Progestogens (also sometimes spelled progestagens or gestagens) are a class of steroid hormones that bind to and activate the progesterone receptor (PR). The most important progestogen in the body is progesterone (P4). Other endogenous progestogens include 17α-hydroxyprogesterone, 20α-dihydroprogesterone, 5α-dihydroprogesterone, 11-deoxycorticosterone, and 5α-dihydrodeoxycorticosterone. Synthetic progestogens are generally referred to as progestins. However, the terms progesterone, progestogen, and progestin are frequently used interchangeably both in the scientific literature and in clinical settings.
The progestogens are one of the five major classes of steroid hormones, in addition to the androgens, estrogens, glucocorticoids, and mineralocorticoids, as well as the neurosteroids. All progestogens are characterized by their basic 21-carbon skeleton, called a pregnane skeleton (C21). In similar manner, the estrogens possess an estrane skeleton (C18), and androgens, an andrane skeleton (C19).
- Production by the ovary 1.1
- Production by the placenta 1.2
- Female indications 2.1
- As antiandrogens 2.2
- As antigonadotropins 2.3
- Cachexia 2.4
- References 3
- Further reading 4
- External links 5
In the first step in the steroidogenic pathway, cholesterol is converted into pregnenolone (P5), which serves as the precursor to the progestogens progesterone and 17-hydroxyprogesterone. These progestogens, along with another steroid, 17-hydroxypregnenolone, are the precursors of all other endogenous steroids, including the androgens, estrogens, glucocorticoids, mineralocorticoids, and neurosteroids. Thus, many tissues producing steroids, including the adrenal glands, testes, and ovaries, produce progestogens.
In some tissues, the enzymes required for the final product are not all located in a single cell. For example, in ovarian follicles, cholesterol is converted to androstenedione, an androgen, in the theca cells, which is then further converted into estrogen in the granulosa cells. Fetal adrenal glands also produce pregnenolone in some species, which is converted into progesterone and estrogens by the placenta (see below). In the human, the fetal adrenals produce dehydroepiandrosterone (DHEA) via the pregnenolone pathway.
Production by the ovary
Progesterone is the major progestogen produced by the corpus luteum of the ovary in all mammalian species. Luteal cells possess the necessary enzymes to convert cholesterol to pregnenolone, which is subsequently converted into progesterone. Progesterone is highest in the diestrus phase of the estrous cycle.
Production by the placenta
The role of the placenta in progestogen production varies by species. In the sheep, horse, and human, the placenta takes over the majority of progestogen production, whereas in other species the corpus luteum remains the primary source of progestogens. In the sheep and human, progesterone is the major placental progestogen.
The equine placenta produces a variety of progestogens, primarily 5α-dihydroprogesterone and 5α,20α-tetrahydroprogesterone, beginning on day 60. A complete luteo-placental shift occurs by day 120–150.
In women, progestogens are commonly used to prevent endometrial hyperplasia from unopposed estrogen during hormone replacement therapy. They also used to treat secondary amenorrhea, dysfunctional uterine bleeding and endometriosis.
In a normal menstrual cycle, declining levels of progesterone triggers menstruation. Norethindrone acetate and medroxyprogesterone acetate may be used to artificially induce progestogen-associated breakthrough bleeding.
In addition to their progestogen properties, some progestins are
- Progestins at the US National Library of Medicine Medical Subject Headings (MeSH)
- The Nomenclature of Steroids
- The Million Women Study
- (the Women's Health, Osteoporosis, Progestin, Estrogen study)
- Hulley S, Grady D, Bush T, et al. (August 1998). "Randomized trial of estrogen plus progestin for secondary prevention of coronary heart disease in postmenopausal women. Heart and Estrogen/progestin Replacement Study (HERS) Research Group". JAMA 280 (7): 605–13.
- Tekoa L. King; Mary C. Brucker (25 October 2010). Pharmacology for Women's Health. Jones & Bartlett Publishers. p. 373.
- Michelle A. Clark; Richard A. Harvey; Richard Finkel; Jose A. Rey; Karen Whalen (15 December 2011). Pharmacology. Lippincott Williams & Wilkins. p. 322.
- Bhattacharya (1 January 2003). Pharmacology, 2/e. Elsevier India. p. 378.
- Tara Parker-Pope (25 March 2008). The Hormone Decision. Simon and Schuster. p. 228.
- Hickey M, Fraser IS (August 2000). "A functional model for progestogen-induced breakthrough bleeding". Hum. Reprod. 15 Suppl 3: 1–6.
- Botella, J.; Paris, J.; Lahlou, B. (1987). "The cellular mechanism of the antiandrogenic action of nomegestrol acetate, a new 19-nor progestagen, on the rat prostate". European Journal of Endocrinology 115 (4): 544–550.
- Raudrant D, Rabe T (2003). "Progestogens with antiandrogenic properties". Drugs 63 (5): 463–92.
- Georg Wick; Cecilia Grundtman (3 December 2011). Inflammation and Atherosclerosis. Springer Science & Business Media. pp. 560–.
- Armen H. Tashjian; Ehrin J. Armstrong (21 July 2011). Principles of Pharmacology: The Pathophysiologic Basis of Drug Therapy. Lippincott Williams & Wilkins. pp. 523–.
- Kenneth Hugdahl; René Westerhausen (2010). The Two Halves of the Brain: Information Processing in the Cerebral Hemispheres. MIT Press. pp. 272–.
- Kuhl H (1996). "Comparative pharmacology of newer progestogens". Drugs 51 (2): 188–215.
- Chaudhuri (1 January 2007). Practice Of Fertility Control: A Comprehensive Manual (7Th Edition). Elsevier India. pp. 122–.
- Volodymyr Dvornyk (22 January 2013). Current Topics in Menopause. Bentham Science Publishers. pp. 357–.
- A.R. Genazzani (15 May 2001). Hormone Replacement Therapy and Cardiovascular Disease: The Current Status of Research and Practice. CRC Press. pp. 94–.
- de Lignières B, Silberstein S (April 2000). "Pharmacodynamics of oestrogens and progestogens". Cephalalgia : an International Journal of Headache 20 (3): 200–7.
- Chassard D, Schatz B (2005). "[The antigonadrotropic activity of chlormadinone acetate in reproductive women]". Gynécologie, Obstétrique & Fertilité (in French) 33 (1-2): 29–34.
- Brady BM, Anderson RA, Kinniburgh D, Baird DT (April 2003). "Demonstration of progesterone receptor-mediated gonadotrophin suppression in the human male". Clinical Endocrinology 58 (4): 506–12.
- Neumann F (1978). "The physiological action of progesterone and the pharmacological effects of progestogens--a short review". Postgraduate Medical Journal. 54 Suppl 2: 11–24.
- Andrea R. Genazzani (15 January 1993). Frontiers in Gynecologic and Obstetric Investigation. Taylor & Francis. p. 320.
- Maltoni M, Nanni O, Scarpi E, Rossi D, Serra P, Amadori D (March 2001). "High-dose progestins for the treatment of cancer anorexia-cachexia syndrome: a systematic review of randomised clinical trials". Ann. Oncol. 12 (3): 289–300.
- Lelli G, Montanari M, Gilli G, Scapoli D, Antonietti C, Scapoli D (June 2003). "Treatment of the cancer anorexia-cachexia syndrome: a critical reappraisal". J Chemother 15 (3): 220–5.
In many people suffering from solid malignancy, especially gastric and pancreatic cancer, high doses of certain progestins can be employed to improve appetite and reduce wasting. In general, they are used in combination with certain other steroids such as dexamethasone. Their effects take several weeks to become apparent, but are relatively long-lived when compared to those of corticosteroids. Furthermore, they are recognized as being the only drugs to increase lean body mass. Megestrol acetate is the lead drug of this class for the management of cachexia, and medroxyprogesterone acetate is also used.
Progestogens, similarly to the androgens and estrogens through their own respective receptors, inhibit the secretion of the gonadotropins follicle-stimulating hormone (FSH) and luteinizing hormone (LH) via activation of the progesterone receptor. This effect is a form of negative feedback on the hypothalamic-pituitary-gonadal (HPG) axis that the body uses to prevent sex hormone levels from becoming too elevated. Accordingly, progestogens, both endogenous and exogenous (i.e., progestins), have antigonadotropic effects, and progestins in sufficient amounts can markedly suppress the body's normal production of progestogens, androgens, and estrogens, as well as, in theory, neurosteroids. As such, some of the more potent progestins, including chlormadinone acetate, cyproterone acetate, medroxyprogesterone acetate, and megestrol acetate are sometimes used to suppress sex hormone levels in a variety of androgen and estrogen-associated conditions. Examples of indications include treating sex hormone-sensitive cancers (e.g., breast cancer), suppressing precocious puberty and puberty in transgender youth, and reducing sex drive in sex offenders and individuals with paraphilias or hypersexuality.