In vitro main pathways of steroid action in cultured hair follicle cells: vascular approach.

The known role of steroids on the hair follicle leads us to investigate their effects on hair follicle cell angiogenic responses in vitro. We verified, using the immunohistochemical technique, whether human occipital scalp follicle cells express steroid receptors in vitro. We showed that androgen and estrogen receptors were expressed by dermal papilla cells (DPC) and keratinocytes from the outer root sheath in vitro. With regard to steroidal enzymes (type I and II 5alpha-reductases and Cytochrome-p-450-aromatase), the type I 5alpha-reductase gene is much more expressed in DPC than in dermal fibroblasts; however, the type II 5a-reductase gene is transcribed more in dermal fibroblasts than in DPC. The transcription of the two 5alpha-reductase isoform genes in cultured DPC is regulated by a 5alpha-reductase inhibitor. We also demonstrated that DPC, dermal fibroblasts, and outer root shealth keratinocytes expressed cytochrome-p-450-aromatase. Using ELISA and reverse transcriptase-polymerase chain reaction, we investigated the role played by some steroids (estrogens, androgens, antiandrogens) in the modulation of vascular endothelial growth factor (VEGF) expression by DPC. The association of different treatments of DPC (5alpha-reductase inhibitor and androgen receptor antagonist) shows a great stimulation of VEGF and aromatase expression. Strong stimulation of VEGF protein and gene expression is observed in the presence of 17beta-estradiol. Also, the concentration-dependent inhibition of VEGF expression by DPC using the cytochrome-p-450-aromatase inhibitor, confirms the involvement of this estrogenic pathway in the regulation of VEGF expression in vitro.