Bryan said:
Can you post those studies? I'd be very curious to know how/why IGF-1 would increase 5AR function...
Bryan
IGF-1 regulating 5-Alpha-Reductase activity:
http://endo.endojournals.org/cgi/conten ... 447?ck=nck
http://www.ihop-net.org/UniPub/iHOP/pm/ ... id=8344190
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'In summary, regulation of human hair growth by androgen is probably mediated by IGF-1 in the dermal papilla. In male scalp, high levels of IGF-1 may increase the androgen receptor activity and dihydrotestosterone levels and these result in an increased propensity for baldness.'
http://dermatology.cdlib.org/DOJvol5num ... ws/su.html
'Human hair follicles are targets of sex steroids. In particular, androgens induce regression of terminal (large) hair during the development of male-pattern baldness and transform vellus (small) hair to terminal hair in genital skin during puberty.[55] These effects may be associated with high levels of circulating IGF-1 [56] which directly stimulates the activity of the androgen receptor.[57] It is also possible that IGF-1 stimulates the activity of 5-reductase in the skin which increases the local production of dihydrotestosterone converted from testosterone.'[58]
57. Culig Z, Hobisch A, Cronauer MV, radmayr C, Trapman J, Hittmair A, Bartsch G, Klocker H: Androgen receptor activation in prostatic tumor cell lines by insulin-like growth factor-I, keratinocyte growth factor, and epidermal growth factor. Cancer Res 1994;54:5474-8.
58. Horton R, Pasupuletti V, Antonipillai I: Androgen induction of steroid 5 alpha-reductase may be mediated via insulin-like growth factor-I. Endocrinol 1993;133:447-51.
'Aberrant activation of the Androgen Receptors has been demonstrated in vitro with IGF-1, keratinocyte growth factor, and epidermal growth factor. These agents can directly activate the Androgen Receptors in the absence of androgens and may contribute to the progression of prostate cancer and AA (43 , 44) .
http://cebp.aacrjournals.org/cgi/conten ... /6/549#B13
Gabe Mirkin M.D. points out the connection:
http://www.drmirkin.com/men/M119.htm
This is from a cancer doctor Neil D. Barnard M.D.:
By the way, the enzyme (5-alphareductase) that turns testosterone into DHT is also found in the scalp,9 where it works mischief of a different sort. DHT plays a critical role in baldness. Without it, men will not lose their hair, no matter what their genetics may dictate. DHT activity in the scalp may be subject to dietary manipulation.
http://www.cancerproject.org/survival/c ... health.php
***IGF-1 can lead to aberrant activation of the Androgen Receptor***
Blok G. J., de Boer H., Gooren L. J., van der Veen E. A. Growth hormone substitution in adult growth hormone-deficient men augments androgen effects on the skin. Clin. Endocrinol., 47: 29-36, 1997
CONCLUSIONS
Overdosage of IGF-I can lead to androgenization, a previously undescribed undesirable effect of IGF-I. Long-term IGF-I treatment necessitates progressive adjustment of the IGF-I dose to avoid overtreatment.
http://www.blackwell-synergy.com/links/ ... 98.00356.x
Here are some excerpts from some other medical Articles cited online:
'Our findings suggest that high levels of IGF-1 may be associated with
increased risk of vertex baldness. Substantial clinical evidence
appears to support this finding.'
'It has also been recently reported that GH treatment of GH-deficient
men increases hair scores in androgen-dependent areas. These effects
can be explained either by IGF-1 directly stimulating the androgen
receptor, or by IGF-1 increasing local 5alpha-reductase activity and
thus stimulating the local conversion of testosterone to
dihydrotestosterone.'
Signorello LB et al. Hormones and hair patterning in men: A role for insulin-like growth factor-1. Journal of the American Academy of Dermatology February, 1999;40:200-203.