Estrogens: types, functions and effects on the body

The endocrine system is made up of all the organs and tissues in the body, which secrete one type of substance: hormones. here we will know a type of female sex hormone, estrogen, As well as the different types of estrogen that exist.

Hormones are released into the bloodstream and regulate certain functions of the body. The main female sex hormones, naturally secreted by the body, are estradiol, estrone and estriol.

    Characteristics of estrogen

    estrogen they are steroid sex hormones, mostly female, although they are also secreted in men (To a lesser extent). They are responsible for the development of female secondary sex characteristics, such as breast growth.

    The different types of estrogen are produced by the ovaries, the placenta (during pregnancy) and to a lesser extent by the adrenal glands. The hypothalamic-pituitary axis plays an essential role in its secretion. More precisely, in the ovaries, they occur in response to signals from the brain and other organs, In vertebrates and invertebrates.

    Chemistry of these hormones

    At the chemical level, the estrogen molecule it is based on the structure of phenanthrene (Type of chemical structure).

    As for its biosynthesis, it includes the aromatization of testosterone by the aromatase enzyme. Aromatase is found in many tissues, including fatty tissue and the brain.

      Types of estrogen

      Depending on its type of synthesis or origin, we can speak of three types of estrogen:

      1. Natural estrogens

      They are the ones who are separated by the body itself. The most important: estradiol, estrone and estriol.

      2. Semi-synthetic estrogens

      These are steroids derived from estradiol. There are three different ones:

      • Ethinyl estradiol: Of great estrogenic power, it is very active by the oral route.
      • Mestranol: It is generally used in combination with progestins.
      • Quinestrol.

      3. Synthetic non-steroidal estrogens

      They are not steroids and are orally active. They acquire a certain chemical similarity to steroids and they are able to activate strong estrogen receptorsThey are therefore of great therapeutic utility. The main ones are three:

      • Dienestrol: Used or used to treat symptoms of menopause.
      • Dietylethylbestrol or ethylbestrol: it is the best known and the most classic.
      • Chlorotrianisene: In the body is converted into an active long-acting estrogen (proestrogen).

      Mechanism of action and functions

      In humans (and in all vertebrates), the three main natural estrogens are estrone, estradiol and estriol. Of these three, estradiol is the most potent, as it has the highest affinity for estrogen receptors.

      These three main estrogens are mainly secreted by developing follicles the ovaries, the corpus luteum of the placenta, the adrenal cortex, the brain, the testes, the liver and fatty tissue.

      But how does estrogen work in the body? The mechanism of action of estrogen is linked to nuclear receptors in cells. Its function is that of regulate gene expression and promote the synthesis of specific mRNA (Messenger RNA).

      In addition, estrogen induces the synthesis of receptors for the production of progesterone in cells of different tissues.

      Effects on men and women

      The effects of estrogen are also noticeable in prenatal and postnatal development, in men and women. Thus, the specific relationship between estrogens and androgens (male sex hormones) is necessary for the proper differentiation and formation of reproductive organs. If this relationship is disrupted, the reproductive organs may develop incompletely or abnormally.

      In women, the function of these hormones is prepare the uterus to accept the fertilized egg, In addition to helping with pregnancy and breastfeeding. One author, Hileman (1994), proposed that estrogen reduces the risk of heart attack and osteoporosis, but increases the risk of breast and uterine cancer.

      In men, estrogen regulate spermatogenesis (Sperm Synthesis) in the male reproductive system. However, if the estrogen concentration in men is high, it can inhibit sperm production.

      pharmacological actions

      Pharmacologically, estrogen has various actions. These actions can be specific (when they act in specific places of action, for example in the breasts, genitals, vagina, fallopian tubes, …) or non-specific (for example in relation to prolactin, thyroid, adrenals, …).

      Let’s look at some examples of non-specific pharmacological actions of estrogens:

      1. Prolactin

      estrogen increase the synthesis and release of prolactin, A hormone that stimulates the secretion of milk, especially when a woman is pregnant.

      2. Thyroid

      The thyroid gland is an endocrine gland that regulates the body’s metabolism and the body’s sensitivity to other hormones. In this case, estrogen in low doses increases its activity (hyperthyroidism) and in high doses it inhibits it (hypothyroidism).

      3. Protein anabolism

      The presence of estrogen increases protein anabolism, i.e. protein synthesis from amino acids.

      4. Coagulation

      Some of the different types of estrogen also promote blood clotting. Coagulation involves the blood turning into gel to form a clot.

      side effects

      Depending on whether there is an excess or a low concentration of estrogen, we can find different undesirable effects on the body:

      1. By high concentration

      Some of the side effects of high estrogen concentration are increased cervical mucus (cervical flow in women), as well as an increase in the size of the uterus. Excess estrogen also causes hypermenorrhea (Very intense menstrual bleeding at regular intervals) and dysmenorrhea (pain before menstruation).

      Pharmacological treatments used for hormone replacement, menstrual cycle regulation or contraceptive methods are a possible cause of exposure to high levels of estrogen.

      2. By decrease in concentration

      There are mainly two side effects: metrorrhagia (unexpected vaginal bleeding) and amenorrhea (Absence of menstruation).

      Other treatments in animals

      Estrogens, in addition to contraceptive treatments in men, also they are used in hormonal therapies with animals (Won to produce food and pets).

      Some of its therapeutic goals are: the use of estradiol to induce and synchronize the zealous period in cows, or estriol for the treatment of urinary incontinence in dogs.

      Bibliographical references:

      • Hileman, B. (1994). Environmental estrogens linked to reproductive abnormalities, cancer. Chemical & Engineering News, 72 (5), 19-23.
      • Ramírez-Sánchez, I., Martínez-Austria, P., Quiroz-Alfaro, M. and Bandala, I. (2015). Effects of estrogen as an emerging pollutant on health and the environment. Water Technology and Science, 6 (5), 31-42.

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