Effects of estradiol and progesterone on seizure sensitivity in oophorectomized DBA/2J mice and C57/EL hybrid mice.

We investigated the effects of 17 beta-estradiol (E2) and progesterone (PG) on seizure sensitivity in two genetically epilepsy-prone strains, the DBA/2J and the C57/EL hybrid. In the DBA/2J, subject to audiogenic seizures when juvenile, oophorectomy produced a marked decrease in seizure sensitivity, both with and without E2 or PG replacement. In the C57/EL, subject to vestibular seizures, E2 significantly reduced seizure frequency and increased lag time to seizure onset. PG did not affect these variables. Both E2 and PG significantly prolonged seizure duration. These results support a role of ovarian hormones in regulating paroxysmal activity in collicular and tegmental regions associated with audiogenic seizures in the DBA/2J and in temporal structures associated with vestibular seizures in the C57/EL.