Background: Recently a hyperthermic rat hippocampal slice model system has been used to investigate febrile seizure pathophysiology. Our previous data indicates that heating immature rat hippocampal slices from 34 to 41Â°C in an interface chamber induced epileptiform-like population spikes accompanied by a spreading depression (SD). This may serve as an in vitro model of febrile seizures. Results: In this study, we further investigate cellular mechanisms of hyperthermia-induced initial population spike activity. We hypothesized that GABAA receptor-mediated 30-100 Hz Î³ oscillations underlie some aspects of the hyperthermic population spike activity. In 24 rat hippocampal slices, the hyperthermic population spike activity occurred at an average frequency of 45.9 Â± 14.9 Hz (Mean Â± SE, range = 21-79 Hz, n = 24), which does not differ significantly from the frequency of post-tetanic Î³ oscillations (47.1 Â± 14.9 Hz, n = 34) in the same system. High intensity tetanic stimulation induces hippocampal neuronal discharges followed by a slow SD that has the magnitude and time course of the SD, which resembles hyperthermic responses. Both post-tetanic Î³ oscillations and hyperthermic population spike activity can be blocked completely by a specific GABAA receptor blocker, bicuculline (5-20 Î¼M). Bath-apply kynurenic acid (7 mM) blocks synaptic transmission, but fails to prevent hyperthermic population spikes, while intracellular diffusion of QX-314 (30 mM) abolishes spikes and produces a smooth depolarization in intracellular recording. Conclusion: These results suggest that the GABAA receptor-governed Î³ oscillations underlie the hyperthermic population spike activity in immature hippocampal slices. Â© 2001 Wu et al; licensee BioMed Central Ltd.
Digital Object Identifier (DOI)
Wu, Jie; Javedan, Sam P.; Ellsworth, Kevin; and Fisher, Robert S., "Gamma Oscillation Underlies Hyperthermia-Induced Epileptiform-Like Spikes In Immature Rat Hippocampal Slices" (2001). Neurobiology. 426.