ozagrel and Diabetic-Nephropathies

We used rats (the Otsuka Long-Evans Tokushima Fatty strain) as a model of type 2 diabetes to find whether thromboxane (TX) A2 is involved in diabetic nephropathy, and if so, to identify where it is synthesized. We measured urinary excretion of TXB2 and 2,3-dinor-TXB2 in rats up to 60 weeks of age as markers of renal and platelet synthesis of TXA2, respectively. Some diabetic rats were given daily oral doses of OKY-046 (100 mg/kg), a TXA2 synthase inhibitor, starting when they were 10 weeks of age. Healthy Long-Evans Tokushima Otsuka rats served as the controls. Urinary excretion of protein was greater in diabetic rats at 26 weeks than in controls, and the difference increased with age. Urinary excretion of TXB2 by diabetic rats was about 150% that of controls at 14 weeks, and remained at that level. In diabetic rats, urinary excretion of 2,3-dinor-TXB2 increased with age in parallel to increases in proteinuria, but in controls, excretion of these metabolites did not change with age. In diabetic rats, OKY-046 prevented the increase in urinary excretion of both metabolites, and decreased the proteinuria. Histologic examination at 60 weeks showed intraglomerular thrombi in diabetic rats but not in controls. OKY-046 reduced intraglomerular thrombi formation and the score for glomerulosclerosis. When platelet aggregation began, more TXA2 than before was released from the thrombi that formed, and the TXA2 contributed to the progress of nephropathy in this rat model of type 2 diabetes.

Topics: 6-Ketoprostaglandin F1 alpha; Aging; Animals; Blood Glucose; Blood Pressure; Body Weight; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Disease Progression; Enzyme Inhibitors; Glomerular Mesangium; Male; Methacrylates; Prostaglandins; Proteinuria; Rats; Rats, Inbred OLETF; Thrombosis; Thromboxane A2; Thromboxane-A Synthase

To examine the effects of endogenous thromboxane A2 on the development of diabetic nephropathy, we administered OKY-046, an inhibitor of thromboxane synthesis, to streptozotocin-induced diabetic rats. Animals were divided into three groups; nondiabetic control, diabetic, and diabetic with OKY-046, and were sacrificed 16 weeks after experimental procedures. The chronic oral administration of OKY-046 to diabetic rats significantly decreased plasma and urinary thromboxane B2 levels. Urinary protein excretion and serum glucose levels were significantly lower in the OKY-046-treated diabetic rats than in the untreated diabetics (60.8 +/- 23.2 vs. 94.1 +/- 33.4 mg/day in the 16th week, p less than 0.05 and 424.4 +/- 93.3 vs. 614.4 +/- 102.3 mg/dl in the 16th week, p less than 0.01, respectively). Platelet aggregation was inhibited by OKY-046. Blood urea nitrogen was unaffected. Ultrastructural examination revealed that the thickness of glomerular basement membrane was markedly thinner in the OKY-046-treated diabetic rats than in the untreated diabetics (197.4 +/- 29.6 vs. 288.6 +/- 46.9 nm, p less than 0.01). These results suggest that thromboxane A2 may play an important role in the development and progression of diabetic nephropathy in rats.

Topics: 6-Ketoprostaglandin F1 alpha; Administration, Oral; Animals; Blood Glucose; Blood Pressure; Blood Urea Nitrogen; Body Weight; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Insulin; Kidney; Male; Methacrylates; Microscopy, Electron; Platelet Aggregation; Proteinuria; Rats; Rats, Inbred Strains; Thromboxane A2; Thromboxane B2; Thromboxane-A Synthase