Effect of Glycine on Protein Oxidation and Advanced Glycation End Products Formation

ObjectiveGlycine has been proposed as an immune modulator and cell protector for several pathologies. Results of several in vivo studies have shown that glycine inhibits glycation of hemoglobin; however, its role or effects on protein oxidation and formation of advanced glycation end products (AGEs) have not been studied yet. The present investigation aims to determine the effect of daily administration of glycine on the end products of glucose toxicity conformation in experimentally diabetic mice induced by streptozotocin.MethodsFour groups of mice were set as follows: Group 1, healthy controls; Group 2, diabetic controls; Group 3, diabetic and administered with aminoguanidine (0.1 g/kg/day); Group 4, diabetic and administered with glycine (0.2 g/kg/day). After treatment for 25 days, the animals were sacrificed and samples of serum, liver, and kidneys were isolated. Glycated hemoglobin (HbA1C), fructosamine, and formation of AGE of bovine serum albumin (AGE-BSA) were quantified together along with determination of liver and kidney protein oxidation. In addition, histological studies were also conducted.ResultsThe experimental data demonstrate that glycine reduced glucose, HbA1C, and fructosamine levels in blood. Even more, glycine significantly reduced AGE-BSA conformation, but the reduction of protein oxidation occurred only in the kidneys. With regard to morphological studies, it was observed that diabetic mice had liver and kidney alterations such as liver steatosis and kidney glomerulosclerosis, respectively, with a diminished activity of alanine aminotransferase linked to glycine treatment.ConclusionAdministration of glycine prevents some glucose toxicity, suggesting prevention of development of vascular complications in mice with diabetes mellitus.