| Backgroud Diabetic retinopathy (DR), as one of the most commonly seen and severe microvascular complications of diabetes mellitus, can explain 80 percent blindness among all diabetic eye complications and is the first reason of adult blindness in developed coutries. The pathogenesis of DR has not been fully explained yet, it's progression is a very complicated course refering to kinds of risk factors, including various growth factors, inheritance inclination and self immune. Recently, there has been a great deal of interest in the role of oxidant stress in DR. Oxygen free radicals or "reactive oxygen species" liberated by metabolic processes can cause tissue damage. Normally the body has an abundant supply of "antioxidants" which are naturally occurring substances that delay or inhibit oxidation and neutralize the oxygen free radicals. However, in diabetic patients, there is an imbalance, either an excess of free radicals or a deficiency of antioxidant supply, tissue damage can occur. So antioxidant therapy seems to be a necessary approach. Tea polyphenol and tea pigment, which have excellent antioxidant activity, have been widely studied for its alleged beneficial porperties in the treatment or prevention of human diseases. To date, >500 articles referencing "tea polyphenol" or "tea pigment" are listed in Medline. Tea polyphenol and tea pigment are reported to delay or prevent certain forms of cancer, arthritis, cardiovascular and others, lowing blood glucose and used for diabetic nephropathy arealso been studied. But, to our knowledge, no systematic study of its efficacy in the prevention of diabetic retinopathy in our country. Therefore, in this paper, we mean to study the efficacy of tea polyphenol and tea pigment on diabetic retinopathy of alloxan-induced diabetic mice.Objective To study the effect of tea polyphenol and tea pigment on the retinal expression of vascular endothelial growth factor(VEGF) and retinal neovascularization of diabetic mice.Methods The diabetic mice were induced by alloxan. There were four groups such as normal contrast group, diabetic model group, tea polyphenol group and tea pigment group, each group had 10 mice. Tea polyphenol and tea pigment were given as 150 mg/kg by stomach perfusion every day and after 30 days we enucleated eyeball and get the blood to examine the blood sugar. The eyeballs were made into paraffin sections so that we could do VEGF immunohistochemistry, then determined the amount of expression of VEGF by half. At the same time, the PAS stain was used to take count of the endotheliocyte nuclei of new vessels breakthroughing the retinal inner limiting membrane.Results (1)the expression of VEGF: There were nearly no expression of VEGF in retina of the normal contrast group; the expression in diabetic model group was significantly increased; however, tea polyphenol and tea pigment significantly inhibited the expression of VEGF. (2) the average number of endotheliocyte nuclei breakthroughing the retinal inner limiting membrane in four groups was (0.30±0.48), (6.80±1.93), (2.30±1.64), (1.90±1.45) in every section, and there was statistical significances among groups.Conclusions Antioxidants tea polyphenol and tea pigment can suppress the retinal expression of VEGF and neovascularization in alloxan-inducend diabetic mice.
|
PDF Full Text Request