The effects of a single exposure of UVB on morphologic changes and proliforation in cultured normal melanocytes

Lee, Sung Han; Hwang, Jung Yuel; Lee, Mu Hyoung; Park, Jai Kyung; Haw, Choong Rim

Abstract

In humans, the major stimulus for cutaneous pigmentation is ultraviolet radiation. Little is known about the mechanism underlying this response, in part, because of the complexity of the interactions involving the whole epidermis. The present stucy was undertake to evaluate the effects of a single exposure of UVB on cultured normal melanocytes. Melanocytes were exposed to UVB from 5.1 mJ/cm to 203 mJ/cm. The results were as follows : 1. The main morphologic changes in UVB-exposed groups w re larger sized cells, more blunted dendrites, and shorter dendrites than in the control group. These cells increased sized according to the increased doses of VVB, but above 101.5 mJ/cm, the melanocytes shrunk and were destroyed. 2. From 20.3 mJ/cm of UVB, the proliferation of melanocyte was decreased, Especially, there was statistical!y significant difference above 50.8 mJ/cm (p<0.05, p<0.01). 3. The antiproliferativo effect increased with the passage of tirie after UVB exposure. So, cell count could not be done in 101.5 mJ/cm and 203 mJ/cm on the third day, and in 50.8 mJ/cm, 101.5 m J/cm and 203 mJ/cm on the seventh day. 4. Statistically the melanin content per well was significantl dicreased to 11-28% of each control group with dose above 50.8 mJ/cm (p<0.05, p<0.01). The melanin content per cell was increased to 107-128% of each control group when doses were below 20.3 mJ/cm and decreased to 49-79% of each control group when above 0.8 mJ/cm on the third day, but there was no statistically significant difference. In summary, when melarocytes were exposed to UVB, morphclogic changes progressed to cell differentiation. The results also suggested that a low or dose of UVB has an antiproliferative arid mild melanogenic effect, and a higher dose of UVB has a direct cytotoxic effect.