Gestagens

Progestins are a group of female sex hormones with antiestrogenic and antigonadotropic effects. The most important is progesterone.

Progesterone
It is formed in the corpus luteum of the ovaries and placenta (after 6-8 weeks of pregnancy ; 30-40 times more), as an intermediate in the synthesis of androgens and estrogens also in the adrenal cortex and in small amounts in testes.

It is synthesized from cholesterol via the intermediate pregnenolone, from which it differs in its arrangement on the A ring.

náhled|Progesteron

It binds to the protein carrier in plasma. It is rapidly metabolised in the liver - it has a very low bioavailability and a short biological half-life. Due to active metabolism in the liver, progesterone p.o. is ineffective.

After conjugation with glucuronic acid (inactivation) in the liver, it is excreted in the urine as pregnanediol.

Effect
Progestins lead to:




 * development of secretory tissues in the mammary glands (acins) - however, lactation is blocked and begins after delivery (sharp drop in progesterone levels), maintained by prolactin
 * maturation of the endometrium in the second half of the menstrual cycle - transition from the proliferative to the secretory phase (increase in the volume and size of glandular secretion and increase in glycogen content ) -> preparation of the uterine mucosa for egg reception + narrowing of the cervix and thickening of cervical mucus.
 * reducing the effect of estrogens on the vaginal wall
 * influencing peripheral blood flow – reduces heat loss, ie increases body temperature (on average by 0.5 ° C during the luteal phase of the cycle - ovulation indicator )

Compared to estrogens, progestagens have a minimal effect on the composition of plasma proteins (they do not affect plasma fibrinogen levels). They significantly affect sugar metabolism and stimulate fat storage.

Progestogens and estrogens act synergistically - estrogens initiate the formation of progesterone receptors.

Clinical use
The main indication is contraceptive application. Long-term application can also be used for long-term suppression of ovaries, eg in endometriosis. They have no effect on inducing abortion. Progestin toxicity is low, although they may cause an increase in blood pressure and a decrease in HDL.

Synthetic steroids are also used as oral contraceptives - 17alpha-hydroxyprogesterone derivatives and 17alpha-alkyl-substituted 19-nortestosterone derivatives, medroxyprogesterone acetate, etc. The inhibitory effect on cell growth is used to treat differentiated endometrial cancer.

Related articles

 * Antikoncepce
 * Estrogeny
 * Psychophysiology of human sexuality
 * Hormonal and biological treatment