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Dietary oxidized cholesterol modulates cholesterol metabolism and linoleic acid desaturation in rats fed high‐cholesterol diets
Author(s) -
Osada Kyoichi,
Kodama Takehiro,
Yamada Koji,
Nakamura Shingo,
Sugano Michihiro
Publication year - 1998
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/s11745-998-0267-x
Subject(s) - cholesterol , linoleic acid , medicine , endocrinology , metabolism , clinical chemistry , reverse cholesterol transport , chemistry , lipidology , arachidonic acid , reductase , biochemistry , biology , enzyme , fatty acid , lipoprotein
The interactive effect of high dietary levels of oxidized cholesterol on exogenous cholerterol and linoleic acid metabolism was examined in male 4‐wk‐old Sprague‐Dawley rats given high‐cholesterol diets. The rats were pair‐fed purified diets free of or containing either 0.5% cholesterol alone or both 0.5% cholesterol and 0.5% oxidized cholesterol mixture (containing 93% oxidized cholesterol) for 3 wk. Hepatic 3‐hydroxy‐3‐methylglutaryl CoA reductase activity was reduced in rats given cholesterol alone or both cholesterol and oxidized cholesterol. However, hepatic cholesterol 7α‐hydroxylase activity was lowered only when rats were given both cholesterol and oxidized cholesterol, although dietary cholesterol increased this activity. Reflecting this effect, acidic steroid excretion was lowest among the groups of rats given cholesterol and oxidized cholesterol. On the other hand, the activity of hepatic Δ6 desaturase, a key enzyme in the metabolism of linoleic acid to arachidonic acid, was increased in rats given both cholesterol and oxidized cholesterol, although dietary cholesterol alone lowered its activity. As a result, the Δ6 desaturation index, 20∶3n‐6+20∶4n‐6/18∶2n‐6, in liver and serum phosphlipids tended to be higher in the group fed both cholesterol and oxidized cholesterol than in the one fed cholesterol alone. Thus, dietary oxidized cholesterol significantly modulated exogenous cholesterol metabolism and promoted linoleic acid desaturation even when it was given at high levels together with a high cholesterol diet.