Epilepsy

Epilepsy is a debilitating neurological disorder, which occurs in 1.5 to 2% of the population in western countries of which 70% can be controlled by medication. It is caused by repetitive seizures resulting from the intense stimulation created by nervous cells. They are categorized as partial epilepsy when they are the result of a trauma, tumors, infections or encephalic complications and generalized epilepsy when they have a genetic cause. For many patients, there are no satisfactory treatments despite some anti-epileptic drugs such as benzodiazepines, which have no long-lasting effects. Mechanisms at the cellular or molecular level can be studied in various in vitro systems of culture for which animals are to be killed to collect the tissue. In contrast, in vivo experiments are used to study integrated mechanisms to look for the direct cause of the disease, the symptoms and the behavioral effects of drugs.

Seizures can occur naturally in cats or can be induced by different techniques, such as the electrical stimulation of specific regions of the brain or the application of convulsants. It is also possible to use photosensitive species, cortical freezing and intracerebral injections of tetanus toxin. (1-2) Nevertheless, it has been difficult to establish satisfactory animal models of epilepsy because they do not show recurring seizures, one important clinical symptom of the human disease.

In fact, such animal models are considered models for seizures and not epilepsy. In epilepsy research, several strains of genetic mutant rats are available. For instance, WAG/Rij rats and the spontaneous epileptic rats show some electrographic and behavioral patterns observed in humans but seizures do not disappear with age and the rats exhibit ataxia (i.e. lack of co-ordination of movements) in contrast to human patients. (3) Furthermore, electroencephalographic studies (EEG) indicate that the electric discharges are typically faster than 3 Hertz, whereas in the patients, it is rare to see discharges above 4 Hertz.

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