P#54  Melanocytes in human scalp epidermis and hair follicles express the androgen receptor (AR) and both estrogen receptors (ERa) & (ERb)

Desmond J. Tobin1, Anthony H. Taylor3, Andrew G. Messenger2 and M. Julie Thornton1. 1Dept of Biomedical Sciences, University of Bradford, Bradford, West Yorkshire, 2Dept of Dermatology, Royal Hallamshire Hospital, Sheffield; 3Dept of Obstetrics & Gynaecology, Leicester Royal Infirmary, England

Androgens and estrogens have significant and distinct roles in hair and skin physiology. Both can regulate the hair cycle and may have a direct role in the regulation of skin and hair pigmentation. The recent identification of a second estrogen receptor (ERb), distinct from the classical estrogen receptor (ERa), indicates the potential for enhanced diversity in the mechanism of estrogen action. The presence of androgen receptor (AR), or either ERa or ERb in human melanocytes has not yet been shown. Here, we examine AR, ERa and ERb expression in NKI/beteb (gp 100)-positive epidermal (EM) and hair bulb melanocytes (HFM) in normal male occipital scalp by double immunofluorescence and in cultured HFM. Strong cytoplasmic and weak nuclear expression of AR was detected in pigmented and dendritic EM. Strong, though heterogeneous, AR expression was also detected in pigmented hair bulb melanocytes, and in amelanotic melanocytes of the outer root sheath and basal layer of the sebaceous gland. Expression of ERb in EM was mainly cytoplasmic and correlated positively with melanocyte differentiation. Similar heterogeneous ERa expression patterns were also observed in the hair follicle, although expression was much higher in pigmented bulbar melanocyte than in amelanotic melanocytes located in the outer root sheath and infundibulum. ERa expression in EM was heterogeneous with punctate staining present throughout cell dendrites. ERa was also detected in outer root sheath and hair bulb melanocytes, follicular papilla and proximal connective tissue sheath in situ and in hair follicle melanocytes in vitro. This study demonstrates for the first time the presence of androgen and estrogen receptors in human EM and HFM, suggesting a direct role for estrogens and androgens in the regulation of epidermal and hair follicle pigmentation. Since it is now emerging that the interaction of androgens and estrogens and their receptors is of the utmost importance in other steroid-dependent tissues, the co-localization of ERa, ERb and AR in human melanocytes is significant. To understand the effects of reproductive hormones on skin ageing and skin cancer, we need to understand how steroid hormones and their receptors interact in human skin.