The effect of kindled seizures on the locomotory behavior of Long-Evans rats

The incidence of attention deficit hyperactivity disorder (ADHD) is higher in children with epilepsy than in the general childhood population. The origin of the symptoms of ADHD seen in children with epilepsy is unknown. This experiment used an animal model to investigate whether seizures could be a cause of the hyperactivity sometimes associated with epilepsy. Sixteen male Long-Evans rats were implanted with electrodes, and 8 of them were kindled until generalized stage 5 seizures were elicited. Eight subjects were handled, but not kindled. The behavior of the rats in the two groups was compared in an open field test. The time spent in four behaviors was measured: exploratory behavior, immobility, eating, and grooming. Rats were tested after 5 stage 5 seizures, after 10 stage 5 seizures, after 15 stage 5 seizures, after a 2-week rest period, and after 5 more stage 5 seizures. Data were analyzed using the Mann-Whitney rank sum test. Twenty-four hours after a seizure, the kindled rats displayed a greater level of exploratory behavior than did the controls. They were not found to differ on any other measure. After a 2-week rest period, the group difference in behavior disappeared. When kindling was reinitiated, the kindled rats again showed increased exploratory behavior. The findings suggest that the increased exploratory behavior found in the kindled rats resulted from recent seizure activity. It may be that the hyperactivity seen in some children with epilepsy also results from recent seizure activity.