고ㆍ저 콜레스테롤 식이로 사육된 쥐에서 PUFA 식이가 체내 지방 대사에 미치는 영향

The Effect of PUFA Diet on Lowering Serum Cholesterol Levels in Rats Raised on High or Low Cholesterol Diets

This study was designed to observe the effects of PUFA in the diet on cholesterol and lipid metabolism in rats which had been fed a high fat, high cholesterol diet. Two experiments were carried out. Male rats weighing approximately 240g and semipurified diets were used for experiment A, and rats weighing 85g and stock based diets for experiment B. The rats were assigned into a control and a high fat, high cholesterol(atherogenic) diet groups for 4 weeks(the first experimental period), and then each diet group was subdivided into saturated fat(SAT) and unsaturated fat(PUFA) diet groups for another 4 weeks (the second experimental period). The liver cholesterol levels were higher in animals fed an atherogenic diet in the first experimental period than in rats fed control diet, but serum cholesterol concentrations were not differed significantly. After the second experimental period, rats fed PUFA diet did not show a lower serum cholesterol concentrations than those fed SAT diet, probably because the experimental diets did not contain cholesterol. However, the liver cholesterol levels and the fecal cholesterol excretions were higher in animals fed PUFA diet than in those fed SAT diet. Therefore it seems that the general hypocholesterolemic effect of PUFA id due in part to an increase of cholesterol storage in liver and in part to the higher cholesterol excretion, and that serum cholesterol concentrations are not a measure of cholesterol accumulation by organs. Serum triglycerides levels were higher ir control groups in the experiment A compared to atherogenic group due its higher carbohydrates content. In both experiments, rats fed SAT diet showed higher serum triglycerides levels than those fed PUFA diet. The various effects of PUFA on lipid levels in the rats fed atherogenic diet during the first period did not differ from the effects in those fed control diet. Therefore it is concluded that the present diet of an animal has more profound effects on lipid metabolism than the diet the animal had been raised on the past, regardless the age of experimental animals.