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

We investigated the effects of 17 β-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.