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Cell swelling, seizures and spreading depression: an impedance study
T Olsson1, M Broberg, K J Pope
1Department of Signals and Systems, Chalmers University of Technology, SE-412 96, Göteborg, Sweden.
Neuroscience
|April 4, 2006
Summary
Cerebral cells swell during epilepsy models, with accelerated cell swelling preceding seizures. These findings in rats reveal key cellular changes during seizure development.
Area of Science:
- Neuroscience
- Epilepsy Research
- Cellular Biology
Background:
- The precise cellular mechanisms underlying the transition from pre-seizure to seizure states are not fully understood.
- Investigating cellular volume changes offers a potential avenue to define these processes.
Purpose of the Study:
- To investigate cellular volume changes during acute epilepsy models using electrical impedance.
- To correlate these changes with electroencephalographic (EEG) activity and seizure onset.
Main Methods:
- Utilized awake, paralyzed rats with extradural electroencephalographic (EEG)/impedance electrodes.
- Administered convulsant agents (picrotoxin, kainic acid, fluorocitrate) to induce epilepsy models.
- Measured changes in extracellular intracranial volume via electrical impedance to estimate cell swelling.
Main Results:
- Kainic acid and picrotoxin induced increases in baseline electrical impedance, indicating cell swelling.
- Accelerated increases in impedance were observed preceding epileptiform discharges.
- Increased baseline impedance correlated with higher power of non-ictal high-frequency EEG activity.
- Seizures and convulsant treatments were associated with impedance increases and transient EEG changes, potentially indicating spreading depression.
Conclusions:
- Cerebral cells demonstrably swell in convulsant models of epilepsy.
- Pre-ictal accelerations in cell swelling occur before seizure onset.
- Spreading depression-like events are frequently associated with seizures in these models.