S2  ENZYMOLOGY OF THE HAIR FOLLICLE

Hoffmann R. Philipp University, Department of Dermatology, Deutschhausstrasse 9, Marburg, Germany

Androgens are well known to modulate human hair growth and previous studies have shown that human hair follicles are not only targets for androgens but also reveal an active androgen metabolism, with the ability to convert several androgens by different steroidogenic enzymes. Therefore the HF is able to modulate an androgen-driven cell response via its own  metabolic capacity, thus making it important to know what types of enzymes are expressed where within the hair follicles. We therefore analyzed the metabolic activity of different steroidogenic isoenzymes within the defined compartments of human hair follicles by the use of  microdissected intact subunits of human hair follicles (dermal papilla, connective tissue sheath and root sheath) and different androgens as substrates (+/- specific inhibitors). Our results show that within the hair follicles the dermal papilla has the highest type 2 5alpha-reductase activity whereas, most of the 17ßHSD and 3ßHSD is localized within the root sheath. Interestingly, isolated hair follicles  are also able to convert DHEAS to DHEA and further via androstenediol and testosterone to DHT, indicating that even steroid sulfatase activity is present in HF and that adrenal steroids, such as DHEAS, might provide an additional source of DHT.