The effect of ultraviolet radiation and pretreatment of dehydroepiandrosterone on RMK cells in culture.

Recent reports suggest that ultraviolet radiation (UV) can easily target the genome as well as damage the cell membrane and contribute to cell death. Dehydroepiandrosterone (DHEA) is believed to be a powerful endogenous antioxidant, and is important in protection against aging as well as an immune stimulant. The purpose of this investigation is twofold. First, to determine the duration of UV exposure that causes cellular damage and second to determine if pretreatment of cells with various doses of DHEA can protect the cells from the damaging effects of UV radiation. Rhesus monkey kidney (RMK) cells were obtained in glass tubes at a density of 2 x 10(5) cells/tube. The tubes were divided into five equal groups for the first specific aim. The tubes in group I were untreated, cells in group II-V were treated with UV light at a distance of 10" or 22" for 30 or 60 minutes. At the end of each UV incubation period, the cells were place in a 37 degrees C 5% CO2 incubator for 72 hours. Cellular damage (MDA), as well as, cell counts and cell morphology was evaluated. The results for phase I revealed a marked increase in the MDA levels with a reduction in cell number after both 30 and 60 minute of UV exposure. From this information a second experimental design was established. RMK cells were divided into eight groups of 6 tubes/group. The cells in-groups 1-4 were not exposed to UV radiation and was treated with 0 ng, 2.5 ng, 25 ng and 250 ng of DHEA, respectfully. The cells in-groups 5-8 were exposed to UV radiation at 22" for 30 minutes after pretreatment with 0 ng, 2.5 ng, 25 ng and 250 ng of DHEA, respectively. The results obtained indicate that the tubes with low and medium DHEA levels without UV exposure caused a significant decrease in MDA levels whereas after UV treatment the MDA levels increased indicating that DHEA was efficient in protecting the cells from damage. Morphological evaluation of the cells treated with UV radiation showed an increase in degeneration of chromatin and a decrease in cell size as compared to non-treated groups.