OBJECTIVETo investigate the interference effect of nicotinamide on UVA-induced cell proliferation in human skin melanocyte.

METHODSTo apply the optimum UVA dose expected to cause cell proliferation: 0.2 cm2, nicotinamide was added after the 0.2 cm2 UVA exposure immediately or 48 h later, then the rate of cell proliferation, calcium concentration and the activities of Na+-K+, Ca2+-ATP enzymes of melanocytes were measured respectively.

RESULTSAfter treatment with 1.000 mg/ml nicotinamide following UVA exposure, the rate of cell proliferation was decreased significantly 24 hours later. Treatment with 0.125 mg/ml nicotinamide 48 hours after UVA exposure also significantly inhibited the cell proliferation; 1.25 mg/ml nicotinamide increased calcium concentration in cells; 0.250 mg/ml nicotinamide increased the activities of Na+-K+, Ca2+-ATP enzymes in melanocytes (P < 0.05).

CONCLUSIONNicotinamide has more obvious effect on inhibiting melanocyte's proliferation if added immediately following UVA exposure. Our discovery indicated that nicotinamide may affect the melanocyte through modulating the calcium concentration. It is possible to consider nicotinamide as an efficient and safe sun screen to provide a certain level of protection for UVA exposed skin.

Cell Proliferation ; drug effects ; radiation effects ; Cells, Cultured ; Humans ; Melanocytes ; cytology ; Niacinamide ; pharmacology ; Skin ; cytology ; Ultraviolet Rays

OBJECTIVETo investigate the interference effect of nicotinamide on UVA-induced melanin genesis and melanin transport in human skin melanocyte.

METHODSThe optimum UVA dose expected to cause cell proliferation: 0.2 J/cm(2), nicotinamide was added immediately after the 0.2 J/cm(2) UVA exposure and the melanin content, cell cycles, cell apoptosis and mRNA express level were measured respectively.

RESULTSMelanin content in melanocytes was increased significantly after exposed to 0.2 J/cm(2) UVA. Melanin content in melanocytes was decreased after treatment with 10.0 mmol/ml nicotinamide following UVA exposure, but the cell cycles and the cell apoptosis rate were not significantly altered. mRNA express levels of TYR, TRP-1 were modulated by nicotinamide.

CONCLUSIONNicotinamide has more effect on decreasing melanin genesis after UVA exposure, nicotinamide also plays a role in modulating the mRNA express of TYR, TRP-1 gene. It is possible to consider nicotinamide as an efficient and safe sun screen to provide a certain level of protection for UVA exposed skin.

Cells, Cultured ; Humans ; Melanins ; biosynthesis ; Melanocytes ; drug effects ; metabolism ; radiation effects ; Niacinamide ; pharmacology ; Ultraviolet Rays ; adverse effects