The effects of dietary verbascoside on blood and liver oxidative stress status induced by a high n-6 polyunsaturated fatty acids diet in piglets

Twenty-four weaned female Hypor piglets (mean BW 10.9 ± 0.1 kg) were used to evaluate the antioxidant effect of a natural extract, titrated in verbascoside, on blood and liver oxidative status in relation to a high intake of n-6 polyunsaturated fatty acids (PUFA), inducing oxidative stress. Piglets were assigned to 1 of 3 experimental groups: the first group was fed a diet with 9% sunflower oil (T1), the second received the sunflower oil diet supplemented with 5 mg of verbascoside/kg feed form Verbenaceae extract (Lippia spp.) (T2). The third group was fed a control diet (CTR), where an isoenergetic replacement of oil by starch was done. Blood samples were collected at the beginning and the end of the trial (30 d). At the end of the trial, the animals were slaughtered and the liver specimens were collected. Oxidative stress markers, including total antiradical activity, superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase (CAT) activities were determined in blood samples. Alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyl transferase (GGT) plasma levels were also evaluated. Immunohistochemistry and Western blot analyses were performed in liver to evaluate Heat Shock Protein (Hsp) 70, Hsp 90, Kupffer and Ito cell activation. Liver activities of SOD, GPX and CAT were also determined. Total antiradical activity in blood and red blood cells were affected (P < 0.01) by dietary treatments. The n-6 PUFA supplementation at a high dosage for 30 d, induced oxidative stress, decreasing total antiradical activity in blood and red blood cells (CTR vs T1+T2, P < 0.01) and plasma CAT activity (CTR vs T1+T2, P = 0.088) and increasing ALT value (CTR vs T1+T2, P < 0.01). Also in liver, the CAT and GPX activities tended to be lower in pigs fed n-6 PUFA diets than pigs fed a control diet (CTR vs T1+T2, P = 0.090 and P = 0.085 respectively). The liver samples presented a normal architecture and no Ito and Kupffer cell activations were observed. In liver, the SOD activity tended to be lower in T1 group (P = 0.064) than CTR and T2. Moreover, the level of Hsp 70 was higher (P<0.01) in T1 group than control and T2. These data suggest that the dose of dietary verbascoside partially restores the antioxidant status of the liver, without affecting the systemic responses to oxidative stress, induced by a high fat diet.