Studies on Cholesterol Metabolism in Experimental Diabetic Rat

In either ad libitum or restricted feeding of the high cholesterol diet for 10 days, total plasma and liver cholesterol level of the diabetic rats were remarkably higher than those of the controls. The significant difference of the plasma cholesterol between control and diabetic rats was not observed in the groups fed the low cholesterol diet, while the liver cholesterol content was more in the diabetic rats than in the controls. The reduced biliary excretion of the total radioactivity in the diabetic rats was demonstrated using 4-14C cholesterol. Either the excretion of labeled cholic acid or cholesterol was also reduced in diabetic state, but the per cent of labeled cholesterol to total radioactivity in the bile of diabetic rats was larger than that of controls and the per cent of labeled cholic acid in the diabetic rats was less than that in controls. The production of expiratory CO2 following administration of 26-14C cholesterol in vivo was lower in the diabetic rats than controls, showing the decreased conversion rate of cholesterol to cholic acid in the diabetic rats. When labeled cholic acid was administered, excretion of the radioactivity from the bile fistula was not affected in diabetic rats and the conjugation pattern of the cholic acid with taurine and glycine was not altered. It suggests that the conjugation process of cholic acid with amino acid and excretion of cholic acid was little altered between control and diabetic rats. From these results it is concluded that the rapid progress of alimentary hypercholesteremia in the diabetic rats might be mainly accounted for the accumulation of cholesterol caused by the impairment of its conversion to cholic acid which delayed the excretion.