Copper deficiency in rats increases pancreatic enkephalin-containing peptides and insulin

Effect of dietary copper addition on lipid metabolism in rabbits

The present study was conducted to investigate the effect of copper supplementation on lipid metabolism in rabbits. Our study showed dietary copper addition (5-45 mg/kg) increased body mass gain, but decreased fat and liver weights compared with those in the control group (P < 0.05). Copper (45 mg/kg) addition significantly increased the skeletal muscle weight, but inhibited cytoplasmic lipid accumulation in liver, skeletal muscle and adipose tissue (P < 0.05). Compared with the control group, dietary copper addition (45 mg/kg) significantly increased plasma triglyceride levels but decreased very low density lipoprotein levels (P < 0.05). Copper treatment significantly increased gene expression of carnitine palmitoyltransferase (CPT) 1, CPT2 and peroxisome proliferator-activated receptor (PPAR) a in liver (P < 0.05). In skeletal muscle, CPT1, CPT2, fatty acid transport protein, fatty acid-binding protein, and PPARa mRNA as well as phosphorylated AMP-activated protein kinase (AMPK) levels were significantly up-regulated by copper treatment (P < 0.05). Rabbits receiving copper supplementation had higher CPT1, CPT2, PPARa and hormone-sensitive lipase mRNA levels in adipose tissue (P < 0.05). In conclusion, copper promoted skeletal muscle growth and reduced fat accretion. PPARa signaling in liver, skeletal muscle and adipose tissues and AMPK signaling in skeletal muscle tissue were involved in the regulation of lipid metabolism by copper.

Hepatic fructose-metabolizing enzymes and related metabolites: role of dietary copper and gender

The purpose of this study was to further examine the hypothesis that variations in hepatic fructose-metabolizing enzymes between males and females might account for the differences in the severity of copper (Cu) deficiency observed in fructose-fed male rats. Weanling rats of both sexes were fed high-fructose diets either adequate or deficient in copper for 45 days. Cu deficiency decreased sorbitol dehydrogenase activity and dihydroxyacetone phosphate levels and increased glyceraldehyde levels in both sexes. Gender effects were expressed by higher activities of glycerol 3-phosphate dehydrogenase and aldehyde dehydrogenase in male than in female rats and higher levels of dihydroxyacetone phosphate and fructose 1,6-diphosphate (F1,6DP) in female than in male rats. The interactions between dietary Cu and gender were as follows: alcohol dehydrogenase activities were higher in female rats and were further increased by Cu deficiency in both sexes; aldehyde dehydrogenase activities were decreased by Cu deficiency only in male rats; sorbitol levels were higher in male rats and were further increased by Cu deficiency in male rats; fructose 1-phosphate (F1P) levels were increased by Cu deficiency in both sexes, but to a greater extent in male rats; glyceraldehyde 3-phosphate levels were higher in female rats, but were decreased by Cu deficiency in female and increased in male rats. Though most of the examined hepatic fructose-metabolizing enzymes and metabolites showed great differences between rats fed diets either adequate or deficient in Cu, it is the activity of fructokinase and aldolase-B, and the concentrations of their common metabolites, F1P and notably F1,6DP, that could be in part responsible for differences in the severity of pathologies associated with Cu deficiency observed between female and male rats.

Early and advanced glycation end-products are increased in dietary copper deficiency

The hypothesis that nonenzymatic glycosylation of proteins (glycation) contributes to damage associated with dietary copper deficiency has depended largely on indirect evidence. Thus far, the observation of an elevated percentage of glycated hemoglobin in copper-deficient rats has provided the only direct evidence of an increase in glycation. We sought further direct evidence of increased glycation in copper deficiency. Male weanling rats were fed a copper-adequate (CuA, 6.4 mg Cu/kg diet) or copper-deficient diet (CuD, 0.4 mg Cu/kg diet) for 5 weeks. Rats fed the CuD diet were copper deficient as judged by depressed organ copper concentrations and a variety of indirect indices. Measurements of hemoglobin A(1) and serum fructosamine (both early glycation end-products) as well as serum pentosidine (an advanced glycation end-product) indicated that all three compounds were elevated in CuD rats relative to CuA rats. This finding further supports the view that glycation is enhanced and thus may contribute to defects associated with dietary copper deficiency.

Cardiovascular effects of dietary copper deficiency

Dietary copper deficiency may impair cardiovascular health by contributing to high blood pressure, enhancement of inflammation, anemia, reduced blood clotting and arteriosclerosis. The purpose of this review is to compile information on the numerous changes of the heart, blood and blood vessels that may contribute to these cardiovascular defects. These alterations include weakened structural integrity of the heart and blood vessels, impairment of the use of energy by the heart, reduced ability of the heart to contract, altered ability of blood vessels to control their diameter and to grow, and altered structure and function of circulating blood cells. The fundamental causes of these changes rest largely on reduced effectiveness of enzymes that depend on copper for their activity.

Nutritional factors adversely influencing the glucose/insulin system

For the majority of people, particularly if they do not smoke, the food they eat is the largest controllable factor determining their long-term health. The disproportionate consumption of foods high in fat, especially high in saturated fat, and high in simple sugars at the expense of foods high in complex carbohydrate and unsaturated fat has the potential of inducing abnormal metabolic processes in a normal healthy individual and to promote chronic degenerative diseases. Some of the effects of individual macronutrients such as fat, refined sugars and alcohol in promoting abnormalities in glucose/insulin system are presented. These nutrients were chosen because they also have the ability to alter oxidative state of the individual, which in turn could affect the glucose/insulin system. This review focuses on the role of dietary nutrient interactions in influencing the glucose/insulin system through the generation of reactive oxygen species. The importance of dietary macronutrient interaction with micronutrients such as copper and iron and the potential it has in affecting the glucose/insulin system is addressed.

Benfluorex, a hypotriglyceridemic drug, reduces lipid peroxidation and alleviates adverse metabolic complications of copper deficiency

The pathologies associated with copper deficiency in rats fed fructose may be induced, in part, by hypertriglyceridemia and lipid peroxidation. Reducing triacylglycerol levels in plasma may result in lowering lipid peroxidation, which in turn could ameliorate metabolic effects resulting from the combination of fructose feeding and copper deficiency. Benfluorex, a hypolipidemic factor able to reduce hypertriglyceridemia, was administered to weanling male rats fed either copper-deficient (0.6 microgram Cu/g) or adequate (6.0 micrograms Cu/g) diets containing fructose as the sole dietary carbohydrate. In copper-deficient rats, benfluorex (50 micrograms.kg-1.d-1) reduced plasma triacylglycerols from 45 to 31 mg/dL, reduced lipid peroxidation by approximately 50%, and prevented the enlargements of heart and liver size and the atrophy of the pancreas, and ameliorated anemia. It is suggested that lipid peroxidation associated with hypertriglyceridemia may be responsible for the pathologies induced by the combination of fructose consumption and copper deficiency.

Hepatic iron overload may contribute to hypertriglyceridemia and hypercholesterolemia in copper-deficient rats

The present study was conducted in order to determine whether hepatic iron retention in rats fed a copper-deficient diet containing fructose is associated with hypertriglyceridemia and hypercholesterolemia, and whether a reduction of iron intake will prevent elevation of blood triglycerides and cholesterol. Rats were fed from weaning either a copper-deficient (0.6 microgram Cu/g) or copper-adequate (6.0 micrograms Cu/g) diet for 4 weeks. Half the rats consumed either an adequate level of iron (50 micrograms Fe/g) or a low level (17 micrograms Fe/g). Reduction of iron intake reduced blood levels of both triglycerides and cholesterol in rats fed a copper-deficient diet containing fructose. In addition, hepatic lipid peroxidation was also decreased. The combination of high iron, low copper, and fructose may be responsible for increased levels of risk-factor metabolites associated with heart disease.

Responses of insulin to oral glucose and fructose loads in marginally copper-deficient rats fed starch or fructose

The purpose of this study was to assess the effects of dietary fructose either alone or in combination with marginal copper deficiency in weanling male rats exposed to their respective diets for only 2 wk. This short duration of exposure to inadequate copper intake prevents progressive morbidity brought about by increasing periods of exposure to dietary copper deprivation. Weanling male rats were fed a copper-deficient (0.6 microgram Cu/g) or a copper-adequate (6.0 micrograms Cu/g) diet containing 62% fructose or 62% starch for 2 wk. Either an oral glucose or an oral fructose tolerance test was conducted after an overnight fast. Insulin levels were elevated by either oral glucose or oral fructose at fasting and at 30 min postload in rats fed fructose compared with those fed starch. Despite high levels of plasma, insulin blood glucose was not reduced. Marginal copper deficiency had no effect on either plasma insulin or blood glucose. Data identify fructose as the sole agent responsible for inducing adverse changes in glucose metabolism. Two weeks of fructose consumption was sufficient to produce these changes.

Fructose metabolizing enzymes in the rat liver and metabolic parameters: Interactions between dietary copper, type of carbohydrates, and gender

This study was conducted to determine the effects of nutrient interactions between dietary carbohydrates and copper levels on fructose-metabolizing hepatic enzymes in male and female rats. Male and female rats were fed diets for 5 weeks that were either adequate or deficient in copper that contained either starch or fructose. Rats of both sexes fed fructose as compared with those fed starch showed higher activity of hepatic fructose metabolizing enzymes. There were also significant differences in fructose metabolism of liver between the male and female rats. Female rats had lower hepatic ketohexokinase and triose kinase but higher triosephosphate isomerase activities compared with male rats. Male rats fed copper-deficient diets had lower aldolase B activity compared with those fed copper-adequate diets. Female rats fed copper-deficient diets had higher triosephosphate isomerase activity compared with rats fed copper-adequate diets. Our data suggest that gender differences in hepatic fructose metabolism may not be the primary reason for the severity of copper deficiency syndrome in male rats fed copper-deficient diet with fructose.

Alcohol consumption mimics the effects of a high-fructose, low-copper diet in rats

The consumption of a high-fructose diet that is inadequate in copper produces numerous pathologies which eventually lead to the mortality of the animals. In contrast, the consumption of a high-starch diet that is inadequate in copper does not produce abnormalities and the animals survive. Ethanol has been chosen as an agent to mimic the fructose effect in copper deficiency. The administration of 20% ethanol in the drinking water of rats fed a starch-based diet that was inadequate in copper resulted in a depressed growth rate, anemia, pancreatic atrophy, and heart hypertrophy. All these signs were similar to the signs exerted by fructose feeding when it was combined with copper deficiency. Polyol pathway in the liver and kidney was affected by both ethanol and fructose consumption. Ethanol did not aggravate the signs associated with copper deficiency in rats fed fructose, but it exacerbated the signs associated with copper deficiency in rats fed starch. Certain metabolic pathways that are unique for fructose and ethanol may be responsible for the exacerbation of copper deficiency.

Garlic oil extract ameliorates the severity of copper deficiency

This study was undertaken to determine whether a reduction in hepatic lipogenesis would be beneficial in the amelioration of copper (Cu) deficiency when fructose is fed. Garlic was chosen as the agent for reducing hepatic lipogenesis. Forty-eight weanling rats were fed Cu-deficient or adequate diets containing fructose or starch with or without garlic for 5 weeks. Garlic ameliorated the signs associated with Cu deficiency, although hepatic lipogenesis was not affected. Administration of garlic reduced the activity of the lipogenic enzyme glucose-6-phosphate dehydrogenase only in Cu-adequate rats. Consumption of garlic resulted in increased epididymal fat pad and pancrease sizes, and higher hematocrits, insulin and thyroxine concentrations. Mechanisms other than lipogenesis that could be responsible for this phenomenon are discussed.

Simultaneous extraction of beta-endorphin and leu- and met-enkephalins from human and rat plasma

A simple, rapid and reliable procedure is described to simultaneously concentrate and purify beta-endorphin, leu- and met-enkephalins from small volumes of human and rat plasma before radioimmunoassay is performed. It uses C18 Sep-Pak reverse phase cartridges. The effectiveness of different protease inhibitors in preventing degradation of opiates by plasma and different solvent systems for eluting opiates is also evaluated.