Automated quantitative gait analysis in animal models of movement disorders.

BACKGROUND: 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. RESULTS: 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. CONCLUSION: The automated quantitative gait analysis test may be a useful tool to study both motor impairment and recovery associated with various neurological motor disorders.

CNS-targeted LIF expression improves therapeutic efficacy and limits autoimmune-mediated demyelination in a model of multiple sclerosis.

Multiple sclerosis (MS) is a demyelinating disease of the central nervous system (CNS) with an inflammatory and a neurodegenerative component. The neuropoietic cytokine leukemia inhibitory factor (LIF) is expressed in MS lesions, but its effect on lesion development is far from understood. LIF is an interesting candidate for MS therapy, as it has neuroprotective properties and may also promote the survival of myelinating oligodendrocytes (OLGs). However, therapeutic administration of LIF is complicated by its limited ability to cross the blood-brain barrier and its pleiotropic actions outside the CNS. In this study, lentiviral vectors (LVs) were used to achieve stable expression and secretion of LIF in the CNS of adult mice. CNS-targeted expression of LIF significantly reduced demyelination in a murine model of MS. In addition, local expression of LIF ameliorated clinical symptoms with enhanced efficacy compared to systemic treatment with recombinant protein. These findings demonstrate that gene therapeutic administration of LIF is a promising approach to limit lesion burden and clinical symptoms in neuroinflammatory disease.

Diffusion tensor imaging in a rat model of Parkinson's disease after lesioning of the nigrostriatal tract.

Parkinson's disease (PD) is characterised by degeneration of the nigrostrial connection causing dramatic changes in the dopaminergic pathway underlying clinical pathology. Till now, no MRI tools were available to follow up any specific PD-related neurodegeneration. However, recently, diffusion tensor imaging (DTI) has received considerable attention as a new and potential in vivo diagnostic tool for various neurodegenerative diseases. To assess this in PD, we performed DTI in the acute 6-hydroxydopamine (6-OHDA) rat model of PD to evaluate diffusion properties in the degenerating nigrostriatal pathway and its connecting structures. Injection of a neurotoxin in the striatum causes retrograde neurodegeneration of the nigrostriatal tract, and selective degeneration of nigral neurons. The advantage of this model is that the lesion size is well controllable by the injected dose of the toxin. The degree of functional impairment was evaluated in vivo using the amphetamine rotation test and microPET imaging of the dopamine transporter (DAT). Despite a nearly complete lesion of the nigrostriatal tract, DTI changes were limited to the ipsilateral substantia nigra (SN). In this study we demonstrate, using voxel-based statistics (VBS), an increase in fractional anisotropy (FA), whereas all eigenvalues were significantly decreased. VBS enabled us to visualise neurodegeneration of a cluster of neurons but failed to detect degeneration of more diffuse microstructures such as the nigrostriatal fibres or the dopaminergic endings in the striatum. VBS without a priori information proved to be better than manual segmentation of brain structures as it does not suffer from volume averaging and is not susceptible to erroneous segmentations of brain regions that show very little contrast on MRI images such as SN.

The orphan G protein-coupled receptor 3 modulates amyloid-beta peptide generation in neurons.

Deposition of the amyloid-beta peptide is a pathological hallmark of Alzheimer's disease. A high-throughput functional genomics screen identified G protein-coupled receptor 3 (GPR3), a constitutively active orphan G protein-coupled receptor, as a modulator of amyloid-beta production. Overexpression of GPR3 stimulated amyloid-beta production, whereas genetic ablation of GPR3 prevented accumulation of the amyloid-beta peptide in vitro and in an Alzheimer's disease mouse model. GPR3 expression led to increased formation and cell-surface localization of the mature gamma-secretase complex in the absence of an effect on Notch processing. GPR3 is highly expressed in areas of the normal human brain implicated in Alzheimer's disease and is elevated in the sporadic Alzheimer's disease brain. Thus, GPR3 represents a potential therapeutic target for the treatment of Alzheimer's disease.