Figure 2.

Abnormal Ca²⁺ signals in hippocampal astrocytes cause epileptogenesis. Four weeks, but not 1 day, after pilocarpine (Pilo)-evoked status epilepticus (SE), hippocampal astrocytes became reactive and showed increased glial fibrillary acidic protein (GFAP) expression and frequent abnormal Ca²⁺ signaling (right cartoon). Reactive astrocytes were highly associated with the development of epileptogenesis as assessed by ictal spikes (electroencephalogram; EEG) or seizure susceptibility to Pilo and, thus, they were named “epileptogenic astrocytes”. Epileptogenesis appeared dependent on abnormal Ca²⁺ signaling in epileptogenic astrocytes. The mechanism by which epileptogenic astrocytes cause epileptogenesis is a subject for future research.