Anemia plays a major role in myocardial hypertrophy of copper deficiency.

The present study was undertaken to establish whether anemia plays a role in the cardiomegaly and myocardial pathology of copper deficiency. Fifteen weanling male rats were fed a copper-deficient (0.6 microgram Cu/g) diet for 5 weeks. Six rats were intraperitoneally injected once a week with packed red blood cells (RBC) that were obtained from copper-deficient rats fed starch. The remainder (n = 9) served as controls. The administration of RBC to copper-deficient rats fed fructose prevented the anemia. As a result, none of the injected rats exhibited heart hypertrophy or gross pathology and they all survived. In contrast, all other control, nontreated copper-deficient rats that were fed fructose were anemic and all exhibited severe signs of copper deficiency, which included heart hypertrophy with gross pathology, and four died of the deficiency. The data suggest that the anemia of copper deficiency contributes to heart pathology. Once the anemia is prevented, the copper-deficient rats should be protected against heart pathology and mortality.     

The influence of dietary carbohydrate and deferoxamine on developing copper deficiency of rats.

The present investigation was conducted to follow the development of copper deficiency in male rats from weaning (day 0) to day 31 of dietary copper deprivation and to correlate changes in tissue sizes with copper and iron concentrations. Male rats were fed for 31 days from weaning copper-deficient or adequate diets containing fructose or starch. Another copper-deficient group of rats that was fed fructose was treated with deferoxamine. Rats were killed at day 0, 8, 16, 24, and 31 of the study. In general, no correlation could be found between the development of heart hypertrophy, pancreatic and thymic atrophy, and tissue copper concentrations in copper-deficient rats fed fructose. In contrast, in the heart and pancreas a negative correlation existed between tissue size and iron concentration. In addition, anemia preceded heart hypertrophy. Deferoxamine lowered hepatic iron concentrations, ameliorated the anemia, and decreased heart size compared with untreated rats. The data of the present study suggest that tissue atrophy and hypertrophy and the severity of copper deficiency are not solely due to tissue concentrations of iron and/or copper.     

Copper deficiency in pregnancy: effect on maternal and fetal polyol metabolites

The present study was undertaken to determine whether the mortality of the fetus and the neonate of copper-deficient rats consuming fructose during pregnancy is associated with an aberration in carbohydrate metabolism. A total of 84 Sprague-Dawley rats were fed a copper-deficient or a copper-adequate diet containing fructose or starch for 19 or 21 days after conception. The consumption of a fructose-based diet during pregnancy resulted in higher concentrations of maternal blood fructose, sorbitol, triglyceride, and uric acid when compared with a starch diet. The placenta contained more than 10-fold the concentration of glucose and more than double the concentrations of fructose, triglycerides, and sorbitol when fructose was the dietary carbohydrate compared with starch. The livers of fetuses belonging to the fructose dietary group exhibited high concentrations of glucose and sorbitol. In addition, fetal blood contained higher concentrations of glucose, fructose, sorbitol, and triglycerides than the corresponding values from the starch dietary group. The consumption of a copper-deficient diet containing fructose during pregnancy resulted in massive subcutaneous hemorrhages of the fetus. In contrast, this pathology was rare in other dietary groups. The combination of copper deficiency with fructose feeding resulted in more than double the concentration of sorbitol in fetal liver, and higher concentrations of insulin and dopamine of fetal blood compared with the consumption of a copper-deficient diet containing starch.(ABSTRACT TRUNCATED AT 250 WORDS)     

Dietary fructose exacerbates the cardiac abnormalities of copper deficiency in rats

Copper deficiency has been shown to result in severe cardiovascular lesions in several species of animals. The principal carbohydrate in the copper-deficient diet most often used with rats is sucrose, which is known to have adverse effects on carbohydrate and lipid metabolism and thus may contribute to cardiovascular disorders. These observations prompted experiments in which starch and fructose were substituted for sucrose in a copper-deficient diet, to see if the effects of the copper deficiency might be modified. In the hearts from rats fed copper-deficient diets with fructose or sucrose, there was marked, mostly ventricular hypertrophy, and mild to severe myocardial inflammation, degeneration, and fibrosis. Aneurysm of the left ventricle and pericarditis also were common. Hearts from the starch, copper-deficient groups were much less hypertrophic, and very few were affected by myocardial inflammation, degeneration, or fibrosis. Defects of elastin or other structures were not observed in the aortas or pulmonary or coronary arteries of any specimens.     

The role of the adrenals in copper deficiency

The present study was undertaken in order to establish whether (1) a decrease in catecholamines will prevent the heart hypertrophy of copper deficient rats fed fructose, and (2) an increase in hepatic copper concentration will ameliorate the signs associated with copper deficiency when fructose-based diets are consumed. Adrenalectomy resulted in reduced plasma glucocorticoids and a threefold increase in hepatic copper concentration. The signs associated with the deficiency were not ameliorated in rats fed fructose. In addition, the reduction in catecholamine concentration did not protect the copper-deficient rats fed fructose against cardiomegaly and mortality. The data support the contention that the severity of copper deficiency in rats fed fructose is not solely dependent on hepatic copper concentration and/or levels of catecholamines.     

Accumulation of sorbitol in copper deficiency: dependency on gender and type of dietary carbohydrate

The present study was designed to examine tissue sorbitol levels in copper-deficient rats consuming dietary fructose as the only source of carbohydrate and to determine if any changes in tissue sorbitol levels are influenced by the sex of the rat. Tissue levels of glucose, sorbitol, fructose, and glyceraldehyde were measured along with the activities of aldose reductase and sorbitol dehydrogenase of male and female rats consuming copper-deficient or adequate diets containing either fructose or starch for 3 weeks. Regardless of copper status, sorbitol accumulated in the livers of males consuming fructose compared to females and to males eating starch. The greatest sorbitol accumulation in the kidney occurred in the copper-deficient male rat consuming the fructose diet. These results strongly suggest that the pathology and complications of copper deficiency in the male rat fed fructose may be due to the increased sorbitol contents of tissues.     

The severity of copper deficiency can be ameliorated by deferoxamine.

The present study was undertaken in order to determine whether hepatic iron overload plays a role in the exacerbation of copper deficiency. Weanling male Sprague-Dawley rats were fed a copper-deficient (0.6 microgram Cu/g) diet containing 62% fructose for 5 weeks. Some of the copper-deficient rats were injected daily with deferoxamine (DFX), an iron chelator that has been widely used to reduce iron overload. DFX reduced hepatic iron concentrations, which in turn ameliorated the pathology of copper deficiency when compared with nontreated copper-deficient animals. It is suggested that hepatic iron overload in a reduced environment plays a major role in the exacerbation of copper deficiency. Once the concentration of hepatic iron is reduced, the severity of the deficiency should be improved.     

The influence of gender on developing copper deficiency and on free radical generation of rats fed a fructose diet.

The present investigation was conducted to determine whether differences in copper and iron status between male and female rats can be detected during the development of copper deficiency. These differences may explain the protection of the female against the severity of copper deficiency. In addition, the livers of all rats were exposed to electron-spin resonance (ESR) spectroscopy for the presence of free radicals. Male and female rats were fed from weaning either copper-deficient or -adequate diets containing fructose for 31 days. Rats were killed at day 0, 8, 16, 24, and 31 of the study. Throughout the study, copper-deficient males exhibited the same organ copper concentrations as copper-deficient female rats. However, only in the male did copper deficiency cause a reduction in body weight and an increase in liver and heart sizes but a decrease in pancreas size. In contrast, organ iron concentrations were different between males and females. Only copper-deficient males were anemic. Only the livers of copper-deficient males showed the presence of free radicals. Although the livers of copper-deficient female rats exhibited higher concentrations of hepatic iron than their male counterparts, their livers did not show the presence of free radicals. The data of the present study suggest that changes in organ sizes and the severity of copper deficiency are not solely due to the total concentrations of iron and/or copper. The type of iron compound and the presence of free radicals may be involved in the pathology of copper deficiency of the male.     

Dietary Carbohydrate Accelerates Ethanol Elimination, But Does Not Alter Hepatic Alcohol Dehydrogenase

In naive animals the rate of ethanol elimination is dependent on the hepatic alcohol dehydrogenase activity. Carbohydrates have been shown to modify ethanol metabolism by a mechanism that has not been determined. In this study, adult female rats, fed chow diets supplemented with fructose or glucose in their drinking water for 10 days demonstrated significantly greater ethanol elimination rates (4.85 ± 0.28 and 4.92 ± 1.5 μ m ethanol/min/g liver, respectively) than rats receiving water (3.65 ± 0.29). The hepatic alcohol dehydrogenase activity of the fructose (1687 ± 101 n m ethanol/min/g liver) and the glucose (1832 ± 15)-supplemented rats were not significantly different from that of control rats (1845 ± 160). Dietary carbohydrate supplementation, therefore, enhanced ethanol elimination, but did not alter the activity of alcohol dehydrogenase. Thus the changes in the ethanol elimination rate following carbohydrate loading were not the consequence of an alteration in hepatic alcohol dehydrogenase.     

Effects of chronic ethanol ingestion and folate deficiency on the activity of 10-formyltetrahydrofolate dehydrogenase in rat liver

BACKGROUND: We recently observed that ethanol feeding impairs 10-formyltetrahydrofolate (10-FTHF) dehydrogenase (EC 1.5.1.6.) and 10-FTHF hydrolase activity in rats. In the present study, we explored the effects of folate deficiency or sufficiency combined with alcoholic intake on 10-FTHF and possible mechanisms by which chronic ethanol ingestion produces folate deficiency. METHODS: Sprague-Dawley rats were fed either folate-sufficient (FS) or folate-deficient (FD) diets; with or without ethanol (E) for four weeks. Hepatic 10-FTHF dehydrogenase and hydrolase activity, plasma folate and homocysteine were measured at baseline and after feeding experimental diets. RESULTS: Liver weight increased slightly with either folate deficiency or ethanol consumption. In rats fed the folate-sufficient diet with ethanol (FSE), plasma folate was decreased slightly (p<0.05) and plasma homocysteine elevated compared to rats fed the FS diet without ethanol. Ethanol did not affect plasma folate and plasma homocysteine in FD rats. Red-blood cell (RBC) folate was increased similarly in rats by ethanol feeding (FSE and FDE>FS and FD). Feeding folate deficient or ethanol (FSE, FD and FDE) diets depressed hepatic activities of 10-FTHF dehydrogenase, which catalyzes the oxidative deformylation of 10-FTHF to tetrahydrofolate (THF) and carbon dioxide. Rats consuming the FDE diet had the lowest enzyme activities of the experimental groups, implying that folate deficiency and ethanol consumption each affect enzyme activity. CONCLUSIONS: We confirm that ethanol decreases hepatic 10-FTHF dehydrogenase activity and show that this decrease occurs irrespective of folate status. This shows that modulation of 10-FTHF is one possible mechanism by which ethanol intake decreases folate status and affects one-carbon metabolism.     

Effects of Ethanol on Tissue Folate Incorporation and Recovery from Folate Deficiency in Rats

Studies in folate-deficient alcoholics suggest that ethanol interferes with the recovery of folate status and the hematopoietic response to folate. Previous animal studies have suggested diverse effects of ethanol on intestinal absorption, hepatic metabolism, and urinary excretion of folate. In order to examine the effects of ethanol on folate distribution during folate deficiency, tissue incorporation of a tracer dose of folate was studied in rats chronically fed ethanol-containing and/or folate-deficient diets. Rats fed these diets were also used to study the effect of chronic ethanol consumption on the dietary reversal of folate deficiency by changing the diets (adding folate or replacing ethanol) from 12 to 16 weeks. After 16 weeks, tissue folate depletion was severe in rats fed folate-deficient diets. Plasma and whole body retention of the tracer dose of folate was decreased in folate-deficient rats consuming ethanol. In folate-deficient rats, ethanol consumption increased the incorporation of folate by the kidney and brain, but had no effect in other tissues (liver, lung, spleen, intestine, testis). In ethanol-fed folate-deficient rats that continued to consume ethanol, but with added folate in their diets, urine, plasma, liver, and kidney folate levels returned to control levels in 4 weeks. In the rats that stopped ethanol, but continued low folate diet consumption, no recovery of tissue folate levels was seen in 4 weeks. These results suggest that chronic ethanol consumption can exacerbate folate requirements by inhibiting body retention of small doses of folate. However, these effects are minor because ethanol consumption does not block recovery from folate deficiency when rats are fed sufficient amounts of folate.     

Polyunsaturated fatty acid deficiency reverses effects of alcohol on mitochondrial energy metabolism

BACKGROUND/AIMS: Polyunsaturated fatty acids (PUFA) deficiency is common in patients with alcoholic liver disease. The suitability of reversing such deficiency remains controversial. The aim was to investigate the role played by PUFA deficiency in the occurrence of alcohol-related mitochondrial dysfunction. METHODS: Wistar rats were fed either a control diet with or without alcohol (control and ethanol groups) or a PUFA deficient diet with or without alcohol (PUFA deficient and PUFA deficient+ethanol groups). After 6 weeks, liver mitochondria were isolated for energetic studies and fatty acid analysis. RESULTS: Mitochondria from ethanol fed rats showed a dramatic decrease in oxygen consumption rates and in cytochrome oxidase activity. PUFA deficiency showed an opposite picture. PUFA deficient+ethanol group roughly reach control values, regarding cytochrome oxidase activity and respiratory rates. The relationship between ATP synthesis and respiratory rate was shifted to the left in ethanol group and to the right in PUFA-deficient group. The plots of control and PUFA deficient+ethanol groups were overlapping. Phospholipid arachidonic over linoleic ratio closely correlated to cytochrome oxidase and oxygen uptake. CONCLUSIONS: PUFA deficiency reverses alcohol-related mitochondrial dysfunction via an increase in phospholipid arachidonic over linoleic ratio, which raises cytochrome oxidase activity. Such deficiency may be an adaptive mechanism.     

1-Week Withdrawal from 8 Weeks Alcohol Consumption Protects the Heart from Sepsis-Induced Dysfunction

Gram-negative sepsis causes a depression of the myocardium such that ventricular function curves generated on isolated perfused hearts removed from septic rats are displaced downward and to the right of control. Alcohol consumption can also cause a depression of the myocardium, especially if the period of alcohol feeding is prolonged. However, even before overt changes in the myocardium can be measured as a result of alcohol consumption, chronic alcoholism can result in a potentiation of sepsis-induced cardiac depression ( Am. J. Physiol. 250:H1857-H1863, 1991). The purpose of the present study was to determine if 1 week of withdrawal of alcohol from the diet after 8 weeks of alcohol consumption would reverse the potentiation by alcohol of sepsis-induced cardiac depression. Animals were fed an ethanol-containing diet in which ethanol contributed 36% of the total calories. Rats were fed this diet or a control liquid diet for 8 weeks, and then some animals were taken off the alcohol diet and placed on the control diet for 1 week. Sepsis was induced in control-fed, alcohol-fed or withdrawal animals by the administration of Escherichia coli into the dorsal subcutaneous space. Nonseptic animals received sterile saline in this space. The following day animals were anesthetized, and the hearts were removed and studied as isolated working hearts. Hearts removed from septic and alcohol septic animals showed severe depression of cardiac contractile performance. Hearts from the withdrawal group, however, were less compromised by sepsis and showed only a few signs of cardiac dysfunction. Withdrawal from alcohol for 1 week thus resulted in protection of the heart from sepsis-induced cardiac depression.     

Effects of zinc and copper deficiency associated with protein or lipid deficiency on rat exocrine pancreatic secretion

Copper and zinc are both secreted by the pancreas but are necessary for pancreatic secretion. We have studied the effects of a 4- or 8-week zinc or copper-deficient diet associated with or without lipid or protein deficiency on rat pancreatic secretion after stimulation by secretin, cerulein, or intraduodenal oleic acid. Twenty animals were in the control group; 40 rats were fed a copper-deficient diet (20 copper-deficient only and 20 copper- plus lipid-deficient). Ninety rats were deprived of zinc (30 of zinc-deficient only, 30 zinc-plus protein-deficient, 30 of zinc- plus lipid-deficient). Only the zinc- plus lipid-deficient diet for 8 weeks decreased basal bicarbonate and basal protein secretion (-42 and -70%, respectively, of the control values). Stimulated secretion was not markedly altered by copper deficiency while zinc deficiency, zinc plus protein deficiencies, and zinc plus lipid deficiencies suppressed almost responses to hormonal stimulation: After 8 weeks, the maximal protein response to oleic acid was reduced to 19.00 +/- 3.40, 18.58 +/- 3.00, and 12.04 +/- 2.91 microgram/30 min/g body weight in zinc- zinc and protein-; and zinc- and lipid-deficient diet, respectively, versus 39.87 +/- 6.33 microgram/30 min/g body weight (p less than 0.05) in controls. In all types of stimulation, lipid deficiency potentiated the deleterious effect of zinc deficiency on pancreatic secretion. This might be paralled with an extremely low level of lipid in the diet of people living in countries in which nutritional pancreatitis is observed and with the relative risk of developing an alcoholic chronic pancreatitis being increased by a low fat diet.     

Reversal by glucose of pancreatic amylase insufficiency in chronic alcoholic rats

Carbohydrate consumption regulates pancreatic amylase synthesis in rats. The Lieber-DeCarli 36% alcohol diet employed in chronic alcohol studies and the isocaloric control diet contain 11 and 47% of total calories from carbohydrates, respectively. Young rats fed ad libitum the 36% ethanol diet for 2 weeks obtained 1.2 g/day of carbohydrate, whereas those pair-fed with control diet received 5.8 g/day. Rats fed the 36% ethanol diet and given an intramuscular injection of a solution of 1.5 g of glucose daily for 2 weeks received twofold greater amounts of carbohydrate than saline-injected controls (2.7 versus 1.2 g). These changes in carbohydrate intake produced proportionate changes in pancreatic amylase levels. The secretory responses to cholecystokinin-octapeptide (CCK8) of acini from control and glucose-injected rats were significantly higher compared with those in the saline-injected or noninjected alcohol groups. The blood alcohol levels in glucose-injected rats were markedly reduced compared with other alcohol groups (71.7 versus 274.9 mg/dl) despite similar amounts of ethanol ingestion daily (2.4 g) in the three groups. In vitro experiments with acini from rats fed a nutritionally optimal diet revealed that high pharmacologic concentrations of ethanol, while inducing basal secretion, inhibited CCK8-stimulated amylase secretion. These results indicate that: (a) the amount of alcohol consumption does not correlate with either the levels of blood alcohol or of pancreatic amylase; (b) the carbohydrate availability in rats regulates pancreatic amylase levels despite significant levels of alcohol in blood; (c) blood alcohol levels observed in vivo may not affect synthetic and secretory processes of amylase in pancreatic acini.     

Individual differences in ethanol self-administration following withdrawal are associated with asymmetric changes in dopamine and serotonin in the medial prefrontal cortex and amygdala

BACKGROUND: Ethanol withdrawal alters brain neurochemistry, causes asymmetric activation of neurons in the medial prefrontal cortex (mPFC) and amygdala (AMY), and increases ethanol craving and drinking. Rats with intrinsic rightward-turning preferences drink more ethanol than those with left or no preferences; they also exhibit an ethanol-induced neurochemical activation that favors the right side of the mPFC. Our experiments used rats with different turning preferences to assess differences in withdrawal effects on mPFC and AMY neurochemistry as well as ethanol self-administration. METHODS AND RESULTS: Rats with left-turning, right-turning, and nonturning preferences were fed a 6% ethanol-containing liquid diet (WD) or a pair-fed control diet for 14 days. Differences in dopamine (DA), serotonin (5HT), norepinephrine (NE), and metabolite [3,4-dihydroxphenylacetic acid, homovanillic acid (HVA), and 5-hydroxyindoleacetic acid) concentrations were assessed in each side of the mPFC and AMY during acute withdrawal. Similar groups were fed the same diets and tested for consumption of 10% ethanol versus water and 1% sucrose versus water. WD increased HVA/DA in the mPFC and caused depletions of DA and 5HT in the mPFC and 5HT in the AMY. These effects were greater in the right than in the left side of these structures in rats with right-turning preferences. WD reduced ethanol drinking but right turners drank significantly more than left turners on day 2 of testing and drank more on days 2 and 3 than on day 1. No effects were observed on sucrose drinking. Similar groups were also trained to self-administer ethanol using a sucrose-fade sipper tube procedure that separated measures of ethanol seeking (bar pressing) and consumption. Following 14 days of vapor chamber exposure to ethanol, rats of all turning preferences had a lower rate of bar pressing on the first postwithdrawal day and shorter latencies to begin bar pressing on the third withdrawal day versus prewithdrawal baseline. Only right-turning-preference rats consumed more ethanol following withdrawal. CONCLUSIONS: These studies show that individual rats differ in postwithdrawal brain neurochemistry and ethanol consumption and that these differences are associated with differences in functional brain asymmetry.     

Reactive free radical generation in vivo in heart and liver of ethanol-fed rats: correlation with radical formation in vitro.

Rats fed a high-fat ethanol-containing diet for 2 weeks were found to generate free radicals in liver and heart in vivo. The radicals are believed to be carbon-centered radicals, were detected by administering spin-trapping agents to the rats, and were characterized by electron paramagnetic resonance spectroscopy. The radicals in the liver were demonstrated to be localized in the endoplasmic reticulum. Rats fed ethanol in a low-fat diet showed significantly less free radical generation. Control animals given isocaloric diets without ethanol showed no evidence of free radicals in liver and heart. When liver microsomes prepared from rats fed the high-fat ethanol diet were incubated in a system containing ethanol, NADPH, and a spin-trapping agent, the generation of 1-hydroxyethyl radicals was observed. The latter was verified by using 13C-substituted ethanol. Microsomes from animals fed the high-fat ethanol-containing diet had higher levels of cytochrome P-450 than microsomes from rats fed the low-fat ethanol-containing diet. The results suggest that the consumption of ethanol results in the production of free radicals in rat liver and heart in vivo that appear to initiate lipid peroxidation.     

Mild copper deficiency alters gene expression of proteins involved in iron metabolism

Iron and copper homeostasis share common proteins and are therefore closely linked to each other. For example, copper-containing proteins like ceruloplasmin and hephaestin oxidize Fe(2+) during cellular export processes for transport in the circulation bound to transferrin. Indeed, copper deficiency provokes iron metabolism disorders leading to anemia and liver iron accumulation. The aim of the present work was to understand the cross-talk between copper status and iron metabolism. For this purpose we have established dietary copper deficiency in C57BL6 male mice during twelve weeks. Hematological parameters, copper and iron status were evaluated. cDNA microarray studies were performed to investigate gene expression profiles of proteins involved in iron metabolism in the liver, duodenum and spleen. Our results showed that copper deficiency induces microcytic and hypochromic anemia as well as liver iron overload. Gene expression profiles, however, indicate that hepatic and intestinal mRNA expression neither compensates for hepatic iron overload nor the anemia observed in this mouse model. Instead, major modifications of gene expression occurred in the spleen. We observed increased mRNA levels of the transferrin receptors 1 and 2 and of several proteins involved in the heme biosynthesis pathway (ferrochelatase, UroD, UroS,...). These results suggest that copper-deficient mice respond to the deficiency induced anemia by an adaptation leading to an increase in erythrocyte synthesis.     

High-sugar diets increase cardiac dysfunction and mortality in hypertension compared to low-carbohydrate or high-starch diets

OBJECTIVE: Sugar consumption affects insulin release and, in hypertension, may stimulate cardiac signaling mechanisms that accelerate left ventricular hypertrophy and the development of heart failure. We investigated the effects of high-fructose or sucrose diets on ventricular function and mortality in hypertensive Dahl salt-sensitive rats. METHODS: Rats were fed chows that were either high starch (70% starch, 10% fat by energy), high fat (20% carbohydrates, 60% fat), high fructose (61% fructose, 9% starch, 10% fat), or high sucrose (61% sucrose, 9% starch, 10% fat). Hypertension was induced by adding 6% salt to the chow (n = 8-11/group). RESULTS: After 8 weeks of treatment, systolic blood pressure and left ventricular mass were similarly increased in all rats that were fed high-salt diets. Hypertension caused a switch in mRNA myosin heavy chain isoform from alpha to beta, and this effect was greater in the high-salt sucrose and fructose groups than in starch and fat groups. The cardiac mRNA for atrial natriuretic factor was also increased in all high-salt groups compared to respective controls, with the increase being significantly greater in the hypertensive sucrose fed group. Mortality was greater in the sucrose group (44%) compared to all the other hypertensive groups (12-18%), as was cardiomyocyte apoptosis. Left ventricular ejection fraction was lower in the high-salt sucrose group, which was due to an increase in end-systolic volume, and not increased end-diastolic volume. CONCLUSION: Diets high in sugar accelerated cardiac systolic dysfunction and mortality in hypertension compared to either a low-carbohydrate/high-fat or high-starch diet.     

Copper deficiency: A potential model for determining the role of mitochondria in cardiac aging

Heart mitochondria experience age-related declines in cytochrome c oxidase (CCO) activity and increases in the generation of reactive oxygen species (ROS) that may contribute to loss of cardiac function and the development of disease that occur with advancing age. In a manner similar to aging, copper deficiency also suppresses heart CCO activity and has cardiovascular consequences related to increased peroxidation. Food restriction is often used as a tool to study oxidative mechanisms of aging and the present study examines the potential of copper deficiency to model the role of mitochondria in cardiac aging by determining if the effect of food restriction on CCO activity and oxidative stress in heart mitochondria parallels its effect on cardiac mitochondria during aging. Overall, copper deficiency severely inhibited CCO activity and increased both Mn superoxide dismutase (MnSOD) and glutathione peroxidase (GPX) in isolated heart mitochondria. However, a 20% reduction in food intake by copper-deficient rats increased CCO activity by 65% and decreased MnSOD activity by 25% but had no effect in rats fed adequate copper. Copper deficiency also reduced the carbonyl content of 80–100 kDa mitochondrial proteins, but the reduction in carbonyl content was unaffected by food restriction. Food restriction did, however, completely prevent the enlargement of cardiac mitochondria in copper-deficient rats. Together, these findings indicate that copper deficiency induces mitochondrial antioxidant enzyme activity and hypertrophy in cardiac tissue in response to reduced CCO activity and that food restriction may counteract these changes by reducing oxidative stress. Because the action of food restriction on CCO activity and mitochondrially generated oxidative stress are similar in copper deficiency and aging, copper deficiency may serve as a short-term model for studying the potential roles of mitochondria in cardiac aging. The U.S. Department of Agriculture, Agricultural Research Service, Northern Plains Area, is an equal opportunity/ affirmative action employer and all agency services are available without discrimination. Mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable.