Effects of UV-A LED light irradiation on growth of cultured RAW 264.7 cells |
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Authors: | Toshitaka Ikehara Mutsumi Nakahashi Su Zehong Masatake Akutagawa Koichiro Tsuchiya Mitsuo Kitamura |
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Institution: | 1. Department of Human Welfare, Faculty of Health and Welfare, Tokushima Bunri University, Tokushima, Japan;2. Division of Life Style Disease, Institute for Health Sciences, Tokushima Bunri University, Tokushima, Japanikehara@tks.bunri-u.ac.jp;4. Department of Preventive Environment and Nutrition, Institute of Health BioSciences, The University of Tokushima Graduate School, Tokushima, Japan;5. Department of Life System, Institute of Technology and Sciences, The University of Tokushima Graduate School, Tokushima, Japan;6. Department of Medical Pharmacology, Institute of Health BioSciences, The University of Tokushima Graduate School, Tokushima, Japan;7. Department of Physiology, Institute of Health BioSciences, The University of Tokushima Graduate School, Tokushima, Japan |
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Abstract: | The aim of this study was to examine the effects of ultraviolet A (UV-A) irradiation-induced damage on cultured macrophage RAW 264.7 cells and determine which components produced these manifestations. RAW 264.7 cells were irradiated with 365 nm UV-A using a light-emitting diode (LED). Cell viability and damage were determined using a calcein-AM and propidium iodide dual-staining assay and lactate dehydrogenase leakage, respectively. Intracellular reactive oxygen species (ROS) were measured by H2DCF-DA. The components of ROS in each medium were measured using an electron paramagnetic resonance (EPR) spectrometer in the presence of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and 2,2,5,5-tetramethyl-3-pyrroline-3-carboxamide (TPC). While UV-A irradiation for 2 min significantly suppressed cell growth, LDH leakage did not occur. Addition of N-acetyl cysteine restored inhibition of cell proliferation, and reduced intracellular ROS levels. The EPR signal in the presence of TPC increased with time but was decreased by sodium azide. In addition, a typical EPR spectrum was obtained in the presence of DMPO, indicating the presence of a hydroxyradical. The spectrum was diminished by L-histidine. Data suggest that ROS generated in cells or culture medium by UV-A irradiation is predominantly singlet oxygen, and this singlet oxygen suppressed cell proliferation. |
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Keywords: | 365 nm LED light reactive oxygen species Raw 264 7 cells scavenger |
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