Effect of Overnight Fasting on the Fatty Acid Composition of Tissue Lipids in Rats Fed with Different Proteins

Koba, Kazunori; Abe, Koji; Wakamatsu, Kosaburo; Sugano, Michihiro

doi:10.1080/00021369.1991.10870778

Cited by 2 publications

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“…This increase in the n-6 and n-3 metabolites of 18 : 2n-6 and a-linoleic acid might indicate an increase in A6 desaturase activity. Similar observations about the influence of a high-casein diet on the metabolism of 18 : 2n-6 have been made previously Koba et al , 1991Koba et al , 1993.…”

Section: Discussionsupporting

confidence: 85%

Influence of dietary protein and fat on serum lipids and metabolism of essential fatty acids in rats

1997

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A 120 d feeding study with adult rats was conducted to evaluate the inhence of two protein sources (casein and gelatin), two protein levels (50 and 300g/kg diet) and two fat levels (50 and 150g/kg diet) on serum lipids (total cholesterol, HDL-cholesterol and triacylglycerols) and liver polyunsaturated fatty acid levels. In general, the concentrations of serum triacylglycerols and total cholesterol and liver phospholipid levels of arachidonic acid (AA) and docosahexaenoic acid (DHA) were higher in rats fed on casein diets compared with those fed on the gelatin diets. These effects were more pronounced in rats fed on the high-casein (300 g/kg)-high-fat (150 g/kg) diet. Gelatin was hypocholesterolaemic and also suppressed the liver phospholipid levels of AA and DHA (reported for the first time). The difference in the amino acid composition between casein and gelatin may be responsible for the observed effects. Casein contains higher levels of glutamic acid, methionine, phenylalanine and tyrosine, while gelatin contains higher levels of arginine, glycine and hydroxyproline. It is suggested that a protein source which increases serum cholesterol may also increase the concentrations of AA and DHA in rat tissues.

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Section: Discussionsupporting

confidence: 85%

Influence of dietary protein and fat on serum lipids and metabolism of essential fatty acids in rats

1997

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“…On the other hand, the activity of J6-desaturase in liver microsomes was suppressed by feeding of cholesterol as reported,34) but it increased significantly in adult rats when oxidized cholesterol was fed. Since the reductase activity also is reduced by fasting 35 ) or ageing,12) we suggest that this observation is one of the specific biological activities of oxidized cholesterols. In consequence, the desaturation index of linoleic acid expressed as the ratio of (20:3 +20:4)/18:2 tended to increase in liver phospholipids of adult rats.…”

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Effects of Dietary Oxidized Cholesterol on Lipid Metabolism in Differently Aged Rats

Osada

Kodama

Cui

et al. 1994

Bioscience, Biotechnology, and Biochemistry

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Male Sprague-Dawley rats, 4 weeks (young) or 8 months (adult) of age, were fed one of three purified diets free of or containing either 0.5% cholesterol or 0.5% oxidized cholesterol (92°!cl oxidized cholesterol) for 3 weeks. Feeding of oxidized cholesterol caused a significant reduction of food intake, body weight gain, and relative liver weight in rats of both ages. The activity of the HMG-CoA reductase and cholesterol 7~-hydroxylase of liver microsomes, the key enzymes in cholesterol synthesis and catabolism, respectively, was lowered by oxidized cholesterol compared to the diet free of cholesterol in both ages, and the difference was significantly in the adult. On the other hand, the activity of A6-desaturase of liver microsomes, a key enzyme in linoleic acid metabolism to arachidonic acid, was significantly increased by oxidized cholesterol in adult rats, leading to the increase in linoleic acid desaturation index [(20:3n-6 + 20:4n-6)/18:2n-6] in liver phospholipids. Oxidized cholesterol reduced the concentration of cholesterol in serum and liver. Also, the fecal excretion of acidic steroids was lower in rats fed the oxidized cholesterol diet than in those fed the cholesterol-free diet. Thus, oxidized cholesterol significantly influenced cholesterol and fatty acid metabolism in particular in adult rats.Lipid peroxidation is considered to be implicated in a number of human disorders. 1) Similarly, oxidized cholesterol displays a wide range of untoward effects. Oxidized cholesterols are readily formed in foods when it is exposed to air, free radicals, and high temperatures. In fact, processed foods such as egg products, meat products, butter, dairy products, pancake mix, French fries, and seafoods contain various types of oxidized cholesterols at the ppm level. 2 -4) Approximately 30% of oxidized cholesterols is absorbed in rats (unpublished observation). Several oxidation products of cholesterol have been reported to have various biological activities such as cytotoxicity,5) mutagenicity,5) carcinogenicitY,6) atherogenicity,7) and inhibition of cholesterol biosynthesis. 8 ) However, the information is mainly based on observations in vitro, and their effects in vivo are not well understood.Numerous epidemiological studies show an aged-related increase in coronary heart disease. The development of this disease is largely associated with the elevation of serum cholesterol, presumably due to the disturbance of cholesterol homeostasis with age. 9,10) Since cholesterol metabolism is modulated with age, the effects of dietary oxidized cholesterol on cholesterol metabolism may be different in young and adult individuals. Choi et al. 1 1) showed that cholesterol levels in serum and liver were increased and the activities of both 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase and cholesterol 7a-hydroxylase in rat liver were decreased with age. Therefore, in this communication, we studied the effects of oxidized cholesterols on the metabolism of cholesterol and fatty acid using young (4 weeks old) and adult (8 month...

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Effect of Overnight Fasting on the Fatty Acid Composition of Tissue Lipids in Rats Fed with Different Proteins

Cited by 2 publications

References 0 publications

Influence of dietary protein and fat on serum lipids and metabolism of essential fatty acids in rats

Influence of dietary protein and fat on serum lipids and metabolism of essential fatty acids in rats

Effects of Dietary Oxidized Cholesterol on Lipid Metabolism in Differently Aged Rats

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