Streptozotocin- and alloxan-induced diabetes modifies total plasma and lipoprotein lipid concentration and composition without altering cholesteryl ester transfer activity

The objectives of this study were to determine the total plasma and lipoprotein lipid concentration and composition and cholesteryl ester transfer activity in two diabetic animal models (alloxan-induced diabetes in rabbits and streptozotocin-induced diabetes in rats). Furthermore, we wanted to determine if the severity of diabetes influences lipoprotein lipid profiles and cholesteryl ester transfer activity. Rats and rabbits were randomly divided into non-diabetic and diabetic groups. Rats were administered either 55 mg/kg or 100 mg/kg of streptozotocin intravenously through the tail vein, while rabbits were administered 100 mg/kg or 200 mg/kg of alloxan intravenously through the marginal ear vein under light anesthesia. Hyperglycaemia was tested for at 48 hr following the doses. Total and lipoprotein cholesterol and triglyceride concentrations using enzymatic kits and cholesteryl ester transfer activity from low-density lipoproteins to high-density lipoproteins using H-3-cholesteryl ester incorporated into low density lipoproteins were determined. Elevations in both total and lipoprotein cholesterol and triglyceride concentrations and alterations in lipoprotein lipid composition are observed following the onset of drug-induced diabetes in rats and rabbits compared to non-diabetics. However, these findings were observed only in animals administered the higher streptozotocin and alloxan dose. Furthermore, cholesteryl ester transfer from low-density lipoproteins to high-density lipoproteins is not significantly different in drug-induced diabetic compared to non-diabetic rats and rabbits, regardless of which streptozotocin and alloxan dose was used. These findings suggest that difference in lipoprotein lipid concentration and composition as a result of drug-induced diabetes is independent of cholesteryl ester transfer activity in both rats and rabbits. Furthermore, diabetic severity may influence lipoprotein metabolism in these animal models.