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PloS One 2017The cuprizone animal model, also known as the toxic demyelination model, is a well-reproducible model of demyelination- and remyelination in mice, and has been useful in...
The cuprizone animal model, also known as the toxic demyelination model, is a well-reproducible model of demyelination- and remyelination in mice, and has been useful in studying important aspect of human demyelinating diseases, including multiple sclerosis. In this study, we investigated the role of acid sphingomyelinase in demyelination and myelin repair by inducing acute and chronic demyelination with 5- or 12-week cuprizone treatment, followed by a 2-week cuprizone withdrawal phase to allow myelin repair. Sphingolipids, in particular ceramide and the enzyme acid sphingomyelinase, which generates ceramide from sphingomyelin, seem to be involved in astrocyte activation and neuronal damage in multiple sclerosis. We used immunohistochemistry to study glial reaction and oligodendrocyte distribution in acid sphingomyelinase deficient mice and wild-type C57BL/6J littermates at various time intervals after demyelination and remyelination. Axonal injury was quantified using amyloid precursor protein and synaptophysin, and gene expression and protein levels were measured using gene analysis and Western blotting, respectively. Our results show that mice lacking acid sphingomyelinase had a significant increase in myelin recovery and a significantly higher oligodendrocyte cell count after 2 weeks remyelination compared to wild-type littermates. Detrimental astroglial distribution was also significantly reduced in acid sphingomyelinase deficient animals. We obtained similar results in experiments using amitriptyline to inhibit acid sphingomyelinase. These findings suggest that acid sphingomyelinase plays a significant role in myelin repair, and its inhibition by amitriptyline may constitute a novel therapeutic approach for multiple sclerosis patients.
Topics: Amitriptyline; Amyloid Precursor Protein Secretases; Animals; Astrocytes; Axons; Cell Count; Cuprizone; Demyelinating Diseases; Disease Models, Animal; Enzyme Inhibitors; Gene Expression Regulation; Humans; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Microglia; Multiple Sclerosis; Nerve Regeneration; Oligodendroglia; Recovery of Function; Sphingomyelin Phosphodiesterase; Synaptophysin
PubMed: 28582448
DOI: 10.1371/journal.pone.0178622 -
Biochimica Et Biophysica Acta Feb 2011Myelin is critical in maintaining electrical impulse conduction in the central nervous system. The oligodendrocyte is the cell type responsible for myelin production... (Review)
Review
Myelin is critical in maintaining electrical impulse conduction in the central nervous system. The oligodendrocyte is the cell type responsible for myelin production within this compartment. The mutual supply of trophic support between oligodendrocytes and the underlying axons may indicate why demyelinated axons undergo degeneration more readily; the latter contributes to the neural decline in multiple sclerosis (MS). Myelin repair, termed remyelination, occurs in acute inflammatory lesions in MS and is associated with functional recovery and clinical remittances. Animal models have demonstrated that remyelination is mediated by oligodendrocyte progenitor cells (OPCs) which have responded to chemotactic cues, migrated into the lesion, proliferated, differentiated into mature oligodendrocytes, and ensheathed demyelinated axons. The limited remyelination observed in more chronic MS lesions may reflect intrinsic properties of neural cells or extrinsic deterrents. Therapeutic strategies currently under development include transplantation of exogenous OPCs and promotion of remyelination by endogenous OPCs. All currently approved MS therapies are aimed at dampening the immune response and are not directly targeting neural processes.
Topics: Animals; Cell Differentiation; Demyelinating Diseases; Disease Models, Animal; Humans; Multiple Sclerosis; Myelin Sheath; Nerve Regeneration; Oligodendroglia; Stem Cells
PubMed: 20887785
DOI: 10.1016/j.bbadis.2010.09.010 -
NeuroImage Jan 2023To investigate the association of ihMT (inhom signals with the demyelination and remyelination phases of the acute cuprizone mouse model in comparison with histology,...
BACKGROUND
To investigate the association of ihMT (inhom signals with the demyelination and remyelination phases of the acute cuprizone mouse model in comparison with histology, and to assess the extent of tissue damage and repair from MRI data.
METHODS
Acute demyelination by feeding 0.2% cuprizone for five weeks, followed by a four-week remyelination period was applied on genetically modified plp-GFP mice. Animals were scanned at different time points of the demyelination and remyelination phases of the cuprizone model using a multimodal MRI protocol, including ihMT T-filters, MPF (Macromolecular Proton Fraction) and R (longitudinal relaxation rate). For histology, plp-GFP (proteolipid protein - Green Fluorescent Protein) microscopy and LFB (Luxol Fast Blue) staining were employed as references for the myelin content. Comparison of MRI with histology was performed in the medial corpus callosum (mCC) and cerebral cortex (CTX) at two brain levels whereas ROI-wise and voxel-based analyses of the MRI metrics allowed investigating in vivo the spatial extent of myelin alterations.
RESULTS
IhMT high-pass T-filters, targeted toward long T components, showed significant temporal variations in the mCC consistent with the effects induced by the cuprizone toxin. In addition, the corresponding signals correlated strongly and significantly with the myelin content assessed by GFP fluorescence and LFB staining over the demyelination and the remyelination phases. The signal of the band-pass T-filter, which isolates short T components, showed changes over time that were poorly correlated with histology, hence suggesting a sensitivity to pathological processes possibly not related to myelin. Although MPF was also highly correlated to histology, ihMT high-pass T-filters showed better capability to characterize the spatial-temporal patterns during the demyelination and remyelination phases of the acute cuprizone model (e.g., rostro-caudal gradient of demyelination in the mCC previously described in the literature).
CONCLUSIONS
IhMT sequences selective for long T components are specific and sensitive in vivo markers of demyelination and remyelination and have successfully captured the spatially heterogeneous pattern of the demyelination and remyelination mechanisms in the cuprizone model. Interestingly, differences in signal variations between the ihMT high-pass and band-pass T-filter, suggest a sensitivity of the ihMT sequences targeted to short Ts to alterations other than those of myelin. Future studies will need to further address these differences by examining more closely the origin of the short T components and the variation of each T component in pathology.
Topics: Animals; Mice; Cuprizone; Demyelinating Diseases; Remyelination; Magnetic Resonance Imaging; Myelin Sheath; Mice, Inbred C57BL; Disease Models, Animal
PubMed: 36464096
DOI: 10.1016/j.neuroimage.2022.119785 -
Annals of Neurology Apr 2016Demyelination is a cardinal feature of multiple sclerosis, but it remains unclear why new lesions form, and whether they can be prevented. Neuropathological evidence...
OBJECTIVE
Demyelination is a cardinal feature of multiple sclerosis, but it remains unclear why new lesions form, and whether they can be prevented. Neuropathological evidence suggests that demyelination can occur in the relative absence of lymphocytes, and with distinctive characteristics suggestive of a tissue energy deficit. The objective was to examine an experimental model of the early multiple sclerosis lesion and identify pathogenic mechanisms and opportunities for therapy.
METHODS
Demyelinating lesions were induced in the rat spinal dorsal column by microinjection of lipopolysaccharide, and examined immunohistochemically at different stages of development. The efficacy of treatment with inspired oxygen for 2 days following lesion induction was evaluated.
RESULTS
Demyelinating lesions were not centered on the injection site, but rather formed 1 week later at the white-gray matter border, preferentially including the ventral dorsal column watershed. Lesion formation was preceded by a transient early period of hypoxia and increased production of superoxide and nitric oxide. Oligodendrocyte numbers decreased at the site shortly afterward, prior to demyelination. Lesions formed at a site of inherent susceptibility to hypoxia, as revealed by exposure of naive animals to a hypoxic environment. Notably, raising the inspired oxygen (80%, normobaric) during the hypoxic period significantly reduced or prevented the demyelination.
INTERPRETATION
Demyelination characteristic of at least some early multiple sclerosis lesions can arise at a vascular watershed following activation of innate immune mechanisms that provoke hypoxia, and superoxide and nitric oxide formation, all of which can compromise cellular energy sufficiency. Demyelination can be reduced or eliminated by increasing inspired oxygen to alleviate the transient hypoxia.
Topics: Animals; Demyelinating Diseases; Disease Models, Animal; Hypoxia; Lipopolysaccharides; Male; Multiple Sclerosis; Oxygen Inhalation Therapy; Rats; Rats, Sprague-Dawley; Spinal Cord
PubMed: 26814844
DOI: 10.1002/ana.24607 -
Turkish Neurosurgery 2023To demonstrated demyelination and remyelination of the optic nerve histologically by electron microscopy in an experimental model similar to the compression of pituitary...
AIM
To demonstrated demyelination and remyelination of the optic nerve histologically by electron microscopy in an experimental model similar to the compression of pituitary adenomas on the optic chiasm.
MATERIAL AND METHODS
The rats were fixed to a stereotaxic device under deep anesthesia, and a balloon catheter was placed under the optic chiasm through a burr hole which was in front of the bregma in accordance with the brain atlas of rats. The animals were divided into five groups (n=8): control, mild compression demyelination, severe compression demyelination, mild compression remyelination, severe compression remyelination. The fine structures of the tissues obtained were evaluated using electron microscopy.
RESULTS
We found a significant difference in the severity of degeneration when comparing group 1 with group 5 (p < 0.001); there was no degeneration in group 1 rats and severe degeneration in all of the group 5 rats. Oligodendrocytes were found in all rats in group 1 and none of the rats in no group 2. The nuclei were preserved in the group 1 rats but damaged in all of the group 5 rats. There were no lymphocytes or erythrocytes in group 1 and all positives in group 5.
CONCLUSION
This technique, which induced degeneration without causing damage to the optic nerve with toxic or chemical agents, revealed Wallerian degeneration similar to tumoral compression. After compression relief, the optic nerve remyelination process can be better understood, particularly for sellar lesions. In our opinion, this model may guide future experiments to identify protocols to induce and accelerate remyelination.
Topics: Rats; Animals; Optic Chiasm; Remyelination; Optic Nerve; Demyelinating Diseases; Models, Theoretical
PubMed: 37309627
DOI: 10.5137/1019-5149.JTN.41743-22.2 -
Neurology(R) Neuroimmunology &... Sep 2019To evaluate the combined effect of lesion activity and pathologic processes occurring in both chronically demyelinated lesions and normal-appearing white matter (NAWM)...
OBJECTIVE
To evaluate the combined effect of lesion activity and pathologic processes occurring in both chronically demyelinated lesions and normal-appearing white matter (NAWM) on brain atrophy in MS.
METHODS
Pre- and post-gadolinium T1, fluid attenuation inversion recovery, and diffusion tensor imaging images were acquired from 50 consecutive patients with relapsing-remitting MS (all, but one, on disease-modifying therapy) at baseline and 5 years. Brain atrophy was measured using structural image evaluation, using normalization of atrophy percent brain volume change (PBVC) analysis.
RESULTS
During follow-up, brain volume diminished by 2.0% ± 1.1%. PBVC was not associated with patient age, disease duration, sex, or type of treatment. PBVC moderately correlated with baseline lesion load ( = -0.38, = 0.016), but demonstrated strong association with new lesion activity ( = -0.63, < 0.001). Brain atrophy was also strongly linked to the increase of water diffusion within chronic MS lesions ( = -0.62, < 0.001). In normal-appearing white matter (NAWM), PBVC demonstrated a significant correlation with both baseline and longitudinal increase of demyelination as measured by radial diffusivity (RD, = -0.44, = 0.005 and = -0.35, = 0.026, respectively). Linear regression analysis explained 62% of the variance in PBVC. It confirmed the major role of new lesion activity ( = 0.002, standardized beta-coefficient -0.42), whereas change in diffusivity inside chronic lesions and NAWM RD at baseline also contributed significantly ( = 0.04 and 0.02, standardized beta-coefficient -0.31 and -0.29, respectively), increasing predictive power of the model by 55%.
CONCLUSION
In addition to new lesion activity, progressive loss of demyelinated axons in chronic lesions and the degree of demyelination in NAWM significantly contribute to accelerated loss of brain tissue in patients with MS receiving immunomodulatory therapy.
Topics: Adult; Atrophy; Brain; Chronic Disease; Cohort Studies; Demyelinating Diseases; Diffusion Magnetic Resonance Imaging; Female; Humans; Male; Middle Aged; Multiple Sclerosis, Relapsing-Remitting
PubMed: 31454773
DOI: 10.1212/NXI.0000000000000593 -
Neuroreport Jan 2019Cerebral demyelination is possibly one of the main pathological factors involved in the development of schizophrenia. Our previous studies have showed that Areca catechu...
Cerebral demyelination is possibly one of the main pathological factors involved in the development of schizophrenia. Our previous studies have showed that Areca catechu nut extract could ameliorate cognitive decline by facilitating myelination processes in the frontal cortex in a cuprizone (CPZ)-induced mouse model of schizophrenia. The aim of the present study was to evaluate the effects of arecoline, one of the alkaloids in A. catechu nut extract, on memory impairment and cerebral demyelination in CPZ-treated mice. Mice were treated with CPZ (0 or 0.2%) in chow food and arecoline hydrobromide (0, 2.5, or 5 mg/kg/day) in drinking water for 12 weeks before Y-maze behavioral test. After the behavioral test, the mice were sacrificed for the measurement of myelin basic protein in the frontal cortex. We showed that arecoline-attenuated spatial working memory impairment, concurrent with attenuated demyelination related to vehicle-treated CPZ mice for the first time. Arecoline is one of the primary active ingredients in A. catechu nut responsible for attenuating memory impairment and demyelination in CPZ mice, cerebral demyelination may have a role in memory impairment, and modulation of cerebral demyelination could be a useful strategy in schizophrenia treatment.
Topics: Animals; Arecoline; Chelating Agents; Cholinergic Agonists; Cuprizone; Demyelinating Diseases; Disease Models, Animal; Dose-Response Relationship, Drug; Male; Maze Learning; Memory Disorders; Mice; Mice, Inbred C57BL; Schizophrenia
PubMed: 30571667
DOI: 10.1097/WNR.0000000000001172 -
Journal of Neurochemistry Mar 2022Multiple sclerosis (MS), especially in its progressive phase, involves early axonal and neuronal damage resulting from a combination of inflammatory mediators,...
Multiple sclerosis (MS), especially in its progressive phase, involves early axonal and neuronal damage resulting from a combination of inflammatory mediators, demyelination, and loss of trophic support. During progressive disease stages, a microenvironment is created within the central nervous system (CNS) favoring the arrival and retention of inflammatory cells. Active demyelination and neurodegeneration have also been linked to microglia (MG) and astrocyte (AST)-activation in early lesions. While reactive MG can damage tissue, exacerbate deleterious effects, and contribute to neurodegeneration, it should be noted that activated MG possess neuroprotective functions as well, including debris phagocytosis and growth factor secretion. The progressive form of MS can be modeled by the prolonged administration to cuprizone (CPZ) in adult mice, as CPZ induces highly reproducible demyelination of different brain regions through oligodendrocyte (OLG) apoptosis, accompanied by MG and AST activation and axonal damage. Therefore, our goal was to evaluate the effects of a reduction in microglial activation through orally administered brain-penetrant colony-stimulating factor-1 receptor (CSF-1R) inhibitor BLZ945 (BLZ) on neurodegeneration and its correlation with demyelination, astroglial activation, and behavior in a chronic CPZ-induced demyelination model. Our results show that BLZ treatment successfully reduced the microglial population and myelin loss. However, no correlation was found between myelin preservation and neurodegeneration, as axonal degeneration was more prominent upon BLZ treatment. Concomitantly, BLZ failed to significantly offset CPZ-induced astroglial activation and behavioral alterations. These results should be taken into account when proposing the modulation of microglial activation in the design of therapies relevant for demyelinating diseases. Cover Image for this issue: https://doi.org/10.1111/jnc.15394.
Topics: Animals; Colony-Stimulating Factors; Cuprizone; Demyelinating Diseases; Disease Models, Animal; Mice; Mice, Inbred C57BL; Microglia; Multiple Sclerosis; Myelin Sheath
PubMed: 34935149
DOI: 10.1111/jnc.15566 -
International Journal of Molecular... Aug 2023The development of new neurotherapeutics depends on appropriate animal models being chosen in preclinical studies. The cuprizone model is an effective tool for studying...
The development of new neurotherapeutics depends on appropriate animal models being chosen in preclinical studies. The cuprizone model is an effective tool for studying demyelination and remyelination processes in the brain, but blood-brain barrier (BBB) integrity in the cuprizone model is still a topic for debate. Several publications claim that the BBB remains intact during cuprizone-induced demyelination; others demonstrate results that could explain the increased BBB permeability. In this study, we aim to analyze the permeability of the BBB for different macromolecules, particularly antibody conjugates, in a cuprizone-induced model of demyelination. We compared the traditional approach using Evans blue injection with subsequent dye extraction and detection of antibody conjugates using magnetic resonance imaging (MRI) and confocal microscopy to analyze BBB permeability in the cuprizone model. First, we validated our model of demyelination by performing T2-weighted MRI, diffusion tensor imaging, quantitative rt-PCR to detect changes in mRNA expression of myelin basic protein and proteolipid protein, and Luxol fast blue histological staining of myelin. Intraperitoneal injection of Evans blue did not result in any differences between the fluorescent signal in the brain of healthy and cuprizone-treated mice (IVIS analysis with subsequent dye extraction). In contrast, intravenous injection of antibody conjugates (anti-GFAP or non-specific IgG) after 4 weeks of a cuprizone diet demonstrated accumulation in the corpus callosum of cuprizone-treated mice both by contrast-enhanced MRI (for gadolinium-labeled antibodies) and by fluorescence microscopy (for Alexa488-labeled antibodies). Our results suggest that the methods with better sensitivity could detect the accumulation of macromolecules (such as fluorescent-labeled or gadolinium-labeled antibody conjugates) in the brain, suggesting a local BBB disruption in the demyelinating area. These findings support previous investigations that questioned BBB integrity in the cuprizone model and demonstrate the possibility of delivering antibody conjugates to the corpus callosum of cuprizone-treated mice.
Topics: Animals; Mice; Cuprizone; Blood-Brain Barrier; Diffusion Tensor Imaging; Evans Blue; Gadolinium; Antibodies; Immunoconjugates; Coloring Agents; Demyelinating Diseases
PubMed: 37628867
DOI: 10.3390/ijms241612688 -
NeuroImage. Clinical 2022Multiple Sclerosis (MS) lesions are pathologically heterogeneous and the temporal behavior in terms of growth and myelination status of individual lesions is highly...
BACKGROUND
Multiple Sclerosis (MS) lesions are pathologically heterogeneous and the temporal behavior in terms of growth and myelination status of individual lesions is highly variable, especially in the early phase of the disease. Thus, monitoring the development of individual lesion myelination by using quantitative magnetic resonance myelin water imaging (MWI) could be valuable to capture the variability of disease pathology and get an individual insight into the subclinical disease activity.
OBJECTIVE
The goal of this work was (1) to observe the variation and longitudinal change of in vivo lesion myelination by means of MWI and its parameter Myelin Water Fraction (MWF), and, (2) to identify individual lesion myelination patterns in early MS.
METHODS
In this study n = 12 patients obtained conventional MRI and quantitative MWI derived from multi-component driven equilibrium single pulse observation of T1 and T2 (mcDESPOT) within four weeks after presenting a clinically isolated syndrome and remained within the study if clinically definitive MS was diagnosed within the 12 months study period. Four MRI sessions were acquired at baseline, 3, 6, and 12 months. The short-term and long-term variability of MWF maps was evaluated by scan-rescan measures and the coefficient of variation was determined in four healthy controls. Tracking of individual lesions was performed using the Automatic Follow-up of Individual Lesions (AFIL) algorithm. Lesion volume and MWF were evaluated for every individual lesion in all patients. Median lesion MWF change was used to define lesion categories as decreasing, varying, increasing and invariant for MWF variation.
RESULTS
In total n = 386 T2 lesions were detected with a subset of n = 225 permanent lesions present at all four time-points. Among those, a heterogeneous lesion MWF reduction was found, with the majority of lesions bearing only mild MWF reduction, approximately a third with an intermediate MWF decrease and highest MWF reduction in acute-inflammatory active lesions. A moderate negative correlation was determined between individual lesion volumes and median MWF consistent across all time-points. Permanent lesions featured variable temporal dynamics with the majority of varying MWF (58 %), however decreasing (16 %), increasing (15 %) and invariant (11 %) subgroups could be identified resembling demyelinating activity and post-demyelinating inactivity known from histopathology studies. Inflammatory-active enhancing lesions showed a distinct pattern of MWF reduction followed by partial recovery after 3 months. This was similar in new enhancing lesions and those with a non-enhancing precursor lesion.
CONCLUSION
This work provides in vivo evidence for an individual evolution of early demyelinated MS lesions measured by means of MWF imaging. Our results support the hypothesis, that MS lesions undergo multiple demyelination and remyelination episodes in the early acute phase. The in vivo MRI surrogate of myelin turnover bears capacity as a novel biomarker to select and potentially monitor personalized MS treatment.
Topics: Humans; Myelin Sheath; Multiple Sclerosis; Water; Demyelinating Diseases; Magnetic Resonance Imaging; Brain
PubMed: 36162236
DOI: 10.1016/j.nicl.2022.103192