Akira Matsubara

Determination of monosaccharides and sugar alcoholsin tissues from diabetic rats by high-performance liquid chromatography with pulsed amperometric detection

A sensitive and simple high-performance liquid chromatographic method has been developed to determine the concentration of monosaccharides and sugar alcohols in animal tissues. Five neutral monosaccharides (D-glucose, D-galactose, D-mannose, D-fructose, and D-ribose) and three neutral sugar alcohols (myo-inositol, glycerol, and D-sorbitol) predominate in the renal cortices and sciatic nerves of rats. These monosaccharides and sugar alcohols were extracted with distilled water, purified by deproteinization with ethanol, a Sep-Pak C18 cartridge, and columns of Dowex 50W-X8 and Amberlite CG-400, then separated on Ca2+ and Pb2+ cation-exchange columns, eluted with deionized distilled water at 80 degrees C, and detected using integrated pulsed amperometry. About 10 pmol of each sugar was detectable with a signal-to-noise ratio of 10:1. D-Glucose, D-fructose, D-sorbitol, and D-mannose were higher in both the renal and sciatic tissues of diabetic rats than in those of normal animals. D-Ribose and glycerol were higher in the renal cortex of diabetic animals.

Effect of long-term treatment with a new aldose reductase inhibitor, (2S,4S)-6-fluoro-2′,5′-dioxospiro-[chroman-4,4′-imidazolidine]-2-carboxamide (SNK-860), on peripheral neuropathy in streptozotocin-induced diabetic rats

Abstract We studied the long-term effects of a new aldose reductase inhibitor, (2 S ,4 S )-6-fluoro-2′,5′-dioxospiro-[chroman-4,4′-imidazolidine]-2-carboxamide (SNK-860), on functional, biochemical, and structural changes in peripheral nerve of streptozotocin (STZ)-induced diabetic rats. During the experimental period of 26 weeks, the delayed motor-nerve conduction in diabetic rats was significantly prevented by SNK-860 treatment, and elevated sorbitol levels and reduced myo -inositol levels were normalized to 100% and 71% of control levels, respectively. Teased nerve fiber studies demonstrated that the frequency of abnormal fibers was significantly reduced in treated diabetic rats. Morphometric analysis of myelinated fibers also disclosed prevention of axonal atrophy, distorted axonal circularity and preservation of large-sized fibers following SNK-860 treatment. These results suggest that long-term treatment with SNK-860 has a beneficial preventive effect on the development of experimental diabetic neuropathy.

Inhibitory effect of orally administered aldose reductase inhibitor SNK-860 on corneal polyol accumulation in galactose-fed rats

Abstract · Background: Diabetic keratopathy, frequently observed after vitreous surgery, has been thought to be related to the aldose reductase-catalyzed reaction. However, few reports have been published on the chronological changes in polyol accumulation and the effect of the aldose reductase inhibitor in the corneal epithelium or endothelium of galactosemic rats. Consequently, the polyol accumulation in corneal epithelium and endothelium with stroma of 50% galactose-fed rats and the preventive effect of an aldose reductase inhibitor, SNK-860, were biochemically analyzed. · Methods: Four-week-old male Sprague-Dawley rats were fed a 50% galactose diet without supplement or supplemented with a low (3 mg/kg b.w.) or high (30 mg/kg b.w.) dose of SNK-860 (Sanwa Kagaku Kenkyusho, Japan), or a normal diet. Polyol contents in the corneal epithelium or endothelium with stroma were individually measured using gas-liquid chromatography. · Results: Polyol in corneal epithelia accumulated quickly in the 1st week, reached a maximum at the 3rd week of feeding and then gradually decreased. Low- and high-dose SNK-860 treatment significantly inhibited polyol accumulation in the epithelium and endothelium with stroma, respectively. Changing to the normal or SNK-860 supplemented diets significantly inhibited polyol accumulation. · Conclusion: This finding indicates that oral administration of a new aldose reductase inhibitor, SNK-860, or systematic treatment of diabetes may be effective in preventing polyol pathway-induced corneal damage by quickly reducing the polyol level.