Hormonal effects on the brain.

Changes in seizure frequency over the course of the menstrual cycle (i.e., catamenial epilepsy) have long been documented. Ovarian steroid hormones have a number of important short- and long-term effects on the brain that may contribute to this phenomenon. In particular, estrogen induces structural and functional changes in hippocampal neurons which may contribute significantly to increasing seizure susceptibility. This article reviews the mechanisms of action of steroid hormones on the basis of findings in animal models, with particular emphasis on the effects of estrogen on the hippocampus.