Astrocyte reactivity in a mouse model of SCN8A epileptic encephalopathy
| Autor: | Pravin K. Wagley, Manoj K. Patel, Jeremy A. Thompson, Wenxi Yu, Ian C. Wenker, Raquel M Miralles, Eric R. Wengert |
|---|---|
| Rok vydání: | 2022 |
| Předmět: |
medicine.medical_specialty
Encephalopathy Inhibitory postsynaptic potential Mice Epilepsy Glutamate-Ammonia Ligase Internal medicine Glutamine synthetase medicine Animals Humans Microglia Glial fibrillary acidic protein biology Chemistry Glutamate receptor medicine.disease Disease Models Animal medicine.anatomical_structure Endocrinology Neurology NAV1.6 Voltage-Gated Sodium Channel Astrocytes Potassium biology.protein Epilepsy Generalized Neurology (clinical) Astrocyte |
| Zdroj: | Epilepsia Open. 7:280-292 |
| ISSN: | 2470-9239 |
| DOI: | 10.1002/epi4.12564 |
| Popis: | Objective SCN8A epileptic encephalopathy is caused predominantly by de novo gain-of-function mutations in the voltage-gated-sodium channel Nav 1.6. The disorder is characterized by early onset of seizures and developmental delay. Most patients with SCN8A epileptic encephalopathy are refractory to current anti-seizure medications. Previous studies determining the mechanisms of this disease have focused on neuronal dysfunction as Nav 1.6 is expressed by neurons and plays a critical role in controlling neuronal excitability. However, glial dysfunction has been implicated in epilepsy and alterations in glial physiology could contribute to the pathology of SCN8A encephalopathy. In the current study, we examined alterations in astrocyte and microglia physiology in the development of seizures in a mouse model of SCN8A epileptic encephalopathy. Methods Using immunohistochemistry we assessed microglia and astrocyte reactivity before and after the onset of spontaneous seizures. Expression of glutamine synthetase, Nav 1.6 and Kir 4.1 channel currents were assessed in astrocytes in wildtype (WT) mice and mice carrying the N1768D SCN8A mutation (D/+). Results Astrocytes in spontaneously seizing D/+ mice become reactive and increase expression of glial fibrillary acidic protein (GFAP), a marker of astrocyte reactivity. These same astrocytes exhibited reduced barium-sensitive Kir 4.1 currents compared to age-matched WT mice and decreased expression of glutamine synthetase. These alterations were only observed in spontaneously seizing mice and not before the onset of seizures. In contrast, microglial morphology remained unchanged before and after the onset of seizures. Significance Astrocytes, but not microglia, become reactive only after the onset of spontaneous seizures in a mouse model of SCN8A encephalopathy. Reactive astrocytes have reduced Kir 4.1-mediated currents, which would impair their ability to buffer potassium. Reduced expression of glutamine synthetase would modulate the availability of neurotransmitters to excitatory and inhibitory neurons. These deficits in potassium and glutamate handling by astrocytes could exacerbate seizures in SCN8A epileptic encephalopathy. Targeting astrocytes may provide a new therapeutic approach to seizure suppression. |
| Databáze: | OpenAIRE |
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