Combined effects of ethanol and protein deficiency on hepatic iron, zinc, manganese, and copper contents

The Role of Micronutrients in the Pathogenesis of Alcohol-Related Liver Disease

AIMS

Chronic alcohol consumption may result in liver injury and chronic liver disease, but other factors are likely to influence disease progression. Malnutrition, specifically micronutrient deficiency, is frequently associated with both alcohol use disorder and chronic liver disease. We hypothesize that micronutrient deficiencies may affect the progression of liver disease in this population.

METHODS

Systematic integrative review of the medical literature; electronic search of MEDLINE 1950-2021; studies investigating role of any micronutrient in the acceleration of alcohol-related liver injury in humans or animals. Studies which specifically related to alcoholic hepatitis were excluded. Outcomes were extracted and recorded in tabulated form and discussed narratively.

RESULTS

We identified 46 studies investigating the role of micronutrient deficiencies in the pathogenesis of alcohol-related liver disease. Specific micronutrients which were identified included folic acid or related B vitamins (n = 9 studies), Vitamin D (n = 9 studies), magnesium (n = 8 studies), zinc (n = 8 studies) and selenium (n = 12 including one systematic review). Observational evidence suggests a potential role of magnesium deficiency in accelerating alcohol-related liver injury with weak or negative evidence for other micronutrients.

CONCLUSIONS

Magnesium deficiency may increase the risk of alcohol-related liver injury and adverse liver outcomes. However, currently, there is insufficient evidence to support magnesium supplementation except for clinically relevant magnesium deficiency. Long-term prospective cohort studies assessing the impact of micronutrients on liver disease progression in patients with alcohol use disorder are lacking and may help determine whether there is a causal role for micronutrient deficiencies in alcohol-related liver injury.

Chamomile decoction extract inhibits human neutrophils ROS production and attenuates alcohol-induced haematological parameters changes and erythrocytes oxidative stress in rat

BACKGROUND

The aim of this study was to evaluate the protective effects of subacute pre-treatment with chamomile (Matricaria recutita L.) decoction extract (CDE) against stimulated neutrophils ROS production as well as ethanol (EtOH)-induced haematological changes and erythrocytes oxidative stress in rat.

METHODS

Neutrophils were isolated and ROS generation was measured by luminol-amplified chemiluminescence. Superoxide anion generation was detected by the cytochrome c reduction assay. Adult male wistar rats were used and divided into six groups of ten each: control, EtOH, EtOH + various doses of CDE (25, 50, and 100 mg/kg, b.w.), and EtOH+ ascorbic acid (AA). Animals were pre-treated with CDE extract during 10 days.

RESULTS

We found that CDE inhibited (P ≤ 0.0003) luminol-amplified chemiluminescence of resting neutrophils and N-formyl methionylleucyl-phenylalanine (fMLF) or phorbolmyristate acetate (PMA) stimulated neutrophils, in a dose-dependent manner. CDE had no effect on superoxide anion, but it inhibited (P ≤ 0.0004) H2O2 production in cell free system. In vivo, CDE counteracted (P ≤ 0.0034) the effect of single EtOH administration which induced (P < 0.0001) an increase of white blood cells (WBC) and platelets (PLT) counts. Our results also demonstrated that alcohol administration significantly (P < 0.0001) induced erythrocytes lipoperoxidation increase and depletion of sulfhydryl groups (-SH) content as well as antioxidant enzyme activities as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). More importantly, we found that acute alcohol administration increased (P < 0.0001) erythrocytes and plasma hydrogen peroxide (H2O2), free iron, and calcium levels while the CDE pre-treatment reversed increased (P ≤ 0.0051) all these intracellular disturbances.

CONCLUSIONS

These findings suggest that CDE inhibits neutrophil ROS production and protects against EtOH-induced haematologiacal parameters changes and erythrocytes oxidative stress. The haematoprotection offered by chamomile might involve in part its antioxidant properties as well as its opposite effect on some intracellular mediators such as H2O2, free iron, and calcium.

Hepatoprotective effect of manganese chloride against CCl4-induced liver injury in rats

The aim of the present study is to evaluate the protective effect of manganese chloride against carbon tetrachloride (CCl4)-induced liver injury in rats. Manganese chloride (0.001, 0.01, 0.05 and 0.1 g/kg bw) was administered intragastrically for 28 consecutive days to male CCl4-treated rats. The hepatoprotective activity was assessed using various biochemical parameters such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), γ-glutamyltransferase (GGT) and superoxide dismutase (SOD). Histopathological changes in the liver of different groups were also studied. Administration of CCl4 increased the serum ALT, AST, ALP and GGT but decreased SOD levels in rats. Treatment with manganese chloride significantly attenuated these changes to nearly normal levels. The animals treated with manganese chloride have shown decreased necrotic zones and hepatocellular degeneration when compared to the liver exposed to CCl4 intoxication alone. Thus, the histopathological studies also supported the protective effect of manganese chloride. Therefore, the results of this study suggest that manganese chloride exerts hepatoprotection via promoting antioxidative properties against CCl4-induced oxidative liver damage.

Relative and combined effects of selenium, protein deficiency and ethanol on hepatocyte ballooning and liver steatosis

Oxidative damage plays a key role in alcohol-mediated liver alterations. Selenium, a potent antioxidant, is decreased in alcoholics. This study was conducted to analyse if the supplementation with selenium may alter liver changes in a murine model fed ethanol and/or a 2 % protein-containing diet, following the Lieber-DeCarli design. Adult male Sprague Dawley rats were divided into eight groups which received the Lieber-DeCarli control diet; an isocaloric, 36 % ethanol-containing diet; an isocaloric, 2 % protein-containing diet; and an isocaloric diet containing 2 % protein and 36 % ethanol diet; and other similar four groups to which selenomethionine (1 mg/kg body weight) was added. After sacrifice (5 weeks later), liver fat amount and hepatocyte areas of pericentral and periportal cells were measured, and liver and serum selenium, activity of liver glutathione peroxidase (GPX), and liver malondialdehyde were determined. Ethanol-fed rats showed increased hepatocyte areas and fat accumulation especially when ethanol was added to a 2 % protein diet. Selenium caused a decrease in hepatocyte ballooning and liver fat amount, but an increase in GPX activity, and a marked increase in serum and liver selenium. The present study demonstrates that selenium, added to the diet of rats in the form of seleniomethionine, prevents the appearance of early signs of ethanol-mediated liver injury under the conditions of the Lieber-DeCarli experimental design.

Protective Effects of Zinc on Oxidative Stress Enzymes in Liver of Protein-Deficient Rats

Persons afflicted with protein malnutrition are generally deficient in a variety of essential micronutrients like zinc, copper, iron, and selenium, which in turn affects number of metabolic processes in the body. To evaluate the protective effects of zinc on the enzymes involved in oxidative stress induced in liver of protein-deficient rats, the current study was designed. Zinc sulfate at a dose level of 227 mg/L zinc in drinking water was administered to female Sprague-Dawley normal control as well as protein-deficient rats for a total duration of 8 weeks. The effects of zinc treatment in conditions of protein deficiency were studied on rat liver antioxidant enzymes, which included catalase, glutathione peroxidase (GPx), glutathione reductase (GR), superoxide dismutase (SOD), glutathione reduced (GSH), and glutathione-S-transferase (GST). Protein deficiency in normal rats resulted in a significant increase in hepatic activities of catalase, glutathione peroxidase, glutathione reductase, and glutathione-S-transferase and the levels of lipid peroxidation. A significant inhibition in the levels of reduced glutathione and the enzyme activity of superoxide dismutase has been observed after protein deficiency in normal rats. Interestingly, Zn treatment to protein-deficient animals lowered already raised activity catalase, glutathione peroxidase, and glutathione-S-transferase and levels of lipid peroxidation to significant levels when compared to protein-deficient animals. Also, Zn treatment to the protein-deficient animals resulted in a significant elevation in the levels of GSH and SOD activity as compared to their respective controls, thereby indicating its effectiveness in regulating their levels in adverse conditions. It has also been observed that concentrations of zinc, copper, iron, and selenium were found to be decreased significantly in protein-deficient animals. However, the levels of these elements came back to within normal limits when zinc was administrated to protein-deficient rats. This study concludes that zinc has the potential to regulate the activities of oxidative stress enzymes as well as essential hepatic elements.

Zinc and the liver: an active interaction

Zinc is an essential trace element, exerting important antioxidant, anti-inflammatory, and antiapoptotic effects. It affects growth and development and participates in processes such as aging and cancer induction. The liver is important for the regulation of zinc homeostasis, while zinc is necessary for proper liver function. Decreased zinc levels have been implicated in both acute and chronic liver disease states, and zinc deficiency has been implicated in the pathogenesis of liver diseases. Zinc supplementation offers protection in experimental animal models of acute and chronic liver injury, but these hepatoprotective properties have not been fully elucidated. In the present review, data on zinc homeostasis, its implication in the pathogenesis of liver diseases, and its effect on acute and chronic liver diseases are presented. It is concluded that zinc could protect against liver diseases, although up to now the underlying pathophysiology of zinc and liver interactions have not been defined.

Time dependent study to evaluate the efficacy of zinc on hepatic marker enzymes and elemental profile in serum and liver of protein deficient rats

This study was designed to determine the time dependent protective effects of zinc sulfate on the serum and liver marker enzymes along with elemental profile in protein deficient Sprague Dawley (S.D.) female rats. Zinc sulfate in the dose of 227 mg/l in drinking water was administered to normal control as well as protein deficient rats for a total duration of 8 weeks. The effects of different treatments were studied on enzymes like alkaline phosphatase (ALP), aspartate aminotransferases (AST) and alanine aminotransferases (ALT) in rat serum at different time intervals of 1, 2, 4 and 8 weeks and in the rat liver at the end of study. The status of different essential elements in liver was also studied. The serum ALP activity got significantly depressed when estimated at the intervals of 4 and 8 weeks. Activity of serum ALT was significantly increased after 4 weeks interval in protein deficient rats and the increasing trend continued upto 8 weeks of protein deficiency. On the other hand, activity of AST showed a significant increase just after 2 weeks and activity continued to be increased up to 8 weeks. Moreover activities of all the hepato marker enzymes showed a significant increase in liver of protein deficient rats. Interestingly, supplementation of Zn to protein deficient rats helped in regulating the altered activities of ALP, AST and ALT both in serum and liver. However, zinc treatment alone to normal rats did not indicate any significant change in the activities of all the enzymes in liver as well serum except at the interval of 2 weeks where a marginal increase in the activity of AST was seen. It has also been observed that concentrations of zinc, copper, iron and selenium were found to be decreased significantly in protein deficient animals. However, the levels of these elements came back to within normal limits when zinc was administered to protein deficient rats.

Iron, zinc and copper levels in brain, serum and liver of neonates exposed to 2,4-dichlorophenoxyacetic acid

The effects of 2,4-dichlorophenoxyacetic acid (2,4-D, 70 or 100 mg/kg dam's body weight) on iron (Fe), zinc (Zn) and copper (Cu) in brain, liver and serum of well-nourished and undernourished pups exposed through dam's milk were determined. Undernourishment produced a high Fe decrease (serum and brain) and a delay in weight gain similar to that produced by the highest dose of 2,4-D on well-fed pups. In the latter animals, copper was found to be the most altered ion, increasing its level in serum, liver and some brain areas and decreasing in whole brain. Zinc was the most affected ion in brain areas. Well-nourished pups lactationally exposed to 70 mg 2,4-D/kg dam's body weight altered neither their metal levels nor their body weight in any of the tissues studied. Undernourished pups were more vulnerable to the 2,4-D effect than well-nourished pups. Undernourished pups exposed to a lower 2,4-D dose showed a decrease in their body, brain and liver weight similar to well-fed animals exposed to 100 mg 2,4-D/kg. A noticeable decrease in liver L-tryptophan peroxidase activity by 2,4-D was also registered. This effect was higher in undernourished and 2,4-D-exposed pups. These results suggest that brain areas have a different susceptibility to the herbicide and that undernourishment produces a higher vulnerability to the herbicide and exacerbates the 2,4-D effect.

Effect of lithium on hepatic and serum elemental status under different dietary protein regimens

Lithium carbonate at the dose level of 1.1 g/kg was administered in diet to normal (18% protein), low-protein- (LP; 8%) and high-protein (HP; 30% diet)-fed rats for a period of 1 mo. The LP diet resulted in a significant decrease in the hepatic levels of zinc, iron, copper, manganese, calcium, and serum levels of calcium and sodium. The HP diet caused a marked decrease in copper and calcium levels in liver, but an increase in potassium levels in serum was observed. Lithium treatment to normal rats led to a significant reduction in the hepatic contents of zinc, copper, potassium, calcium, and serum contents of potassium and sodium, whereas an elevation in serum contents of calcium was noticed. Administration of lithium to protein-deficient rats increased the hepatic concentration of manganese and serum concentration of calcium and the levels almost reached the normal limits. On the other hand, there was a marked depression in potassium contents in the serum of LP- as well as HP-fed rats following lithium treatment when compared to LP and HP groups, respectively.

Relative and combined effects of ethanol and protein deficiency on zinc, iron, copper, and manganese contents in different organs and urinary and fecal excretion

The relative contribution of protein deficiency to the altered metabolism of certain trace elements in chronic alcoholics is not well defined, so this study was performed to analyse the relative and combined effects of ethanol and protein deficiency on liver, bone, muscle, and blood cell content of copper, zinc, iron, and manganese, and also on serum levels and urinary and fecal excretion of these elements in four groups of eight animals each that were pair-fed during 8 weeks with a nutritionally adequate diet, a 36% (as energy) ethanol-containing isocaloric diet, a 2% protein isocaloric diet, and a 36% ethanol 2% protein isocaloric diet, respectively, following the Lieber-DeCarli model. Five additional rats were fed ad lib the control diet. Protein malnutrition, but not ethanol, leads to liver zinc depletion. Both ethanol and protein malnutrition cause muscle zinc depletion and increase urinary zinc and manganese excretion, whereas ethanol also increases urinary iron excretion and liver manganese content. No differences were observed regarding copper metabolism.

Zinc, copper, manganese, and iron in chronic alcoholic liver disease

Ethanol consumption and/or liver damage may alter liver content of several trace elements, as iron, zinc, copper, and manganese. This alteration may play a role on ongoing liver fibrogenesis. Based on these facts we have determined liver, serum, and urinary Mn, Cu, Zn, and Fe levels in a group of alcoholic cirrhotics and noncirrhotics with normal renal function, comparing them with those of controls. We have observed low liver zinc and high liver copper--this last in relation with histomorphometrically determined total amount of liver fibrosis--and manganese contents in cirrhotics, together with increased excretion of zinc and iron and decreased excretion of manganese. Zinc, iron, and copper excretion kept a relation with data of severity of cirrhosis, including mortality in the case of urinary copper, independently of the use of diuretics. Thus, liver copper and urinary iron, zinc, and copper excretion seem to be related with data of severity of chronic alcoholic liver disease. Low urinary manganese excretion may play a role on liver manganese overload.

Alcohol mediates increases in hepatic and serum nonheme iron stores in a rat model for alcohol-induced liver injury

The notion that prolonged ethanol consumption promotes hepatocellular damage through interactions with iron was evaluated in rats fed ethanol with or without supplemental dietary carbonyl iron. The individual and combined pro-oxidant potential of these agents was evaluated in terms of their ability to perturb iron homeostasis and initiate hepatocellular injury. Sprague-Dawely rats received a high fat liquid diet for 8 weeks supplemented with: 35% ethanol-derived calories (Alcohol group), 0.02 to 0.04% (w/v) carbonyl iron (Iron group), ethanol plus carbonyl iron (Alcohol + Iron group), or a diet containing carbohydrate-derived isocaloric calories (Control group). Hepatic and serum nonheme iron stores were significantly elevated (p < 0.05) in all treatment groups, compared with the Controls. Catalytically active low-molecular weight iron was detected in rats consuming alcohol and was markedly elevated (p < 0.05) in rats ingesting iron alone or iron in combination with alcohol. Elevations in serum ALT indicated significant hepatocellular injury in rats ingesting only alcohol, but was most prominent in the rats consuming ethanol in combination with iron (p < 0.05). Significant hepatic fatty infiltration, increased hydroxyproline content, and perturbations in reduced glutathione were also observed in the Alcohol and Iron treatment groups. Histochemical assessment of hepatic iron sequestration revealed that alcohol feeding resulted in deposition of ferric iron in the centrilobular area of the liver lobule. This unique alcohol-mediated iron deposition was histologically graded above Control group and was observed in both hepatocytes and Kupffer cells. Data presented herein suggest that alcohol alone or in combination with iron results in rather specific lobular patterns of hepatic iron deposition relevant to iron overload observed in human alcoholics. Furthermore, data suggest that alcohol- and iron-initiated prefibrotic events occur before extensive hepatocellular necrosis.

Effect of age and dietary protein level on tissue mineral levels in female rats

Mineral (phosphorus, sulfur, potassium, calcium, magnesium, iron, zinc, copper, and manganese) concentrations were measured in plasma, and several tissues from female Wistar rats (young: 3-wk-old; mature: 6-mo-old) were fed on a dietary regimen designed to study the combined or singular effects of age and dietary protein on mineral status. Three diets, respectively, contained 5, 15, and 20% of bovine milk casein. Nephrocalcinosis chemically diagnosed by increased calcium and phosphorus in kidney was prevented in rats fed a 5% protein diet. Renal calcium and phosphorus were more accumulated in young rats than mature rats. A 5% protein diet decreased hemoglobin and blood iron. The hepatic and splenic iron was increased by a 5% protein diet in mature rats but was not altered in young rats. Mature rats had higher iron in brain, lung, heart, liver, spleen, kidney, muscle, and tibia than young rats. A 5% protein diet decreased zinc in plasma and liver. Zinc in tibia was increased with dietary protein level in young rats but was not changed in mature rats A 5% protein diet decreased copper concentration in plasma of young rats but not in mature rats. Mature rats had higher copper in plasma, blood, brain, lung, heart, liver, spleen, and kidney than young rats. With age, manganese concentration was increased in brain but decreased in lung, heart, liver, kidney, and muscle. These results suggest that the response to dietary protein regarding mineral status varies with age.

Development of glial cells cultured from prenatally alcohol treated rat brain: effect of supplementation of the maternal alcohol diet with a grape extract

The aim of this work was to investigate the effect of supplementation of a maternal alcohol diet with a grape extract on glial cell development. Glial cells were cultured during 4 weeks from cortical brain cells of the new born offspring in DMEM medium supplemented with fetal calf serum. Enzymatic markers of nerve cell development were measured (enolase isoenzymes and glutamine synthetase). Since alcohol consumption produces free radicals the antioxidant system superoxide dismutase was also investigated. Compared to the decrease found in only alcohol treated animals, all parameters except neuron-specific enolase were antagonized and even stimulated after grape extract supplementation. The effect was more important after only 1 month than 3 months of treatment. Also in the total brain an alcohol antagonizing effect and a glutamine synthetase activation were found. Our data demonstrate that addition of a grape extract to the maternal alcohol diet may partially or completely overcome the alcohol induced retardation of glial cell development.

Effect of manganese on the development of glial cells cultured from prenatally alcohol exposed rats

Maternal alcohol abuse is known to produce retardation in brain maturation and brain functions. Using cultured glial cells as a model system to study these effects of alcohol we found an alcohol antagonizing property for manganese (Mn). Mn was added to the alcohol diet (MnCl2 25 mg/l of 20% v/v ethanol) of pregnant rats. Glial cells were cultured during 4 weeks from cortical brain cells of pups born to these mothers. Several biochemical parameters were examined: protein levels, enzymatic markers of glial cell maturation (enolase and glutamine synthetase), superoxide dismutase a scavenger of free radicals produced during alcohol degradation. The results were compared to appropriate controls. A beneficent effect of Mn was observed for the pups weight which was no more significantly different from the control values. Protein levels, enolase and glutamine synthetase activities were increased mainly during the proliferative period when Mn was added to the alcohol diet compared to the only alcohol treated animals. This Mn effect was not found for superoxide dismutase in cultured glial cells but exists in the total brain of the 2 week-old offspring. In the total 2 and 4 week-old brain the alcohol induced decrease of enolase and glutamine synthetase was also antagonized by the Mn supplementation. Our data suggest that Mn may act as a factor overcoming at least partially some aspects of alcohol induced retardation of nerve cell development.

Haematological and serum biochemical changes in the rat due to protein malnutrition and gossypol-ethanol interactions

The effects of protein malnutrition on haematological and serum biochemical values were evaluated in gossypol-treated rats which were simultaneously fed with ethanol. Gossypol caused anaemia, leucopenia and thrombocytopenia in malnourished animals, suggesting a depression of bone marrow activity. Gossypol also caused a significant elevation of serum alkaline phosphatase and alanine aminotransferase activities and increases in the concentrations of Mg++ and Ca++ with reduced albumin, regardless of the nutritional status. These changes were more severe with malnutrition. Ethanol alone caused a thrombocytopenia but no other significant haematological changes. However, it appeared to cause derangement of lipid and protein metabolism as reflected in serum cholesterol and urea. The toxic effects seen in gossypol-treated rats were significantly reduced in animals simultaneously given ethanol. As the livers of gossypol-treated rats were significantly heavier than in these animals, it seems possible that ethanol consumption enhances the ability of the liver to metabolize gossypol, thereby reducing its accumulation and consequently its toxicity. However, further studies are needed to determine the mechanisms responsible.

Relative and combined effects of ethanol and protein deficiency on gonadal function and histology

The aim of the present study is to analyse the relative and combined effects of ethanol and protein deficiency on serum testosterone and LH, and on gonadal histology, in ethanol fed rats. The study was performed in 32 animals divided into four groups, fed with the Lieber & DeCarli control, 36% ethanol, 2% protein, and 36% ethanol 2% protein containing diets, respectively. Two months later, rats were anaesthetized with pentobarbital and sacrificed, and the right testes and epididymus were carefully removed. Both ethanol and protein deficiency independently lead to a decrease in serum testosterone levels, and to testicular atrophy, lowest testosterone levels and highest degrees of atrophy being observed in the rats receiving the 36% ethanol, 2% protein containing diet. Both serum testosterone and testicular size and weight significantly correlated with final weight and serum albumin. Hypospermia, atrophy of the seminiferous tubules, and reduced epididymal diameter were also observed in this last group of animals. Thus, protein deficiency may contribute to hypogonadism of alcoholics.

Ethanol consumption and early murine retrovirus infection influence liver, heart, and muscle levels of iron, zinc, and copper in C57BL/6 mice

The relative and combined roles of ethanol and murine acquired immunodeficiency syndrome (MAIDS) on the mineral status (Fe, Zn, and Cu) of liver (storage site), heart, muscle (nutrient mobile sites) were investigated. C57BL/6 mice were randomly assigned to four groups: (a) uninfected mice fed isocaloric, adequate nutrient diet (NRC), (b) uninfected mice fed the NRC diet with 25% of energy derived from ethanol, (c) LP-BM5 retrovirus-infected mice fed the isocaloric NRC diet, and (d) retrovirus-infected mice fed the NRC diet with 25% of its energy derived from ethanol. The levels of Cu and Zn levels in the liver did not significantly change as a result of ethanol consumption. However hepatic Zn concentration was increased significantly in retrovirus-infected mice. This may be correlated to the increase in their liver weight. Ethanol administration significantly increased Fe concentration in the liver, yet significantly decreased concentration of Cu in the heart. Retrovirus infection alone, which had not proceeded to murine AIDS, resulted in a significant increase in heart Cu and Zn concentration as compared with uninfected mice. Retrovirus infection in C57BL/6 mice significantly increased Fe and Zn level/g of muscle. Early retrovirus infection alters tissue micronutrient levels, and may thus contribute to immunological changes.

Ethanol-induced oxidative stress and nutritional status

The ability of dietary ethanol, administered over a 10-day period, to elevate production rates of reactive oxygen species and to alter glutathione levels has been determined in both liver and cerebellum, a brain region known to be susceptible to ethanol-induced damage. Two groups of ethanol-consuming rats were used. One set of treated animals that received an all-liquid ethanol-containing diet experienced weight gain, and this gain was matched in a pair-fed control group. The other ethanol-treated group that had free access only to solid chow and water containing ethanol lost weight during the exposure period. The corresponding control group that received unlimited water and chow was allowed to gain weight normally. In animals that lost weight as a consequence of ethanol in the drinking water, evidence of oxidative stress was enhanced relative to that in animals receiving ethanol by way of the liquid diet. This latter set gained weight, despite higher blood ethanol levels than the group that lost weight. An excess prooxidant condition prevailed in the liver and cerebellum of the ethanol-dosed malnourished group. In the case of liver, this difference may relate to a greater lability of iron-containing proteins in the rats that experienced weight loss, leading to the appearance of low molecular weight iron in the cytosol.