Abstracts

Systemic administration of kainic acid (KA) in rats induces a syndrome characterized by acute limbic seizures, and results in neuronal death and biochemical changes, mainly in the limbic structure. This KA-induced cell death exhibits apoptotic features leads to a degeneration of pyramidal cells in the CA1 and CA3 areas of the hippocampus. The pattern of damage after status epilepticus may be modified by administration of some current antiepileptic drugs (AEDs).We used EEG as a parameter of KA-induced status epilepticus to test the protection effect of current first line AEDs for the status epilepticus induced neuronal death.
48 male Wistar rats (National Science Council, Taiwan) were used for all the experiments. Six EEG screws were mounted on the skull 7 days before the experiment. Systemic administration of kainic acid (KA) 10 mg/Kg in a room maintained at 22[plusmn]0.5 .C with an alternating 12-h light/dark cycle. The video-EEG was recorded before the injection till 4 hours after drug treatment. The drugs were given after the continuous epileptic discharges reached 60 minutes. All procedures were performed in accordance with the Guide for Care and Use of Laboratory Animals published by the National Institutes of Health.
Animals were sacrificed at 3 days after status epilepticus. The 500 mM thin slices were stained with cresyl violet for histological assessment of neuronal damage. In another set of brain sections DNA fragmentation after status epilepticus was determined by the TUNEL (terminal deoxynucleotidyl transferase-mediated uridine 5[rsquo]-triphosphate-biotin nick end labeling) method. TUNEL was used to [italic]in-situ[/italic] label free 3[rsquo]-OH ends, which could occur in the apoptotic process.
We divided the test into six groups including control, diazepam, phenytoin, valproic acid, diazepam and phenytoin, diazepam and valproic acid to see which regimen could protect the neuronal loss.
In all of the control animals, no DNA fragmentation was observed in the hippocampus. In the KA-treated rats, DNA fragmentation was distributed mainly in the CA1, CA3 area of the hippocampus, hilus of dentate gyrus, and entorhinal cortex. The diazepam plus phenytoin group showed significantly decreasing amounts of the DNA fragmentation. The diazepam, phenytoin, valproic acid and diazepam plus valproic acid group were no difference from the control group.
In the clinical practice, we use the 60 minutes as a critical point for stopping the status epilepticus. The first line regimen for the status epilepticus included diazepam, phenytoin, valproic acid, and combination of the diazepam and the above drugs. In present experiment, we test which regimen in current practice has the neuroprotective effect in the rat KA-induced status epileptics. From the point of the DNA fragmentation, the diazepam plus phenytoin group showed the most promising result for 60 minutes continuous epileptic discharges in the rat.
[Supported by: National Science Council, Taiwan]