Hyperexcitability in organotypic mouse hippocampal explants.
We have developed an organotypic hippocampal tissue culture model for analyses of sustained hyperexcitability in which repetitive electric stimulation of the dentate area enhances the amplitude and complexity of evoked normal and epileptiform field potentials recorded extracellularly from CA3/2 areas of neonatal mouse hippocampal explants. In explants where spontaneous field potentials are not detectable at the onset of the experiment, brief repetitive electric stimulation elicits self-sustained epileptiform discharges that continue for the duration of the recorded period (2-10 hours). Lowering the extracellular Ca++ level to 0.1-0.2 mM markedly attenuates these discharges and repetitive stimulation during a 2-4 hr period fails to elicit hyperexcitability. When tested after return to normal media repetitive stimulation can elicit hyperexcitability. Raising the extracellular K+ levels to 8-9 mM enhances the complexity of evoked as well as spontaneous field potentials and, in some cases, elicits self-sustained epileptiform discharges in the absence of repetitive electric stimulation.
D000818:Animals; D002118:Calcium / Q000502:physiology; D046508:Culture Techniques; D004594:Electrophysiology; D004827:Epilepsy / Q000503:physiopathology*; D005071:Evoked Potentials / Q000187:drug effects; D006624:Hippocampus / Q000503:physiopathology*; D051379:Mice; D008959:Models, Neurological; D009928:Organ Specificity; D011188:Potassium / Q000494:pharmacology
D011188:Potassium; D002118:Calcium