COMPARISON OF HYPOCHOLESTEROLEMIC EFFECTS INDUCED BY DIETARY LINOLEIC-ACID AND OLEIC-ACID IN HAMSTERS

We investigated the differences between the hypocholesterolemic effect s induced by dietary linoleic acid and those induced by oleic acid in hamsters. Addition of 5% linoleic acid or oleic acid to a 0.1% cholest erol-supplemented diet diminished the increases in plasma total and lo w density lipoprotein (LDL) cholesterol induced by cholesterol alone. Linoleic acid decreased high density lipoprotein (HDL) cholesterol in comparison with cholesterol alone, whereas oleic acid did not. As comp ared with a standard diet or a cholesterol-supplemented diet, linoleic acid and oleic acid each prevented hepatic LDL receptor suppression, although linoleic acid was more effective. Oleic acid prevented the in crease in plasma cholesteryl ester transfer protein (CETP) activity in duced by dietary cholesterol, whereas linoleic acid did not. Neither l inoleic acid nor oleic acid altered hepatic 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase activity. Only oleic acid increased he patic cholesterol 7 alpha-hydroxylase activity. These results suggest that dietary linoleic and oleic acids diminish the cholesterol-induced increases in plasma total and LDL-cholesterol by preventing hepatic L DL receptor suppression, and in the case of oleic acid by also prevent ing the increase in the plasma CETP activity. These effects on cholest erol 7 alpha-hydroxylase activity may influence bile lipid metabolism.