Expression of mRNA for androgen receptor, 5alpha-reductase and 17beta-hydroxysteroid dehydrogenase in human dermal papilla cells

In order to determine whether adrenal and gonadal weak androgens are utilized to form active androgens in human hair, we studied the expression of mRNA for androgen receptor (AR), 5alpha-reductase and 17beta-hydroxysteroid dehydrogenase (17beta-HSD) in cultured dermal papilla cells (DPCs) from various body sites. AR mRNA was expressed in beard (Be) and axillary hair (Ax) DPCs from both sexes, but only at a low level in DPCs from occipital scalp hair (OS). Type I 5alpha-reductase mRNA was expressed by all DPCs. Type II 5alpha-reductase mRNA was identified in beard DPCs, but was absent from OS and Ax DPCs. Type II 17beta-HSD mRNA was strongly expressed in outer root sheath cells (ORSCs), while DPCs except for male Ax expressed no type II 17beta-HSD mRNA. In contrast, type III 17beta-HSD mRNA was strongly expressed in Be DPCs and Ax DPCs from both sexes; ORSCs showed a low level of expression. Expression of type III 17beta-HSD mRNA was not regulated by androgen in DPCs. These results suggest that the sensitivity of hairs to androgen is partially controlled by the site-specific expression of AR, 5alpha-reductase and 17beta-HSD in DPCs.