Effect of dietary fat and alpha-tocopherol administration on the susceptibility to oxidative damage of rabbit jejunal mucosa

Forty-eight Californian x New Zealand 3-week-old white rabbits were fed on diets containing non-added far (NF), 3 % olive oil (OL) or 3 % sunflower oil (SUN) with either a basal (10 mg/kg feed) or supplemented (200 mg/kg) level of alpha-tocopherol acetate. Polyunsaturated fatty-acid concentration was higher in animals fed the NF or SUN diets than in those fed the OL diets (p < 0.05). There were differences between the NF and the SUN groups in the relative proportion of each fatty acid. Animals fed the SUN diets had a higher concentration of n-6 fatty acids (particularly C18:2, p < 0.05) and lower proportion of n-3 fatty acids (C18:3, p < 0.05) than animals receiving the NF diets. The phospholipid classes of jejunal mucosa did nor show any differences between groups. The ratio phospho photidylcholine/phosphatidyl ethanolamine was 1.18 in animals receiving non-far-enriched diets and 0.72 and 0.54 in animals receiving OL and SUN respectively. This may be important, since higher ratios are related to membrane fluidity. Mucosa homogenate from rabbits fed the NF and SUN diets were significantly more susceptible to iron-induced lipid oxidation than homogenate from animals receiving OL diets (p < 0.001). In all cases, dietary supplementation with alpha-tocopherol considerably reduced mucosa oxidation (p < 0.001).