Estrogens are hormones naturally secreted by the body, and mainly by the ovaries. While most women have heard of it, their role is often unclear. What are these hormones for, where do they work, where are they produced, and until when? We take stock.
Estrogens are natural hormones called “feminizing”. They are mainly produced by the ovaries, but also in small quantities by the testes in humans, by the adrenal glands, by the mammary glands or by fatty tissue.
Estrogens, especially estradiol produced by the ovaries, have the role of developing and maintaining secondary sexual characteristics in young women at puberty . These are the hormones that cause breast growth, menstruation, pubic hair and ovulation.
Etymologically, the word “estrogen” comes from elsewhere “estrus” which qualifies all the phenomena linked to ovulation, and from the suffix “-gene” which means to generate, to provoke.
Along with progesterone, estrogen regulates a woman’s menstrual cycle. They also modify the cervical mucus, making it more or less permeable to the passage of sperm at the level of the cervix.
On the sexual level, estrogens are also linked to libido and vaginal lubrication.
At menopause, the ovaries tend to become inactive and therefore no longer produce estrogen. This period then leads to a hormonal imbalance, source of vaginal dryness, decreased libido or mood swings. These symptoms can be temporary or settle in the long term according to women.
Hormones that work beyond the female reproductive system
While estrogens work primarily in the genitals and sexuality, they have other equally important functions in other parts of the body. Estrogens, when they are in sufficient quantity, help the bones to regenerate, by stimulating the cells responsible for producing “new” bone and by slowing down the cells responsible for bone breakdown. These are therefore hormones that act against osteoporosis, hence the emergence of this disease during menopause, in the absence of estrogen.
In addition, estrogens have an influence on the brain, and can thus play on a woman’s mood or mental state. The PMS is an example: after ovulation and in the absence of fertilization, some women are prone to a sense of fatigue and sadness punctuated irritability, partly due to the drop in estrogen levels.
Estrogens also play a role in the skin, which they help make flexible, elastic and firm. Menopause thus causes atrophy of tissues dependent on estrogen, including the skin, which then loses its hydration and firmness.
What are the roles of estrogen?
- They help regulate body temperature and fight memory loss.
- They control the production of cholesterol to prevent blockage of the coronary arteries.
- They stimulate the maturation of the ovaries and trigger the menstrual cycle.
- They contribute to the lubrication of the vagina by strengthening its wall.
- They stimulate breast development at puberty and prepare them for milk production.
- They help the uterus to nourish the developing fetus.
- They maintain bone density and prevent osteoporosis … and the list is far from exhaustive!
Although their name is often cited in connection with the many clinical signs of menopause or hormone deficiency such as hot flashes, vaginal dryness, reduced libido or mood disorders, estrogens are above all hormones essential to the proper functioning of many vital functions in women . It is said that estrogen and progesterone make and break health!
What is the role of estrogens at the genital level?
Natural estrogens are made up of three main hormones: 17 B-Oestradiol, estrone and estriol. It is the first which is used in hormone replacement therapy (HRT) and, recently, in contraception in combination with a progestin. This hormone circulates in plasma in a form very linked to a transporter (99%), SHBG.Estrogens play a decisive role at the genital level:
- On the vaginal mucosa: increased proliferation of the mucosa and substantial improvement in trophicity;
- On the uterine lining: a powerful proliferative effect;
- On the cervix: opening of the cervix , increased secretion of mucus (fern leaf crystallization) characteristic of cervical mucosa pre-ovulatory;
- On the mammary gland: 17 B-Oestradiol induces the development of the breasts and the proliferation of the milk ducts as well as of the glandular tissue from puberty;
- On the whole genital tract: trophic role on the labia minora, the urethra, the Bartholin glands, the ovaries and the myometrium;
- Large sebaceous: regulation (decrease) of secretions from the sebaceous glands as opposed to the effects induced by androgens.
- What is the role of estrogens at the extra-genital level?
The action of estrogens is not limited to the genitals:
- Effects on bone metabolism: we talk about it in the next paragraph;
- Effects on lipid metabolism: 17 B-Oestradiol plays a crucial role in the transformation of the lipid profile into an anti-atheromatous profile. It lowers cholesterol by increasing the HDL / LDL ratio. It also acts to lower plasma triglyceride concentrations and increases the resistance of LDL to oxidation;
- Cardiovascular protection:this function is currently controversial and is the subject of debate within the scientific community. In fact, the risk of stroke is lower in women compared to men before menopause. However, the risk increases after stopping ovarian function and therefore the drop in estrogen levels. This clinical observation was a strong argument in the recommendations of hormone replacement therapy for menopause. However, doctors agree today that estrogens, natural or synthetic, are not an appropriate response to prevent coronary heart attacks. It would even appear that if estrogen therapy begins more than 10 years after the onset of menopause,
What is the role of estrogen for bones?
The effect of estrogen on bones was first described in the mid-20th century. However, the mechanisms of action of these hormones are still poorly understood at the molecular level.In addition to their regulatory action on the female sexual cycle, estrogens play a role in growth and bone turnover. This function has been clinically “suspected” following the observation of menopausal symptoms. The drop in ovarian production of estrogen results in a loss of bone mass which leads to weakening of the bones, thus increasing the risk of fracture. This is called osteoporosis.Experimental oophorectomy in mice reproduces this phenomenon. The most effective treatments for osteoporosis are based on so-called replacement strategies . These include Hormone Replacement Therapy (HRT) based on bioidentical estrogen derivatives associated with progesterone. This treatment aims to restore hormonal balance, thus reversing the loss of bone mass.
Estrogen and men
Women are not the only ones to suffer from the effects of hormonal changes. Men’s hormones also have their whims and can contribute to a disruption of male attributes. Unlike what happens in women from their forties, the hormonal changes that operate in men are very gradual . Some changes can take ten years to appear, with an increase in the rate around fifty. Symptoms revolve around loss of strength, endurance and muscle mass.Here is a non-exhaustive list of clinical signs which can direct the diagnosis towards a male hormonal imbalance with the decrease in the level of testosterone and the abnormal increase in the level of estrogen:
- Unusual fatigue which tends towards asthenia;
- Irritability, nervousness, anger or moody character;
- Weight gain especially around the waist;
- Sensation of swelling;
- Decreased libido;
- Depression, more or less intense sleep disturbances (insomnia and night awakenings in particular);
- Gradual thinning of the hair, especially if the man suffers from androgenic alopecia;
- Impairment of certain physiological functions such as memory and concentration;
- Asthma and sinusitis;
- “Softening” of the muscles;
- Loss of muscle tone, easy shortness of breath;
- Restlessness, nervousness.