CHANGES IN SERUM-LIPID AND LIPOPROTEINS I N ALLOXAN-DIABETIC RATS - STUDIES FOR ONE-YEAR

Alloxan-diabetic rats were kept on an ordinary or 0.25% cholesterol su pplemented diet for up to 12 months, and changes in the serum lipid an d lipoprotein levels were examined. The diabetic rats showed IRI level s of 3 approximately 5 IU/ml, which were 1/5 approximately 1/10 that o f the normal rats, and about 10 times higher serum glucose levels than the normal rats. The diabetic rats consumed 1.5 approximately 2 fold amounts of diet but their body weights were almost constant. The diabe tic rats showed marked hyperlipidemia, especially in the cholesterol a nd triglyceride levels. The phospholipid level also increased but for a lesser extent and the c/p ratio increased. The serum lipoprotein lev els increased in the diabetic rats, 5 approximately 10 times in the or dinary diet fed groups and 10 approximately 20 times in the cholestero l diet fed groups. Chylomicron, VLDL, IDL and LDL increased but HDL de creased. These changes were more significant in the diabetic rats fed the cholesterol diet. The triglyceride levels in the lipoprotein fract ions increased in the diabetic rats, but the increase in cholesterol w as more significant and the relative composition ratios of triglycerid e decreased. The composition ratios of phospholipids, however, remaine d almost constant in all the lipoprotein fractions. The increase in ID L, especially cholesterol in the IDL fraction, was remarkable in the d iabetic rats. The responsiveness of the diabetic rat VLDL to lipoprote in lipase (release of free fatty acids) was less than a half of that o f the normal rat VLDL. In conclusion, the diabetic rats showed an incr ease in triglyceride but more significant increase in cholesterol in t he lipoprotein fractions. These changes in serum lipid and lipoprotein levels and compositions appeared as early as 3 months after the allox an injection and lasted for 12 months without any progress in the dist urbance.