IMMUNOCHEMICAL DETECTION OF ADVANCED GLYCATION END-PRODUCTS IN RENAL-CORTEX FROM STZ-INDUCED DIABETIC RAT

To reassess the accumulation of advanced glycation end products in dia betic renal cortex, we used a newly developed enzyme-linked immunosorb ent assay to measure AGEs in renal cortex from STZ-induced diabetic an d age-matched control rats. Kidneys and aortas were obtained from rats after 5 and 20 wk of STZ injection. At 5 wk of diabetes, the mean AGE content in collagenase-digested materials of renal cortex was >16-fol d higher in diabetic animals compared with controls (1044.4 +/- 151.8 vs. 64.3 +/- 5.7 arbitrary units, P < 0.01). At 20 wk of diabetes, it was >45-fold higher in diabetic compared with control animals (3841.0 +/- 1077.3 vs. 83.8 +/- 12.8 AUs, P < 0.01). These increases were surp risingly large compared with the <1.5-fold increase in the fluorescenc e levels both after 5 and 20 wk of diabetes. In control animals, neith er the AGE content nor the fluorescence level increased during this pe riod. Moreover, at 20 wk of diabetes, the AGE content was 39-fold high er in renal cortex compared with aorta. This study provided the first immunochemical evidence that collagenase-digested materials of renal c ortex, as well as aorta, contained AGE products and that these product s were present in much higher levels in diabetic animals than in contr ol animals. With duration of diabetes, the AGE contents increased sign ificantly both in renal cortex and aorta. The excessive accumulation o f AGEs was most apparent in the diabetic kidney. These findings sugges t that the actual level of AGEs, in particular, in diabetic renal cort ex is much higher than previously anticipated, and a newly developed e nzyme-linked immunosorbent assay may be a powerful tool for investigat ing the role of the advanced Maillard reaction in the development of d iabetic nephropathy.