Long-Term Ultraviolet A Eye Irradiation Causes Retina Denaturation in Mice

Background: Long-term ultraviolet (UV) A eye irradiation in mice initiates the induction of photoaging. However, the changes in the eye due to long-term exposure to UVA radiation are still unclear. Methods: Male C57BL/6j (control) and inducible nitric oxide synthase knockout (iNOS –/– ) mice were used in this study. The eyes of the mice were locally exposed to UVA radiation for 12 months. Results: The expression of iNOS, matrix metalloproteinase-2 (MMP-2), MMP-9, vascular endothelial growth factor, β-amyloid, and macrophages in the retina all increased after UVA irradiation. Furthermore, in the iNOS –/– mice, no retinal changes were induced by UVA eye irradiation. Conclusions: These results indicated that long-term UVA eye irradiation led to iNOS-induced denaturation of the retina; however, further studies are needed to confirm these findings. © 2017 The Author(s) Published by S. Karger AG, Basel Received: July 8, 2016 Accepted: November 15, 2016 Published online: February 1, 2017 Keiichi Hiramoto, PhD Department of Pharmaceutical Sciences Suzuka University of Medical Science 3500-3 Minamitamagakicho, Suzuka, Mie 513-8670 (Japan) E-Mail hiramoto @ suzuka-u.ac.jp www.karger.com/bmh This article is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND) (http://www.karger.com/Services/OpenAccessLicense). Usage and distribution for commercial purposes as well as any distribution of modified material requires written permission. What Is It about? Mice that received ultraviolet (UV) A eye irradiation for 12 months suffered marked retina denaturation. The expression of inducible nitric oxide synthase (iNOS), matrix metalloproteinase-2 (MMP-2), MMP-9, and vascular endothelial growth factor in UVA eye irradiation mice was significantly higher than in control mice. Furthermore, following UVA eye irradiation, the expression of β-amyloid and macrophages was increased. In addition, the increase in these parameters observed due to denaturation was not seen in iNOS knockout mice. These results indicate that long-term UVA eye irradiation induces retina denaturation and that this phenomenon is similar to age-related macular degeneration. D ow nl oa de d by : 54 .7 0. 40 .1 1 10 /3 /2 01 7 4: 55 :0 9 P M 2 Biomed Hub 2017;2:453542 ( DOI: 10.1159/000453542 ) Hiramoto et al.: Long-Term Ultraviolet A Eye Irradiation Causes Retina Denaturation in Mice www.karger.com/bmh © 2017 The Author(s). Published by S. Karger AG, Basel