D. A. Safi

Hormonal regulation of superoxide dismutase, catalase, and glutathione peroxidase activities in rat macrophages

This study examined the effects of glycocorticoids, insulin, thyroxine, and epinephrine upon the activities of CuZn- and Mn-superoxide dismutases (SOD), catalase, and glutathione peroxidase (GPX) and upon hydrogen peroxide production in rat macrophages obtained from the intraperitoneal cavity. The experiments were performed in vivo under conditions causing hormonal dysfunctions: adrenal demedullation, dexamethasone treatment, thyroidectomy, administration of L-tri-iodothyronine (T3) and L-thyroxine (T4), and diabetes. Macrophages were also cultured for 24 hr in the presence of dexamethasone, thyroid hormones, and insulin as to evaluate possible interferences caused in vivo by changes in other hormones. The results indicated that these hormones do control the activities of the antioxidant enzymes and hydrogen peroxide production both in vivo and in vitro. Insulin increased the activities of CuZn-SOD, catalase, and GPX and reduced that of Mn-SOD. Thyroid hormones raised the activities of CuZn- and Mn-SOD and decreased that of GPX, whereas glucocorticoids reduced both Mn-SOD and GPX. The removal of the adrenal medulla caused a decrease of Mn-SOD and GPX activities in the macrophages. Hydrogen peroxide production was increased by insulin and reduced by thyroid hormones and glucocorticoids. The changes in antioxidant enzyme activities caused by these hormones in macrophages may indicate important mechanisms for the establishment of impaired immune function in endocrine pathologies.

Superoxide dismutase, catalase, and glutathione peroxidase activities in muscle and lymphoid organs of sedentary and exercise-trained rats

The effect of swimming-training upon the activities of the enzymes involved in the generation of reducing-equivalents (citrate synthase-mitochondria and glucose-6-phosphate dehydrogenase-cytosol) and of antioxidant enzymes (CuZn- and Mn-SOD, catalase and glutathione peroxidase) in the lymphoid organs (thymus, mesenteric lymph nodes and spleen) was examined. The skeletal muscles (soleus-red and gastrocnemius-white) were also studied. Although our data suggest an apparently random, organ-specific change in enzymatic activity, some interesting trends can be observed. Firstly, the increased citrate synthase and Mn-SOD activities observed in red, but not in white muscle, corroborate the well-known effect of endurance exercise-training on mitochondrial oxidative metabolism. Secondly, there was an inverse relationship between TBARs-monitored lipoperoxidation and glutathione peroxidase activity in all tissues studied, what is in accordance with the previous findings showing that such enzyme exerts the fine control of intracellular lipoperoxide concentration. Except in the case of the spleen, there was a trend for elevated glucose-6-phosphate dehydrogenase activity, coadjuvant of glutathione peroxidase in the antioxidant response to physical exercise in all tissues. Thirdly, Mn-SOD and catalase were conspicuously associated to oxidative stress in the thymus, while glutathione and catalase could be linked to this parameter in the spleen. Fourthly, the lymph nodes seem to be more dependent on the glucose-6-phosphate dehydrogenase/glutathione peroxidase pair for protection against damage promoted by physical exercise. Mn-SOD and catalase activities were lower in the lymph nodes after swimming training.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of epinephrine on glucose metabolism and hydrogen peroxide content in incubated rat macrophages

The effects of epinephrine on glucose metabolism and hydrogen peroxide content were examined in incubated rat macrophages. An increase in the activities of hexokinase and citrate synthase and a reduction in that of glucose-6-phosphate dehydrogenase was found in resident, inflammatory and activated macrophages incubated for 1 hr in the presence of epinephrine. Glucose utilization by incubated resident, inflammatory and activated macrophages was augmented markedly by the addition of epinephrine, whereas lactate formation was depressed. Under the same conditions, there was a 2.6-fold increment of hydrogen peroxide content and of [U-14C]glucose decarboxylation in activated macrophages incubated for 40 min. Similar results were obtained when pyruvate and oxoglutarate was substituted for glucose. These findings suggest that epinephrine may increase hydrogen peroxide production in activated macrophages possibly through a mitochondrial mechanism other than the pentose-phosphate pathway. Between 40 and 90 min of incubation, the content of hydrogen peroxide decreased markedly, and there was no detectable glucose utilization in the presence of epinephrine. These observations are consistent with the idea that this catecholamine stimulates both hydrogen peroxide production and metabolism, the first process being dependent on mitochondrial fuels.

Metabolic and functional changes in lymphocytes and macrophages as induced by ageing.

Key enzyme activities of glycolysis, pentosephosphate pathway, Krebs cycle, and glutaminolysis were measured in lymphocytes and macrophages of 3- and 15-month-old rats from the control, thioglycollate-injected, and Walker 256 tumor-implanted groups. The percentage of phagocytosis, phagocytic index, and production of H2O2 in macrophages and the rates of [2-14C]-thymidine and [5-3H]-uridine incorporation in cultured lymphocytes were also determined. The results indicate that the percentage of phagocytosis was not affected but the phagocytic index increased by twofold as a consequence of ageing, whereas the production of H2O2 reduced. The rates of both [2-14C]-thymidine and [5-3H]-uridine incorporation in lymphocytes from aged rats were lower as compared to those of mature animals in the three groups. Taken as a whole, the results of enzyme activities suggest that ageing may reduce the capacity for glucose utilization in lymphocytes and macrophages under the three conditions. Lymphocyte and macrophage glutamine metabolism was not markedly affected by ageing. Therefore, an impaired glucose metabolism during ageing may be one important mechanism for the alteration in lymphocyte proliferation and macrophage phagocytosis observed and also for the modification of the response to inflammatory and tumor challenges.

Antioxidant enzyme activities in the lymphoid organs and muscles of rats fed fatty acids-rich diets subjected to prolonged physical exercise-training.

Rats weighing 45-50 g were fed 3 diets for 8 wk: a balanced control diet (CD) consisting of 4% fat (polyunsaturated/saturated fatty acids [P/S] ratio 2.9/1) and two fat-rich diets: polyunsaturated (UD)--P/S 7.6/1 and saturated (SD) P/S 0.3/1. After 8 wk feeding on the respective diets, rats were subjected to swimming for 90 min at 30 degrees C daily, 5 d/wk for 8 wk. At the end of this period, the rats were killed and the lymphoid organs (LO--thymus, spleen, and mesenteric lymph nodes) and muscles (soleus and gastrocnemius) removed for the measurement of TBARs (Thiobarbituric Acid Reactant Substances) content and of the activities of antioxidant enzymes (CuZn- and Mn-Superoxide dismutase--SOD--, catalase, and glutathione peroxidase). To evaluate the changes in the sites of generation of reducing equivalents involved in the formation of free radicals, the activities of citrate synthase and glucose-6-phosphate dehydrogenase were measured. The exercise-training clearly modified the enzyme activities and TBARs content of the lymphoid organs and skeletal muscles, but this effect was dependent upon the diet given to the rats. However, fatty acid rich diets had presented a more pronounced effect on the studied aspects than did physical activity. Although one could expect a summatory effect of polyunsaturated fatty acid-rich diet and exercise-training, swimming increased the activities of CuZn- and Mn-SOD in almost all tissues from the elevated level promoted by fat-rich diets.

The effect of N-3 PUFA rich diet upon macrophage and lymphocyte metabolism and function.

A large body of evidence from experimental studies has documented that n‐3 fatty acids can modify a variety of cell functions and disease states. As lymphocytes and macrophages are important cells for the development of the inflammatory and non‐inflammatory immune response and are known to utilize high rates of glucose and glutamine, we have evaluated the effect of n‐3 PUFA rich diet on the metabolisation of glucose and glutamine these cells, as well as the effect of one such diet upon the proliferative response of lymphocytes and the phagocytic capacity and hydrogen peroxide production by macrophages. The diet provoked an increase in the flux of glucose through the Krebs cycle in macrophages as well as a reduction in G6PDh and glutaminase activity in these cells. Lymphocytes from n‐3 PUFA rich diet‐fed rats showed a reduction in glucose and glutamine decarboxylation. Taken together the data show that, at least in part, the functional changes observed in macrophages and lymphocytes from n‐3 PUFA‐rich diet fed rats are related to the effect of this diet upon glucose and glutamine metabolism, leading to immunosupression