S4  ANDROGEN RESPONSIVE GENES AS THEY AFFECT HAIR GROWTH

Marty E. Sawaya, MD, PhD, ARATEC (Alopecia Research & Associated Technologies) Clinics & University of Miami School Medicine, Florida, USA.

Androgens have profound affects on scalp hair follicles causing growth  inhibitory activity hence,  miniaturization of hair follicles  in the case of men with Androgenetic alopecia (AGA).  In human scalp hair follicles,  androgens are thought to be growth inhibitory, whereas on beard and body hair, androgens upregulate hair growth. The biochemical activity and immunohistochemical expression of 5a-reductase isoenzymes type I and II has been assessed in scalp of men with  AGA, as well as the cytochrome P-450 aromatase enzyme, androgen receptor (AR), estrogen receptor (ER) alpha and beta. Studies in 10 men with AGA where scalp biopsies are obtained before and after 6 months treatment with finasteride (a specific type II 5a-reductase inhibitor) reveal interesting results with regard to the effects of suppressing  DHT and how it affects  these androgen associated factors. Differences in expression were found for some of the  enzymes as well as transcription proteins, AR, ER-alpha and beta.   All scalp biopsies from patients obtained 6 months after finasteride treatment revealed intense upregulation of  AR expression in comparison  to pre-treatment biopsies of the same patient, whereas ERs were not affected, indicating that AR is very sensitive to the affects of 5a-R type II suppression of DHT. Results suggest that  as the hair growth returns in these previously miniaturized follicles,  DHT suppression also alters the expression of specific Caspase genes inhibiting programmed cell death, apoptosis. Therefore, we can learn alot about the multiple effects of DHT by looking at its suppression in human scalp hair follicle to gain a  better understanding of the many androgen responsive genes involved in hair growth regulation.