About progesterone...
Volume 18a of Elsevier's New Comprehensive
Biochemistry, Titled 'Hormones and Their Actions, Part I', editors BA
Cooke, RJB King and HJ van der Molen. Published 1988. ISBN
0-444-80996-1. Dewey 612.405.
Chapter 14: Progesterone action and receptors, by
Nancy L Krett, Dean P Edwards and Kathryn B Horwitz, of the University
of Colorado Health Sciences Centre, Denver.
"Progesterone also acts synergistically with estrogen in the normal
development of the breast. Estrogen stimulates cell mitosis and growth
of the ductal system, while lobular development and differentiation is
dependent on progesterone. When estrogen is administered in the absence
of progesterone, the tubular system proliferates and the ducts dilate
resulting in the formation of cysts and fibroses. These changes are
comparable to those observed in fibrocystic disease and are suppressed
by progestins, so that normal breast development requires that estrogen
and progesterone be administered together.[2-4]"
"Depending on the physiological state, progesterone may antagonise
estrogen action. One effect of estradiol is to increase the levels of
progesterone receptors (PR). Binding of progesterone to its receptors
then leads not only to progestational effects, but also antiestrogenic
effects by causing a reduction in estrogen secretion into the systemic
circulation; by stimulating the enzyme 17B-hydroxysteroid dehydrogenase
which converts estradiol to the less active estrogen estrone; and by
lowering the levels of estrogen receptors in cells thereby decreasing
the ability of target tissue to respond to estradiol [4]."
Hum Reprod. 1999 Mar;14(3):606-10.
"Natural progesterone is devoid of any androgenic activity that might compromise lipoprotein metabolism or induce teratogenicity. Moreover, it probably has a direct beneficial effect on blood vessels »
Climacteric. 2013 Aug;16 Suppl 1:69-78.
"Natural progesterone and some of its derivatives, as
well as the non-ethinylated drospirenone and dienogest, do
not exert any androgenic effect and have no negative effect
on the lipids or on the endothelial cells 1,70 ."
Climacteric. 2013 Aug;16 Suppl 1:44-53.
"Natural, 'body-identical' progesterone, devoid of any androgenic as well as glucocorticoid activities but being slightly hypotensive due to its antimineralocorticoid activity, appears to be the optimal progestogen in terms of cardiovascular effects, blood pressure, VTE, probably stroke and even breast cancer »
Clin Endocrinol (Oxf). 2003 Apr;58(4):506-12.
"In this study the effects of progesterone, with no significant androgen-receptor affinity are compared to desogestrel, a synthetic gestogen with relatively low affinity for the androgen receptor, on gonadotrophin secretion in normal men."
"Both progesterone and desogestrel administration resulted in decreases in the concentration of both LH and FSH secretion, as well as testosterone. Analysis of the pulsatile nature of LH secretion indicated that both treatments reduced LH pulse amplitude, and that progesterone reduced LH pulse frequency. Progesterone, but not desogestrel, treatment also reduced the increase in LH secretion in response to GnRH."
Fertil Steril. 2002 Jun;77(6):1125-7.
"To determine whether the use of oral micronized progesterone (OMP) to induce withdrawal bleeding in women suspected of having polycystic ovary syndrome (PCOS) alters circulating androgen levels. »
"The mean values of TT, FT, SHBG, DHEAS, A4, and 17-OHP did not change with OMP administration."
"We conclude that the administration of OMP (...) to induce withdrawal bleeding in women with PCOS does not significantly alter circulating androgen or 17-OHP levels, and can be used to time blood sampling in these patients."
The dose used was relatively high.
Steroids. 2011 Jun;76(7):636-52.
"Prog has been reported to lack androgenic or estrogenic activity [11], [52] and [53], while possessing anti-estrogenic and anti-mineralocorticoid properties, as well as weak glucocorticoid-like properties [54],[55] and [56]. However, some of the biological activities reported in the literature are not consistent (Table 2). For example, some report that Prog has weak androgenic properties, and no glucocorticoid activity."
Contraception 62 (2000) 29–38
"The results showed that(1) drospirenone and progesterone inhibit aldosterone-induced mineralocorticoid activity and weakly induce reporter gene transcription on their own; (2) both progestogens have no androgenic activity but display antiandrogenic activity in terms of inhibition of androgen-receptor–mediated transcription in a dose-dependent manner [10]. »
BUT, in Table 2, progesterone is shown to have negligible anti-androgenic effect at therapeutic doses.
"this direct antiantiandrogenic effect is in addition to the more indirect antiandrogenic effect of progestogens in general, that is mainly explained by the suppression of androgen production from the adrenals or ovaries."
