Dietary protein modifies oxidized cholesterol-induced alterations of linoleic acid and cholesterol metabolism in rats.
Effects of dietary protein on oxidized cholesterol-induced alterations in linoleic acid and cholesterol metabolism were studied in 4-wk-old male Sprague-Dawley rats, using casein and soybean protein as dietary protein sources. The rats were fed one of the two proteins in cholesterol-free, 0.3% cholesterol or 0.3% oxidized cholesterol mixture diets using a pair-feeding protocol for 3 wk. In the soybean protein-fed group, rats fed oxidized cholesterol did not have lower activity of liver microsomal delta6 desaturase, the rate-limiting enzyme in the metabolism of linoleic acid to arachidonic acid, compared with rats fed cholesterol-free diet, whereas in the casein-fed group the desaturase activity was significantly greater in rats fed oxidized cholesterol than in those fed cholesterol-free diet. This was in contrast to a significant reduction in liver microsomal delta6 desaturase activity by cholesterol, irrespective of protein source. In general, these changes were reflected in the desaturation indices of liver phospholipids. Furthermore, soybean protein significantly increased the fecal excretion of neutral and acidic steroids and tended to reduce (P = 0.082) the accumulation of oxidized cholesterols in the liver. Thus, soybean protein partly modified some of the undesirable effects of oxidized cholesterol through its hypocholesterolemic effect and possibly through the modulation of hepatic delta6 desaturase activity.
Osada
K
K
Laboratory of Food Science, Department of Food Science and Technology, Faculty of Agriculture, Kyushu University, Fukuoka 812, Japan.
Kodama
T
T
Minehira
K
K
Yamada
K
K
Sugano
M
M
D000818:Animals; D002364:Caseins / Q000008:administration & dosage / Q000494:pharmacology; D002784:Cholesterol / Q000378:metabolism*; D002791:Cholesterol, Dietary / Q000008:administration & dosage / Q000494:pharmacology*; D004044:Dietary Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D044943:Fatty Acid Desaturases / Q000378:metabolism; D019787:Linoleic Acid; D008041:Linoleic Acids / Q000378:metabolism*; D050602:Linoleoyl-CoA Desaturase; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology; D010084:Oxidation-Reduction; D014674:Plant Proteins, Dietary / Q000008:administration & dosage / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D030262:Soybean Proteins
D002364:Caseins; D002791:Cholesterol, Dietary; D004044:Dietary Proteins; D008041:Linoleic Acids; D014674:Plant Proteins, Dietary; D030262:Soybean Proteins; D002784:Cholesterol; D019787:Linoleic Acid; D044943:Fatty Acid Desaturases; D050602:Linoleoyl-CoA Desaturase