TY - JOUR
T1 - Gamma oscillation underlies hyperthermia-induced epileptiform-like spikes in immature rat hippocampal slices
AU - Wu, Jie
AU - Javedan, Sam P.
AU - Ellsworth, Kevin
AU - Fisher, Robert S.
PY - 2001/11/28
Y1 - 2001/11/28
N2 - 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 41°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 γ 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 ± 14.9 Hz (Mean ± SE, range = 21-79 Hz, n = 24), which does not differ significantly from the frequency of post-tetanic γ oscillations (47.1 ± 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 γ oscillations and hyperthermic population spike activity can be blocked completely by a specific GABAA receptor blocker, bicuculline (5-20 μM). 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 γ oscillations underlie the hyperthermic population spike activity in immature hippocampal slices.
AB - 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 41°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 γ 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 ± 14.9 Hz (Mean ± SE, range = 21-79 Hz, n = 24), which does not differ significantly from the frequency of post-tetanic γ oscillations (47.1 ± 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 γ oscillations and hyperthermic population spike activity can be blocked completely by a specific GABAA receptor blocker, bicuculline (5-20 μM). 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 γ oscillations underlie the hyperthermic population spike activity in immature hippocampal slices.
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U2 - 10.1186/1471-2202-2-18
DO - 10.1186/1471-2202-2-18
M3 - Article
C2 - 11747470
AN - SCOPUS:2642527134
SN - 1471-2202
VL - 2
JO - BMC Neuroscience
JF - BMC Neuroscience
M1 - 18
ER -