Serum Lipoproteins of Diabetic Rats Fed a High Cholesterol Diet

Feeding a diet containing 2% cholesterol and 1% cholic acid (wt/wt) to rats made diabetic by administration of streptozotocin (45 mg/kg) produced marked hypercholesterolemia characterized by high concentrations of very low density lipoproteins (VLDL) and intermediate density lipoproteins (IDL) and a reduction in concentration of high density lipoproteins (HDL). The VLDL was unique in that it contained apo A-I and apo A-IV in addition to its usual complement of apoproteins: apo B, apo E, and the C apoproteins. IDL had a similar apoprotein composition. The HDL from these rats was deficient in apo E. Nondiabetic rats fed the same diet exhibited similar qualitative changes in lipoprotein concentration and composition but with lesser increases in VLDL and IDL concentrations. The altered apoprotein composition suggested that the hyperlipoproteinemia associated with cholesterol feeding in the rat is due to an inadequate rate of removal of lipoproteins of intestinal origin, and that this is greatly exacerbated by diabetes.