The role of oestrogens on the regulation of human hair growth is poorly understood. Using whole human scalp hair follicle organ culture, we have recently demonstrated, that human hair growth is inhibited by 17beta-oestradiol, but not by the biologically inactive isomer 17alpha-oestradiol. Using immunohistochemistry, we have also demonstrated the presence of both ERalpha and ERbeta in the pilosebaceous unit and the dermal papilla, a mesenchymal structure that controls the differentiation and growth of the epithelial cells that form the hair follicle and hair fibre. Since steroid hormones regulate ERalpha and ERbeta expression in other tissues, we tested the hypothesis that oestrogens, androgens or glucocorticoids would similarly modulate oestrogen receptor expression in cultured dermal papilla cells.
Primary cultures of scalp dermal papilla cells (n=5) were established from microdissected hair follicles and grown to sub-confluence in vitro and then treated with testosterone (10nM), 17beta-oestradiol (10nM) or dexamethasone (100nM) in phenol red-free, serum-free medium. After 24h, total RNA was prepared and the relative amounts of ERalpha and ERbeta mRNA assessed using semi-quantitative RT-PCR.
The results showed that the amount of ERalpha mRNA to ERbeta mRNA in untreated dermal papilla cells was ~ 2-fold. Incubation with either testosterone or 17beta-oestradiol did not change ERalpha mRNA expression (p.0.05; Mann Whitney U-test), but treatment with dexamethasone reduced ERalpha levels to 38% of the untreated control (p=0.0079; Mann Whitney U-test). By contrast, ERbeta mRNA expression was unaffected by any steroid treatment.
These data show for the first time that glucocorticoid modulates oestrogen receptor expression in the human hair follicle, and provide further evidence for the independent regulation of oestrogen receptor isoform expression in the human.