Gonadotropin-releasing Hormone: What Is It, Agonists, Antagonists, Drugs

2024 Author: Rachel Wainwright | [email protected]. Last modified: 2023-12-15 07:39

Gonadotropin-releasing hormone, its functions in the body and its use in medicine

The content of the article:

Functions and role of gonadoliberin in the body
Production
The use of gonadoliberin in medicine
1. Analogues of gonadoliberin
2. Agonists of gonadotropin-releasing hormone and its antagonists
Video

Gonadotropin-releasing hormone (GnRH, gonadotropin-releasing factor, gonadoliberin, gonadorelin) is a biologically active substance, chemically a polypeptide (decapeptide), which is produced by the hypothalamus.

Gonadoliberin is a hypothalamic releasing hormone whose function is to control other endocrine glands.

Functions and role of gonadoliberin in the body

Releasing hormones are a class of biologically active substances that are produced by the hypothalamus and affect the functions of the thyroid gland, ovaries, testes, mammary gland, pituitary gland, and adrenal glands. A common property of all releasing hormones is the implementation of their action through the stimulation of the production and secretion into the blood of certain biologically active substances of the pituitary gland. Releasing factors have an effect on the cells of the anterior pituitary gland, which produces a number of hormones (thyroid-stimulating, somatotropic, adrenocorticotropic, etc.).

Representatives of the class of hypothalamic releasing hormones, in addition to gonadoliberin, are also:

somatotropin-releasing factor;
thyrotropin-releasing factor;
corticotropin-releasing factor, etc.

Gonadoliberin is involved in the regulation of the human reproductive system. This substance stimulates the production of luteinizing hormone (LH) and follicle stimulating hormone (FSH) hormone, while to a greater extent it affects the production of luteinizing hormone. LH and FSH belong to the gonadotropins (gonadotropic hormones), which regulate the functioning of the gonads and are secreted by the anterior pituitary gland and the placenta. LH in the body of women stimulates the production of estrogens (female sex hormones) by the ovaries, and in the body of men - testosterone, the main androgen (male sex hormone). FSH stimulates the development of follicles in the ovaries and the production of estrogen, and also triggers the process of spermatogenesis in women and men, respectively.

Production

The production of gonadoliberin does not occur constantly, but at certain intervals:

in men, every 90 minutes;
in women - every 15 minutes in the follicular, every 45 minutes in the luteal phase of the menstrual cycle and during pregnancy.

Such a rhythm provides a normal ratio of sex hormones, the synthesis of which it affects, which is especially important for the female body.

Catecholamines produced by the adrenal glands stimulate the secretion of gonadoliberin:

adrenalin;
norepinephrine;
dopamine.

Inhibits secretion:

serotonin;
nervous overstrain;
constant lack of sleep.

Frequent or continuous secretion leads to loss of sensitivity of receptors and the development of a number of pathological conditions, for example, to menstrual irregularities. A decrease in secretion is observed less often, this can lead to amenorrhea, lack of ovulation.

The use of gonadoliberin in medicine

Medicines based on gonadoliberin are prescribed if a patient has reproductive system disorders, for example, infertility, during his treatment by artificial insemination and in a number of other cases.

The introduction of exogenous gonadoliberin in a constant intravenous drip infusion or its long-acting synthetic analogs leads to a short-term increase in the production of gonadotropins, after which the function of the gonads and the gonadotropic function of the pituitary gland is suppressed. However, with the introduction of exogenous gonadoliberin by means of a pump that imitates the rhythm of the natural pulsation of the production of this substance, a prolonged and persistent stimulation of the gonadotropic function of the pituitary gland occurs. With the correct mode of such a pump, women are observed to ensure the secretion of luteinizing and follicle-stimulating hormones, which corresponds to the phases of the menstrual cycle, and in men - to the ratio of gonadotropins characteristic of their sex.

GnRH preparations are available in various forms:

solutions for intramuscular and subcutaneous injections;
nasal spray;
subcutaneous capsules (depot capsules).

If the patient has benign and malignant neoplasms and some other diseases, GnRH drugs can also be prescribed (for example, for breast tumors, prostate cancer, endometriosis, endometrial hyperplastic processes, etc.).

In order to prevent the development of the pathological process and in addition to the main treatment, it is recommended to correct the daily regimen, avoid stress, a balanced diet, and rejection of bad habits.

Analogues of gonadoliberin

To date, natural gonadoliberin as a drug is practically not used, since it has a short half-life. Instead, its analogs are used, the action of which is longer. In addition, synthetic analogs of gonadoliberin are 50-100 times more active than gonadotropin-releasing hormone itself.

GnRH analogs bind to gonadoliberin receptors in the pituitary gland and cause the release of luteinizing and follicle-stimulating hormones, while reducing the production of ovarian hormones. This property of these drugs is used to treat patients with uterine fibroids. They can be used for premature puberty in children, before and after surgery for endometriosis.

Buserelin is one of the synthetic analogs of gonadoliberin

Synthetic analogs of gonadotropin-releasing hormone have found application not only in gynecology, but also in oncology - they are able to affect tumor cells, inhibiting tumor growth. Specific GnRH receptors have been identified in the tissues of many malignant neoplasms (breast, prostate, and ovarian cancer samples).

Agonists of gonadotropin-releasing hormone and its antagonists

In medicine, GnRH agonists and antagonists are used. Agonists assist in enhancing its production, and antagonists, by direct action on the GnRH receptors, block them and suppress GnRH secretion.

The table lists the names of some of the commonly prescribed GnRH agonists and antagonists.

GnRH agonists	GnRH antagonists
Goserelin	Orgalutran
Zoladex	Cetrotide
Buserelin	Firmagon

GnRH agonists are used in the treatment of endometriosis, in combination with iron supplements, in the treatment of iron deficiency anemia associated with menorrhagia.

Antagonists of gonadotropin-releasing hormone are used in assisted reproductive technologies, for example, a certain injection scheme is used when it is necessary to achieve superovulation (simultaneous maturation of several eggs, that is, preparation of not one, but two follicles by the ovaries in one menstrual cycle) during artificial insemination. Also, agonists can be used for 2-4 months for preoperative preparation for uterine myoma and menorrhagia.