Disentangling the Effects of Daily Stress, Sleep, and Sex Hormones on Accelerated Vascular Aging in Midlife Women

Ganirelix acetate (Antagon) will be used to prevent endogenous production of ovarian hormones in young women. Ganirelix is derived from native GnRH, and acts by competitively blocking GnRH receptors on the pituitary and subsequent pathways. Thus, administration of the GnRH antagonist (GnRHant) suppresses steroidogenesis, leading to low or undetectable serum estrogen and progesterone concentrations, which occurs within two days of initiation of administration. Women will self-administer subcutaneous injections (0.25 mg/day in 0.5 ml of normal saline) of the GnRH antagonist ganirelix acetate (Antagon, Organon, Inc., West Orange, New Jersey,) every day for \~12-15 days (starting on day \~2-4 of the menstrual cycle). Testing will occur on day 3-4 and day14-15 of using Antagon.