what does proviron do ?

[trainer]

what does it do? how does it work?

[MuscleMcMannus]

It's an oral androgen.  A weak anabolic/androgenic steroid.  It's medical use is for androgen replacement therapy i.e. hypoganadism etc.  It works like any other steroid.  Stimulates the androgen receptor.  The unique property of Proviron is its ability to free up bound testosterone. 

[tbombz]

its a very weak steroid with slight anti estrogenic properties.

[Emmortal]

It's also quite helpful for attaching to SHGB.  Pretty much the only reason I run it on heavy cycles of test.

[tbombz]

It's also quite helpful for attaching to SHGB.  Pretty much the only reason I run it on heavy cycles of test.

yes, but is that even something worth doing?

Horm Metab Res. 2006 Apr;38(4):279-90.

The role of plasma-binding proteins in the cellular uptake of lipophilic vitamins and steroids.

Andreassen TK.

Department of Medical Biochemistry, University of Aarhus, Denmark.

Steroid hormones and many other lipophilic compounds are believed to enter cells solely by free diffusion through the plasma membrane. However, recent work using a megalin-deficient mouse model has identified a new endocytic pathway responsible for the delivery of steroids to renal and gonadal tissues. This review describes these new pathways for uptake of 25-hydroxy-vitamin-D3 and the gonadal sex-steroids (17beta-estradiol and testosterone) bound to vitamin D-binding protein and sex hormone-binding globulin respectively. Furthermore examples of other lipophilic molecules that enter cells by receptor-mediated pathways will be presented and the receptors responsible for their uptake described.


Mol Interv. 2005 Dec;5(6):338-40.

Few things in life are "free": cellular uptake of steroid hormones by an active transport mechanism.
Lin BC, Scanlan TS.

Departments of Pharmaceutical Chemistry and Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94143-2280, USA.


Conventional dogma holds that steroid hormones traverse cell membranes passively, owing to their lipophilic nature. The recently characterized protein megalin, however, functions as a transport protein on cell surfaces to carry steroids across the plasma membrane. Upon hydrolysis of steroid-associated binding globulins in lysosomes, free hormone is liberated and may exert its effects in the cell. Megalin-independent mechanisms of steroid uptake are likely important too, as the phenotypes of megalin-deficient mice do not completely mimic the phenotypes of androgen receptor– or estrogen receptor–null mice.

Steroid hormones participate in the regulation of normal vertebrate homeostasis, development, and reproduction. The best understood mechanism of steroid action is for these signaling molecules to enter target cells and bind to their cognate intracellular receptors that, subsequently, regulate the transcription of corresponding steroid responsive genes.


Science. STKE, 13 September 2005
Vol. 2005, Issue 301, p. tw325

Does Megalin Mediate Steroid Hormone Uptake?


Androgens and estrogens circulate through the bloodstream bound to sex hormone binding globulin (SHBG), in what has been believed to be an inactive form that prevents these small, lipophilic steroids from diffusing across the plasma membrane to activate intracellular targets (see Adams). A research group that previously showed that the low-density lipoprotein receptor-related protein megalin acts as an endocytic receptor for carrier-bound vitamins A and D has now implicated megalin in the uptake of SHBG-bound sex steroids. Hammes et al. showed that 125I-labeled SHBG was taken up and degraded by rat choriocarcinoma (BN16) cells, which express megalin, and that this was blocked by receptor-associated protein (RAP), an antagonist of ligand binding to megalin. Most circulating sex steroids are bound to carrier, and the ability of RAP to inhibit [3H]testosterone uptake depended on the ratio of SHBG and testosterone, such that inhibition was maximal when most of the testosterone was bound, whereas RAP was ineffective when most of the testosterone was free. RAP also inhibited the uptake of SHBG-bound dihydrotestosterone (DHT) and 17ß-estradiol. Uptake of fluorescein isothiocyanate (FITC)-labeled DHT together with SHBG was confirmed with confocal immunofluorescence microscopy; moreover, DHT internalized together with SHBG activated an androgen-sensitive reporter. The phenotypes of megalin knockout mice were consistent with impaired sex-steroid signaling: Megalin—/— females exhibited vaginal blockade whereas megalin—/— males exhibited impaired descent of the testes. Further, megalin-deficient embryonic tissues were resistant to the effects of exogenous androgens. Thus, the authors conclude that megalin plays a role in the cellular uptake of carrier-bound sex steroids that is critical to the proper development of steroid-responsive tissues.


Cell. 2005 Sep 9;122(5):751-62.

Role of endocytosis in cellular uptake of sex steroids.

Hammes A, Andreassen TK, Spoelgen R, Raila J, Hubner N, Schulz H, Metzger J, Schweigert FJ, Luppa PB, Nykjaer A, Willnow TE.

Max-Delbrueck-Center for Molecular Medicine, 13125 Berlin, Germany.

Androgens and estrogens are transported bound to the sex hormone binding globulin (SHBG). SHBG is believed to keep sex steroids inactive and to control the amount of free hormones that enter cells by passive diffusion. Contrary to the free hormone hypothesis, we demonstrate that megalin, an endocytic receptor in reproductive tissues, acts as a pathway for cellular uptake of biologically active androgens and estrogens bound to SHBG. In line with this function, lack of receptor expression in megalin knockout mice results in impaired descent of the testes into the scrotum in males and blockade of vagina opening in females. Both processes are critically dependent on sex-steroid signaling, and similar defects are seen in animals treated with androgen- or estrogen-receptor antagonists. Thus, our findings uncover the existence of endocytic pathways for protein bound androgens and estrogens and their crucial role in development of the reproductive organs.

free test is destroyed very quickly, while bound test stays inthe body for a very long time. lowering shgb may not be a good thing.