The influence of acute diabetes (8 days), induced by streptozotocin (45 mg.kg'1 body weight) on myocardial and renal antioxidative conditions was investigated. The animals were given subtherapeutical doses of insulin (Interdep 6 (J. kg'1 body weight, s.c.). Considerably increased levels of malondialdehyde (MDA), as well as of superoxide dismutase (SOD) and catalase (CAT) activity were found in the myocardium of diabetic animals. The oxidized glutathione (GSSG) level and glutathione peroxidase (GSH-PX) activity remained unchanged. The reduced glutathione (GSH) level as well as the activity of glutathione S-transferase (GST) were significantly lower. The activity of GSH-PX in the kidneys of diabetic rats increased by 60 % and that of GST by 105 %, respectively. CAT and SOD activity values were unchanged.
We have investigated the effect of a diet containing of 4 % oyster fungus (Pleurotus ostreatus) and 0.1 % cholesterol on glycaemia and hyperlipoproteinaemia in rats with insulin-dependent diabetes (streptozotocin 45 mg/kg). After two months, the rats with diabetes kept on the oyster fungus diet, had a significantly lower basal and postprandial glycaemia, the insulinaemia remained unchanged. The cholesterol concentration was decreased by more than 40 %, the lipoprotein profile was upgraded by the decrease of the cholesterol in both the low density and very low density lipoproteins. The oyster fungus decreased the cholesterol accumulation in the liver and had no significant effects on the levels of serum and liver triacylglycerols.
The effect of 3 months feeding with diets of different protein and sucrose content (9 % casein -f 70 % sucrose vs. 18 % casein + 61 % sucrose) on the development of diabetic nephropathy and changes in serum lipid spectrum was investigated in rats with insulin-dependent diabetes (streptozotocin 45 mg.kg-1). Metabolism of diabetic animals (before the nutritional regimen) was characterized by hyperglycaemia, moderate hyperlipidaemia, lipid accumulation in the liver and elevated creatinine concentration in the blood. Kidney weight and protein content were not significantly changed. Histological picture of kidneys showed initial changes of glomerular structure. After three months hyperlipoproteinaemia was more accentuated in animals given either of the two diets, the kidneys were hypertrophic with a higher protein content and displayed morphological changes of diabetic nephropathy. Animals given the low-protein diet developed smaller morphological changes both in glomeruli and tubuli. The study indicates that dietary protein and not hyperlipoproteinaemia is the major factor, which may significantly influence the progress of diabetic nephropathy.
Metabolism of palmitate-14C was studied in the rat liver and muscle incubated with 1 mmol.1-1 tolbutamide in vitro experiments: Tolbutamide reduces the utilization of free fatty acids in the liver by inhibiting their uptake, incorporation into total lipids, and oxidation to 14CC>2. Tolbutamide stimulates the incorporation into the triacylglycerol fraction in individual liver lipid fractions and inhibits the incorporation into the free fatty acid fraction. As in the liver, tolbutamide inhibits the uptake, incorporation into total lipids, and oxidation to 14C02 in the muscle. In individual lipid fractions, tolbutamide only inhibits the incorporation of palmitate into cholesterol esters. It can be concluded that tolbutamide directly interferes with fatty acid metabolism and thus improves glucose utilization and insulin resistance.