DIABETES/METABOLISM RESEARCH AND REVIEWS RESEARCH ARTICLE Diabetes Metab Res Rev 2006; 22: 38–45. Published online 12 May 2005 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/dmrr.562 Antioxidants and an inhibitor of advanced glycation ameliorate death of retinal microvascular cells in diabetic retinopathy Shigeru Yatoh 1 * Masakazu Mizutani 1,3 Tomotaka Yokoo 1 Tadahiko Kozawa 3 Hirohito Sone 1 Hideo Toyoshima 1 Seiji Suzuki 1 Hitoshi Shimano 1 Yasushi Kawakami 1,2 Yukichi Okuda 1 Nobuhiro Yamada 1 1 Division of Endocrinology and Metabolism, Department of Internal Medicine, Institute of Clinical Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan 2 Department of Clinical Pathology, Institute of Clinical Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan 3 Kozawa Eye Hospital, Mito, Ibaraki, Japan *Correspondence to: Shigeru Yatoh, Division of Endocrinology and Metabolism, Department of Internal Medicine, Institute of Clinical Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan. E-mail: s-yatoh@yf6.so-net.ne.jp Received: 1 February 2004 Accepted: 29 March 2005 Abstract Background Pericyte ghosts and acellular capillaries are well known as early histological changes resulting from diabetic retinopathy. These histological changes mean that the cell death of retinal microvessels has accelerated. It was reported that apoptosis of retinal microvascular cells (RMCs) was increased in diabetic patients. Therefore, we investigated apoptosis of RMCs in Goto-Kakizaki (GK) rats, a type 2 diabetic model, and involvement with antioxidants (a combination of vitamins C and E) or a novel inhibitor of advanced glycation, OPB-9195. Methods GK rats were treated with the antioxidants combination or OPB- 9195 for 36 weeks. We obtained isolated preparations of the vascular network from their retinas by trypsin digestion. Apoptosis of retinal vascular cells was detected with terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. Results We found that apoptosis of RMCs was increased in the diabetic GK rats. Furthermore, a combination of vitamins C and E and an advanced glycation end-products inhibitor mostly inhibited this increased apoptosis. Conclusions We concluded that apoptosis of RMCs was a good marker that indicates the progression of diabetic retinopathy in GK rats. Both oxidative stress and the accumulation of advanced glycation end-products appears to promote the apoptosis of retinal microvascular cells, and antioxidants or advanced glycation end-products inhibitors might ameliorate diabetic retinopathy. Copyright  2005 John Wiley & Sons, Ltd. Keywords apoptosis; diabetic retinopathy; antioxidant; advanced glycation end- product Diabetic retinopathy remains one of the main causes of vision loss and blindness in many countries. There have been recent advancements in treatments for preproliferative or proliferative diabetic retinopathy, laser photocoagulation and intra-ocular surgery, such as vitrectomy; however, the prognosis of difficult cases with maculopathy, rubeotic glaucoma, retinal detachment, and so on, is still poor. Therefore, it is important to prevent the progression of retinopathy at an early stage, that is, when it is back- ground retinopathy. In background retinopathy, before dot hemorrhages and microaneurysms are seen with funduscopy, microscopic changes, such as thickening of basement membranes or pericyte ghosts, have already occurred in microvascular walls. Pericyte ghosts, which are the pockets in basement Copyright  2005 John Wiley & Sons, Ltd.