The main hormone secreted by the male sex glands. Female sex hormones. What you need to know about sex hormone binding globulin

Each female sex hormone plays an important role in a woman’s health. And sometimes a slight deviation from the norm of even one hormone can provoke serious changes in her body.

Produced by the ovaries in women, almost all female sex hormones are carried through the bloodstream throughout the body. Thus penetrating into the required organs, they support the woman’s body in a reproductive state and contribute to the development of certain character traits.

All sex hormones in women are divided into several subgroups:

• Estrogens. It includes types of hormones related exclusively to female hormones, which give a girl feminine beauty, elastic skin, special seductive forms and the ability to give birth to children;
• Progestins. These hormones are relevant only to fertilization and the course of pregnancy;
• Androgens. Despite the fact that these are male hormones, they are important for the female body, as they participate in the formation of certain secondary sexual characteristics. That is, male hormones give women such qualities as determination and aggression.

It is worth knowing that the slightest disruption in the production of hormones carried throughout the body can radically not only change a woman’s character, but also create serious health problems. Therefore, for many women who complain of a certain kind of ailment, the diagnosis of the disease begins with a sex hormone test.

Any sex hormone may decrease in production or, on the contrary, increase in level, for various reasons:

The systems and all organs of women, like men, are dependent on hormones. They are the ones who contribute to their proper functioning. And if the production of at least one hormone fails, serious changes occur in the body of women that contribute to the development of diseases.

Major sex hormones

In total, women have 6 sex hormones, but the main ones are only two, progesterone and estrogen. It is these types of hormones that have a huge impact on the state of the reproductive system in women.

Progesterone is produced by the corpus luteum, which appears after ovulation. All the effects this hormone has on the female body relate to its preparation for pregnancy and subsequent gestation. It is this hormone that promotes the fertilized cell to securely attach to the uterus and prevent its contraction. During pregnancy, it increases blood pressure and stops menstruation during pregnancy.

It is during pregnancy that progesterone provokes increased sebum production and tissue development. The enlargement of the uterus during pregnancy is also due to the effect of this hormone. Normally, this hormone is 0.32 nmol\\l to 56.63 nmol\\l. Its level of production in the body directly depends on the phase. At the early stage of pregnancy, progesterone does not rise above 503.1 nmol\\l. In the third trimester it can reach up to 771.5 nmol\\l.

It is worth knowing that a significant increase in progesterone in a woman’s body is considered normal only during pregnancy. In other cases, it is a sign of the development of a serious illness.

An increase in progesterone levels may indicate that the body is developing a tumor in the adrenal gland or ovaries. A decrease in the hormone below the permitted norm most often occurs due to the presence of inflammatory processes in the genital organs that are in the chronic stage. Also, low levels of progesterone production may be due to poor functioning of the corpus luteum.

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All about the hormone progesterone: norm and deviations

Estrogen promotes cell and tissue regeneration. It is this hormone that gives women’s skin elasticity, softness, and silky hair. Its effect is also reflected on blood vessels, being a kind of protector, it actively protects them from the formation of cholesterol plaques. Its norm in women of reproductive age is 11 – 191 pg\\ml. Its special effect on the body occurs during adolescence. It is at this moment that this hormone promotes increased growth of the mammary glands, expansion of the pelvis and the appearance of hair in the armpits and pubic area.

If these sex hormones are produced less than normal during adolescence, then their deficiency manifests itself in the form of delayed puberty. Also, its low level affects the size of the uterus, making it smaller, and provokes a lack of menstruation. In adult women, estrogen deficiency manifests itself in the form of increased hair growth throughout the body, early aging of the skin and the acquisition of masculine characteristics. But if this type of sex hormones are produced in excess of the norm, then women begin to gain excess weight. Also, excess levels of this hormone can trigger the development of uterine fibroids.

Other female sex hormones

Despite the fact that other types of female hormones are considered secondary, they still perform no less important functions in a woman’s body.

Hormone	Purpose	Norm	Shortage	Oversupply
Prolactin	Promotes the growth of mammary glands and hair. At the birth of a child, it provokes milk production. Regulates the immune system.	4-23 ng\\ml During pregnancy, this figure increases significantly, the maximum concentration can reach 386 ng\\ml.	It appears when the fetus is overdue or the pituitary gland is not functioning well.	It may indicate the development of a tumor, polycystic ovary syndrome, liver cirrhosis, vitamin deficiency, or problems in the thyroid gland. Infertility, lack of menstruation.
follicle-stimulating	Promotes the production of estrogen, regulates the functioning of the sex glands.	From 2.45 to 15.67 mU\\l	Obesity, polycystic ovary syndrome.	Inflammatory processes in the gonads, uterine bleeding.
Testosterone	Participates in the growth of genital organs and hair in the armpits and pubic area. Provokes the development of sexual desire.	Up to 20 years of age, the maximum concentration reaches 3.09 pg\\ml. Up to 39 years old, only 3 pg\\ml. Then the concentration decreases to 2.6 pg\\ml and remains until 59. From 60 years of age, the level should not exceed 1.8 pg\\ml.	Muscle weakness, baldness, frigidity, children's voice, obesity.	Hairiness, short temper.
Luteotropic	Controls the ovulation process.	At ovulation it reaches 114 honey\\l. During the follicular phase up to 26.97, during the secretory phase the minimum level is 0.61, the maximum is 15.91.	Simmonds disease, obesity.	Fasting, endometriosis, brain tumor, stress.

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Male gonads

The gonads (sometimes called gonads) are the ovaries in women and the testes in men. The two testicles are located inside the scrotum on the anterior pelvis. Their main function is the production of sperm, which are released through the penis.

Male reproductive tract

Location and structure

The testicles are the primary male reproductive organs, located in the testes.

Functions

The testicles are responsible for producing sperm and semen, but they also contain special cells with endocrine function. They produce male sex hormones called androgens, of which the main hormone is testosterone.

Testosterone is responsible for:
. growth and development of male genital organs and maintenance of their adult sizes;

. enlargement of the larynx (and, as a result, changes in voice);
. increased bone and muscle growth;
. male sexual arousal.

How is testosterone produced?

Testosterone is produced by the action of hormones from the hypothalamus and the anterior pituitary gland. Testosterone levels are regulated by negative feedback.

Female gonads

The ovaries are the primary female reproductive organs, located in the lower abdominal cavity on the sides of the uterus. They produce eggs for reproduction, but also other systems - ovarian follicles and the corpus luteum - which have endocrine functions related to the body's reproductive activities.

Functions

Ovarian follicles secrete the hormone estrogen, which at the beginning of puberty is responsible for:
. maturation of female genital (reproductive) organs, such as the uterus and vagina;
. breast development;
. growth and distribution of body hair;
. distribution of fat on the hips, legs and chest.

The corpus luteum also secretes some estrogen, but its main hormone is progesterone, which causes the lining of the uterus to thicken to prepare the body for pregnancy. Both estrogen and progesterone are responsible for the changes that occur during the menstrual cycle.

How estrogen and progesterone are produced

Like testosterone, estrogen and progesterone are released as a result of the actions of hormones from the hypothalamus and pituitary gland. Estrogen and progesterone levels are regulated by negative feedback.

Female reproductive tract

Pituitary gland control of the ovulation cycle

The ovaries are under the control of the anterior pituitary gland. Under the influence of estrogen produced by the ovarian follicle, the pituitary gland produces follicle-stimulating hormone (Prolan A, FSH) and luteinizing hormone (Prolan B, LH). These hormones cause the follicle to mature and release an egg during ovulation. The remainder of the follicle forms the corpus luteum, which produces progesterone. If the egg is not fertilized, progesterone levels drop and menstruation occurs.

Without exaggeration, we can say that a woman’s hormonal background is a determining factor in her health and well-being. Female hormones affect appearance, psycho-emotional and physical state (body structure, weight and height, skin type, hair structure and color, speed of reactions, appetite, expression of emotions). The female reproductive system is entirely dependent on the production and level of hormones in the body. Female sex hormones determine mood, thinking processes and character.

How are hormones produced?

Since female sex hormones are fundamental factors ensuring good health and mood, we should talk in more detail about the types of sex hormones. This will allow you to better understand the functional component of this aspect.

The endocrine system consists of endocrine glands, which to a large extent are the “producers” of hormones. The glands include:

1. pituitary;
2. thyroid gland;
3. ovarian follicles;
4. thymus;
5. adrenal glands;
6. epithelial body;
7. hypothalamus.

After the production of hormones by these glands, the blood transports these substances to all internal organs.

To date, science has identified more than 60 substances that are involved in the process of balancing hormonal levels. Moreover, these processes do not depend on age and gender.

The influence of female sex hormones on processes in the body

Female hormones are a fragile world that can easily lose balance due to the influence of a variety of factors.

The balance of hormones in the body ensures:

• stable functioning of the nervous system;
• the ability to conceive and bear a baby;
• physical health;
• proper functioning of internal organs.

Read also: How to get pregnant the first time. What is the probability and odds

The modern pharmacological industry partially solves the problems of women with hormonal levels, since today quite a lot of drugs are produced that contain female sex hormones. Of course, this makes life easier for women who need to stabilize their hormonal levels. Female sex hormones in tablets make it possible to prolong the reproductive period and protect against premature aging.

Hormonal imbalance and hormonal changes in women occur when they do not get enough rest.

The highest concentration of hormones, as determined by scientists, is observed in blondes.

Main types of hormones

Hormones are divided into two main groups: estrogenic (female) and androgenic (male).

Female hormones are unique to the fair sex. They give women unique abilities to bear children. Estrogen also gives women a beautiful body and attractive appearance. At the same time, in the female body, in small concentrations, there are male hormones responsible for primary and secondary sexual characteristics.

Some hormones are responsible for sensitivity, emotions, and perception of everything around us. The correct balance of hormones provides a woman with harmony in her worldview, endowing her with instincts. With a lack of hormones, a woman’s health is impaired, diseases of varying severity appear, and years of life are reduced.

Estrogen

Estrogen is considered one of the main female hormones. Estrogen is a group of hormonal substances that are produced in the ovaries. This group of hormones is responsible for the structure of the figure: breasts, roundness of the hips. Estrogen is involved in the dynamics of body renewal at the cellular level, preserving the youth and beauty of skin and hair, affects the condition of blood vessels and fights cholesterol. The emotional outline and character are also influenced.

If there is not enough estrogen in the body, a woman can recognize this by the following signs:

• decreased sex drive;
• failure of the monthly cycle;
• brittle hair and weak nails;
• pale and dry facial skin;
• premature skin aging and wrinkles;
• male type vegetation;
• memory loss;
• migraine;
• hyperhidrosis.

Read also: Delayed menstruation - 23 reasons why you don’t have your period

Normal estrogen levels in women look like this:

1. follicular phase - 57-227 pg/ml;
2. ovulatory - 127 - 476 pg/ml;
3. luteal - 77 - 227 pg/ml.

Progesterone

The hormone progesterone can be called the second most important hormone for the female body. Progesterone is a male hormone, as it is dominant in representatives of the stronger half of humanity. Progesterone is produced in the body of women only after the release of the egg from the follicle and the production of the corpus luteum. If this process does not occur, it means that this hormone is not produced.

The level of progesterone is highest on the day of ovulation, so it is not surprising that the ability to conceive and bear children depends on the levels of the hormone in the body.

Lack of progesterone can be determined by the following symptoms:

• emotional instability;
• bleeding between periods;
• soreness in the mammary glands;
• problems in the gastrointestinal tract;
• bloating.

Progesterone levels should be balanced. In different phases of the cycle and during pregnancy, the level of the hormone is also different. If you suspect that the progesterone levels in your body are abnormal, you should consult your doctor. Progesterone tests are taken 2-3 days after ovulation. The problem of deviations from the norm must be solved together with a qualified doctor, since an excess or deficiency of the hormone negatively affects the female body.

Indicators of the norm of progesterone in the female body:

1. follicular phase - 0.32 - 2.23;
2. ovulatory period - 0.48 - 9.41;
3. luteal phase - 6.99 - 56.63;
4. early pregnancy - 8.90 - 468.40;
5. second trimester - 71.50 - 303.10;
6. late stages of pregnancy - 88.70 - 771.50;
7. after menopause -<0,64.

Luteinizing hormone

LH or luteinizing hormone is a hormone produced by the anterior pituitary gland. For women, this hormone is important as a stimulator of estrogen synthesis, the formation of the corpus luteum and a regulator of progesterone secretion.

You can understand that the luteinizing hormone is not in order by the following signs:

• anovulation;
• decreased sexual desire;
• hirsutism;
• infertility;
• amenorrhea and oligomenorrhea;
• uterine bleeding (dysfunctional);
• not carrying a child;
• delayed sexual development or precocious development;
• sexual infantilism;
• growth retardation;
• polycystic ovary syndrome;
• endometriosis.

Indicators of normal LH in the female body:

1. Ovulatory period - 17.0 - 77.0;
2. Luteinizing period -<14,7;
3. Taking oral contraceptives -<8,0;
4. The period after menopause is 11.3 - 39.8.

Follicle stimulating hormone (FSH)

Follicle-stimulating hormone stimulates the growth and further maturation of the follicle in women, and the maturation of sperm in men. FSH refers to gonadotropic hormones that are produced by the anterior pituitary gland. The action of follicle-stimulating hormone is also associated with the birth of a new life.

Around the seventh day of the follicular period, one follicle stands out and begins its growth and development. After a 2-week period, the egg matures in the follicle, which is ready for subsequent fertilization by sperm.

FSH tends to enhance:

• transformation of testosterone into estrogens;
• follicle growth process;
• process of estrogen synthesis.

With a lack of follicle-stimulating hormone, a woman is accompanied by the following symptoms:

1. scanty discharge during menstruation;
2. infertility;
3. the process of atrophy of the breast and genital organs;
4. lack of ovulation.

When FSH levels are elevated, a woman’s body reacts as follows:

• bleeding between periods;
• absence of menstruation.

If the ratio of the hormones FSH and LH is 2.5, then these indicators indicate:

1. polycystic ovary syndrome;
2. ovarian exhaustion;
3. pituitary tumors.

The level of follicle-stimulating hormone in a woman’s body also differs at different periods of the menstrual cycle:

• follicular period - 2.8 - 11.3 mU/l;
• ovulatory period - 5.8 - 21.0 mU/l;
• luteal period - 1.2 - 9.0 mU/l.

Testosterone in the body of women

The adrenal glands produce testosterone. The levels of this hormone in the body are insignificant, since this hormone is of the male type. Testosterone promotes sexual desires and affects the expression of character traits such as determination and perseverance. A woman under the influence of testosterone becomes passionate and loving. Such women not only know how to accept attention from the opposite sex, but also show an active interest in potential partners.

The higher the testosterone levels in a woman’s body, the more interested she is in sports. In addition, testosterone helps pump up muscles. Women with high testosterone levels look younger than their age.

An excess of male hormones in women manifests itself in the following diseases:

1. hirsulism;
2. amenorrhea;
3. infertility;
4. anovulation;
5. oligomenorrhea;
6. acne;
7. bleeding not associated with menstrual bleeding;
8. miscarriage;
9. polycystic ovary syndrome;
10. endometriosis;
11. myoma;
12. the appearance of tumors in the breast.

Testosterone levels in women:

• During reproductive age, the hormone level is<4,1 пг/мл;
• during menopause the indicators are equal<1,7 пг/мл.

Prolactin

Refers to female sex hormones produced by the anterior pituitary gland. Prolactin takes an active part in the growth and development of the breast, as well as lactation. During pregnancy, prolactin supports the corpus luteum and the production of progesterone. A woman should consult a doctor if she experiences the following symptoms:

1. galactorrhea;
2. mastopathy;
3. periodic chest pain;
4. anovulation;
5. amenomea or oligomenorrhea;
6. uterine bleeding between periods;
7. sexual infantilism;
8. inflammatory processes in the internal genital organs;
9. problems with lactation after childbirth;
10. obesity;
11. menopause;
12. hirsulism;
13. osteoporosis;
14. low libido level.
15. infertility

The normal prolactin level ranges from 109 to 557 mU/ml.

Oxytocin

Oxytocin is produced by the adrenal glands. Oxytocin can be called the hormone of tenderness and care. With an excess of oxytocin, hysteria, scandalousness for no reason, obsession and excessive care for loved ones appear.

The highest levels of the hormone are in the postpartum period, when oxytocin promotes love and trepidation. Oxytocin is characterized by increased sensitivity to stress: it is in a stressful state that the maximum release of oxytocin into the blood occurs. As a result, in order to get rid of anxiety, a woman begins to care for loved ones with greater intensity.

The hormone promotes feelings of pity, which is why women pick up stray animals and are touched by little kittens and puppies.

A lack of oxytocin in a woman’s body manifests itself:

• depressed state of a woman;
• depressed mood;
• indifference to others;
• decrease in energy level.
• gaining excess weight

It is possible to restore normal oxytocin levels without medication. Often it is enough for a woman to change her lifestyle: pay more attention to herself, find an exciting activity.

Endocrine diseases

The endocrine system is a kind of factory for the production of hormones. The thyroid gland plays one of the main roles. But with a high degree of significance, the level of its capriciousness and instability is quite high. Therefore, the thyroid gland in women is a vulnerable spot. Thyroid diseases negatively affect hormonal levels, so a logical question arises about how to restore the balance of hormones. In this situation, female sex hormones in tablets are a great help. The main condition for the effectiveness of drugs is timely consultation with a doctor and compliance with his recommendations. A qualified doctor will quickly determine the hormonal imbalance in the body and select the correct treatment without complications.

Menopause and hormones

The menopausal period consists of three phases:

1. Premenopause.
2. Menopause.
3. Postmenopause.

Each phase has a different manifestation, but the main sign of menopause is a significant decrease in hormonal levels.

There are two pauses in the menstrual cycle: the first is dominated by estrogens, and the second by progesterones. Menopause may have enough hormones to continue menstruation, but these substances are not always enough for cycle regularity. During menopause, female hormones gradually decrease at the beginning of the period and actively respond to indicators of the thickness of the endometrium of the uterus.

The premenopausal period is characterized by a high risk of malignant neoplasms.

When menopause occurs, hormones decrease to such an extent that menstruation stops completely. During postmenopause, female hormones stop being produced, and the ovaries and uterus become smaller in size. This is how biological aging of the body begins.

The endocrine system is a truly complex mechanism, since immediately after a decrease in hormones, metabolism also deteriorates. As a result, the woman experiences hot flashes, nausea, increased blood pressure, and tinnitus. Also, a drop in hormone levels negatively affects bone strength, and women experience nervous system disorders:

• Depression;
• Fear of dying;
• Anxiety;
• Panic attacks;
• Irritability;
• Tearfulness.

The main organs that produce sperm and eggs are the gonads - the testes and ovaries. These organs also produce sex hormones, which according to their chemical structure belong to two different classes - steroids and peptides.

Steroid hormones- these are male sex hormones - androgens, which are produced mainly by the interstitial cells of the testes, and female sex hormones - estrogens and gestagens, produced mainly in the ovaries. The biosynthesis of sex steroids in the testes and ovaries occurs in a similar way.

The period of circulation of sex hormones in the blood is short - up to 2.5-3 hours. The most active metabolism of sex hormones occurs in the liver. Here, the breakdown of hormone molecules and the destruction of their steroid structure occurs. Water-soluble steroid compounds are formed with glucuronic, sulfuric and phosphoric acids, which are then excreted in the urine. Partially, sex hormones are excreted unchanged in the urine. A certain amount of steroid hormones from the liver enters the intestine through the bile duct and is again absorbed into the blood or excreted in the feces.

Androgens- male sex hormones are steroid compounds with 19 carbon atoms. Androgens include testosterone, androstenedione, androsterone And dehydroepiandrosterone. The main and most active of them is testosterone. Androstenedione and androsterone are 6-10 times, and dehydroepiandrosterone 25-30 times less active than testosterone.

Testosterone and androstenedione are produced in the testes and adrenal glands, while androsterone and dehydroepiandrosterone are produced only in the adrenal glands. Androsterone, testosterone and hormonal preparations similar in action to them are obtained chemically.

Androgens are also formed in females - in the adrenal glands, follicles, corpus luteum, but in 10-15 times less quantity than in males. Their content increases slightly during estrus and pregnancy. The main role of androgens in females is to have an anabolic effect in various tissues. In the ovaries, the formation of androgens is an intermediate step in the biosynthesis of estrogen. Estrone is formed from androstenedione through further chemical transformations, and estradiol is formed from testosterone.

In males, they have a specific effect on the development and function of the reproductive organs, the maturation of sperm and the preservation of their viability in the epididymis, the development of secondary sexual characteristics and sexual behavior. In addition, androgens increase basal metabolism, enhance protein synthesis and the development of skeletal muscles, that is, they have an anabolic effect. They increase growth especially actively during puberty. The influence of androgens is carried out by influencing the permeability of cell membranes for amino acids and various metabolites, the functional activity of ribosomes, the synthesis of RNA and proteins. The anabolic effect of androgens is partially carried out indirectly, with the participation of somatotropin, insulin and corticosteroids.

So-called anabolic steroids, which have low androgenic activity and a pronounced anabolic effect, are obtained synthetically based on natural androgens. Our country produces anabolic steroids - dianabol, methylandrostenediol and others, which are of great interest as stimulants of animal productivity.

The incretion of androgens is regulated by the neurohumoral pathway with the participation of the hypothalamus and gonadotropic hormones of the adenohypophysis (LH and FSH). According to N.E. Chazov and V.A. Isachenkov (1974), the regulation of the functions of the gonads is also influenced by the pineal gland, through which the effects of light are realized. These effects cause the release of serotonin, melatonin and other biologically active substances in the pineal gland that affect the hypothalamic-pituitary system. The pineal gland has an inhibitory effect on the gonads by suppressing the incretion of gonadotropins in the adenohypophysis.

Estrogens- female sex hormones, their molecules contain 18 carbon atoms. This group includes estradiol- the most active of estrogens, estrone(folliculin) and estriol. They are synthesized in the ovaries, placenta and partly in the adrenal glands and testes (in Sertoli cells).

Estrone and estriol are formed during metabolism as metabolites of estradiol. These hormones are found in large quantities in urine. Synthetic drugs have an active estrogenic effect - sinestrol, diethylstilbestrol (DES), dienestrol and other stilbene derivatives. In the blood, estrogens circulate bound to albumin, globulins and lipoproteins. Estrogens have an active effect only in a free state.

Estrogens are found in many organs - muscles, bones, kidneys, liver and, mainly, in the reproductive organs. Their physiological action ensures the development, differentiation and functional activity of the female reproductive organs, stimulates the growth and development of follicles, and increases the sensitivity of the ovaries to the action of gonadotropins. By their action, estrogens influence the development of secondary sexual characteristics. Under their influence, mitoses of vaginal epithelial cells are activated, the uterine glands intensively enlarge, their secretion and mucus secretion increase, the cervix opens, blood vessels dilate and blood flow to the genitals increases, and estrus occurs. Estrogens sensitize the uterus during childbirth, and after childbirth accelerate the involution of the uterus and the separation of the placenta. This, in particular, determines their use in veterinary practice. They stimulate the incretion of lutropin, accelerate the resorption of the corpus luteum and the onset of the next sexual cycle. Estrogens excite the nuclei of the hypothalamus, which synthesize ocytocin, and stimulate the formation of prostaglandins in the uterus, which act as luteolysins. Under the influence of estrogens in the blood, the number of red blood cells and hemoglobin content increases, blood clotting accelerates, which reduces blood loss during childbirth. Estrogens stimulate the body's nonspecific resistance and resistance to infections.

In the mammary glands, estrogens, with the participation of FSH, prolactin and somatotropin, ensure cell proliferation and growth of glandular ducts. Both directly and through the corresponding endocrine glands, estrogens influence tissue growth and animal productivity. Under their influence, the incretion of growth hormone (by 20-30%) and other triple hormones increases. They activate the incretion of glucocorticoids. In the blood of animals, the content of androgens, growth hormone and insulin increases, which have a stimulating effect on protein synthesis and the activity of enzymes that ensure this synthesis. The nitrogen balance in the body increases and the utilization of feed nutrients improves, especially in ruminants. Estrogens affect the gene apparatus and enzyme activity in cells, influence lipid metabolism, in particular, they reduce the content of cholesterol and beta-lipoproteins in the blood serum, and increase the content of phospholipids and alpha-lipoproteins.

The formation of estrogen is regulated by gonadotropic hormones of the pituitary gland - FSH and LH, prolactin and releasing hormones of the hypothalamus.

Gestagens- the second group of female sex hormones. These include progesterone, which is produced by the corpus luteum (partially by the adrenal glands and placenta), as well as many synthetic drugs that have the properties of progesterone - melen-gestrol-acetate (MGA), megestrol acetate (AMG), medroxyprogesterone (MAP), amol, diamol , superlutin, fluorogestone (cronolon), etc.

The content of progesterone in the blood begins to increase 1-2 days after ovulation, as soon as the corpus luteum begins to function, and reaches a maximum on the 10-16th day after ovulation. If fertilization does not occur, then at the end of the sexual cycle the corpus luteum undergoes involution and sharply reduces hormonal activity. It is believed that in the process of involution of the corpus luteum, luteolytic factors secreted by the uterus, in particular prostaglandin F-2 alpha, are important.

In females, gestagens have a multifaceted effect. They inhibit the function of the reproductive centers of the brain, the incretion of lutropin and the onset of heat and ovulation. Under the influence of progesterone, the stroma and muscles of the uterus are loosened, its contractions are weakened, which promotes the fixation of embryos in the uterus and prevents their miscarriage. Progesterone ensures the restructuring of the uterus for the development of pregnancy. It weakens the effect of estrogens on the uterus, enhances the development of the uterine glands and their secretion. The secretion of the glands increases the content of substances and enzymes necessary to nourish the embryo (uterine jelly). The development of endometrial vessels increases. Progesterone stimulates the development of the alveoli of the mammary gland, which manifests itself following the action of estrogens, which stimulate the development of the milk ducts. Progesterone inhibits the incretion of prolactin by the pituitary gland and, therefore, inhibits lactogenesis. After childbirth, the content of progesterone in the blood decreases, which contributes to an increase in the concentration of prolactin in the blood, which stimulates milk production. Progesterone and its analogues also have an anabolic effect. Due to this, pregnant animals utilize feed nutrients better.

Progesterone is inactivated in the liver by combining with glucuronic and sulfuric acids. A certain amount of progesterone is converted into sexogens - androgens and estrogens or excreted from the body in the urine. The development of the corpus luteum and the incretion of progesterone in animals is regulated mainly by the luteinizing hormone of the adenohypophysis.

Peptide sex hormones. These include relaxin and inhibin.

Relaxin is formed mainly in the cells of the corpus luteum of the ovaries, partly in the placenta and uterus. It is a polypeptide with a molecular weight of about 8000 and is close in chemical composition to insulin. As pregnancy progresses, the concentration of this hormone in the blood increases and reaches a maximum before childbirth. The physiological role of relaxin is mainly limited to the preparation of childbirth. It helps relax the connective tissue ligaments of the pelvic bones, especially the symphysis pubis, dilates the cervix, reduces the tone of the uterus and its contractile activity before childbirth, and enhances the growth of the mammary glands. The action of relaxin is stimulated by other sex hormones.

Inhibin- produced by cells of seminiferous tubules. It is also found in the follicular fluid of the ovaries. The main effect of this hormone is that it inhibits the production of gonadotropins, especially FSH, in the anterior pituitary gland. Testosterone and other testicular steroid hormones also suppress FSH incretion, but less strongly than inhibin.

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