Novel, multidisciplinary findings to solve pathogenesis of epilepsy : role of astrocytes in impairment of extracellular potassium homeostasis

Abstract

The cardinal findings of basic and clinical physiology of epileptic seizures have been regarded as “paroxysmal depolarization shifts” (PDS) at the postsynaptic membrane and it correspond to epileptiform discharge in EEG.

In addition, a recent new finding is that the impairment of extracellular K homeostasis in the synaptic cleft. It is mediated by astrocyte dysfunction at tripartite synapses. Namely, decreased expression of Kir 4.1 channel activity in the astrocytes is one of the most responsible factors in both animal and human epilepsy. It is also directly involved in the generator mechanism of ictal DC shifts (Ikeda et al, 1996), and would play a significant role in the propagation mechanisms of focal seizures.