- Reaction score
- 42
docj077 said:
I'm going to assume that you're referring exclusively to scalp hair follicles.
So are you saying that you think there is a biphasic effect of androgens on human scalp hair? That they stimulate scalp hair follicles up to a certain minimal level, but then begin to suppress them at higher levels? If so, that's a very interesting claim that I've not heard anyone else make. Neither can I think of any evidence out there that would support that idea. Can you?
docj077 said:
In fact, scalp hair seems to thrive in the total ABSENCE of androgens (I'm referring to subjects with CAIS). Until I see any scientific evidence to the contrary, I'm going to continue to assume that androgens can only have either a (nearly) neutral effect on scalp follicles, or a negative one.
docj077 said:
Docj, we talk about so many hairloss studies and articles on these Web sites, it's hard to remember what's been discussed with whom! :wink: Have you read that relatively recent short article titled "Estrogens and Human Scalp Hair Growth -- Still More Questions than Answers"? If not, here's a PDF file of the whole thing, which is only about 2 1/2 pages long:
http://www.geocities.com/bryan50001/Topical_E2.pdf
The topic of estrogens and scalp hair has been a rather hot issue for years, going all the way back to alt.baldspot. While some individuals believe that estrogens have a negative effect on scalp hair, I have always supported the view held by Dr. Proctor, which is that sex hormones (including estrogen) generally have opposite effects on body hair and scalp hair, with estrogen being beneficial overall for scalp hair. The small in vitro experiment described in the article above clearly seems to support that idea; in fact, I'm a little surprised that THEY seem surprised by their results, considering that it's definitely not the first in vitro experiment showing a hairgrowth stimulation of scalp follicles by estrogen (see Kiesewetter et al study below).
Out of all the studies I've seen over the years having to do with estrogens and human scalp hair, the preponderance of the evidence is that estrogens do appear to be beneficial for it. There was only one oddball Japanese study that I can recall seeing that got a conflicting result, so the evidence seems to be reasonably consistent, but not perfect.
docj077 said:
Hmmm...I vaguely recall your saying something about that before, but I forget the details. That's quite interesting.
docj077 said:
Agreed. Like the authors said in that article above, we need to settle the estrogen/scalp hair issue once and for all.
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J Invest Dermatol. 1993 Jul;101(1 Suppl):98S-105S.
"Sex hormones and antiandrogens influence in vitro growth of dermal papilla cells and outer root sheath keratinocytes of human hair follicles." Kiesewetter F, Arai A, Schell H.
Department of Dermatology, University of Erlangen-Nürnberg, Germany.
Anagen hair bulb papillae, interfollicular dermal fibroblasts, and interfollicular keratinocytes isolated from fronto-parietal scalp biopsies as well as outer root sheath keratinocytes from plucked anagen hairs were separately grown in subculture for 14 d. The effect of different concentrations (2.4 nM-17.3 microM) of testosterone, dihydrotestosterone, and the antiandrogens cyproterone acetate or 17 alpha-propylmesterolone on growth behavior of the mesenchymal and epithelial cell types of the hair follicle were comparatively studied by means of growth curves, cell doubling times, and 3H-thymidine incorporation. For control, all cell lines were subcultured in hormone-free medium. Testosterone and dihydrotestosterone (345 nM) significantly reduced proliferation of papilla cells compared with dermal fibroblasts (p < 0.01) and outer root sheath keratinocytes compared with interfollicular keratinocytes (p < 0.01), as well as compared with cells cultured in control medium. Low concentrations of 17 beta-estradiol were ineffective, whereas doses of 180 nM 17 beta-estradiol increased the growth velocities of all cell types, especially of papilla cells, compared with dermal fibroblasts. Low doses of either cyproterone acetate (24 nM) or 17 alpha-propylmesterolone (29 nM) induced a growth enhancement, especially of papilla cells and outer root sheath keratinocytes, whereas high doses of cyproterone (1.20 microM) and 17 alpha-propylmesterolone (1.45 microM) had opposite effects. These changes were significant between papilla cells and dermal fibroblasts as well as between outer root sheath keratinocytes and interfollicular keratinocytes. Applying increasing doses of androgens to cyproterone acetate (24 nM)- or 17 alpha-propylmesterolone (29 nM)-containing media neutralized the growth-stimulating effect of antiandrogens, particularly in papilla cells and outer root sheath keratinocytes. However, minor differences between testosterone and dihydrotestosterone effects on cell growth were found. The data clearly demonstrate that the changes of in vitro growth of hair follicle cells depend on the concentrations of androgens and antiandrogens, as higher doses of both antiandrogens tested retarded the cell proliferation similar to testosterone or dihydrotestosterone. The papilla cells and outer root sheath keratinocytes reacted more sensitively to the hormones tested, thereby confirming the concept of a distinct androgen sensitivity of these specialized hair follicle cells.
