Poster presentation, P119

Official XXIst International Pigment Cell Conference website - 21-24 Sept 2011, Bordeaux - France | updated: September 04 2011

Influence of estrogens on melanosome distribution in keratinocytes: An ultrastructural study on irradiated skin organ culture

SPEAKER M. Cario-André #whois submiter ?
AUTHOR(s) M. Cario-André, Y. Gauthier, S. Lepreux, C. Pain, A. Taïeb

BACKGROUND: Melasma occurs mainly in women during pregnancy, taking oral contaceptives or hormone replacement therapy. By histological examinations, epidermal melanin deposition is found in all skin layers including horny layer, sometimes associated with dermal melanin deposition. Konrad and Wolff (1973) have previously observed in melasma skin samples by electronic microscopy a non-aggregated distribution of melanosomes in keratinocytes. The mechanisms of action of estrogen and progesterone in human cutaneous pigmentation are largely unknown. Despite the presence of estrogen and progesterone receptors in human skin, physiological and pregnant levels of estrogen and progesterone do not induce in vitro significant effects on proliferation of human melanocytes and on tyrosinase activity. We have previously treated pigmented epidermal reconstructs with estrogen without detecting any change in pigmentation and melanosome distribution. OBJECTIVE: To study with electron microscopy the effects of estrogens on melanosome distribution in irradiated skin organ culture METHODS: We have treated phototype III skin samples with 2, 10 and 100 nM of 17 b-estradiol for 3 days before a single irradiation (UVB 50 mJ.cm-²). Skin samples were fixed for optical and electronic analysis 3 days after irradiation to allow stimulation of melanogenesis. RESULTS: By Fontana-Masson staining, we could not detect visible change in pigmentation in our irradiated, treated samples as compared to irradiated control. However, our preliminary data suggested that the addition of 10mM 17 b-estradiol in culture medium prior to UVB irradiation induced a modification of melanosome distribution with non aggregated melanosomes within keratinocytes. CONCLUSION: We have reproduced with our experimental model of irradiated skin organ culture pre-treated with estrogen the same non aggregated distribution of melanosomes reported in melasma skin samples. The combination UV and estrogen may be implicated in the modifications of melanosome distribution observed in melasma explaining why melasma is observed in photoexposed skin.



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Université de Bordeaux 2 & Conseil Régional Aquitaine