Concentration of iron and distribution of iron and transferrin after experimental iron overload in rat tissues in vivo: study of the liver, the spleen, the central nervous system and other organs

Sub-Chronic 30 mg/kg Iron Treatment Induces Spatial Cognition Impairment and Brain Oxidative Stress in Wistar Rats

Iron overload has been shown to have deleterious effects in the brain through the formation of reactive oxygen species, which ultimately may contribute to neurodegenerative disorders. Accordingly, rodent studies have indicated that systemic administration of iron produces excess iron in the brain and results in behavioral and cognitive deficits. To what extent cognitive abilities are affected and which neurobiological mechanisms underlie those deficits remain to be more fully characterized. In the present study, we looked at the effects of a 30 mg/kg iron sub-chronic treatment on cognitive abilities in two hippocampal-dependent spatial tasks (place navigation, spatial/non-spatial object recognition), in relation with iron content and oxidative stress biomarkers (MDA, SOD, CAT) in the cerebellum, hippocampus, prefrontal cortex and striatum, four brain areas known to be involved in the processing of spatial information. Iron-treated rats were impaired in acquisition and retention of the platform location in the navigation task and in the spatial/non-spatial object recognition task. Iron content and MDA were found to be increased in the four brain regions of interest, but activity of the antioxidant enzymes was not modified. The results indicate that the ability of rats to process spatial information whether in place navigation or spontaneous object spatial/non-spatial recognition is disrupted following a 30 mg/kg sub-chronic treatment. The deficits are hypothesized to result from iron excess-induced oxidative stress in the network of brain areas involved in the processing of spatial information.

Ferulic acid protects HepG2 cells and mouse liver from iron-induced damage

Liver as iron storage organ is particularly susceptible to oxidative stress-induced injury from excess iron. Thus, antioxidant therapies are often used to reverse oxidative damage and protect cells and tissues. This study investigated the protective effects of phenolic acids; ferulic acid (FA) and its metabolite, ferulic acid 4-O-sulfate disodium salt (FAS) against oxidative stress under iron overload conditions in mouse and HepG2 cells. Cells were exposed to FA or FAS and then treated with iron-induced oxidative stress complex of 50 μmol/L FAC and 20 μmol/L of 8-hydroxyquinoline 8HQ (8HQ-FAC). Iron dextran was injected intraperitoneally on alternate days for 10 days to induce the iron overload condition in BALB/c mice. The study revealed that the phenolic acids were protective against ROS production, lipid peroxidation and antioxidant depletion in HepG2 cells and liver tissues of BALB/c mice during iron-induced oxidative stress. The protective function of phenolic acids was achieved by the transcriptional activation of nuclear factor erythroid-2-related factor 2 (Nrf2) to regulate antioxidant genes. In conclusion, the study provides evidence that FA has the potential as a therapeutic agent against iron-related diseases such as T2D.

Scutellaria baicalensis and its constituents baicalin and baicalein as antidotes or protective agents against chemical toxicities: a comprehensive review

Scutellaria baicalensis (SB), also known as the Chinese skullcap, has a long history of being used in Chinese medicine to treat a variety of conditions ranging from microbial infections to metabolic syndrome and malignancies. Numerous studies have reported that treatment with total SB extract or two main flavonoids found in its root and leaves, baicalin (BA) and baicalein (BE), can prevent or alleviate the detrimental toxic effects of exposure to various chemical compounds. It has been shown that BA and BE are generally behind the protective effects of SB against toxicants. This paper aimed to review the protective and therapeutic effects of SB and its main components BA and BE against chemical compounds that can cause intoxication after acute or chronic exposure and seriously affect different vital organs including the brain, heart, liver, and kidneys. In this review paper, we had a look into a total of 221 in vitro and in vivo studies from 1995 to 2021 from the scientific databases PubMed, Scopus, and Web of Science which reported protective or therapeutic effects of BA, BE, or SB against drugs and chemicals that one might be exposed to on a professional or accidental basis and compounds that are primarily used to simulate disease models. In conclusion, the protective effects of SB and its flavonoids can be mainly attributed to increase in antioxidants enzymes, inhibition of lipid peroxidation, reduction of inflammatory cytokines, and suppression of apoptosis pathway.

Longitudinal CSF Iron Pathway Proteins in Posthemorrhagic Hydrocephalus: Associations with Ventricle Size and Neurodevelopmental Outcomes

OBJECTIVE

Iron has been implicated in the pathogenesis of brain injury and hydrocephalus after preterm germinal matrix hemorrhage-intraventricular hemorrhage, however, it is unknown how external or endogenous intraventricular clearance of iron pathway proteins affect the outcome in this group.

METHODS

This prospective multicenter cohort included patients with posthemorrhagic hydrocephalus (PHH) who underwent (1) temporary and permanent cerebrospinal fluid (CSF) diversion and (2) Bayley Scales of Infant Development-III testing around 2 years of age. CSF proteins in the iron handling pathway were analyzed longitudinally and compared to ventricle size and neurodevelopmental outcomes.

RESULTS

Thirty-seven patients met inclusion criteria with a median estimated gestational age at birth of 25 weeks; 65% were boys. Ventricular CSF levels of hemoglobin, iron, total bilirubin, and ferritin decreased between temporary and permanent CSF diversion with no change in CSF levels of ceruloplasmin, transferrin, haptoglobin, and hepcidin. There was an increase in CSF hemopexin during this interval. Larger ventricle size at permanent CSF diversion was associated with elevated CSF ferritin (p = 0.015) and decreased CSF hemopexin (p = 0.007). CSF levels of proteins at temporary CSF diversion were not associated with outcome, however, higher CSF transferrin at permanent CSF diversion was associated with improved cognitive outcome (p = 0.015). Importantly, longitudinal change in CSF iron pathway proteins, ferritin (decrease), and transferrin (increase) were associated with improved cognitive (p = 0.04) and motor (p = 0.03) scores and improved cognitive (p = 0.04), language (p = 0.035), and motor (p = 0.008) scores, respectively.

INTERPRETATION

Longitudinal changes in CSF transferrin (increase) and ferritin (decrease) are associated with improved neurodevelopmental outcomes in neonatal PHH, with implications for understanding the pathogenesis of poor outcomes in PHH. ANN NEUROL 2021;90:217-226.

Krill oil alleviates oxidative stress, iron accumulation and fibrosis in the liver and spleen of iron-overload rats

Krill oil (KO) is a recent supplement which is rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). These fatty acids are found in both krill oil and fish oil. In krill oil, they esterified to phospholipids, but in fish oil, they are esterified to triacylglycerols. The target of this study was to investigate whether KO could help against iron overload-induced toxicity in liver and spleen. Rats were randomly assigned into 3 categories: control rats, rats received iron in a drinking water for 8 weeks followed by either vehicle or KO (40 mg/kg) treatment for an extra 8 weeks. Extent of hepatic and splenic injury was assessed via biochemical, histopathological and immunohistochemical evaluations. KO effectively improved the microscopic features of liver and spleen. Moreover, it decreased the increased levels of serum transaminases, ALP, LDH, iron, and ferritin and increased albumin serum level as well. In addition, it restored the balance between oxidants and antioxidants in the hepatic and splenic tissues. Furthermore, it decreased HO-1 levels, upregulated the production of Nrf2, and limited the expression of MMP9. These findings altogether suggest that KO might be a new candidate for treatment of iron overload-induced toxicity. Graphical abstract Graphical abstract.

Animal Models of Normal and Disturbed Iron and Copper Metabolism

Research on the interplay between iron and copper metabolism in humans began to flourish in the mid-20th century, and diseases associated with dysregulated homeostasis of these essential trace minerals are common even today. Iron deficiency is the most frequent cause of anemia worldwide, leading to significant morbidity, particularly in developing countries. Iron overload is also quite common, usually being the result of genetic mutations which lead to inappropriate expression of the iron-regulatory hormone hepcidin. Perturbations of copper homeostasis in humans have also been described, including rare genetic conditions which lead to severe copper deficiency (Menkes disease) or copper overload (Wilson disease). Historically, the common laboratory rat (Rattus norvegicus) was the most frequently utilized species to model human physiology and pathophysiology. Recently, however, the development of genetic-engineering technology combined with the worldwide availability of numerous genetically homogenous (i.e., inbred) mouse strains shifted most research on iron and copper metabolism to laboratory mice. This created new opportunities to understand the function of individual genes in the context of a living animal, but thoughtful consideration of whether mice are the most appropriate models of human pathophysiology was not necessarily involved. Given this background, this review is intended to provide a guide for future research on iron- and copper-related disorders in humans. Generation of complementary experimental models in rats, swine, and other mammals is now facile given the advent of newer genetic technologies, thus providing the opportunity to accelerate the identification of pathogenic mechanisms and expedite the development of new treatments to mitigate these important human disorders.

Zinc and Manganese of serum were negatively, but Copper positively influenced by Iron elevation in diet of male Wistar rats

The purpose of the study was to determine the effect of dietary iron on distribution of zinc, manganese, copper, calcium and magnesium in the body of Wistar rats. Commercial Sangak, an Iranian traditional flat bread was used in this study. It was prepared by additionof yeast and sourdough. Different doses of iron (35, 70, 140, and 210 mg/kg per diet) were added to bread vehicle for 30 days with or without baking soda (250 mg/kg per diet). The concentrations of the above elements were determined by graphite furnace and flame atomic absorption spectroscopy. Serum zinc and manganese concentrations were significantly lower (P < 0.05) in rats that received higher concentrations of iron compared to the controls. Serum iron, and copper concentrations increased significantly (P < 0.05) with an increase in dietary iron compared to the controls. Increments of dietary concentrations of iron raised the concentration of iron, zinc and manganese in the feces, and lowered the concentration of copper and calcium in the feces (P < 0.05). Diets that contained baking soda showed a statistically significant increase in phytic acid (P < 0.05). Lower serum iron was seen in rats that received baking soda with diet of the control group. Conversely, feces iron and zinc were increased in this group. It is concluded that iron absorption might interfere with zinc and manganese because of similar physicochemical properties. Knowledge about these interactions is essential when supplementation of some elements is recommended in populations with a high risk of some deficiencies such as iron and zinc.

The preventive effect of<em> Mangifera foetida</em> L. leaf extract administered simultaneously to excess iron on markers of iron overload in Spraque-Dawley rats

Background: Recently, there is no agent available for the prevention of iron overload (IO) in thalassemia patients. Previous studies showed that Mangifera foetida L. leaf extracts reduced the levels of iron in IO in vitro and in vivo models. The present study aimed to determine the efficacy of Mangifera foetida L. leaf extract in the prevention of IO induced in rats.Methods: Thirty male Sprague-Dawley rats were divided into 5 groups: control (untreated), IO, 3 treatment groups with leaf extract equivalent to 50, 100, and 200 mg of mangiferin per kg BW. Fe-dextran (15 mg) was administered intraperitoneally twice a week for 4 weeks to all groups except control (IO, DSM50, DSM100, and DSM200). Urine and blood samples were taken before and after treatments. After 4 weeks of treatment, rats were terminated, and samples of spleen, liver, and heart were taken. Ferritin and mangiferin levels and SOD activities were determined in plasma. Iron levels were measured in plasma, urine, and spleen.Results: Experimental IO increased plasma Fe content 4.23 times and plasma ferritin levels 6.9 times vs normal. Mangifera foetida L. leaf extract DSM50 resulted in the highest blood levels of 212 ng mangiferin per mL and moderately, although not significant, prevented increased plasma ferritin levels and IO in organs and protected against oxidative stress.Conclusion: Aqueous Mangifera foetida L. leaf extract may be useful to prevent IO and oxidative stress in thalassemia patients.

Impact of chronic and acute inflammation on extra- and intracellular iron homeostasis

Inflammation has a major impact on iron homeostasis. This review focuses on acute and chronic inflammation as it affects iron trafficking and, as a result, the availability of this essential micronutrient to the host. In situations of microbial infection, not only the host is affected but also the offending microorganisms, which, in general, not only require iron for their own growth but have evolved mechanisms to obtain it from the infected host. Key players in mammalian iron trafficking include several types of cells important to iron acquisition, homeostasis, and hematopoiesis (enterocytes, hepatocytes, macrophages, hematopoietic cells, and in the case of pregnancy, placental syncytiotrophoblast cells) and several forms of chaperone proteins, including, for nonheme iron, the transport protein transferrin and the intracellular iron-storage protein ferritin, and for heme iron, the chaperone proteins haptoglobin and hemopexin. Additional key players are the cell membrane-associated iron transporters, particularly ferroportin (FPN), the only protein known to modulate iron export from cells, and finally, the iron-regulatory hormone hepcidin, which, in addition to having antibacterial activity, regulates the functions of FPN. Interestingly, the impact of infection on iron homeostasis differs among pathogens whose mode of infection is mainly intracellular or extracellular. Understanding how inflammation affects each of these processes may be crucial for understanding how inflammation affects iron status, indicators of iron sufficiency, and iron supplementation during inflammation and how it may potentially result in a beneficial or detrimental impact on the host.

Iron phosphate nanoparticles for food fortification: Biological effects in rats and human cell lines

Nanotechnology offers new opportunities for providing health benefits in foods. Food fortification with iron phosphate nanoparticles (FePO₄ NPs) is a promising new approach to reducing iron deficiency because FePO₄ NPs combine high bioavailability with superior sensory performance in difficult to fortify foods. However, their safety remains largely untested. We fed rats for 90 days diets containing FePO₄ NPs at doses at which iron sulfate (FeSO₄), a commonly used food fortificant, has been shown to induce adverse effects. Feeding did not result in signs of toxicity, including oxidative stress, organ damage, excess iron accumulation in organs or histological changes. These safety data were corroborated by evidence that NPs were taken up by human gastrointestinal cell lines without reducing cell viability or inducing oxidative stress. Our findings suggest FePO₄ NPs appear to be as safe for ingestion as FeSO₄.

Nerium indicum leaf alleviates iron-induced oxidative stress and hepatic injury in mice

CONTEXT

Nerium indicum Mill. (Apocynaceae) was reported for its efficient in vitro antioxidant and iron-chelating properties.

OBJECTIVE

This study demonstrates the effect of 70% methanol extract of N. indicum leaf (NIME) towards in vitro DNA protection and ameliorating iron-overload-induced liver damage in mice.

MATERIALS AND METHODS

Phytochemical and HPLC analyses were carried out to standardize the extract and the effect of Fe(2+)-mediated pUC18 DNA cessation was studied. Thirty-six Swiss Albino mice were divided into six groups of blank, negative control (iron overload only), and iron-overloaded mice receiving 50, 100, and 200 mg/kg b.w. doses of NIME and desirox (20 mg/kg b.w.). The biochemical markers of hepatic damage, various liver and serum parameters, and reductive release of ferritin iron were studied.

RESULTS AND DISCUSSION

The presence of different phytocomponents was revealed from phytochemical and HPLC analyses. A substantial supercoiled DNA protection, with [P]50 of 70.33 ± 0.32 µg, was observed. NIME (200 mg/kg b.w.) significantly normalized the levels of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and bilirubin by 126.27, 125.25, 188.48, and 45.47%, respectively. NIME (200 mg/kg b.w.) was shown to alleviate the reduced levels of superoxide dismutase, catalase, glutathione-S-transferase, and non-enzymatic-reduced glutathione, by 48.95, 35.9, 35.42, and 13.22%, respectively. NIME also lowered raised levels of lipid peroxidation, protein carbonyl, hydroxyproline, and liver iron by 32.28, 64.58, 136.81, and 83.55%, respectively.

CONCLUSION

These findings suggest that the active substances present in NIME may be capable of lessening iron overload-induced toxicity, and possibly be a useful drug for iron-overloaded diseases.

Ameliorating role of rutin on oxidative stress induced by iron overload in hepatic tissue of rats

Iron is an essential element that participates in several metabolic activities of cells; however, excess iron is a major cause of iron-induced oxidative stress and several human diseases. Natural flavonoids, as rutin, are well-known antioxidants and could be efficient protective agents. Therefore, the present study was undertaken to evaluate the protective influence of rutin supplementation to improve rat antioxidant systems against IOL-induced hepatic oxidative stress. Sixty male albino rats were randomly divided to three equal groups. The first group, the control, the second group, iron overload group, the third group was used as iron overload+rutin group. Rats received six doses of ferric hydroxide polymaltose (100 mg kg(-1) b.wt.) as one dose every two days, by intraperitoneal injections (IP) and administrated rutin (50 mg kg(-1) b.wt.) as one daily oral dose until the sacrificed day. Blood samples for serum separation and liver tissue specimens were collected three times, after three, four and five weeks from the onset of the experiment. Serum iron profiles total iron, Total Iron Binding Capacity (TIBC), Unsaturated Iron Binding Capacity (UIBC), transferrin (Tf) and Transferrin Saturation% (TS%)}, ferritin, albumin, total Protein, total cholesterol, triacylglycerols levels and aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities were determined. Moreover, total iron in the liver, L-malondialdehyde (L-MDA), glutathione (GSH), Nitric Oxide (NO) and Total Nucleic Acid (TNA) levels and glutathione peroxidase (GPx), catalase (CAT) and superoxide dismutase (SOD) activities were also determined. The obtained results revealed that, iron overload (IOL) resulted in significant increase in serum iron, TIBC, Tf, TS% and ferritin levels and AST and ALT activities and also increased liver iron, L-MDA and NO levels. Meanwhile, it decreased serum UIBC, total cholesterol, triacylglycerols, albumin, total protein and liver GSH, TNA levels and Gpx, CAT and SOD activities when compared with the control group. Rutin administration to iron-overloaded rats resulted in significant decrease in serum total iron, TIBC, Tf, TS%, ferritin levels and AST and ALT activities and liver total iron, L-MDA and NO levels with significant increases in serum UIBC, albumin, total protein and total cholesterol levels and in liver GSH, CAT and SOD activities compared with the IOL group. This study provides in vivo evidence that rutin administration can improve the antioxidant defense systems against IOL-induced hepatic oxidative stress in rats. This protective effect in liver of iron-loaded rats may be due to both antioxidant and metal chelation activities.

Protective effects of hesperidin on oxidative stress, dyslipidaemia and histological changes in iron-induced hepatic and renal toxicity in rats

The present study was to evaluate the protective role of hesperidin (HDN) against iron-induced hepatic and renal toxicity in rats. Administration of iron (30 mg/kg body weight) intraperitoneally for 10 days, the levels of serum hepatic markers, renal functional markers, lipid profile, lipid peroxidation markers and iron concentration in blood were significantly (p < 0.05) increased. The toxic effect of iron was also indicated by significant (p < 0.05) decrease in the levels of plasma, liver and kidney of enzymatic and non-enzymatic antioxidants. Administration of hesperidin at different doses (20, 40 and 80 mg/kg body weight) significantly (p < 0.05) reversed the levels of serum hepatic markers, renal functional markers, lipid profile, lipid peroxidation markers, restored the levels of hepatic, renal enzymatic antioxidants and non-enzymatic antioxidants with decrease in iron concentration in blood. Hesperidin at a dose of 80 mg/kg body weight exhibits significant protection on hepatic and renal when compared with other two doses (20 and 40 mg/kg body weight). All these changes were corroborating by histological observations of liver and kidney. This study demonstrated the protective role of hesperidin in reducing toxic effects of iron in experimental rats.

Iron regulation in C57BL/6 and DBA/2 mice subjected to iron overload

Many genes are likely involved in the control of iron metabolism in brain and in peripheral tissues, and genetically-defined murine strains present the opportunity to investigate genetic variations in iron metabolism. Weanling C57BL/6 (B6) and DBA/2 (D2) mice were divided into two treatment groups receiving distilled water with or without 5000 ppm ferric chloride ad libitum as their sole fluid source for 100 days. Iron overload increased liver, spleen and plasma iron levels in male and female B6 and female D2 mice. In D2 males, liver iron was increased relative to control, but spleen and plasma iron remained unaffected. Brain iron content was not different between control and iron-treated mice in ventral midbrain, caudate, pons or hippocampus, but D2 iron overloaded mice displayed lower iron levels in nucleus accumbens and prefrontal cortex. We conclude that genetic background influences the accumulation of excess iron in the periphery and iron regulation in the central nervous system.

Acute iron overload and oxidative stress in brain

An in vivo model in rat was developed by intraperitoneally administration of Fe-dextran to study oxidative stress triggered by Fe-overload in rat brain. Total Fe levels, as well as the labile iron pool (LIP) concentration, in brain from rats subjected to Fe-overload were markedly increased over control values, 6h after Fe administration. In this in vivo Fe overload model, the ascorbyl (A)/ascorbate (AH(-)) ratio, taken as oxidative stress index, was assessed. The A/AH(-) ratio in brain was significantly higher in Fe-dextran group, in relation to values in control rats. Brain lipid peroxidation indexes, thiobarbituric acid reactive substances (TBARS) generation rate and lipid radical (LR) content detected by Electron Paramagnetic Resonance (EPR), in Fe-dextran supplemented rats were similar to control values. However, values of nuclear factor-kappaB deoxyribonucleic acid (NFκB DNA) binding activity were significantly increased (30%) after 8h of Fe administration, and catalase (CAT) activity was significantly enhanced (62%) 21h after Fe administration. Significant enhancements in Fe content in cortex (2.4 fold), hippocampus (1.6 fold) and striatum (2.9 fold), were found at 6h after Fe administration. CAT activity was significantly increased after 8h of Fe administration in cortex, hippocampus and striatum (1.4 fold, 86, and 47%, respectively). Fe response in the whole brain seems to lead to enhanced NF-κB DNA binding activity, which may contribute to limit oxygen reactive species-dependent damage by effects on the antioxidant enzyme CAT activity. Moreover, data shown here clearly indicate that even though Fe increased in several isolated brain areas, this parameter was more drastically enhanced in striatum than in cortex and hippocampus. However, comparison among the net increase in LR generation rate, in different brain areas, showed enhancements in cortex lipid peroxidation, without changes in striatum and hippocampus LR generation rate after 6h of Fe overload. This information has potential clinical relevance, as it could be the key to understand specific brain damage occurring in conditions of Fe overload.

Hepatoprotective Potential of Caesalpinia crista against Iron-Overload-Induced Liver Toxicity in Mice

The present study was carried out to evaluate the ameliorating effect of Caesalpinia crista Linn. (CCME) extract on iron-overload-induced liver injury. Iron overload was induced by intraperitoneal administration of iron dextran into mice. CCME attenuated the percentage increase in liver iron and serum ferritin levels when compared to control group. CCME also showed a dose-dependent inhibition of lipid peroxidation, protein oxidation, and liver fibrosis. The serum enzyme markers were found to be less, whereas enhanced levels of liver antioxidant enzymes were detected in CCME-treated group. In presence of CCME, the reductive release of ferritin iron was increased significantly. Furthermore, CCME exhibited DPPH radical scavenging and protection against Fe(2+)-mediated oxidative DNA damage. The current study confirmed the hepatoprotective effect of CCME against the model hepatotoxicant iron overload and the activity is likely related to its potent antioxidant and iron-chelating property.

Iron overload-induced rat liver injury: Involvement of protein tyrosine nitration and the effect of baicalin

Baicalin has been reported to protect against liver injury in iron-overload mice, however, the mechanisms underlying the hepatoprotective properties of baicalin are poorly understood. In this study, we systematically studied the protective effect of baicalin on iron overload induced liver injury, as well as the underlying mechanism based on nitrative stress in rat model. We found that when iron overload rats (500mgiron/kg) were fed baicalin-containing diet (0.3% and 1% w/w) for 45days, baicalin dose dependently protected against iron overload induced liver injury, including alleviation of hepatic pathological damage, decrease of SOD activity, iron content, carbonyl content, and the thiobarbituric acid-reactive substances level in hepatic tissues. It also increased serum iron content, SH content and GPx activity, decreased serum ALT and AST activities. Immunohistochemistry and immunoprecipitation analysis revealed that baicalin could also inhibit iron overload induced protein tyrosine nitration in liver. Moreover, in iron overload rat liver, we found that baicalin decreased the iron overload increased level of glutathione-S-transferases (GSTs) expression, oxidation and nitration. These results suggest that not only oxidative stress, but also nitrative stress, is involved in iron overload induced liver injury, and the underlying mechanism might partially relate to the involvement of GSTs expression and post-translational modification. Baicalin can effectively prevent iron overload caused abnormality and can be a candidate medicine for iron overload diseases.

Hepatic distribution of iron, copper, zinc and cadmium-containing proteins in normal and iron overload mice

Subcellular distribution of metal-containing proteins of Fe, Cu, Zn and Cd were determined in the liver samples of iron overload mice by size exclusion high performance liquid chromatography with on-line coupling to UV and inductively coupled plasma mass spectrometry. Collision cell techniques was used to remove polyatomic interferences for some elements, such as Fe. Comparative molecular weight (MW) information of the elemental fraction was obtained within a retention time of 40 min. Fe was present only in high-MW (HMW) protein; Cu, Zn and Cd were found in different MW proteins. It was also observed that these four elements studied showed predominant association with HMW fractions. Moreover, compared with the normal group, we found that the contents of these elements except Cu significantly increased and the distribution of some elements like Cd changed in iron overload mouse liver. It means that excessive iron accumulation in vivo may affect the metabolism of other element such as Zn and Cd.

Study of the eye and lacrimal glands in experimental iron overload in rats in vivo

A variety of syndromes leading to hemosiderosis in men cause ocular lesions. The purpose of the present study was to determine the distribution of iron and of transferrin in the eyes and lacrimal glands of rats in experimental hemosiderosis, so as to achieve a better understanding of the formation of the ocular lesions observed in patients with advanced hemosiderosis. In order to achieve hemosiderosis the rats were fed 3% (w/w) carbonyl iron or received i.p. or i.v. polymaltose iron. Hemosiderin deposits were detected in macrophages lying in the interlobular connective tissue of lacrimal glands, in the interstitial connective tissue of the choroid, in the ciliary body, in the iris and extracellularly in the sclera in all animals that received iron i.v. Also, scanty hemosiderin laden macrophages were found to a lesser degree in interstitial connective tissue of the choroid and in the interlobular connective tissue of lacrimal glands in animals that received iron i.p. No iron deposits were detected in the eye and lacrimal glands of control rats and in rats that were on an iron enriched diet. No transferrin was detected in the eye and in the lacrimal glands, neither in the control rats nor in the rats that received iron. Experimental iron overload leads to increased iron deposition in tissues of the eye and lacrimal glands, whereas no transferrin could be detected in the aforementioned organs.

Dietary supplementation of baicalin and quercetin attenuates iron overload induced mouse liver injury

The introduction of new iron chelating drugs may ultimately improve iron-chelation therapy for patients with iron overload diseases such as thalassaemia and other disorders. In this paper, the in vivo effects of baicalin and quercetin on iron overload induced liver injury were studied on mice. It was found that when iron-dextran induced iron overload mice were fed baicalin or quercetin containing diet (1% w/w) for 45 days, both flavonoids significantly inhibited iron overload induced lipid peroxidation and protein oxidation of liver, decreased hepatic iron and hepatic collagen content, increased the serum non-heme iron level but not serum ferritin level. Flavonoids supplementation also increased the excretion of iron through feces. In vitro study demonstrated that both flavonoids could release iron from ferritin. These results indicate that besides acting as antioxidants, both flavonoids can also release iron from liver and finally excrete it through feces. The present study provides further support for flavonoids to be medicines for iron overload diseases.

Effect of iron lactate overloading on adenine nucleotide levels and adenosine 3'-monophosphate forming enzyme in rat liver and spleen

To elucidate the pathophysiological significance of adenosine 3'-monophosphate (3'-AMP) forming enzyme in rats, the effect of iron lactate overloading on the enzyme activities and adenine nucleotide levels in the liver and spleen was examined. Sprague-Dawley rats were fed a diet supplemented with 0%, 0.625% or 5.0% of iron lactate for 4 weeks. Iron deposition was found in periportal hepatocytes, Kupffer cells and macrophages of red pulp of the spleen. No significant changes in hematological parameters were detected. Although serum alkaline phosphatase and inorganic phosphorus levels elevated slightly in the 5.0% group, activities of alanine aminotransferase and aspartate aminotransferase, and levels of serum urea nitrogen and creatinine were not changed significantly. The ATP levels in the liver and spleen of iron fed groups were significantly decreased, but adenosine 5'-diphosphate (ADP) and adenosine 5'-monophosphate (AMP) levels were within control levels. On the other hand, the levels of ATP, ADP and AMP in the erythrocytes without mitochondria were not suppressed by the iron lactate overloading. Free activity of 3'-AMP forming enzyme, one of ribonucleases (RNase), was not changed in the liver of iron-overloaded rat, and total amount of 3'-AMP and adenosine formed after the treatment of the crude enzyme(s) with p-chloromercuribenzensulfonic acid, a SH blocker of RNase inhibitors, was decreased dose-dependently. On the contrary, free activity of 3'-AMP forming enzyme was enhanced dose-dependently in the spleen of iron-overloaded rat but the total activity was not changed. However, the free and total 3'-AMP forming enzyme activities in the liver and spleen of iron-overloaded rats became equal at the dosage of 5.0% of iron lactate. The results obtained suggested that iron loading might induce significant decrease in hepatic and splenic ATP levels via malfunction of their mitochondria and might lead dissociation of RNase-RNase inhibitor complex to activate 3'-AMP forming enzyme in both tissues.

Saccharated colloidal iron enhances lipopolysaccharide-induced nitric oxide production in vivo

We investigated the effects of iron on the production of nitric oxide (NO), inducible NO synthase (iNOS), and plasma cytokines induced by lipopolysaccharide (LPS) in vivo. Male Wistar rats were preloaded with a single intravenous injection of saccharated colloidal iron (Fesin, 70 mg iron/kg body weight) or normal saline as a control, and then given an intraperitoneal injection of LPS (5.0 mg/kg body weight). Rats, preloaded with iron, had evidence of both iron deposition and strong iNOS induction in liver Kupffer cells upon injection of LPS; phagocytic cells in the spleen and lung had similar findings. LPS-induced NO production in iron-preloaded rats was significantly higher than control rats as accessed by NO-hemoglobin levels measured by ESR (electron spin resonance) and NOx (nitrate plus nitrite) levels. Western blot analysis showed that iron preloading significantly enhanced LPS-induced iNOS induction in the liver, but not in the spleen or lung. LPS-induced plasma levels of IL-6, IL-1beta, and TNF-alpha were also significantly higher in iron-preloaded rats as shown by ELISA, but IFN-gamma levels were unchanged. We conclude that colloidal-iron phagocytosed by liver Kupffer cells enhanced LPS-induced NO production in vivo, iNOS induction in the liver, and release of IL-6, IL-1beta, and TNF-alpha.

Iron-mobilizing properties of the gadolinium-DTPA complex: clinical and experimental observations

BACKGROUND

Gadolinium (Gd) magnetic resonance imaging (MRI) contrast agents are considered to be safe in patients with impaired renal function. Our study investigates a mechanism of severe iron intoxication with life-threatening serum iron levels in a haemodialysis patient following MRI with Gd-diethylenetriaminepentaacetic acid (Gd-DTPA) administration. His previous history was remarkable for multiple blood transfusions and biochemical evidence of iron overload. We hypothesized that Gd-DTPA may have an iron-mobilizing effect in specific conditions of iron overload combined with prolonged exposure to the agent.

METHODS

For the in vitro study, Gd-DTPA was added to mice liver homogenate and iron metabolism parameters were measured after incubation in comparison with the same samples incubated with saline only. For the in vivo study, an experimental model of acute renal failure in iron-overloaded rats was designed. Previously iron-overloaded and normally fed rats underwent bilateral nephrectomy by renal pedicle ligation, followed by Gd-DTPA or saline injection. Iron and iron saturation levels were checked before and 24 h after Gd-DTPA or vehicle administration.

RESULTS

Significant mobilization of iron from mice liver tissue homogenate in mixtures with Gd in vitro was seen in the control (saline) and in the experimental (Gd) groups (513+/-99.1 vs 1117.8+/-360.8 microg/dl, respectively; P<0.05). Administration of Gd-DTPA to iron-overloaded rats after renal pedicle ligation caused marked elevation of serum iron from baseline 143+/-3.4 to 570+/-8 microg/dl (P<0.0001). There were no changes of the named parameter, either in iron-overloaded anuric rats after saline injection or in normal diet uraemic animals, following Gd-DTPA administration.

CONCLUSIONS

The combination of iron overload and lack of adequate clearance of Gd chelates may cause massive liberation of iron with dangerous elevation of free serum iron. It is highly recommended that after Gd contrast study, end-stage renal disease patients with probable iron overload should undergo prompt and intensive haemodialysis for prevention of this serious complication.

Iron intake increases infarct volume after permanent middle cerebral artery occlusion in rats

Experimental and clinical data suggest an important role of iron in cerebral ischaemia. We measured infarct volume and analysed the oxidative stress, and also the excitatory and inflammatory responses to brain injury in a rat stroke model after an increased oral iron intake. Permanent middle cerebral artery occlusion (MCAO) was performed in ten male Wistar rats fed with a diet containing 2.5% carbonyl iron for 9 weeks, and in ten control animals. Glutamate, interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-alpha) were determined in blood samples before and at 2, 4, 6, 8, 24 and 48 h after MCAO, and thiobarbituric acid reaction substances (TBARS) were analysed at 48 h. Infarct volume was measured at 48 h by image analysis on brain slices stained with 1% TTC. Tissue iron was measured by atomic absorption spectrophotometry. Infarct volume was 66% greater in the iron fed rats than in the control group (178+/-49 mm(3) versus 107+/-53 mm(3), P<0.01). Significant higher levels of glutamate, IL-6 and TNF-alpha were observed in the group with iron intake (peak values were obtained at 6, 8 and 4 h, respectively). Iron-fed animals also showed significantly higher levels of TBARS than those receiving a normal diet (6.52+/-0.59 vs. 5.62+/-0.86 micro mol/l, P=0.033) Liver iron stores (3500+/-199 vs. 352+/-28 micro g Fe/g, P<0.0001), but not brain iron stores (131 vs. 139 micro g Fe/g, P=0.617), were significantly higher in the iron fed rats group. These results suggest that iron intake is associated with larger infarct volumes after MCAO in the rat. This effect seems to be associated with higher oxidative stress, excitotoxicity and inflammatory responses.

Expression of transferrin mRNA in rat oligodendrocytes is iron-independent and changes with increasing age

As transferrin in the brain may originate principally from synthesis by three different cell types, i.e. hepatocytes, oligodendrocytes and choroid plexus, this study employed a morphological analysis to specifically address oligodendrocytic expression of transferrin mRNA in young (P17) and adult (P50) rats. In spite of a lowering of the concentration of brain iron by approximately 22% in the young iron deficient rats transferrin mRNA expression in oligodendrocytes was not affected when measured by quantitative densitometry. In adult rats, the baseline transferrin mRNA expression in oligodendrocytes was higher than in the young animals, but did not change in spite of a reduction in brain iron by approximately 19%. Brain iron and transferrin mRNA expression in oligodendrocytes were unaltered in iron overloaded rats when compared to age-matched controls. As transferrin expression was lower in the young rat, when constituents from the blood have a relatively higher concentration in the brain than during adulthood, it seems unlikely that blood-borne factors such as transition metals act as inducers of transferrin gene expression in oligodendrocytes. Instead, the higher but constitutive expression of transferrin mRNA at later ages, when the blood-brain barrier segregates the brain from other body parts, may indicate that molecules released from the brain interior are responsible for regulating transcription of the transferrin gene.

Expression of stimulator of Fe transport is not enhanced in Hfe knockout mice

Hfe knockout (-/-) mice recapitulate many of the biochemical abnormalities of hereditary hemochromatosis (HH), but the molecular mechanisms involved in the etiology of iron overload in HH remain poorly understood. It was found previously that livers of patients with HH contained 5-fold higher SFT (stimulator of Fe transport) mRNA levels relative to subjects without HH. Because this observation suggests a possible role for SFT in HH, we investigated SFT mRNA expression in Hfe(-/-) mice. The 4- and 10-wk-old Hfe(-/-) mice do not have elevated levels of hepatic SFT transcripts relative to age-matched Hfe(+/+) mice, despite having 2.2- and 3.3-fold greater hepatic nonheme iron concentrations, respectively. Northern blot analyses of various mouse tissues revealed that SFT is widely expressed. The novel observation that SFT transcripts are abundant in brain prompted a comparison of SFT transcript levels and nonheme iron levels in the brains of Hfe(+/+) and Hfe(-/-) mice. Neither SFT mRNA levels nor nonheme iron levels differed between groups. Further comparisons of Hfe(-/-) and Hfe(+/+) mouse tissues revealed no significant differences in SFT mRNA levels in duodenum, the site of increased iron absorption in HH. Important distinctions between Hfe(-/-) mice and HH patients include not only differences in the relative rate and magnitude of iron loading but also the lack of fibrosis and phlebotomy treatment in the knockout animals.

Contents and uptake rates of Mn, Fe, Co, Zn, and Se in Se-deficient rat liver cell fractions

The contents of manganese (Mn), iron (Fe), cobalt (Co), zinc (Zn), and selenium (Se) in nuclear (NU), mitochondrial (MT), microsomal (MC), and cytosolic (CS) fractions of liver homogenates of normal and selenium-deficient (SeD) rats were determined by instrumental neutron activation analysis (INAA). The uptake rates of these elements in the liver cell fractions of both groups of rats were determined by multitracer analysis (MTA). The results indicated that Se-deficiency caused a significant increase in the content of Fe in the MC fractions. The MTA showed that the uptake rate of Fe was highest in the MC fraction, and that the uptake rate in the fraction was similar between the SeD and normal rats.

Disposition, accumulation and toxicity of iron fed as iron (II) sulfate or as sodium iron EDTA in rats

A study was performed to provide data on the disposition, accumulation and toxicity of sodium iron EDTA in comparison with iron (II) sulfate in rats on administration via the diet for 31 and 61 days. Clinical signs, body weights, food consumption, food conversion efficiency, hematology, clinical chemistry and pathology of selected organs were used as criteria for disclosing possible harmful effects. Determination of iron and total iron binding capacity in blood plasma and non-heme iron analysis in liver, spleen and kidneys were used to assess the disposition and accumulation of iron originating from sodium iron EDTA or iron (II) sulfate. It was concluded that, under the conditions of the present study, iron is accumulated from the diet in liver, spleen and kidneys in a dose-dependent manner, and iron derived from FeEDTA is taken up and/or accumulated less efficiently in liver and spleen than iron from FeSO(4). Moreover, feeding iron up to 11.5 and 11.2 mg/kg body weight/day, derived from FeSO(4) and FeEDTA, respectively, did not result in tissue iron excess nor in any other toxicologically significant effects.