RESUMO
Dietary selenium, vitamin B6 and fatty acids modulate both tissue acyl composition by regulating polyunsaturated fatty acid metabolism and antioxidant defences by influencing glutathione peroxidase activity. Alteration in the intake of one of them could therefore lead to different results depending on the intake of the others. To clarify this complex relationship, in the present study we have evaluated the modifications occurring in fatty acid composition and glutathione peroxidase activity in total liver and liver microsomes of rats fed diets containing the same amount of selenium, but different vitamin B6 content and fatty acid composition. Our data indicate that both acyl composition and glutathione peroxidase activity are greatly influenced not only by vitamin B6 deficiency, but also by the diet unsaturation degree. This study underlines that not only selenium availability but also other nutrients can modulate glutathione peroxidase activity.
Assuntos
Gorduras na Dieta/administração & dosagem , Ácidos Graxos/administração & dosagem , Glutationa Peroxidase/metabolismo , Lipídeos/química , Fígado/metabolismo , Deficiência de Vitamina B 6/metabolismo , Vitamina B 6/administração & dosagem , Animais , Gorduras na Dieta/metabolismo , Ácidos Graxos/análise , Ácidos Graxos Insaturados/administração & dosagem , Ácidos Graxos Insaturados/análise , Metabolismo dos Lipídeos/efeitos dos fármacos , Metabolismo dos Lipídeos/fisiologia , Fígado/enzimologia , Masculino , Microssomos Hepáticos/enzimologia , Microssomos Hepáticos/metabolismo , Distribuição Aleatória , Ratos , Ratos Wistar , Selênio/metabolismoRESUMO
Our previous report demonstrated that, when vitamin deficiency is associated with high contents of long chain polyunsaturated fatty acids (LCPUFA) n3, lipid peroxidation susceptibility in rat heart and liver increases. In this paper, we evaluated the effect of the same dietary administration on lipid composition and antioxidant defenses of rat kidney. Results showed that vitamin B(6) deficiency, when associated with a fish oil diet, as compared to vegetable oil condition, increased relative kidney weight and decreased pyridoxal-5P contents. The different LCPUFA n3 dietary contents produced, on kidney phospholipids, effects interlaced with those of vitamin B(6) deficiency; in particular fish oil and vitamin B(6) deficient diet caused a significant decrease of arachidonic acid showing that the processes of elongation and desaturation of linoleic acid were slowed. Also, peroxidation susceptibility was higher, as demonstrated both by increased TBARS formation and glutathione peroxidase activity, and by decreased vitamin E contents and reduced glutathione/oxidized glutathione ratio.