648 Long-term melatonin treatment stimulates human epidermal pigmentation and melanocyte number

Melatonin, the evolutionarily ancient methoxyindoleamine, has long captured attention of investigators since discovery its regulation mammalian fur and amphibian skin pigmentation, as well extrapineal synthesis receptor expression in human skin. Yet, melatonin’s role impact on melanocyte physiology remain unclear. Therefore, we asked whether melatonin stimulates or inhibits epidermal pigmentation through effects melanin content, tyrosinase activity, number proliferation their natural cutaneous habitat with interactions surrounding keratinocytes, at 2 different time points (three six days culture) concentrations (50, 100, 200 ug/mL). Our preliminary data show that after three culture, tendentially decreases activity a dose-dependent manner proliferative melanocytes without affecting present epidermis. Interestingly, decrease situ activity. However, increases intraepidermal content correlated an increased melanocytes. ug/mL stimulated proliferation. Taken together, our showed regulatory ex vivo, are depending concentration used duration treatment. Short-term pulse therapy inexpensive hormone promises to target hyperpigmentary disorders while long-term high may help treating hypopigmentary such vitiligo by increasing intracutaneous pool restoring physiological level pigmentation.