Atypical myelinogenesis and reduced axon caliber in the Scn1a variant model of Dravet syndrome: An electron microscopy pilot study of the developing and mature mouse corpus callosum
| Autor: | Kay L. Richards, Eric Hanssen, Alan Connelly, Nikola Jancovski, Steve Petrou |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
0301 basic medicine
Male Mice 129 Strain Neurogenesis Epilepsies Myoclonic Pilot Projects Biology Gene mutation Corpus callosum Nerve Fibers Myelinated Sodium Channels Corpus Callosum 03 medical and health sciences Epilepsy Myelin Mice 0302 clinical medicine Channelopathy Dravet syndrome Seizures medicine Animals Axon Molecular Biology General Neuroscience Brain medicine.disease Axons Mice Inbred C57BL NAV1.1 Voltage-Gated Sodium Channel Disease Models Animal Microscopy Electron 030104 developmental biology medicine.anatomical_structure nervous system Myelinogenesis Neurology (clinical) Neuroscience 030217 neurology & neurosurgery Developmental Biology |
| Zdroj: | Brain research. 1751 |
| ISSN: | 1872-6240 |
| Popis: | Dravet Syndrome (DS) is a genetic neurodevelopmental disease. Recurrent severe seizures begin in infancy and co-morbidities follow, including developmental delay, cognitive and behavioral dysfunction. A majority of DS patients have an SCN1A heterozygous gene mutation. This mutation causes a loss-of-function in inhibitory neurons, initiating seizure onset. We have investigated whether the sodium channelopathy may result in structural changes in the DS model independent of seizures. Morphometric analyses of axons within the corpus callosum were completed at P16 and P50 in Scn1a heterozygote KO male mice and their age-matched wild-type littermates. Trainable machine learning algorithms were used to examine electron microscopy images of ~400 myelinated axons per animal, per genotype, including myelinated axon cross-section area, frequency distribution and g-ratios. Pilot data for Scn1a heterozygote KO mice demonstrate the average axon caliber was reduced in developing and adult mice. Qualitative analysis also shows micro-features marking altered myelination at P16 in the DS model, with myelin out-folding and myelin debris within phagocytic cells. The data has indicated, in the absence of behavioral seizures, factors that governed a shift toward small calibre axons at P16 have persisted in adult Scn1a heterozygote KO corpus callosum. The pilot study provides a basis for future meta-analysis that will enable robust estimates of the effects of the sodium channelopathy on axon architecture. We propose that early therapeutic strategies in DS could help minimize the effect of sodium channelopathies, beyond the impact of overt seizures, and therefore achieve better long-term treatment outcomes. |
| Databáze: | OpenAIRE |
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