Estrogen, oestrogen, is the primary female sex hormone. It is responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens in females that have estrogenic hormonal activity: estrone, estradiol, and estriol. The estrane steroid estradiol is the most potent and prevalent of these.
Estrogens are a pharmaceutical preparation containing a mixture of water-soluble, conjugated estrogens derived wholly or in part from URINE of pregnant mares or synthetically from ESTRONE and EQUILIN. It contains a sodium-salt mixture of estrone sulfate (52-62%) and equilin sulfate (22-30%) with a total of the two between 80-88%. Other concomitant conjugates include 17-alpha-dihydroequilin, 17-alpha-estradiol, and 17-beta-dihydroequilin. The potency of the preparation is expressed in terms of an equivalent quantity of sodium estrone sulfate.
Types of Estrogen
Overview of actions
- Mediate formation of female secondary sex characteristics
- Accelerate metabolism
- Increase fat store
- Stimulate endometrial growth
- Increase uterine growth
- Increase vaginal lubrication
- Thicken the vaginal wall
- Maintenance of vessel and skin
- Reduce bone resorption, increase bone formation
- Protein synthesis
- Increase hepatic production of binding proteins
- Increase circulating level of factors plasminogen
- Decrease antithrombin III
- Increase platelet adhesiveness
- Increase HDL, triglyceride
- Decrease LDL, fat deposition
- Fluid balance
- Salt (sodium) and water retention
- Increase cortisol, SHBG
- Gastrointestinal tract
- Reduce bowel motility
- Increase cholesterol in bile
- Increase pheomelanin, reduce eumelanin
- Support hormone-sensitive breast cancers (see section below)
- Lung function
- Promotes lung function by supporting alveoli (in rodents but probably in humans).
- Uterus lining
- Estrogen together with progesterone promotes and maintains the uterus lining in preparation for implantation of fertilized egg and maintenance of uterus function during the gestation period, also upregulates oxytocin receptor in myometrium
- The surge in estrogen level induces the release of luteinizing hormone, which then triggers ovulation by releasing the egg from the Graafian follicle in the ovary.
- Sexual behavior
- Promotes sexual receptivity in estrus, and induces lordosis behavior.In non-human mammals, it also induces estrus (in heat) prior to ovulation, which also induces lordosis behavior. Female non-human mammals are not sexually receptive without the estrogen surge, i.e., they have no mating desire when not in estrus.
- Regulates the stereotypical sexual receptivity behavior; this lordosis behavior is estrogen-dependent, which is regulated by the ventromedial nucleus of the hypothalamus.
- Sex drive is dependent on androgen levels only in the presence of estrogen, but without estrogen, free testosterone level actually decreases sexual desire (instead of increases sex drive), as demonstrated for those women who have hypoactive sexual desire disorder, and the sexual desire in these women can be restored by administration of estrogen (using oral contraceptive). In non-human mammals, mating desire is triggered by estrogen surge in estrus.
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