White Matter and Myelin Disorders

Schmidt, Robert E.

doi:10.1016/b978-0-323-44941-0.00024-2

Cited by 1 publication

(2 citation statements)

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“…Many central nervous system disorders stem from pathological changes in myelin structure, which can be broadly categorized into dysmyelination, when myelin is malformed and defective, and demyelination, when the initially normal myelin becomes destroyed [ 1 ]. Dysmyelinating conditions, also known as leukodystrophies, usually have a strong genetic component and, therefore, exhibit early developmental signs [ 2 – 4 ].…”

Section: Introductionmentioning

confidence: 99%

“…Myelin dysfunction in dysmyelinating conditions may be caused by a lack of a particular myelin constituent, e.g., of proteolipid protein 1 in Pelizaeus–Merzbacher disease [ 5 ], delay in myelination, as in Allan-Herndon-Dudley syndrome featuring mutations in the SLC16A2 gene that encodes a thyroid hormone transporter [ 6 ], or metabolic errors, as in Canavan disease, which is caused by mutations in the ASPA gene encoding aspartoacylase, an enzyme enriched in oligodendrocytes [ 7 ]. Demyelinating disorders, such as multiple sclerosis (MS), neuromyelitis optica and acute disseminated encephalomyelitis, usually occur in adults and may be caused by autoimmune processes and infections, with a contribution of genetic, environmental, and dietary factors [ 1 , 8 – 13 ]. Furthermore, other conditions, such as genetic leukoencephalopathies and certain metabolic disorders, also present with myelination defects, though myelin disturbances follow abnormal neuronal development, neuronal loss and profound systemic abnormalities [ 14 ].…”

Section: Introductionmentioning

confidence: 99%

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An in vivo accelerated developmental myelination model for testing promyelinating therapeutics

et al. 2022

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Background Therapeutic agents stimulating the process of myelination could be beneficial for the treatment of demyelinating diseases, such as multiple sclerosis. The efficient translation of compounds promoting myelination in vitro to efficacy in vivo is inherently time-consuming and expensive. Thyroid hormones accelerate the differentiation and maturation of oligodendrocytes, thereby promoting myelination. Systemic administration of the thyroid hormone thyroxine (T4) accelerates brain maturation, including myelination, during early postnatal development. The objective of this study was to validate an animal model for rapid testing of promyelinating therapeutic candidates for their effects on early postnatal development by using T4 as a reference compound. Methods Daily subcutaneous injections of T4 were given to Sprague Dawley rat pups from postnatal day (PND) 2 to PND10. Changes in white matter were determined at PND10 using diffusion tensor magnetic resonance imaging (DTI). Temporal changes in myelination from PND3 to PND11 were also assessed by quantifying myelin basic protein (MBP) expression levels in the brain using the resonance Raman spectroscopy/enzyme-linked immunosorbent assay (RRS-ELISA) and quantitative immunohistochemistry. Results DTI of white matter tracts showed significantly higher fractional anisotropy in the internal capsule of T4-treated rat pups. The distribution of total FA values in the forebrain was significantly shifted towards higher values in the T4-treated group, suggesting increased myelination. In vivo imaging data were supported by in vitro observations, as T4 administration significantly potentiated the developmental increase in MBP levels in brain lysates starting from PND8. MBP levels in the brain of animals that received treatment for 9 days correlated with the FA metric determined in the same pups in vivo a day earlier. Furthermore, accelerated developmental myelination following T4 administration was confirmed by immunohistochemical staining for MBP in coronal brain sections of treated rat pups. Conclusions T4-treated rat pups had increased MBP expression levels and higher MRI fractional anisotropy values, both indications of accelerated myelination. This simple developmental myelination model affords a rapid test of promyelinating activity in vivo within several days, which could facilitate in vivo prescreening of candidate therapeutic compounds for developmental hypomyelinating diseases. Further research will be necessary to assess the utility of this platform for screening promyelination compounds in more complex demyelination disease models, such us multiple sclerosis.

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Section: Introductionmentioning

confidence: 99%