Immunohistochemical distribution and quantitative biochemical detection ofadvanced glycation end products in fetal to adult rats and in rats with streptozotocin-induced diabetes

We used immunohistochemical methods and four monoclonal antibodies for spec ific molecular structures of advanced glycation end products (AGE)-6DI2, KN H-30, 1F6, and 2A2-to examine localization of AGE in fetal, young, and adul t rats, and rats with streptozotocin-induced diabetes. 6D12 recognized N-ep silon-(carboxymethyl)lysine (CML); KNH-30, NE(carboxyethyl)lysine (CEL); an d 1F6, fluorolink. The epitope of 2A2 is as yet unknown. Immunoreactivities for these monoclonal antibodies were found in various organs and tissues i n postnatal and adult rats, and accumulation increased with aging. In the f etuses, AGE structures were detected at 10 fetal days, and their accumulati on increased during ontogeny. Reversed-phase high-performance liquid chroma tography revealed CML in fetuses at 13 fetal days and in lungs of 28-week-o ld rats. In various organs and tissues of fetal, young, and adult rats, CML , GEL, 2A2-positive AGE, and fluorolink accumulated, in that order, which s uggests that the accumulation of CML, a nonfluorescent/noncross-linked AGE, occurs earlier than accumulation of fluorolink, a fluorescent/cross-linked AGE. In diabetic rats, hepatocytes, splenic macrophages, renal glomerular endothelial and mesangial cells, testicular Leydig cells. and erythrocytes showed excessive accumulation of AGE, leading to the pathologic changes cha racteristic of diabetes mellitus. For the induction of these changes, persi stent hyperglycemia and hyperketonemia might be important for acceleration of intracellular AGE accumulation in diabetic rats. Thus, AGE accumulation in tissues and cells occurs not only during aging and in diabetes mellitus but also from an early stage of ontogeny.