ABSTRACT
The broad systemic effects of estrogen influence a wide spectrum of physiological functions throughout a woman’s life. During the earliest phases of life, estrogen controls the development of primary and secondary sex organs, influences the growth of long bones and imprints various behavioral circuits in the brain. Throughout the reproductive years, estrogen is a key player in the regulation of reproductive cycles, continues to maintain a regulatory role in bone turnover and also influences the cardiovascular, immune and integumentary systems. Following the cessation of cyclic exposure to estrogen with the menopause, a variety of pathological states emerge with the relative absence of this important regulatory hormone. Most acutely apparent among the effects of estrogen withdrawal are the discontinuation of reproductive cycles and menses. However, the importance of other beneficial effects of estrogen emerges as well with time, most important being the rapid loss of bone mass, which occurs when bone turnover dramatically rises with estrogen deficiency and which leads to the development of osteoporosis. The incidence of mortality and morbidity due to heart disease also rapidly increases in women following the menopause. The important role of estrogen within the central nervous system (CNS) also becomes apparent when estrogen levels drop, with the incidence of vasomotor symptoms (hot flushes), depression, alterations in mood and cognitive decline.
