What are
As the name suggests, gonadotropins are hormones capable of regulating the activity of the gonads or, more simply, the functions of the male and female reproductive organs.
The best known gonadotropins are two, called, respectively, LH (luteinizing hormone) and FSH (follicle stimulating hormone); this time, however, the interpretation of their names could be misleading, since, while referring to the activity of the ovaries, they are also active on the testicles.
Secretion
Gonadotropins are secreted by the anterior pituitary or adenohypophysis, a small gland the size of a bean located at the base of the skull. Its activity is controlled by a region of the brain called the hypothalamus, through a fine regulatory mechanism that uses hormonal substances. Among these, the main one is the GnRH peptide (from the English gonadotropin-releasing hormone), which favors the release of gonadotropins.
Once secreted, being glycoprotein in nature, LH and FSH are transported by the blood to target cells, where specific membrane receptors await them. By interacting with them, they trigger a series of biochemical and metabolic events that differ according to the organ involved.
Functions
Gonadotropins regulate testicular activity in men and ovarian activity in women.
In the Woman
This gonadotropin induces the maturation of ovarian follicles, which are nothing more than egg cells surrounded by follicular cells. During a woman's fertile period, approximately every 28 days, an ovarian follicle is brought to maturity. As it develops, it produces estrogen, hormones that are important for regulating a woman's fertility.
It stimulates the production of testosterone by the theca cells, which is then readily converted into estrogen by the granulosa cells. Both of these cells are part of the ovarian follicle: the outermost layer is made up of theca cells, the innermost one is made up of granulosa cells.
LH also stimulates ovulation, that is the release from the follicle of the mature egg cell, which at this point can - at least theoretically - be fertilized. The residual corpus luteum will instead produce progesterone, an important hormone to guarantee the eventual implantation of the fertilized egg. and support pregnancy.
In the "man
This gonadotropin favors spermatogenesis in man, the process that leads to the formation and maturation of spermatozoa.
It stimulates the production of testosterone by the interstitial cells of the testis (called Leydig cells). For this reason, in the male, the luteinizing hormone takes the name ICSH (acronym for Interstitial Cell Stimulating Hormone).
HCG
Alongside the luteinizing hormone (LH) and foliculostimulating hormone (FSH), a third hormone, called human chorionic gonadotropin (HCG), is also included in the category of gonadotropins. This substance is secreted by particular cells of the placenta during pregnancy, with the aiming to prolong the stimulating effect of the hormone LH on the synthesis of progesterone by the corpus luteum.
Medical applications
In therapy, gonadotropins are used to stimulate the production of sex hormones in both males and females and / or to increase fertility.
The measurement of Human Chorionic Gonadotropin, performed on urine or blood, is used as a pregnancy test. This gonadotropin is also administered in the sports field to reactivate testicular production of testosterone (for example after taking anabolic steroids in high doses).
