Audiogenic convulsions in moderate seizure genetically epilepsy-prone rats (GEPR-3s)

The moderate seizure genetically epilepsy-prone rat (GEPR-3) typically exhibits a generalized clonic convulsion upon acoustical stimulation. The purpose of this report is to document sex-specific distinctions in the seizure characteristics as well as the effect of prior seizure experience on sensitivity to acoustically induced seizures in members of the GEPR-3 colony. Convulsive behavior was evaluated in approximately 3300 GEPR-3s. Each of these animals was stimulated with sound 3 times at weekly intervals. Audiogenic response score (ARS), latency to the onset of wild running and latency to convulsion were recorded for each animal in each of 3 tests given at 1 week intervals. Statistical analysis revealed that compared to their male littermates, females exhibited significantly shorter latencies to onset of running and convulsion for the last of the 3 weekly tests. Also, in both sexes, a significantly higher incidence of clonic convulsions, an increase in audiogenic response scores and a reduction in latencies to running and convulsion were observed in each succeeding audiogenic stimulation test. The mechanism of this increased seizure facilitation with prior seizure experience may have at least some similarity to that of kindling. The factors responsible for sex-specific distinctions in seizure severity are unknown at the present time.