Our proposed research will addresses the critical role of hormonal change in the precipitation of PMDD symptoms before and after treatment with a continuous OC regimen, an interrupted OC regimen (21/7 platform) and continuous placebo. This study will also permit us to examine the role of neurosteroids in PMDD. While acting acutely as anxiolytic positive modulators of the gamma-aminobutyric acid A (GABAA) receptor, these neurosteroids may paradoxically reduce the response of the GABAA receptor and cause irritability (in rats) following either extended exposure or withdrawal. Further, our prior research suggests that elevated levels of or changes in peripheral neurosteroid levels are associated with dysphoric mood symptoms in women with PMDD. Our hypothesis is that changes in neurosteroids modulate symptom severity rather than appearance in PMDD. The results of our study will suggest therapeutic targets and will inform future studies of both PMDD and related affective disorders.