Effect of dietary vitamin E supplementation on macrophage metabolism during ageing. Study in rats fed fat-rich diets during ageing.

The effect of dietary vitamin E supplementation upon macrophage metabolism and function was examined in aged rats fed a balanced or a polyunsaturated-rich diet. The following parameters were studied: number of cells in the intraperitoneal cavity, maximal activity of hexokinase, citrate synthase, glucose-6-phosphate dehydrogenase, glutathione peroxidase and phosphate-dependent glutaminase. The consumption of glucose and the production of lactate, hydrogen peroxide and thiobarbituric reactive substances were measured in control ONCO-BCG injected rats. The results indicated that vitamin E has no significant effect on the values of the parameters studied in the macrophages of rats fed a balanced diet both for 3 (mature) or 17 months (aged). This antioxidant did not provoke any response on the changes caused by ageing the animals. However, several of the metabolic and functional alterations in macrophage induced by the polyunsaturated-rich diets were reversed by the inclusion of vitamin E in the diet. These changes were associated with macrophage migration capacity, citrate synthase and glucose-6-phosphate dehydrogenase activities and the content of lipid peroxides. The findings suggest that vitamin E has a beneficial effect for macrophage metabolism and function, but the effects are confined to particular circumstances.

Metabolic changes in lymphoid organs as induced by fatty acids-rich diets during ageing.

Previous reports of our laboratory have shown that w-6 PUFA-rich diets (UC) given to rats during 6 weeks causes important changes of the metabolism of the lymphoid organs. In this study, the effect of saturated fatty acids-rich diet (SC) and also the persistence of the changes caused by (UC) were investigated during ageing (14 months). The major changes previously reported for UC fed rats, during 6 weeks, fully persisted when this feeding condition was maintained for 14 months. Moreover, the SC group also showed modifications of the activities of key enzymes of glucose and glutamine metabolism of the lymphoid organs with ageing. Both groups fed fatty acids-rich diets markedly reduced the rate of lipogenesis in the liver, spleen, and thymus in contrast to slight changes reported for 6 weeks. These results suggest that fatty acids-rich diets, by causing important metabolic alterations, may pronounce the impairment of the immune function observed during ageing.

Effect of polyunsaturated (PUFA n-6) and saturated fatty acids-rich diets on macrophage metabolism and function.

Previous reports of our laboratory have shown that PUFA (n-6)-rich diets cause important changes of the metabolism of the immune tissues. In this study, alterations of macrophage metabolism and function were examined in rats fed polyunsaturated (UC) or saturated (SC) fatty acids-rich diets during 6 weeks. The UC group decreased intraperitoneal cell migration and macrophage phagocytosis. These changes were related to modifications of macrophage metabolism. The UC group showed also increased G-6-PDh in inflammatory macrophages. These findings suggest that pentose-phosphate pathway is not the unique metabolic factor to control phagocytosis. PUFA-rich diet reduced glutaminase activity. Therefore, this amino acid might be one of the possible metabolic reasons for the impaired macrophage function observed.

Polyunsaturated and saturated fatty acids-rich diets and immune tissues. 1. Fresh weight, DNA content, percentage of lipids and rate of lipogenesis from 3H2O in thymus, spleen and mesenteric lymph nodes.

It has been widely reported that polyunsaturated fatty acids-rich diets (PUFA n-6) cause immunodeficiency. In this study, fresh weight, DNA and lipid content and rate of lipogenesis from 3H2O of thymus, spleen, mesenteric lymph nodes and liver were assessed in rats fed polyunsaturated (UC) or saturated (SC) fatty acids-rich chows. The results obtained indicate that both types of fatty acids caused similar increment of lipid content in the immune tissues. The rate of lipogenesis was decreased only in the thymus of (UC) rats and liver of both experimental groups as compared to control rats. The results of fresh weight and DNA content was decreased only by (UC) diet.

Polyunsaturated and saturated fatty acids-rich diets and immune tissues. 2. Maximal activities of key enzymes of glutaminolysis, glycolysis, pentose-phosphate-pathway and Krebs cycle in thymus, spleen and mesenteric lymph nodes.

It has been widely reported that polyunsaturated fatty acids (PU-FA n-6) in the diet lead to immunosuppression. In the present study, the activity of key enzymes several metabolic pathways were measured in the immune tissues of rats fed polyunsaturated (UC) or saturated fatty (SC) acids-rich diets. The following enzyme activities were measured: hexokinase, citrate synthase, glucose-6-phosphate dehydrogenase, glutaminase and malic enzyme. The metabolism of immune tissues was markedly changed by the fat content of the diet. However, UC diet determined more significant metabolic changes than SC diet.