同型半胱氨酸与糖尿病视网膜病变的相关性

同型半胱氨酸（Hcy）是一种与半胱氨酸同系的四碳含硫氨基酸，在细胞内由蛋氨酸代谢脱去甲基后形成，是蛋氨酸代谢的中间产物。近年来，越来越多的研究表明同型半胱氨酸是一种反应性血管损伤氨基酸，具有细胞毒性，与微血管疾病如糖尿病视网膜病变（DR）存在着密切的关系。Hcy可通过氧化应激系统影响血管内皮的功能，促进低密度脂蛋白过氧化，造成细胞结构和功能的破坏，通过诱导多种趋化因子、黏附分子等在体内的表达，而导致微血管疾病的发生。就Hcy与DR发病的相关性及其发病机制的研究现状进行综述。

Homocysteine and diabetic retinopathy

Homoeysteine, an intermediary metabolite of methionine, is a thiol containing amino acid formed by demethylation of methionine. Recently, epidemiological, experimental and clinical studies showed that homocysteine is an important risk factor for vascular diseases, and has a very closely relationship with microvascular diseases such as diabetic retinopathy. The stimulation of endothelial nitric oxide production and oxidized low density lipoprotein by homocysteine accelerates endothelial cell senescence and endothelial dysfunction. Homocysteine enhances leukocytes extravasation and platelet adhesion to endothelial cells. The other impact on endothelial cell includes the induction of the expression and secretion of chemokines and adhesion molecules, alters monocyte-endothelial interaction and further results in occurrence of microvascular diseases. The progresses in the association of homocysteine with diabetic retinopathy and the pathogenesis of diabetic retinopathy are summarized.