But until basic science research began to define the mechanism of estrogen action, estrogen was thought to have effects limited to the uterine and breast tissues. In the early 1970s, estrogen was believed to be primarily a reproductive hormone with effects limited to the uterus and mammary glands. As the clinical utility of estrogen has become more commonplace, however, it is increasingly clear that it is a key hormone in the maintenance of skeletal integrity. Figure 8 Other emerging benefits of estrogen include improved cardiovascular tone, cognition, cancer prevention, and protection against tooth loss and macular degeneration. Historically, the concept that estrogen could have effects in so many organs was never taken seriously.
Different estrogens appear to exhibit different activities in different cells.
The potency and efficacy of a specific estrogen can vary from cell to cell and tissue to tissue. Estrogen receptors are more highly concentrated in some areas of the body.