Alteration of polyol metabolism in glomeruli of streptozotocin diabetic rats

—Analysis by gas chromatography-mass spectrometry—

Abstract

The purpose of the present study is to determine polyols and sugars in glomeruli obtained from streptozotocin (STZ) diabetic rats. Sixty milligram per kg body weight of STZ was injected to Sprague-Dawley male rats and then the aminals were sacrificed 4 and 12 weeks after the injection. One group of STZ diabetic rats was treated with 8-14 units of NPH insulin for 3 weeks. Glomeruli were isolated by sieving methods. The concentration of polyols and sugars was measured by gas chromatography mass spectrometry. The levels of glucose, sorbitol, fructose, mannose, ribitol and erythritol in the glomeruli were significantly higher in 4- or 12-week diabetic rats than those in control rats, whereas the level of scyllo-inositol was decreased. In insulin treated 4-week diabetic rats, the levels of all polyols but scyllo-inositol were significantly decreased compared with un-treated diabetic rats. The level of myo-inositol in glomeruli of 12-week diabetic rats was significantly higher than those of control rats, whereas that of erythritol was decreased. The urinary N-acetyl glucosaminidase activity as well as creatinine clearance was increased in 4- and 12-week diabetic rats. Urinary protein was also increased in 12-week diabetic rats. These findings suggest that the alterations of polyol metabolism in glomeruli of dia-betes may play an important role in the pathogenesis and/or progression of daibetic nephropathy. It is likely that treatment with insulin improves the alteration of polyol metabolism in the glomeruli in early stages of diabetes.