An EPR method for estimating activity of antioxidants in mouse skin using an anthralin-derived radical model

Effects of low-dose X-ray irradiation on melanin-derived radicals in mouse hair and skin

To clarify a possible index for long-term and low-dose irradiation, the effects of repeated low-dose X-ray irradiation on the amount of melanin-derived radicals in mouse hair and tail skin were investigated. Eight-week-old female C3H/HeSlc mice were irradiated by X-rays at a dose of 100 mGy/day 5 days/week for 12 weeks. Similarly, a 4-week irradiation experiment was carried out at 500 mGy/day for C3H/HeSlc mice, or at 10, 100, and 500 mGy/day for 8-week-old female C57BL/6NCrSlc mice. The hair sample (~10 mg) was weighed accurately and stuffed into a plastic tube. The 2-cm tip of the tail was sampled and lyophilized. Melanin-derived radicals in hair and tail samples were measured by X-band electron paramagnetic resonance spectrometry. After X-ray irradiation at 100 mGy/day for 12 weeks, no difference was found in the amount of melanin-derived radicals in the hair of the irradiated and non-irradiated groups. X-ray irradiation at 500 mGy/day for 4 weeks increased the amount of melanin-derived radicals in hair compared with the non-irradiated group, but the baseline amount of melanin-derived radicals in hair was varied. The amount of melanin-derived radicals in the tail skin dose-dependently increased. Melanin-derived radicals in skin may be an endogenous marker for long-term and low-dose irradiation.

Edaravone is a free radical scavenger that protects against laser-induced choroidal neovascularization in mice and common marmosets

Choroidal neovascularization (CNV) is a main characteristic in exudative type of age-related macular degeneration (AMD). Our study aimed to evaluate the effects of edaravone, a free radical scavenger on laser-induced CNV. CNV was induced by laser photocoagulation to the subretinal choroidal area of mice and common marmosets. Edaravone was administered either intraperitoneally twice a day for 2 weeks or intravenously just once after laser photocoagulation. The effects of edaravone on laser-induced CNV were evaluated by fundus fluorescein angiography, CNV area measurements, and the expression of 4-hydroxy-2-nonenal (4-HNE) modified proteins, a marker of oxidative stress. Furthermore, the effects of edaravone on the production of H2O2-induced reactive oxygen species (ROS) and vascular endothelial growth factor (VEGF)-induced cell proliferation were evaluated using human retinal pigment epithelium cells (ARPE-19) and human retinal microvascular endothelial cells, respectively. CNV areas in the edaravone-treated group were significantly smaller in mice and common marmosets. The expression of 4-HNE modified proteins was upregulated 3 h after laser photocoagulation, and intravenously administered edaravone decreased it. In in vitro studies, edaravone inhibited H2O2-induced ROS production and VEGF-induced cell proliferation. These findings suggest that edaravone may protect against laser-induced CNV by inhibiting oxidative stress and endothelial cell proliferation.