Dietary fat-dependent changes in hepatic cholesterogenesis and the activity of 3-hydroxy-3-methylglutaryl-CoA reductase in fasted-refed rats.
Effects of various dietary fats on the activity of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase and sterol and fatty acid synthesis from [1-14C]acetate and [2-14C]mevalonate were examined in the liver from fasted-refed rats. Rats fasted for 2 days were refed a fat-free diet or diets containing various fats (tricaprylin, trilaurin, trimyristin, tristearin, camellia oil, or safflower oil) at the 10% level for 1, 3, or 7 days. The activity of HMG-CoA reductase was restored to about one-half of the pre-fasting levels in all groups after refeeding for 1 day and increased to above the pre-fasting levels after 3 days, with the exception of safflower oil, the rise was especially noticeable when fat-free, tricaprylin, and tristearin diets were fed. After 7 days, the activity of HMG-CoA reductase, except for rats refed tristearin, was decreased to levels that were far below those observed after 1 day-refeeding. This was particularly marked with tricaprylin, trilaurin, and camellia oil. The response of sterogenesis resembled that of the reductase. Dietary fat-dependent modification of fatty acid synthesis from [1-14C]acetate was first demonstrated after 7 days. Hepatic esterified cholesterol tended to accumulate and the deposition was marked after 3 days of refeeding. However, fat-dependent alterations of this parameter were remarkable on day 7. The concentration of plasma cholesterol also showed dietary fat-dependent changes after refeeding. Dietary fats appear to play an important role not only in the regulation of hepatic HMG-CoA reductase and sterol synthesis, but also in the overall processes of cholesterol dynamics.
D000818:Animals; D002784:Cholesterol / Q000096:biosynthesis*; D004032:Diet; D004041:Dietary Fats / Q000008:administration & dosage*; D005215:Fasting; D005227:Fatty Acids / Q000096:biosynthesis; D006903:Hydroxymethylglutaryl CoA Reductases / Q000378:metabolism*; D008099:Liver / Q000033:anatomy & histology / Q000378:metabolism*; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism; D009821:Oils / Q000008:administration & dosage; D051381:Rats; D012450:Safflower Oil / Q000008:administration & dosage; D013329:Structure-Activity Relationship; D013997:Time Factors; D014280:Triglycerides / Q000008:administration & dosage
D004041:Dietary Fats; D005227:Fatty Acids; D009821:Oils; D014280:Triglycerides; D012450:Safflower Oil; D002784:Cholesterol; D006903:Hydroxymethylglutaryl CoA Reductases