High Fat Diet and Oxidant-Antioxidant Status of Blood 19 PUFA, polyunsturated fatty acids; EPA, eicosapentaenoic acid; DHA, docosahexaenoic acid. † determined by gas liquid chromatography at the National Food and Nutrition Institute (Warsaw); ‡ given by supplier listed under Table 2. Table 1. Fatty acid composition in dietary fats Fatty acids Saturated fatty acids Monounsaturated fatty acids Polyunsaturated fatty acids Linoleic acid (18:2n-6) Arachidonic acid (20:4n-6) α-Linolenic acid (18:3n-3) EPA (20:5n-3) DHA (22:5n-3) Total n-6 PUFA Total n-3 PUFA Lard† 42.6 50.3 6.5 6.3 — 0.2 — — 6.3 0.2 ROS production in the rat cerebral cortex, and Ronis et al. [12] have demonstrated increased liver membrane resistance to oxidative stress in rats fed high-fat diet. However, tissue differences in response to particular dietary fats are also likely [13]. In this study we investigated effect of saturated fatty acid rich lard on oxidative-antioxidative status in peripheral blood cells and plasma in comparition to PUFA- rich diets. Highly specialized erythrocytes (RBC), despite lacking mitochondria, are subject to free radical exposure due to the auto-oxidation of hemoglobin under high oxygen pressure in the arterial blood and abundant heme iron content. An increased intraerythrocytic ROS concentration results in erythrocytes’ membrane lipid peroxidation, acceleration of their senescence, and can cause damage to other intracellular protein [14]. Maintenance of the prooxidant-antioxidant balance in RBC is also important to other tissues since RBCs are the mobile detoxifying elements in the circulation [15], or when ROS diffuse out of them may be a reason of tissue microinjury [16]. Cellular glutathione (GSH) is non-protein thiol which together with associated enzymes forms the powerful antioxidant and detoxifying system. GSH is readily non-enzymatically oxidized to gluthatione disulfide (GSSG) in the presence of ROS, and the GSH/GSSG ratio is often used as an indicator of the cellular redox state [17]. Because dietary fats greatly modify erythrocyte membrane composition affecting their susceptibility to oxidation [4, 18], the GSH redox status in erythrocytes is an important para- meter of oxidative stress. In this study we investigated the effects of different fats in low-fat and high-fat diets on ROS generation by blood phagocytes, the GSH/GSSG ratio in erythrocytes, and total plasma antioxidant capacity in rats. Vol. 47, No. 1, 2010 Sunflower oil‡ % by weight 9.2 30.5 60.1 59.5 — 0.6 — — 59.5 0.6 Fish oil‡ 29.0 26.0 33.3 1.3 0.7 1.3 12.2 10.8 2.6 30.7 Materials and Methods Chemicals Ethylenediaminetetraacetic acid (EDTA), phorbol 12- myristate 13-acetate (PMA), luminol (5-amino-2,3-dihydro- 1,4-phthalazinedione), 5-sulphosalicilic acid, 5,5'-dithiobis- 2-nitrobenzoic acid (DTNB), glutathionee reductase (E.C.1.6.4.2.), β-nicotinamide adenine dinucleotide phos- phate reduced form (NADPH), reduced glutathione (GSH), 2-vinylpiridyne, 2,4,6-tripyridyl-s-triazyne (TPTZ), 1,1- diphenyl-2-picrylhydrazyl (DPPH), acetonitryl were pur- chased from Sigma-Aldrich Chemical (Poznan, Poland). All chemicals were of the analytical grade purity. Animals and diets Male Wistar rats (150–160 g) were housed in plastic boxes in the controlled animal facility on a 12 h light/dark cycle. The protocol of the experiment was approved by the Government Ethical Committee for Animal Care. After acclimatization, the rats were randomized into six dietary groups. Three control groups were fed low-fat diets (10% energy from fat) prepared with lard (composed mostly with monosaturated and saturated fatty acid), sunflower oil (SO), and fish oil (FO), and three groups were fed high-fat diets (40% energy from fat) compose of the same fats. The fish oil diets were supplemented with soybean oil to 10% of total fat content in the diet, to maintain adequate intake of essential n-6 PUFA. The fatty-acid composition of fats used to pre- pare the diets was analyzed by gas-liquid chromatography or given by a supplier, and summarised in Table 1. Purified diets were prepared once a week and kept in daily rations in sealed bags at −20°C. Their composition, caloric density and compound suppliers are presented in Table 2. Diets and tap water were provided ad libitum daily at 15.00 h. Food intake was recorded daily and corrected for spillage (±0.1 g). After