Research of hormonal regulation of reproductive function
Last reviewed: 20.11.2021
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Radiation examination of hormonal regulation of the reproductive function of the female body
Regulation of all functions of the sexual system of a woman occurs with the participation of the cerebral cortex, subcortical structures, pituitary gland, ovaries, as well as the uterus, vagina, mammary glands. The interrelation and the coordinated interaction of all elements of this complex system are realized by means of the mechanism of multistage negative and positive feedback. Violation of one of the links in the chain of regulatory mechanisms is inevitably accompanied by a misalignment of the remaining hormonal relationships. Early detection of these disorders allows the methods of radioimmunological diagnostics.
Radioimmunological studies of the hormonal status of women are performed with a portion of blood (in vitro), i.e. Without the introduction of radioactive compounds in the body, so they do not pose a danger to either the pregnant or the embryo.
The menstrual cycle of a healthy woman is biphasic. In the first phase - growth and maturation of the follicle (estrogenic, or follicular, phase), the ovaries excrete the hormone estradiol. Its concentration is 0 1-03 nmol / l and increases with the maturation of the follicle. The maximum concentration of 0-6-1.3 nmol / L is observed in the middle of the cycle, 1 to 2 days before ovulation. In the second phase of the cycle - the phase of the yellow body (luteal phase) - the level of estradiol is reduced to 0.3-0.8 nmol / l. Estradiol causes proliferation of the uterine mucosa.
Another hormone produced by the ovaries is progesterone. It is secreted mainly by the yellow body and, consequently, its concentration is maximal in the second phase of the menstrual cycle - 25-55 nmol / l, whereas in the first phase of the cycle - only 2-6 nmol / l. The function of progesterone is to prepare the endometrium for the implantation of a fertilized egg.
The change in the secretion of sex hormones is regulated by the pituitary gland by releasing gonadotrophic hormones - lutropine and follitropin, as well as prolactin. Lutropin stimulates the biosynthesis of progesterone and regulates the function of the yellow body. It is a factor in triggering ovulation. The content of lutropin at the beginning and the end of the cycle is 7-15 units / l, and at the peak of ovulation it rises to 40-100 U / l.
Follotropin stimulates the growth of granular cells of the ovary and promotes the maturation of the follicle. Like lutropin, it triggers an ovulation mechanism. Fluctuations of its concentration in the blood are similar to those of lutropin: it is minimal at the beginning and end of the cycle (6-12 U / L) and is maximal at the peak of ovulation (20-40 U / L).
The physiological role of prolactin is diverse. Like lutropin, it stimulates the secretion of progesterone in a yellow body. Fluctuations in its content in the blood are subject to the same patterns as lutropin: a peak is observed in the phase of ovulation, i.e. In the middle of the menstrual cycle. The concentration of prolactin increases dramatically during pregnancy and lactation.
Gonadotropic function of the pituitary gland is under the control of the hypothalamus. The latter generates releasing hormones: lyuliberin and folliberin, which stimulate the secretion of gonadotropins. Recently, synthetic hypothalamic releasing hormones have been developed, which are used in radioimmunological diagnostics to distinguish between hypothalamic and pituitary lesions. Particularly accurate radioimmunoassays have been developed that allow one to determine the concentration in the blood of the releasing hormones. This opens the possibility for a one-stage radioimmunological study of the entire hormonal "hierarchy": the hypothalamus-pituitary-ovaries.