Oxidative stress and fatty acid profile in Wistar rats subjected to acute food restriction and refeeding with high-fat diets

To assess oxidative stress and the profile of fatty acids incorporated into the hepatic tissue of animals refed with high-fat (HF) diets after acute food restriction. METHODS: Fifty male Wistar rats were divided into five groups and fasting for 48 hours. One group was sacrificed without refeeding (NR), a control group (C) was refed with the standard AIN-93 diet and the remaining groups with HF diets respectively consisting of hydrogenated vegetable oil (PHVO), trans-free (TF) margarine and trans-free margarine enriched with ω-3 and ω-6 (O). After this period the animals were sacrificed for malondialdehyde (MDA), catalase and hepatic fatty acid determination. RESULTS: The groups refed with HF diets showed elevation of MDA levels compared to the C group (p<0.001 for GVH and p<0.01 for TF and O). Hepatic catalase activity was higher in the TF and O groups compared to group C (p<0.05 for both). The amount of saturated fatty acids was lower in the PHVO and O groups compared to the remaining ones (p<0.001). CONCLUSION: The consumption of high-fat diets after prolonged fasting favors oxidative imbalance in hepatic tissue.

Association between hepatic cholesterol and oleic acid in the liver of rats treated with partially hydrogenated vegetable oil / Associação entre colesterol hepático e ácido oleico no fígado de ratos tratados com gordura vegetal parcialmente hidrogenada

OBJECTIVE: The aim of the present study was to investigate the lipid profiles of the hepatic and adipose tissues of Wistar rats treated for 21 days with a diet high in saturated fat (high saturated fat, n=6) or high in hydrogenated fat, that is, having 50% partially hydrogenated vegetable oil in its composition (high hydrogenated fat, n=6), and compare them to those of a control group (control group, n=6). METHODS: Adipose tissue and total hepatic fat were higher in the saturated fat group than in the hydrogenated fat group. Hepatic lipid peroxidation was greatest in the saturated fat group, with consequent lower hepatic vitamin E and A levels. In contrast, serum vitamin A was highest in the saturated fat group. Analysis of hepatic lipid fractions found more cholesterol and less high density lipoprotein-cholesterol in the hydrogenated fat group. The hydrogenated fat group had the highest levels of triacylglycerols, followed by the saturated fat group. RESULTS: Significant amounts of trans fatty acids were detected in the hepatic and adipose tissues of the hydrogenated fat group. Among the identified fatty acids, 18:1n9 had a higher positive association with hepatic cholesterol and triacylglycerols, and a higher negative association with high density lipoprotein-cholesterol. Partially hydrogenated vegetable oil promotes greater accumulation of cholesterol and triacylglycerols in the liver than saturated fats. CONCLUSION: Trans fatty acids were incorporated into hepatocytes and adipocytes in a highly efficient manner.

OBJETIVO: Esta pesquisa investigou a composição lipídica dos tecidos hepático e adiposo de ratos Wistar tratados durante 21 dias com uma dieta rica em gordura saturada (grupo gordura saturada, n=6) ou rica em gordura hidrogenada, ou seja, 50% da gordura consistindo de gordura vegetal parcialmente hidrogenada (grupo gordura hidrogenada, n=6) e compará-los a um grupo-controle (grupo-controle, n=6). MÉTODOS: As quantidades de tecido adiposo e gordura hepática total foram maiores no grupo gordura saturada do que no grupo gordura hidrogenada. A peroxidação lipídica hepática foi maior no grupo gordura saturada, com consequente diminuição dos níveis hepáticos de vitaminas E e A. Por outro lado, o nível sérico de vitamina A foi maior no grupo gordura saturada do que nos outros grupos. A análise das frações lipídicas hepáticas revelou mais colesterol e menos colesterol da lipoproteína de alta densidade no grupo gordura hidrogenada. O grupo gordura hidrogenada apresentou os maiores níveis de triglicérides, seguido do grupo gordura saturada. Quantidades significativas de ácidos graxos trans foram detectados nos tecidos hepático e adiposo do grupo gordura hidrogenada. RESULTADOS: Dentre os ácidos graxos identificados, o 18:1n9 apresentou uma associação positiva maior com o colesterol hepático e triglicérides, e uma associação negativa maior com o colesterol da lipoproteína de alta densidade. A gordura vegetal parcialmente hidrogenada promove um maior acúmulo de colesterol e triglicérides no fígado do que a gordura saturada. CONCLUSÃO: Os ácidos graxos trans foram incorporados aos hepatócitos e adipócitos de forma altamente eficiente.