The feasibility of quantitative analysis of androgen metabolism by use of single dermal papillae from human hair follicles

Androgenetic alopecia (AGA) is a dihydrotestosterone-mediated process, char acterized by continuous miniaturization of androgen sensitive hair follicle s (HF). Although increased Sa-reductase (5aR) activity in affected HF is a key feature in the pathogenesis of AGA, only little is known about the in v ivo expression of 5aR within AGA-affected HE Recent studies have shown that the dermal papilla (DP) is the predominant site of type 2 5aR expression w ithin the human HF, but direct measurements of 5aR activity in intact DP of AGA-affected HF have not been reported so far, mainly because of technical problems. Hence there is a need for a reliable and sensitive method of mea suring 5aR activity in fresh tissues. As a novel approach, we used freshly isolated, intact DP and a highly sensitive HPLC-radiomatic flow scintillati on system to measure 5aR. In this way we were able to measure 5aR even in s mall DPs from miniaturized HE Our results show that DP from the occipital s calp express ex vivo considerable amounts of 5aR activity, but the measurab le enzyme activities of individual DP differ considerably. Therefore the us e of only one or two DP is at present not a reliable tool to analyze 5aR ac tivity ex vivo.