Development of a Seizure and Epileptogenesis in EL Mouse

Abstract

To elucidate the mechnisms of epileptogenesis in the EL mouse which is an excellent animal model of epilepsy. All animals (EL/Suz) were stimulated by our routine tossing-up method once a week through their lives and exibited seizures. The electric activities of the brain were recorded through implanted electrodes in the freely moving state. The following symptoms of an established seizure are observed: tiny auras, wild running, tonic convulsions, clonic convulsions, and finally, stupor repose lasting approximately 1 to 3 min. These symptoms are accompanied by major changes in paroxysmal discharges in the electro-corticogram and the electric activities of the deep brain parts. Paroxysmal activities start at the parietal cortex and are transmitted to other cortical areas. When the paroxysmal activities reach to the thalamus, hippocampus and striatum, the mouse runs; simultaneously, tonic-clonic convulsions start, for which the hippocampus plays a major role. Finally, paroxysms stop, and the animal stands still.  Abortive seizures do not occur until the age of 8 weeks and only occur after routine stimulation. At that time, some small paroxysmal activities are observed in the parietal cortex. After the age of 10 weeks, a running fit appears; however, it is not necessarily observed later in life. The most remarkable symptom of epilepsy, tonic convulsion, occurs after 10 weeks of age, and clonic convulsion continues until the death of animal.  A common course of onset of individual seizures and abnormal plastic formation of seizures during the lifespan of the EL mouse are observed. All individual seizures repeat the developmental process of seizures in order. This paradigm can be demonstrated by longitudinal observations of seizure symptoms and electric activities in the EL mouse brain and by life-long investigations of many animals. In conclusion one could observe all individual seizures repeat the developmental process of seizures in order by the EL mouse investigation.