1. Reactive astrocyte-driven epileptogenesis is induced by microglia initially activated following status epilepticus.
- Author
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Sano F, Shigetomi E, Shinozaki Y, Tsuzukiyama H, Saito K, Mikoshiba K, Horiuchi H, Cheung DL, Nabekura J, Sugita K, Aihara M, and Koizumi S
- Subjects
- Animals, Astrocytes drug effects, Astrocytes pathology, Calcium Signaling, Disease Models, Animal, Disease Progression, Disease Susceptibility, Epilepsy chemically induced, Epilepsy pathology, Epilepsy physiopathology, Gliosis metabolism, Interleukin-1beta metabolism, Mice, Microglia drug effects, Microglia pathology, Muscarinic Agonists toxicity, Organic Chemicals pharmacology, Pilocarpine toxicity, Receptors, Granulocyte-Macrophage Colony-Stimulating Factor antagonists & inhibitors, Sodium Channel Blockers toxicity, Status Epilepticus chemically induced, Status Epilepticus pathology, Status Epilepticus physiopathology, Tetrodotoxin toxicity, Time Factors, Tumor Necrosis Factor-alpha metabolism, Astrocytes metabolism, Epilepsy metabolism, Inositol 1,4,5-Trisphosphate Receptors metabolism, Microglia metabolism, Status Epilepticus metabolism
- Abstract
Extensive activation of glial cells during a latent period has been well documented in various animal models of epilepsy. However, it remains unclear whether activated glial cells contribute to epileptogenesis, i.e., the chronically persistent process leading to epilepsy. Particularly, it is not clear whether interglial communication between different types of glial cells contributes to epileptogenesis, because past literature has mainly focused on one type of glial cell. Here, we show that temporally distinct activation profiles of microglia and astrocytes collaboratively contributed to epileptogenesis in a drug-induced status epilepticus model. We found that reactive microglia appeared first, followed by reactive astrocytes and increased susceptibility to seizures. Reactive astrocytes exhibited larger Ca2+ signals mediated by IP3R2, whereas deletion of this type of Ca2+ signaling reduced seizure susceptibility after status epilepticus. Immediate, but not late, pharmacological inhibition of microglial activation prevented subsequent reactive astrocytes, aberrant astrocyte Ca2+ signaling, and the enhanced seizure susceptibility. These findings indicate that the sequential activation of glial cells constituted a cause of epileptogenesis after status epilepticus. Thus, our findings suggest that the therapeutic target to prevent epilepsy after status epilepticus should be shifted from microglia (early phase) to astrocytes (late phase).
- Published
- 2021
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