The purpose of this study is to attempt to determine why estrogen levels are increased in
African-American women as compared to Caucasian women by evaluating estrogen feedback on the
brain. African-American women have increased bone mineral density, higher rates of twins,
greater incidence of fibroids, and increased incidence of breast cancer below 40 years of age
as compared to Caucasian women. These traits or illnesses are all believed to be
estrogen-dependent. In fact, previous research has demonstrated increased estrogen levels in
African-American women as compared to Caucasian women. However, the reason for these
differences in estrogen levels has not been studied in humans. One possibility is that
estrogen feedback on the brain differs between African-American and Caucasian women. Two
small glands in the brain (hypothalamus and pituitary) respond to estrogen. The hypothalamus
secretes GnRH (Gonadotropin-Releasing Hormone) that signals the pituitary to secrete the
reproductive hormones, LH (Luteinizing Hormone) and FSH (Follicle Stimulating Hormone). These
hormones act on the ovaries and signal the ovaries to produce estrogen and progesterone.
Estrogen in the bloodstream then acts on the brain to stop this system when the blood has
enough estrogen levels. This is called estrogen feedback. This study will determine whether
there are differences in estrogen feedback between African-American and Caucasian women.
Phase:
Phase 1/Phase 2
Details
Lead Sponsor:
Massachusetts General Hospital
Collaborators:
National Institute on Aging (NIA) National Institutes of Health (NIH)