Antioxidant capacity of erythrocytes from sheep chronically poisoned by copper

Copper and Zinc Nutritional Issues for Agricultural Animal Production

Livestock have presented unique requirements and toxicity issues depending on the species for the various concentrations of Cu and Zn and their interactions with other nutrients especially Fe, Se, Mo, and S. Soil concentrations of these elements and their availability to crops influence the health of the crop and the amount found in vegetative tissues and seeds. Hence, many livestock issues are a result of the soils in the area where production is occurring (Loneragan et al. 1981). While water can provide minerals to animals, the amount consumed and availability are highly variable. Many discoveries about Cu were a result of low Cu concentrations and its availability due to interactions with other nutrients in the soils. Anemia, bone disorders, cardiovascular abnormalities, defective wool and hair, and infertility are signs/symptoms of Cu deficiency. Toxicity due to excess Cu is more likely to occur in sheep than other farm species. Swine are tolerant of high concentrations of dietary Cu, and it is often used as a growth stimulant in production. There are many species and physiological stages where the animal's Cu requirement is not known. Grazing animals can exhibit Zn deficiency when soils and forages contain limited concentrations of Zn. Pastures have been observed to be Zn-deficient in many parts of the world. However, non-ruminant animals usually receive adequate Zn when fed corn and soybean meal diets if there is not excessive Ca and Fe in their diets, but this is not true for rapidly growing young animals. Characteristics of a Zn deficiency include loss of appetite, reduced growth and reproduction, and impaired health of bone and skin tissues.

Copper signalling: causes and consequences

Copper-containing enzymes perform fundamental functions by activating dioxygen (O2) and therefore allowing chemical energy-transfer for aerobic metabolism. The copper-dependence of O2 transport, metabolism and production of signalling molecules are supported by molecular systems that regulate and preserve tightly-bound static and weakly-bound dynamic cellular copper pools. Disruption of the reducing intracellular environment, characterized by glutathione shortage and ambient Cu(II) abundance drives oxidative stress and interferes with the bidirectional, copper-dependent communication between neurons and astrocytes, eventually leading to various brain disease forms. A deeper understanding of of the regulatory effects of copper on neuro-glia coupling via polyamine metabolism may reveal novel copper signalling functions and new directions for therapeutic intervention in brain disorders associated with aberrant copper metabolism.

Influence of Dietary Curcumin, Capsaicin and Garlic on the Antioxidant Status of Red Blood Cells and the Liver in High-Fat-Fed Rats

BACKGROUND/OBJECTIVE

An animal study was carried out to examine the beneficial influence of known hypolipidemic spice principles - curcumin and capsaicin - and the spice garlic on the antioxidant status of red blood cells and liver tissue in hyperlipidemic rats.

METHODS

Rats were rendered hyperlipidemic by maintaining them on a high-fat (30%) diet for 8 weeks. Spice principles - curcumin (0.2%) or capsaicin (0.015%) - or garlic (2.0%) were included in the diets of separate animal groups. Erythrocytes isolated at the end of the study were analyzed for intracellular antioxidant molecules and antioxidant enzymes.

RESULTS

Intracellular total thiols in the erythrocytes of high-fat-fed rats were depleted significantly (16%). Similarly, the intracellular glutathione content in erythrocytes was depleted in high-fat-fed rats (28%). The concentration of lipid peroxides in the erythrocytes (intracellular as well as membrane) induced by H(2)O(2) was significantly higher in the high-fat-fed group. Curcumin (0.2%) or capsaicin (0.015%) or garlic (2.0%) in the diet which produced the hypotriglyceridemic effect were also effective in reducing oxidant stress, which was indicated by a significant countering of the depleted intracellular antioxidants - total thiols and glutathione - and elevated lipid peroxides in erythrocytes. The elevated lipid peroxide in blood plasma due to the high-fat diet was also significantly countered by the spice treatments. The severely depleted hepatic glutathione in high-fat treatment was also effectively reversed by dietary curcumin, capsaicin and garlic.

CONCLUSIONS

Thus, dietary hypolipidemic spices were effective in reducing the oxidant stress, which was indicated by countering the depleted antioxidant molecules and antioxidant enzymes in erythrocytes and liver, and decreasing the elevated lipid peroxide content.

Glucose-6-phosphate dehydrogenase activity in erythrocytes from chronically copper-poisoned sheep

The present study was undertaken to investigate the capacity to generate reducing equivalents in erythrocytes from experimentally copper-poisoned sheep. Ten ewes were dosed orally with CuSO4 to induce the Cu toxicity. Copper dosing was stopped at the first day of hemolysis. The activity of glucose-6-phosphate dehydrogenase (G6PD) in the erythrocytes, the levels of reduced glutathione (GSH) and glucose (in serum and erythrocytes) was examined at frequent intervals. The copper-poisoned sheep had reduced levels (25-35% less) of glucose in serum and erythrocytes than controls. The activity of G6PD in erythrocytes from sheep was 50-60% of typical levels found in human erythrocytes. Immediately before the hemolytic period, the copper-poisoned sheep showed decreased activity of G6PD, declining to 65% of the initial activity. In addition, we found decreased blood levels of reduced GSH in copper-poisoned sheep. There appears to be a relationship between decreased capacity to generate reducing equivalents and the overload of copper in sheep erythrocytes.