Developmental changes in audiogenic epilepsy and myoclonus in KM rats

The reaction to a single sound stimulation (a bell) applied daily and the time of the first appearance of myoclonus were recorded in Krushinsky-Molodkina (KM) rats of different ages (30, 60, and 150-200 days). The audiogenic seizures in adult animals were of short latency and always resulted in tonic convulsions, which were stable in their patten. In contrast, in young animals (in particular, in 30-day-old rats), the seizures were less pronounced and unstable. The daily sound stimulation produced a gradual development of myoclonic seizures in young and adult rats. In old rats, the stable myoclonus appeared on the 17th day of stimulation, and in 30-day-old animals the myoclonus was recorded on the 26th day. In 60-day-old rats the myoclonus appeared for the first time on the 20th day of stimulation. It is suggested that these age differences can be explained by the btain immaturity (in particular, of neurotransmitter system) in young animals.