Prodromal Characteristics of Epilepsy in Rats with Pendulum-Like Movements

A model of focal seizures with automatisms is being developed on a strain of rats selected for enhanced pendulum-like movements (PM). At a definitive age, 90% of animals of the PM strain generate seizures to audiogenic stimulation. In contrast to Krushinsky-Molodkina and GEPR-9 (genetically epilepsy-prone rats) strains, populations of which demonstrate generalized seizures, PM rats generate a clonic cascade of seizures-the stereotyped jumps reaching a height of 0.5 m at a speed of one jump per second. The PM strain is a new model of epileptiform responses, and it has not actually been studied in early ontogeny. To detect prodromal symptoms of epilepsy, we set a goal to study behavioral and hormonal/metabolic characteristics of the PM model during the early neonatal period. Wistar rats, the initial strain for selection, served as a control. Prodromal symptoms experimentally detected the PM strain included such characteristics as a slowdown in locomotor activity, decreased body and testes weights, an inhibited rise in plasma cholesterol levels on days 10 and 14. PM rats showed a peak shift in circular movements and an increased manifestation of excitable responses, such as vocalizations and paroxysms. A phase change was detected in the plasma triglyceride level. Correlation analysis revealed that in male Wistar rats, the testosterone level correlates negatively with body and testes weights and positively with the blood triglyceride level. By contrast, in PM rats the same correlations were statistically insignificant. These findings indicate a destabilization of the development of morphophysiological characters in PM rats compared to the control Wistar strain. Considering the revealed prodromal symptoms characterizing enhanced pendulum-like hyperkinesis (retarded developmental rate, phase-shifted circular movements and plasma triglyceride levels, altered relationships between correlated phenotypic characters), the PM rat strain can be considered as a model for further investigating the biological basis of epileptiform pathology.