Advanced glycosylation end products, protein kinase C and renal alterations in diabetic rats

Objective To study the relationship between advanced glycosylation end products (AGE) an d protein kinase C (PKC), and their effects on renal alteration in diabetic rats .Methods Insulin or aminoguanidine was administered to diabetic rats. Blood glucose, hem oglobin A(1C) (HbA(1C)), glomerular tissue extracts AGE (GTE-AGE), PKC, glomerular basement membrane thickness (GBMT) and urine protein/creatinine ( Pr/Cr) ratio in diabetic rats were measured and analysed. Results Levels of blood glucose, HbA(1C) and AGE, PKC activity, the Pr/Cr ratio an d GBMT were all significantly increased (P values all less than 0.01) in di abetic rats. Insulin could decrease the formation of HbA(1C) and AGE, and improve PKC activity. Aminoguanidine had no influence on PKC activity (P >0.05) although it decreased the formation of AGE. Both drugs could delay t he increase of urine Pr/Cr ratio and GBMT (P<0.05 or P<0.01). Conclusions Chronic hyperglycemia may lead to an increase of PKC activity. HbA(1C)and AGE may not directly contribute to alterations of PKC activity, but the increa se of PKC activity could promote the action of AGE on GBM thickening. It is imp ortant t o inhibit the formation of AGE and reduce the PKC activity so as to prevent or d elay the development of diabetic nephropathy.