title: [The intervention of nicotinamide on skin melanocyte's cell proliferation after UVA (365 nm) exposed.].
abstract: OBJECTIVE
  To investigate the interference effect of nicotinamide on UVA-induced cell proliferation in human skin melanocyte.
  
  
  METHODS
  To 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.
  
  
  RESULTS
  After 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).
  
  
  CONCLUSIONS
  Nicotinamide 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.
authors.affiliation: Laboratory of Dermo-physiology and Toxicology, School of Public Health, Fudan University, Shanghai 200032, China.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Patam
authors.forename: Xi-peng
authors.initials: XP
authors.lastname: Jin
authors.forename: Jian-ying
authors.initials: JY
authors.lastname: Pan
authors.forename: Guang-zu
authors.initials: GZ
authors.lastname: Shen
authors.forename: Tai-Yi
authors.initials: TY
authors.lastname: Jin
mesh_terms: D049109:Cell Proliferation / Q000187:drug effects* / Q000528:radiation effects*; D002478:Cells, Cultured; D006801:Humans; D008544:Melanocytes / Q000166:cytology*; D009536:Niacinamide / Q000494:pharmacology*; D012867:Skin / Q000166:cytology; D014466:Ultraviolet Rays
chemical_list: D009536:Niacinamide