TY - JOUR
T1 - Time course and mechanism of hippocampal neuronal death in an in vitro model of status epilepticus
T2 - Role of NMDA receptor activation and NMDA dependent calcium entry
AU - Deshpande, Laxmikant S.
AU - Lou, Jeffrey K.
AU - Mian, Ali
AU - Blair, Robert E.
AU - Sombati, Sompong
AU - Attkisson, Elisa
AU - DeLorenzo, Robert J.
N1 - Funding Information:
This study was supported by National Institute of Neurological Disorders and Stroke Grants RO1NS051505 and RO1NS052529, and award UO1NS058213 from the National Institutes of Health CounterACT Program through the National Institute of Neurological Disorders and Stroke to RJD. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the federal government. In addition, the Milton L. Markel Alzheimer's Disease Research Fund and the Sophie and Nathan Gumenick Neuroscience Research Fund also funded this work.
PY - 2008/3/31
Y1 - 2008/3/31
N2 - The hippocampus is especially vulnerable to seizure-induced damage and excitotoxic neuronal injury. This study examined the time course of neuronal death in relationship to seizure duration and the pharmacological mechanisms underlying seizure-induced cell death using low magnesium (Mg2+) induced continuous high frequency epileptiform discharges (in vitro status epilepticus) in hippocampal neuronal cultures. Neuronal death was assessed using cell morphology and fluorescein diacetate-propidium iodide staining. Effects of low Mg2+ and various receptor antagonists on spike frequency were assessed using patch clamp electrophysiology. We observed a linear and time-dependent increase in neuronal death with increasing durations of status epilepticus. This cell death was dependent upon extracellular calcium (Ca2+) that entered primarily through the N-methyl-d-aspartate (NMDA) glutamate receptor channel subtype. Neuronal death was significantly decreased by co-incubation with the NMDA receptor antagonists and was also inhibited by reduction of extracellular (Ca2+) during status epilepticus. In contrast, neuronal death from in vitro status epilepticus was not significantly prevented by inhibition of other glutamate receptor subtypes or voltage-gated Ca2+ channels. Interestingly this NMDA-Ca2+ dependent neuronal death was much more gradual in onset compared to cell death from excitotoxic glutamate exposure. The results provide evidence that in vitro status epilepticus results in increased activation of the NMDA-Ca2+ transduction pathway leading to neuronal death in a time-dependent fashion. The results also indicate that there is a significant window of opportunity during the initial time of continuous seizure activity to be able to intervene, protect neurons and decrease the high morbidity and mortality associated with status epilepticus.
AB - The hippocampus is especially vulnerable to seizure-induced damage and excitotoxic neuronal injury. This study examined the time course of neuronal death in relationship to seizure duration and the pharmacological mechanisms underlying seizure-induced cell death using low magnesium (Mg2+) induced continuous high frequency epileptiform discharges (in vitro status epilepticus) in hippocampal neuronal cultures. Neuronal death was assessed using cell morphology and fluorescein diacetate-propidium iodide staining. Effects of low Mg2+ and various receptor antagonists on spike frequency were assessed using patch clamp electrophysiology. We observed a linear and time-dependent increase in neuronal death with increasing durations of status epilepticus. This cell death was dependent upon extracellular calcium (Ca2+) that entered primarily through the N-methyl-d-aspartate (NMDA) glutamate receptor channel subtype. Neuronal death was significantly decreased by co-incubation with the NMDA receptor antagonists and was also inhibited by reduction of extracellular (Ca2+) during status epilepticus. In contrast, neuronal death from in vitro status epilepticus was not significantly prevented by inhibition of other glutamate receptor subtypes or voltage-gated Ca2+ channels. Interestingly this NMDA-Ca2+ dependent neuronal death was much more gradual in onset compared to cell death from excitotoxic glutamate exposure. The results provide evidence that in vitro status epilepticus results in increased activation of the NMDA-Ca2+ transduction pathway leading to neuronal death in a time-dependent fashion. The results also indicate that there is a significant window of opportunity during the initial time of continuous seizure activity to be able to intervene, protect neurons and decrease the high morbidity and mortality associated with status epilepticus.
KW - Low Mg model of status epilepticus
KW - NMDA-Ca pathway
KW - Neuronal death
UR - http://www.scopus.com/inward/record.url?scp=39649085329&partnerID=8YFLogxK
U2 - 10.1016/j.ejphar.2008.01.025
DO - 10.1016/j.ejphar.2008.01.025
M3 - Article
C2 - 18289526
AN - SCOPUS:39649085329
SN - 0014-2999
VL - 583
SP - 73
EP - 83
JO - European Journal of Pharmacology
JF - European Journal of Pharmacology
IS - 1
ER -