Progestogens, also sometimes written progestins, progestagens or gestagens,
The progestogens are one of three types of , the others being like estradiol and / like testosterone. In addition, they are one of the five major classes of steroid hormones, the others being the androgens, estrogens, , and mineralocorticoids, as well as the . All endogenous 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 androstane skeleton (C19).
The terms progesterone, progestogen, and progestin are mistakenly used interchangeably both in the scientific literature and in clinical settings.
In addition to their roles as natural hormones, progestogens are used as , for instance in menopausal hormone therapy and transgender hormone therapy for Trans woman; for information on progestogens as medications, see the progesterone (medication) and progestogen (medication) articles.
Types and examples
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
of progesterone, lying downstream of progesterone in terms of biosynthesis.
Biological function
The major tissues affected by progestogens include the
uterus,
vagina,
cervix,
,
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
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 the body. Unlike
, progestogens have little or no role in feminization.
Biochemistry
Biosynthesis
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 the precursors of all other endogenous steroids, including the androgens, estrogens, glucocorticoids, mineralocorticoids, and neurosteroids. Thus, many tissues producing steroids, including the
,
testicle, and
ovary, produce progestogens.
In some tissues, the required for the final product are not all located in a single cell. For example, in , cholesterol is converted to androstenedione, an androgen, in the , which is then further converted into estrogen in the . 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.
Ovarian production
Progesterone is the major progestogen produced by the
corpus luteum of the
ovary in all mammalian species.
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.
Placental production
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.
Chemistry
The endogenous progestogens are
natural product pregnane with
ketone and/or
at the C3 and C20 positions.
Medical use
Progestogens, including both progesterone and
, 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.
Further reading
-
(the Women's Health, Osteoporosis, Progestin, Estrogen study)
External links
