Rage said:
Also, it should be noted that the reduced percentages of DHT is measured from the blood. We still don't know if it is the DHT produced within the follicle, or in the blood, which causes the miniaturization. It's likely to be both.
There are a few separate lines of evidence which, taken together, strongly suggest that it's
follicular DHT which is the much more important factor, and that DHT itself doesn't have much of a role as an endocrine hormone in the body:
1) I read in a medical journal article (I wished I had saved it, so I could cite it) that
most molecules of DHT formed within cells go on to bind to androgen receptors within that same cell. If that's true, then the implications are obvious.
2) Serum DHT is eliminated fairly rapidly, so it obviously can't hang around long enough to have much of an endocrine effect.
3) The animal experiments (and at least one small human experiment) with topical 5a-reductase inhibitors (for example, the hamster study with the topical fatty acids) show an effect only where they're actually applied, strongly implying once again that
serum DHT isn't doing anything to keep those hamster flank organs going. Reducing only the
local DHT was sufficient to sharply inhibit their growth. So if that's the case with sebaceous glands which are exquisitely sensitive to androgenic stimulation, is it really so difficult to believe that it's also the case with hair follicles?
4) Conversely, sharply reducing serum DHT with finasteride had no effect on sebum production in humans in Imperato-McGinley's study which I posted about recently, again showing that serum DHT doesn't seem to have any detectable effect on sebaceous glands. Why would one expect it to have much effect on hair follicles?
5) Dr. Proctor has said numerous times on alt.baldspot that endocrinologists have traditionally been taught that DHT only has an effect where it's actually produced (which is to say, it again doesn't have much of a role as an endocrine hormone).
Bryan