Sex-specific distinctions in audiogenic convulsions exhibited by severe seizure genetically epilepsy-prone rats (GEPR-9s).

The severe seizure genetically epilepsy-prone rat (GEPR-9) is characterized by a broad-based seizure predisposition and is increasingly recognized as a useful model of epilepsy. When sound stimulated, members of the GEPR-9 colony exhibit complete tonic extensor convulsions. Female GEPR-9s appear to experience a higher frequency of more severe seizures than males when they are sound stimulated. The purpose of this report is to examine and document this observation. Convulsive behavior was evaluated in approximately 4400 GEPR-9s. Each of these animals was sound stimulated 3 times at weekly intervals. Audiogenic response score (ARS), latency to wild running and latency to convulsion were recorded for each animal in each of the 3 tests. For the first 2 weekly tests, females exhibited a significantly higher incidence of complete tonic convulsions, a significantly higher ARS and significantly shorter latencies to wild running and convulsions than did males. The significant differences in latencies persisted through the 3 tests, whereas an increase in the incidence of complete tonic convulsions among males led to a diminution of the differences between males and females in the other parameters. The possible underlying biochemical differences that are responsible for this sex difference in seizure severity are, as yet, unknown.