Great Source of Information

[Guest guest]

The following hyperlink is to an Endocrinology page that has a very good (all

inclusive) document about male endocrinology. It is really long but broken down

into chapters of interest.

http://www.endotext.org/male/index.htm

The following is an excerpt from it:

Pathways of Testosterone Action. In men,

most (>95%) testosterone is produced under LH

stimulation through its specific receptor, a heptahelical

G-protein coupled receptor located on the surface

membrane of the steroidogenic Leydig cells. The daily

production of testosterone (5-7 mg) is disposed along

one of four major pathways. The direct pathway of

testosterone action is characteristic of skeletal muscle in

which testosterone itself binds to and activates the

androgen receptor. In such tissues there is little

metabolism of testosterone to biologically active

metabolites. The amplification pathway is characteristic

of the prostate and hair follicle in which testosterone is

converted by the type 2 5a reductase enzyme into the

more potent androgen, dihydrotestosterone. This

pathway produces local tissue-based enhancement of

androgen action in specific tissues according to where

this pathway is operative. The local amplification

mechanism was the basis for the development of

prostate-selective inhibitors of androgen action via 5a

reductase inhibition, the forerunner being finasteride.

The diversification pathway of testosterone action allows

testosterone to modulate its biological effects via

estrogenic effects that often differ from androgen

receptor mediated effects. The diversification pathway,

characteristic of bone and brain, involves the conversion

of testosterone to estradiol by the enzyme aromatase

which then interacts with the ERs a and/or b. Finally the

inactivation pathway occurs mainly in the liver with

oxidation and conjugation to biologically inactive

metabolites that are excreted by the liver into the bile

and by the kidney into the urine.

If you have a lot of time - check it out. - Arkansas

[Guest guest]

Man Dan thanks A LOT for posting this. I could read this for hours.

Wonderful information contained therein. Some might want to print some

of this info and show it to their docs!

Jody

>

> The following hyperlink is to an Endocrinology page that has a very

good (all inclusive) document about male endocrinology. It is really

long but broken down into chapters of interest.

>

> http://www.endotext.org/male/index.htm

>

> The following is an excerpt from it:

>

> Pathways of Testosterone Action. In men,

> most (>95%) testosterone is produced under LH

> stimulation through its specific receptor, a heptahelical

> G-protein coupled receptor located on the surface

> membrane of the steroidogenic Leydig cells. The daily

> production of testosterone (5-7 mg) is disposed along

> one of four major pathways. The direct pathway of

> testosterone action is characteristic of skeletal muscle in

> which testosterone itself binds to and activates the

> androgen receptor. In such tissues there is little

> metabolism of testosterone to biologically active

> metabolites. The amplification pathway is characteristic

> of the prostate and hair follicle in which testosterone is

> converted by the type 2 5a reductase enzyme into the

> more potent androgen, dihydrotestosterone. This

> pathway produces local tissue-based enhancement of

> androgen action in specific tissues according to where

> this pathway is operative. The local amplification

> mechanism was the basis for the development of

> prostate-selective inhibitors of androgen action via 5a

> reductase inhibition, the forerunner being finasteride.

> The diversification pathway of testosterone action allows

> testosterone to modulate its biological effects via

> estrogenic effects that often differ from androgen

> receptor mediated effects. The diversification pathway,

> characteristic of bone and brain, involves the conversion

> of testosterone to estradiol by the enzyme aromatase

> which then interacts with the ERs a and/or b. Finally the

> inactivation pathway occurs mainly in the liver with

> oxidation and conjugation to biologically inactive

> metabolites that are excreted by the liver into the bile

> and by the kidney into the urine.

>

> If you have a lot of time - check it out. - Arkansas

>