Gonadotropic hormones and their functions in the body
The content of the article:
-
Follicle-stimulating hormone
- The role of FSH in women
- The role of FSH in men
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Luteinizing hormone
- LH functions in women
- LH functions in men
- Chorionic gonadotropin
- Video
Gonadotropic hormones (GH) are biologically active substances synthesized by the anterior pituitary gland and the placenta, the main purpose of which is to regulate the work of the gonads. The gonadotropins, as this group of hormones is also called, include:
- follitropin, or follicle-stimulating hormone (FSH);
- lutropin, or luteinizing hormone (LH);
- human chorionic gonadotropin (hCG, hCG).
Gonadotropic hormones are an important link in the neurohumoral regulation system. Knowledge of their functions in the body helps in the diagnosis and treatment of various diseases.
Gonadotropic hormones are responsible for reproductive function in the human body
Follicle-stimulating hormone
FSH is synthesized by basophilic cells of the pituitary gland of men and women. The scope of application of follitropin is the sex glands of both sexes. Receptors for it are located on the cell membranes of target organs: ovaries and testes. The synthesis and secretion of FSH is stimulated by the hypothalamic hormone called folliberin, or follitropin-releasing hormone.
The role of FSH in women
In the female body, FSH is responsible for cyclic changes in the ovaries, its level depends on the phase of the menstrual cycle. Without normal secretion of the hormone, ovulation, fertilization and pregnancy are impossible. The effect of FSH on oogenesis, or the development of the female reproductive cell, is realized through:
- stimulation of the growth of the follicle in the ovary and the maturation of the egg in it in the first half of the menstrual cycle;
- starting the synthesis of estradiol by the growing follicle;
- promoting the transformation of testosterone into estradiol;
- activation of ovulation - rupture of the follicle and release of the egg into the abdominal cavity.
All these processes create favorable conditions for the functioning of the corpus luteum in the second half of the menstrual cycle, allow it to produce a sufficient amount of progesterone.
In the first phase of the cycle, the FSH level progressively increases, reaching a maximum by the middle, after ovulation, it decreases. If fertilization has not occurred, then before menstruation, its content begins to gradually increase.
Determining the level of FSH is of great importance in assessing the state of a woman's reproductive function.
| Cycle phase, age | Hormone rate in IU / ml |
| Follicular phase | 2.8-11.3 |
| Ovulatory phase | 5.8-21.0 |
| Luteal phase | 1.2-9.0 |
| Postmenopause | 21.7-153.0 |
| Girls 1.5 - 9 years old | 0.11-1.6 |
Estradiol, progesterone affect the FSH concentration according to the feedback principle: a large amount of peripheral hormone suppresses the hormonal activity of the pituitary gland. Controls the synthesis and inhibin B produced by granulosa cells of the follicle. High inhibin levels inhibit follitropin secretion.
Lack of FSH in childhood leads to delayed sexual development, and excess production leads to premature puberty. In adults, interruptions in secretion are accompanied by irregularities in the menstrual cycle, problems with conceiving and carrying a pregnancy.
The role of FSH in men
In men, FSH is involved in the growth and functioning of the seminiferous tubules, and promotes spermatogenesis (sperm development). The targets for him are Sertoli cells in the convoluted tubules of the testicles, acting on which the hormone:
- stimulates the formation of androgen-binding protein;
- controls the synthesis of testosterone;
- helps carry testosterone to the epididymis;
- supports the trophic and barrier function of the cells themselves.
The concentration of FSH is influenced by testosterone. The impact is carried out through the hypothalamus and pituitary gland according to the feedback principle. Inhibin, a peptide hormone synthesized by Sertoli cells, inhibits the production of follitropin.
The physiological norm of FSH in men is: 0.7–11.1 IU / ml. Determination of the level is carried out in case of dysfunction of the gonads, impotence, decreased sexual desire, infertility, especially associated with oligo- or azoospermia.
Luteinizing hormone
Lutropin is a peptide gonadotropic hormone of the pituitary gland. Responsible for the normal functioning of the reproductive system of both sexes. Acts in close connection with FSH. LH secretion is controlled by lulitropin-releasing hormone (luliberin) of the hypothalamus, secreted in a certain pulsating mode, and, according to the principle of feedback, the level of estrogens synthesized by the sex glands.
LH functions in women
LH takes an active part in the formation of the menstrual cycle. In the follicular phase, its level is insignificant. Rapid growth occurs during the ovulatory peak, which lasts about 48 hours. Lutropin in a woman's body:
- promotes the synthesis of estradiol in the dominant follicle;
- causes ovulation together with FSH;
- starts luteinization - the transformation of the residual follicle into the corpus luteum;
- stimulates the production of progesterone by the corpus luteum;
- acts on ovarian theca cells that synthesize androgens.
Serum lutropin levels:
| Cycle phase, age | Concentration in honey / ml |
| Follicular phase | 1.1-1.7 |
| Ovulatory phase | 17.1-77.0 |
| Luteal phase | 0.9-14.7 |
| Postmenopause | 11.3-40.0 |
| Girls 1.5 - 9 years old | 0.7-1.4 |
A high level of LH is noted in the syndrome of premature ovarian depletion, hereditary isolated gonadal dysgenesis, Shereshevsky-Turner syndrome, ovarian hypofunction, and some forms of congenital adrenal hyperplasia.
Insufficient activity of lutropin leads to the absence of menstruation and is observed in injuries and tumors of the hypothalamus, Kallman's syndrome, Simmonds disease, amenorrhea of athletes, hyperprolactinemia.
LH functions in men
In men, LH acts on the Leydig interstitial cells located in the testes and controls testosterone synthesis. The latter is the main male sex hormone involved in all types of metabolism, responsible for puberty, the formation of secondary sexual characteristics, and spermatogenesis.
LH stimulates the endocrine function of the testicles through a direct action on Leydig cells: the higher the LH level in the blood, the more actively testosterone is produced. The hypothalamic hormone - luliberin - regulates the synthesis of gonadotropin itself. In addition, the concentration of LH is inversely related to the level of testosterone in the blood: the higher it is, the less intense the production of LH.
The norm of LH content in men is from 0.8 to 7.6 IU / ml. High LH indicates dysfunction of the gonads, low - about disturbances in the work of the pituitary gland and hypofunction of the gonads. With a deviation of the LH level, both in one and the other direction, erectile and reproductive function suffers, and general sexual health is impaired.
Chorionic gonadotropin
HCG is a specific pregnancy hormone produced by the chorion, the shell of the embryo. The synthesis of hCG begins from the first day of pregnancy and rapidly increases to 11-12 weeks, then decreases and remains at a low level until delivery. CG is composed of alpha and beta subunits. The first one coincides in structure with the alpha subunits of FSH and LH, the second is unique and distinguishes it from these hormones.
Due to its chemical similarity, HCG has the properties of both LH and FSH, but the ability to luteinize is much superior to its follicle-stimulating activity, and it is significantly higher than that of pituitary LH. This allows the corpus luteum, which functions for about 14 days in each menstrual cycle, not to dissolve in pregnant women, but to secrete progesterone for the entire Ӏ trimester. Then the placenta does it.
In addition to stimulating the corpus luteum, hCG performs a number of functions without which it is impossible to carry a pregnancy:
- activates the production of estrogens and weak androgens by the ovaries;
- provides immunological tolerance of the maternal organism in relation to the "foreign" fetus;
- supports the functional activity of the placenta.
Sensitivity to urine hCG underlies pregnancy tests
Pregnancy tests are based on determining the level of hCG in urine, but the content of hCG in the blood is a more accurate indicator for diagnosing early pregnancy. Outside of pregnancy, hCG is absent in the norm, but it is often synthesized by malignant tumors, therefore it can serve as a tumor marker. The norm for men and non-pregnant women: 0-5.3 IU / ml. An increase in the level of hCG can be a sign of chorionic carcinoma, a tumor of the testicles, lungs, kidneys, stomach, intestines.
Video
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Anna Kozlova Medical journalist About the author
Education: Rostov State Medical University, specialty "General Medicine".
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