Biological Effects Of Nicotinamide On Human Skin Melanocytes And The Intervention After UVA Radiation

A major gap in the understanding of the pigmentary process is the determinants and the mechanisms involved in the transfer of melanin in melanocytes and to the surrounding keratinocytes. UVR and chemicals are two major regulating factors which affecting the melanin genesis or melanin transport. A lot of researches indicated that continuously UVR radiation may cause diverse skin problems and the effect of UVB on skin were well understood, but the effects of UVA on skin photo-aging were poorly understood. It is significant to prevent the damages caused by UVA radiation on human skin through exploring effective chemicals or other effective methods.There are few reports about the skin lightening effects of nicotinamide. Therefore, the possible mechanism of its skin lightening is still poorly understood. So far, no reports have conducted the systemic research about the biological effects and light intervention of nicotinamide on the skin melanocytes after UVA radiation.To explore the potential mechanism of the biological effect of nicotinamide and the intervention of nicotinamide on the skin melanocytes after UVA radiation, the primary cultured human skin melanocytes from foreskin were selected as target cells in this study. The methods were used included MTT test, RT-PCR, western blot, fluorescent probes (Flu-3AM), flow cytometry analysis, and time-lampse microscope digital skill.The results showed that the treated with 0.25mg/ml~ 1.25mg/ml concentration of nicotinamide for 120h has a potential effect on decreasing melanocyte cell proliferation in a dose-dependent manner, melanin content, the activities of tyrosinase and PI (proliferation index). In addition, the DNA index of the melanocytes were also decreased with the increasing of nicotinamide concentration; and the bound of MITF mRNA expression was up-regulated when 0.05 mg/ml nicotinamide was given while the Rab27a mRNA expression was down-regulated with the increasing of nicotinamide concentration. Our results also revealed that the nicotinamide has no effect on the mRNA expression of TYR and TRP-1. On the other hand, the treatment with movement velocity in melanocytes was accelerated and the distribution...