The estrogen receptors ERα and ERβ are the main mediators of estrogen action and
estrogens play an important role in a variety of aspects of physiology besides their well
acknowledged function in reproduction. In vivo and in vitro studies indicate that the estrogen
receptors are mechanistically implicated in endocrine-related diseases. Recent studies with
estrogen receptor knockout mice have helped to unravel the role of the estrogen receptors in
brain degeneration, osteoporosis, cardiovascular diseases and obesity.