Estrogens (U.S., otherwise oestrogens or œstrogens) are a group of steroid compounds, named for their importance in the estrous cycle, and functioning as the primary female sex hormone.
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Estrogens (U.S., otherwise oestrogens or œstrogens) are a group of steroid compounds, named for their importance in the estrous cycle, and functioning as the primary female sex hormone.
Estrogens are used as part of some oral contraceptives, in estrogen replacement therapy of postmenopausal women, and in hormone replacement therapy for transwomen.
Like all steroid hormones, estrogens readily diffuse across the cell membrane; inside the cell, they interact with estrogen receptors. Additionally, estrogens have been shown to activate a G protein-coupled receptor, GPR30.
Steroidal
The three major naturally occurring estrogens in women are estrone (E1), estradiol (E2), and estriol (E3). Estradiol (E2) is the predominate form in nonpregnant females, estrone is produced during menopause, and estriol is the primary estrogen of pregnancy. In the body these are all produced from androgens through actions of enzymes.
- From menarche to menopause the primary estrogen is 17β-estradiol. In postmenopausal women more estrone is present than estradiol.
- Estradiol is produced from testosterone by aromatase and estrone from androstenedione.
- Estrone is weaker than estradiol.
Premarin, a commonly prescribed estrogenic drug, contains the steroidal estrogens equilin and equilenin, in addition to estrone sulfate but due to its health risk, more genetic estrogen named Progynova (estradiol valerate) are now more often prescribed.Fact: date=February 2009
Nonsteroidal
A range of synthetic and natural substances have been identified that also possess estrogenic activity.
- Synthetic substances of this kind are known as xenoestrogens.
- Plant products with estrogenic activity are called phytoestrogens.
- Those produced by fungi are known as mycoestrogens.
Unlike estrogens produced by mammals, these substances are not necessarily steroids.
Estrogen production
thumb|right|450px|Steroidogenesis, showing estrogens at bottom right as in pink triangle.
Estrogens are produced primarily by developing follicles in the ovaries, the corpus luteum, and the placenta. Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) stimulate the production of estrogen in the ovaries. Some estrogens are also produced in smaller amounts by other tissues such as the liver, adrenal glands, and the breasts. These secondary sources of estrogens are especially important in postmenopausal women.
