial cellphone captured video concepts through prototyping and testing to the final implementation. The system utilizes a GoPro camera, optimally lit walkway design, image processing techniques to capture footfalls, and algorithms for their quantitative assessment. The results gained from live animal study with methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced murine model of PD and treated with 1,1-bis(3'-indolyl)-1-(p-chlorophenyl)methane (C-DIM12) are presented, and it is shown how the quantitative measurements can be used to determine healthy, injured, and recovering gait

Doctor of Philosophy

dissertationParkinson's Disease (PD) motor symptoms, characterized most commonly by bradykinesia, akinesia, rigidity, and tremor, are brought about through the degeneration of dopaminergic neurons in the substantia nigra pars compacta, which leads to changes in electrophysiological activity throughout the basal ganglia. These symptoms are often effectively treated in the early stages of the disease by dopamine replacement therapies. However, as the disease progresses, the therapeutic window of pharmacological approaches reduces and patients develop significant side effects, even under minimally effective doses. When the disease reaches this stage, surgical therapies, such as high-frequency deep brain stimulation (DBS), are considered. DBS of the subthalamic nucleus partially treats the motor symptoms of PD and has been implemented to treat PD over 50,000 times worldwide, but its mechanisms are unclear. In this work, we set out to advance the understanding of the mechanisms, function, and malfunction of DBS as a treatment for PD, keeping in mind the idea that DBS treats PD symptoms without restoring basal ganglia neural activity to that seen under healthy conditions. First, we demonstrated that neuronal information directed from the basal ganglia to the thalamus is pathologically increased in the parkinsonian condition and reduced by DBS in a standard 6-OHDA rat model of PD. Next, we developed a rodent model of DBSs role in the exacerbation of hypokinetic dysarthria, providing a framework for the study of this poorly understood side effect of DBS. Finally, we found that DBS creates action suppression deficits independently from a parkinsonian state, and that PD creates apathy that is not rescued by DBS. Our specific results led to the interpretation that DBS, in its current form, might inherently create side effects that are largely unavoidable. Our work fits into the following overarching idea. DBS successfully treats some motor symptoms of PD through the reduction of pathological information transmission. However, the fact that reducing pathological information does not restore neural activity to that present under healthy conditions underlies some of its failures to improve certain symptoms, as well as its exacerbations and side effects

Activation of the Large-Conductance, Voltage, and Ca2+- Activated K+ (BK) Channel in Acute Spinal Cord Injury in the Wistar Rat Is Neuroprotective

Context/Objectives: Spinal cord injury (SCI) results in significant neuronal and glial cell death resulting in impaired neurological and motor function. Uncontrolled Ca2+ entry results in excitotoxicity and cell death. In this study, we examine the use of a BK channel activator, Isopimaric acid (ISO), as a neuroprotective agent post-SCI as this channel is involved in regulating Ca2+ entry.Design:By using a 25-g clip compression at the T6 level, we generated a SCI event in wistar rats. At 1 h post-injury we administered ISO (BK channel activator), the BK channel inhibitor iberiotoxin (IbTx), or a vehicle control for 4 weeks via mini osmotic pump (pump capacity). For 8 weeks post-injury, gait analysis of motor function was performed. At the end of 8 weeks, the extent of myelination in the spinal cord was assessed in addition to the electrophysiological profile.Results:Our immunohistological data suggests that ISO treatment leads to an increase or preservation of myelinated axonal tracts. This was further supported by our electrophysiological studies which demonstrate higher compound action potential amplitudes and speed of transmission in ISO-treated animals compared to inj-non-treated. Finally, treatment with ISO significantly improved motor function in our test model.Conclusion: In conclusion, activation of the BK channel during acute SCI may be a novel therapeutic target for acute SCI

Nociceptin/orphanin FQ and motor activity: behavioural, biochemical and electrophysiological studies in models of Parkinson’s disease

Nociceptin/orphanin FQ (N/OFQ) is an opioid-like neuropeptide which activates the NOP receptor. N/OFQ exerts an inhibitory control on locomotion through inhibition of dopamine (DA) neurons located in the substantia nigra (SN), which degenerate in Parkinson’s disease (PD). In the present study, we demonstrated that NOP receptor antagonists facilitated and inhibited motor behavior in 1-methyl-4-phenyl-1,2,5,6- tetrahydropyridine (MPTP)-treated mice and nonhuman primates depending on dose. In naïve mice, we found that dual response to NOP receptor antagonists was DAdependent and mediated by D2 postsynaptic (facilitation) and D2 presynaptic receptors (inhibition). Consistently, inhibition induced by high doses of NOP receptor antagonists in MPTP-treated mice was reversed by D2 receptor blockade, leading to a widening of their therapeutic window. Evidence that endogenous N/OFQ not only sustains symptoms but also contributes to neurodegeneration in PD was also provided. In fact, NOP receptor knockout mice were found to be partially resistant against MPTP-induced loss of nigral DA cells. In order to understand the mechanisms underlying motor effects of endogenous N/OFQ, we investigated the role of nigral NOP receptors in the control of motor cortex (M1) output. Motor inhibition induced by exogenous N/OFQ was associated with reduction in M1 excitability while the opposite was true for motor facilitation induced by NOP receptor antagonists. Finally, we investigated M1 reorganization in parkinsonian conditions and found that M1 excitability was decreased after 6-OHDA lesioning in rats. We concluded that endogenous N/OFQ controls motor activity via NOP receptors located in SN and through modulation of DA transmission, leading to changes in activity of the basal ganglia-thalamo-cortical pathway and M1 output. Moreover, we provide evidence that NOP receptor antagonists may represent a novel approach for symptomatic and neuroprotective therapy of PD

Kinematic analysis of bimanual movements during food handling by head-fixed rats

Bimanual coordination, in which both hands work together to achieve a goal, is crucial for the basic needs of life, such as gathering and feeding. Such coordinated motor skill is highly developed in primates, where it has been most extensively studied. Rodents also exhibit remarkable dexterity and coordination of forelimbs during food handling and consumption. However, rodents have been less commonly used in the study of bimanual coordination because of limited quantitative measuring techniques. In this article we describe a high-resolution tracking system that enables kinematic analysis of rat forelimb movement. The system is used to quantify forelimb movements bilaterally in head-fixed rats during food handling and consumption. Forelimb movements occurring naturally during feeding were encoded as continuous three-dimensional trajectories. The trajectories were then automatically segmented and analyzed, using a novel algorithm, according to the laterality of movement speed or the asymmetry of movement direction across the forelimbs. Bilateral forelimb movements were frequently observed during spontaneous food handling. Both symmetry and asymmetry in movement direction were frequently observed, with symmetric bilateral movements quantitatively more common. The proposed method overcomes a limitation in the precise quantification of bimanual coordination in rodents. This enables the use of powerful rodent-based research tools such as optogenetics and chemogenetics in the further investigation of neural mechanisms of bimanual coordination