Progestogens , also sometimes written progestins , progestagens or gestagens , are a class of natural or synthetic steroid hormones that bind to and activate the progesterone receptors (PR). Progesterone is the major and most important progestogen in the body. The progestogens are named for their function in maintaining pregnancy (i.e., progestational ), although they are also present at other phases of the estrous and menstrual cycles .
18-442: The progestogens are one of three types of sex hormones , the others being estrogens like estradiol and androgens / anabolic steroids like testosterone . In addition, they are one of the five major classes of steroid hormones, the others being the androgens, estrogens, glucocorticoids , and mineralocorticoids , as well as the neurosteroids . All endogenous progestogens are characterized by their basic 21-carbon skeleton, called
36-409: A pregnane skeleton (C21). In similar manner, the estrogens possess an estrane skeleton (C18), and androgens, an androstane skeleton (C19). The terms progesterone , progestogen , and progestin are mistakenly used interchangeably both in the scientific literature and in clinical settings. Progestins are synthetic progestogens and are used in medicine. Major examples of progestins include
54-463: A substrate into a product that serves as the substrate for the next reaction . Metabolic intermediates are compounds that form during these steps, and they are neither the starting substrate nor the final product of the pathway. These intermediates are crucial because they allow for regulation, energy storage, and extraction of chemical energy in a controlled manner. Metabolic intermediates can belong to different biochemical classes based on
72-463: Is a semi-synthetic estrogen. Specific compounds that have partial agonist activity for steroid receptors , and therefore act in part like natural steroid hormones, are in use in medical conditions that require treatment with steroid in one cell type, but where systemic effects of the particular steroid in the entire organism are only desirable within certain limits. Metabolic intermediate Metabolic intermediates are compounds produced during
90-403: 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. Progesterone
108-405: 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. The role of the placenta in progestogen production varies by species. In the sheep, horse, and human,
126-540: Is the most important and only naturally occurring human progestogen. In general, androgens are considered "male sex hormones", since they have masculinizing effects, while estrogens and progestogens are considered "female sex hormones" although all types are present in each sex at different levels. Sex hormones include: There are also many synthetic sex steroids. Synthetic androgens are often referred to as anabolic steroids . Synthetic estrogens and progestins are used in methods of hormonal contraception . Ethinylestradiol
144-558: The 17α-hydroxyprogesterone derivative medroxyprogesterone acetate and the 19-nortestosterone derivative norethisterone . The progestins are structural analogues of progesterone and have progestogenic activity similarly, but differ from progesterone in their pharmacological properties in various ways. In addition to their roles as natural hormones, progestogens are used as medications , for instance in menopausal hormone therapy and transgender hormone therapy for transgender women ; for information on progestogens as medications, see
162-525: The androgens , estrogens , and progestogens . Their effects are mediated by slow genomic mechanisms through nuclear receptors as well as by fast nongenomic mechanisms through membrane-associated receptors and signaling cascades . The polypeptide hormones luteinizing hormone , follicle-stimulating hormone and gonadotropin-releasing hormone – each associated with the gonadotropin axis – are usually not regarded as sex hormones, although they play major sex-related roles. Natural sex hormones are made by
180-455: The gonads ( ovaries or testicles ), by adrenal glands , or by conversion from other sex steroids in other tissue such as liver or fat. In many contexts, the two main classes of sex hormones are androgens and estrogens, of which the most important human derivatives are testosterone and estradiol , respectively. Other contexts will include progestogens as a third class of sex steroids, distinct from androgens and estrogens. Progesterone
198-552: 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. The endogenous progestogens are naturally occurring pregnane steroids with ketone and/or hydroxyl groups at
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#1732776821135216-745: The progesterone (medication) and progestogen (medication) articles. The most important progestogen in the body is progesterone (P4). Other endogenous progestogens, with varying degrees of progestogenic activity, include 16α-hydroxyprogesterone (16α-OHP), 17α-hydroxyprogesterone (17α-OHP) (very weak), 20α-dihydroprogesterone (20α-DHP), 20β-dihydroprogesterone (20β-DHP), 5α-dihydroprogesterone (5α-DHP), 5β-dihydroprogesterone (5β-DHP) (very weak), 3β-dihydroprogesterone (3β-DHP), 11-deoxycorticosterone (DOC), and 5α-dihydrodeoxycorticosterone (5α-DHDOC). They are all metabolites of progesterone, lying downstream of progesterone in terms of biosynthesis. The major tissues affected by progestogens include
234-538: The uterus , vagina , cervix , breasts , testes , and brain . The main biological role of progestogens in the body is in the female reproductive system , and the male reproductive system , with involvement in regulation of the menstrual cycle , maintenance of pregnancy , and preparation of the mammary glands for lactation and breastfeeding following parturition in women; in men progesterone affects spermiogenesis , sperm capacitation , and testosterone synthesis. Progestogens also have effects in other parts of
252-553: The C3 and C20 positions. Progestogens , including both progesterone and progestins , are used medically in hormonal birth control , hormone therapy , to treat gynecological disorders , to suppress sex hormone levels for various purposes, and for other indications. Sex hormone Sex hormones , also known as sex steroids , gonadocorticoids and gonadal steroids , are steroid hormones that interact with vertebrate steroid hormone receptors . The sex hormones include
270-448: The body. Unlike estrogens , progestogens have little or no role in feminization . Progesterone is produced from cholesterol with pregnenolone as a metabolic intermediate . In the first step in the steroidogenic pathway , cholesterol is converted into pregnenolone, which serves as the precursor to the progestogens progesterone and 17α-hydroxyprogesterone. These progestogens, along with another steroid, 17α-hydroxypregnenolone , are
288-461: The conversion of substrates (starting molecules) into final products in biochemical reactions within cells . Although these intermediates are of relatively minor direct importance to cellular function, they can play important roles in the allosteric regulation of enzymes , glycolysis , the citric acid cycle , and amino acid synthesis . Metabolic pathways consist of a series of enzymatically catalyzed reactions where each step transforms
306-409: 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
324-420: The type of pathway they are involved in. Some examples include: Some can be useful in measuring rates of metabolic processes (for example, 3,4-dihydroxyphenylacetic acid or 3-aminoisobutyrate ). Because they can represent unnatural points of entry into natural metabolic pathways, some (such as AICA ribonucleotide ) are of interest to researchers in developing new therapies. This biochemistry article
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