An organotypic hippocampal slice culture model of excitotoxic injury induced spontaneous recurrent epileptiform discharges

Abstract

Stroke is the major cause of acquired epilepsy in the adult population. The mechanisms of ischemia-induced epileptogenesis are not completely understood, but glutamate is associated with both ischemia-induced injury and epileptogenesis. The objective of this study was to develop an in vitro model of epileptogenesis induced by glutamate injury in organotypic hippocampal slice cultures (OHSCs), as observed in stroke-induced acquired epilepsy. OHSCs were prepared from 1-week old Sprague-Dawley rat pups. They were exposed to 3.5 mM glutamate for 35 minutes at 21 days in vitro. Field potential recordings and whole-cell current clamp electrophysiology were used to monitor the development of in vitro seizure events up to 19 days after injury. Propidium iodide uptake assays were used to examine acute cell death following injury. Glutamate exposure produced a subset of hippocampal neurons that died acutely and a larger population of injured but surviving neurons. These surviving neurons manifested spontaneous, recurrent epileptiform discharges in neural networks, characterized by paroxysmal depolarizing shifts and high frequency spiking in both field potential and intracellular recordings. This model also exhibited anticonvulsant sensitivity similar to in vivo models. Our study is the first demonstration of a chronic model of acquired epilepsy in OHSCs following a glutamate injury. This in vitro model of glutamate injury–induced epileptogenesis may help develop therapeutic strategies to prevent epileptogenesis after stroke and elucidate some of the mechanisms that underlie stroke-induced epilepsy in a more anatomically in-tact system.

Site-Specific and Time-Dependent Activation of the Endocannabinoid System after Transection of Long-Range Projections

“…This model, well known and highly accepted, allows a clear differentiation between anterograde, retrograde and more distant area changes induced by axonal injury. It should be considered that slice cultures derived from young animals show spontaneous seizure like events when investigated shortly after dissection [32] but these events disappear when cultures are kept in vitro for 7–21 days [33] , [34] , [35] . The activation of endocannabinoid system during the course of status epilepticus has very recently been reported in humans [36] .…”

Organotypic brain slices: a model to study the neurovascular unit micro-environment in epilepsies

“…Since empty vessels respond to angiogenic factors, we studied the vascular remodelling after epileptic seizures using OHCs [20,25,26]. Previously, we observed the presence of angiogenesis and BBB permeability in pharmacoresistant temporal lobe epilepsies [22].…”

Models of drug-induced epileptiform synchronization in vitro

“…This provides approaches to investigate long-term processes such as epileptogenesis, neuroprotection, neuronal degeneration and sclerosis (Thompson et al, 1996;Chaturvedi et al, 2012;Kukko-Lukjanov et al, 2006;Ziobro et al, 2011;Koyama, 2013). One special feature of slice cultures is the ability to co-culture structures that are not adjacent in vivo, but which are functionally connected, e.g.…”