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Dietary fat effects on hepatic lipid peroxidation and enzymes of H 2 O 2 metabolism and NADPH Generation
Author(s) -
Chen LiChuan,
Boissonneault Gilbert,
Hayek Michael G.,
Chow Ching K.
Publication year - 1993
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/bf02536062
Subject(s) - clinical chemistry , lipid peroxidation , malic enzyme , chemistry , polyunsaturated fatty acid , glutathione peroxidase , lipidology , glutathione reductase , enzyme , medicine , catalase , fatty acid , antioxidant , biochemistry , endocrinology , dehydrogenase , biology
The purpose of this study was to determine the effects of dietary fat quantity and fatty acid composition on hepatic H 2 O 2 ‐metabolizing systems, activities of NADPH‐generating enzymes and lipid peroxidation. Onemonth‐old male C57BL/6J mice were fed one of six diets: (i) 5% fat, rich in 18∶2n−6 fatty acid (5% N−6); (ii) 20% fat, rich in 18∶3n−3 (N−3); (iii) 20% fat, rich in 18∶2n−6 (N−6); (iv) 20% fat, rich in 18∶1n−9 (N−9); (v) 20% fat, rich in saturated fatty acids (SAT); and (vi) 20% fat, deficient in essential fatty acids (EFAD); for 11 wk. Comparisons between animal groups receiving different fat quantities showed that activities of glucose‐6‐phosphate dehydrogenase (G6PDH, EC 1.1.1.49) and malic enzyme (ME, EC 1.1.1.40) and the levels of conjugated dienes were significantly lower in the N−6 than in 5% N−6 group. Conversely, activities of catalase (CAT, EC 1.11.1.6) and seleniumglutathione peroxidase (SeGSHPx, EC 1.11.1.9) were higher in the N−6 than in 5% N−6 group. Among the five dietary groups receiving 20% fat but differing in fatty acid composition, CAT activity was lower in the N−9 group, SeGSHPx activity was lower in the EFAD group, and glutathione reductase (GSSGR, EC 1.6.4.2) activity was higher in the N−6 than in the N−3, N−9, SAT and EFAD groups. The EFAD group had much higher levels of total lipids and conjugated dienes, as well as activities of NADPH‐generating enzymes, including G6PDH, ME and isocitrate dehydrogenase (EC 1.1.1.42), than the other four high‐fat groups. The hepatic levels of malondialdehyde were not different among the five groups fed 20% fat. In the EFAD group, higher hepatic lipid content can be attributed to higher activities of NADPH‐generating enzymes, and the elevation of conjugated diene levels may be related to increased oxygenation of 20∶−6 (Mead acid) via the lipoxygenase/cyclooxygenase pathway. In short, both dietary fat quantity and fatty acid composition selectively affected hepatic H 2 O 2 ‐metabolizing systems, activities of NADPH‐generating enzymes and lipid peroxidation status.