Gugliucci A, Menini T
Division of Basic Sciences, Touro University College of Osteopathic Medicine, San Francisco, California 94115, USA.
Life Sci. 1998;62(23):2141-50. doi: 10.1016/s0024-3205(98)00189-1.
As the glycation/glycoxidation hypothesis for the genesis of diabetic complications is achieving widespread acceptance, much attention is being paid to the role of low molecular weight advanced glycation (AGE) adducts, as second generation glycating agents. We set out a study with the objective of attesting the presence of increased amounts of AGE-peptides in the circulation of streptozotocin-induced diabetic rats and to determine the nature of the plasma proteins which are main targets for advanced glycation. AGE (Ex 370/Em 440 nm) and pentosidine fluorescence (Ex 335/Em 385 nm) were significantly higher in plasma from diabetic rats after only one month of hyperglycemia as compared to controls (35 +/- 7 vs 25 +/- 2 AU, p< 0.05 and 54 +/- 14 vs 27 +/- 3 AU, p< 0.01 respectively). AGE-peptides (<10 kDa) were more than two-fold higher in diabetic animals. Immunoblots after SDS-PAGE of plasma proteins showed that AGE-IgG displayed a selective predominant increment in the same animals. When native rat IgG was incubated in the presence of AGE-peptides isolated from diabetic animals, AGE modification was already apparent after only 24 h of incubation, and was particularly important for light chains. AGE-immunoreactive light chains displayed an apparent increase in molecular weight. Aminoguanidine prevented, while copper enhanced AGE binding to IgG light chains. Our data validate the streptozotocin-induced diabetic rat as a model reproducing the presence of circulating AGE-peptides, give evidence that IgG are preferential targets for advanced glycation in plasma and suggest that this modification, mediated by AGE-peptides, can be prevented by aminoguanidine.
随着糖尿病并发症发生的糖基化/糖氧化假说得到广泛认可，低分子量晚期糖基化（AGE）加合物作为第二代糖化剂的作用受到了广泛关注。我们开展了一项研究，目的是证实链脲佐菌素诱导的糖尿病大鼠循环中AGE肽含量增加，并确定晚期糖基化的主要靶血浆蛋白的性质。与对照组相比，高血糖仅1个月的糖尿病大鼠血浆中的AGE（激发波长370nm/发射波长440nm）和戊糖苷荧光（激发波长335nm/发射波长385nm）显著更高（分别为35±7与25±2 AU，p<0.05；54±14与27±3 AU，p<0.01）。糖尿病动物中AGE肽（<10 kDa）高出两倍多。血浆蛋白SDS-PAGE后的免疫印迹显示，同一动物中AGE-IgG有选择性的显著增加。当天然大鼠IgG在从糖尿病动物分离的AGE肽存在下孵育时，仅孵育24小时后AGE修饰就已明显，并且对轻链尤为重要。AGE免疫反应性轻链的分子量明显增加。氨基胍可阻止AGE与IgG轻链结合，而铜则增强这种结合。我们的数据证实链脲佐菌素诱导的糖尿病大鼠可作为再现循环中AGE肽存在的模型，证明IgG是血浆中晚期糖基化的优先靶标，并表明这种由AGE肽介导的修饰可被氨基胍阻止。
