Regression of epileptogenesis by inhibiting TrkB signaling following a seizure

Abstract

Objective

Temporal lobe epilepsy (TLE) is a devastating disease in which seizures persist in 35% of patients despite optimal use of antiseizure drugs. Clinical and preclinical evidence implicates seizures themselves as one factor promoting epilepsy progression. What is the molecular consequence of a seizure that promotes progression? Evidence from preclinical studies led us to hypothesize that activation of TrkB‐PLCγ1 signaling induced by a seizure promotes epileptogenesis.

Methods

To examine the effects of inhibiting TrkB signaling on epileptogenesis following an isolated seizure, we implemented a modified kindling model in which we induced a seizure through amygdala stimulation and then used either a chemical‐genetic strategy or pharmacologic methods to disrupt signaling for two days following the seizure. The severity of a subsequent seizure was assessed by behavioral and electrographic measures.

Results

Transient inhibition of TrkB‐PLCγ1 signaling initiated after an isolated seizure limited progression of epileptogenesis evidenced by the reduced severity and duration of subsequent seizures. Unexpectedly, transient inhibition of TrkB‐PLCγ1 signaling initiated following a seizure also reverted a subset of animals to an earlier state of epileptogenesis. Remarkably, inhibition of TrkB‐PLCγ1 signaling in the absence of a recent seizure did not reduce severity of subsequent seizures.

Interpretation

These results suggest a novel strategy for limiting progression or potentially ameliorating severity of TLE whereby transient inhibition of TrkB‐PLCγ1 signaling is initiated following a seizure.