Iron and copper interact during their uptake and deposition in the brain and other organs of developing rats exposed to dietary excess of the two metals

Iron and Folic Acid Supplementation Affects Mineral Status in Female Rats with a Deficiency of These Micronutrients

Supplementation with iron and folic acid is widely recommended in women of childbearing age and during pregnancy; however, the effect of such supplementation on mineral status is not well-known. The aim of this study was to determine the effects of oral iron and folic acid, administered together and separately, on copper, zinc, calcium, and magnesium concentrations in the tissues of rats with a deficiency of both these micronutrients. The experiment was performed on 8-week-old female Wistar rats. In the first stage of the experiment, the animals were randomly assigned to a control group of rats fed the standard diet (AIN-93 M), and to a study group of rats fed a diet deficient in iron and folate. The study group was then randomly divided to four groups: group D was fed a deficit diet, group FE was fed a deficit diet with iron gluconate, the FOL group was fed a deficit diet with folate acid, and the FEFOL group was fed a deficit diet with iron gluconate and folate acid. After 2, 10, and 21 days of the intervention, ten animals from each group were killed. Mineral concentrations were assayed in the liver, spleen, pancreas, heart, and kidneys using atomic absorption spectrometry. Statistical analysis was performed using Statistica 12.0 with the ANOVA test (p < 0.05). It was found that separate supplementation with iron and folic acid significantly decreased copper concentrations in tissues. The deficit in iron and folic acid decreased, and their simultaneous supplementation increased calcium content in the organs. Separate and simultaneous supplementation decreased magnesium status in deficient rats. In conclusion, iron and folic acid, supplemented separately or simultaneously, affect the copper, calcium, and magnesium level in tissues.

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.

Prospective associations between environmental heavy metal exposure and renal outcomes in adults with chronic kidney disease

AIM

In Taiwan, Changhua County residents were exposed to high heavy metal pollution and exhibited high heavy metal levels in blood and urine. We examined associations between heavy metals in residential soil and renal outcomes of residents with chronic kidney disease (CKD).

METHOD

From 1 January 2003 to 30 June 2015, we retrospectively identified CKD patients with an estimated glomerular filtration rate of <60 mL/min per 1.73 m² at one tertiary care centre. We linked data displaying heavy metal concentrations from farm soil adjacent to the patients' residences to clinical outcomes. We included 2343 CKD patients (533 with progression to end-stage renal disease [ESRD] and 1810 without]. We followed these patients for 3.49 ± 2.27 years, until death or initiation of maintenance dialysis.

RESULTS

There were high correlations among the concentrations of the eight metals: arsenic, cadmium, chromium, mercury, copper, lead, nickel, and zinc. After factor analysis, chromium, copper, nickel, and zinc were grouped and labelled Factor 1. High Factor 1 concentration near the patients' residences was associated with diagnoses of hypertension, diabetes mellitus, and cerebral vascular accident. Patients living in areas with high Factor 1 concentrations were at higher risk of ESRD. After multivariate adjustment [adjusted hazard ratio: 1.08, 95% Confidence interval: 1.01-1.14, P = 0.02], only zinc and nickel were risk factors for progression to ESRD.

CONCLUSION

Patients with CKD, with long-term exposure to soil-based heavy metals, had rapid progression to ESRD. Groups of minerals from the same source of contamination may accumulate and lead to additional harm.

Welding-related brain and functional changes in welders with chronic and low-level exposure

Although an essential nutrient, manganese (Mn) can be toxic at high doses. There is, however, uncertainty regarding the effects of chronic low-level Mn-exposure. This review provides an overview of Mn-related brain and functional changes based on studies of a cohort of asymptomatic welders who had lower Mn-exposure than in most previous work. In welders with low-level Mn-exposure, we found: 1) Mn may accumulate in the brain in a non-linear fashion: MRI R1 (1/T1) signals significantly increased only after a critical level of exposure was reached (e.g., ≥300 welding hours in the past 90days prior to MRI). Moreover, R1 may be a more sensitive marker to capture short-term dynamic changes in Mn accumulation than the pallidal index [T1-weighted intensity ratio of the globus pallidus vs. frontal white matter], a traditional marker for Mn accumulation; 2) Chronic Mn-exposure may lead to microstructural changes as indicated by lower diffusion tensor fractional anisotropy values in the basal ganglia (BG), especially when welding years exceeded more than 30 years; 3) Mn-related subtle motor dysfunctions can be captured sensitively by synergy metrics (indices for movement stability), whereas traditional fine motor tasks failed to detect any significant differences; and 4) Iron (Fe) also may play a role in welding-related neurotoxicity, especially at low-level Mn-exposure, evidenced by higher R2* values (an estimate for brain Fe accumulation) in the BG. Moreover, higher R2* values were associated with lower phonemic fluency performance. These findings may guide future studies and the development of occupation- and public health-related polices involving Mn-exposure.

Association of neurobehavioral performance with R2* in the caudate nucleus of asymptomatic welders

OBJECTIVES

Welding fumes contain several metals including manganese (Mn) and iron (Fe) that may affect the nervous system. Previous studies of potential welding-related neurotoxicity have focused primarily on Mn exposure. The current study examined neurobehavioral and brain imaging changes in asymptomatic welders and their associations with both Mn and Fe exposure measurements.

METHODS

Data were obtained from subjects with (n=46) and without (controls; n=31) a history of welding exposure. Occupational questionnaires estimated recent (HrsW; welding hours and E₉₀; cumulative exposure, past 90days) and lifetime (YrsW; total welding years and ELT; cumulative exposure, lifetime) exposure. Brain MRI pallidal index (PI), R1 (1/T1), and R2* (1/T2*) were measured to estimate Mn and Fe concentrations in the basal ganglia [caudate nucleus (CN), putamen, and globus pallidus], amygdala, and hippocampus. Comprehensive neuropsychological tests were conducted to examine behavioral differences between welders and controls. Correlation analyses were conducted between neuropsychological tests and those exposure measurements that showed significant group differences.

RESULTS

Compared to controls, welders had significantly higher R2* in the CN and lower performance on the Phonemic Fluency test. Correlation analyses revealed that welders' Phonemic Fluency scores were inversely associated with R2* in the CN, but not with the PI or R1 in any brain region of interest studied.

DISCUSSION

The results showed that neurobehavioral performance for the asymptomatic welders in our study was worse than individuals who had not welded, and suggest the differences may be associated with higher Fe accumulation in the CN.

Increased R2* in the Caudate Nucleus of Asymptomatic Welders

Welding has been associated with neurobehavioral disorders. Welding fumes contain several metals including copper (Cu), manganese (Mn), and iron (Fe) that may interact to influence welding-related neurotoxicity. Although welding-related airborne Fe levels are about 10-fold higher than Mn, previous studies have focused on Mn and its accumulation in the basal ganglia. This study examined differences in the apparent transverse relaxation rates [R2* (1/T2*), estimate of Fe accumulation] in the basal ganglia (caudate nucleus, putamen, and globus pallidus) between welders and controls, and the dose-response relationship between estimated Fe exposure and R2* values. Occupational questionnaires estimated recent and lifetime Fe exposure, and blood Fe levels and brain magnetic resonance imaging (MRI) were obtained. Complete exposure and MRI R2* and R1 (1/T1: measure to estimate Mn accumulation) data from 42 subjects with welding exposure and 29 controls were analyzed. Welders had significantly greater exposure metrics and higher whole-blood Fe levels compared with controls. R2* in the caudate nucleus was significantly higher in welders after controlling for age, body mass index, respirator use, caudate R1, and blood metals of Cu and Mn, whereas there was no difference in R1 values in the basal ganglia between groups. The R2* in the caudate nucleus was positively correlated with whole-blood Fe concentration. This study provides the first evidence of higher R2* in the caudate nucleus of welders, which is suggestive of increased Fe accumulation in this area. Further studies are needed to replicate the findings and determine the neurobehavioral relevance.

Neonatal Iron Supplementation Induces Striatal Atrophy in Female YAC128 Huntington's Disease Mice

BACKGROUND

Dysregulation of iron homeostasis is implicated in the pathogenesis of Huntington's disease. We have previously shown that increased iron intake in R6/2 HD neonatal mice, but not adult R6/2 HD mice potentiates disease outcomes at 12-weeks of age corresponding to advanced HD [Redox Biol. 2015;4 : 363-74]. However, whether these findings extend to other HD models is unknown. In particular, it is unclear if increased neonatal iron intake can promote neurodegeneration in mouse HD models where disease onset is delayed to mid-adult life.

OBJECTIVE

To determine if increased dietary iron intake in neonatal and adult life-stages potentiates HD in the slowly progressive YAC128 HD mouse model.

METHODS

Female neonatal mice were supplemented daily from days 10-17 with 120μg/g body weight of carbonyl iron. Adult mice were provided diets containing low (50 ppm), medium (150 ppm) and high (500 ppm) iron concentrations from 2-months of age. HD progression was determined using behavioral, brain morphometric and biochemical approaches.

RESULTS

Neonatal-iron supplemented YAC128 HD mice had significantly lower striatal volumes and striatal neuronal cell body volumes as compared to control HD mice at 1-year of age. Neonatal-iron supplementation of HD mice had no effect on rota-rod motor endurance and brain iron or glutathione status. Adult iron intake level had no effect on HD progression. YAC128 HD mice had altered peripheral responses to iron intake compared to iron-matched wild-type controls.

CONCLUSIONS

Female YAC128 HD mice supplemented with nutritionally-relevant levels of iron as neonates demonstrate increased striatal degeneration 1-year later.

Sub-chronic copper pretreatment reduces oxidative damage in an experimental Huntington's disease model

Quinolinic acid (QUIN) striatal injection in rat reproduces the main neurochemical features of Huntington's disease (HD), including oxidative damage. In this study, we evaluated the effect of a copper (Cu) supplement in drinking water (90 ppm Cu, 28 days) on the QUIN-induced HD model in the rat. Copper exposure caused no signs of liver toxicity; however, it produced significant Cu accumulation in striatum. It is noteworthy that QUIN also caused increased striatal Cu content; when the supplement was administered to animals with QUIN-injury, an even higher metal striatal accumulation was observed. Cu pre-treatment preserved striatal gamma-aminobutyric acid (GABA) content, which was reduced by QUIN intrastriatal injection. Similarly, apomorphine-induced circling behavior was reduced in Cu-pretreated QUIN-damaged rats. Metal supplement in drinking water prevented both lipid peroxidation and reactive oxygen species (ROS) formation caused by QUIN in striatum. In Cu-treated groups, superoxide dismutase-1 (SOD1) activity showed a significant increase, while SOD2 activity was slightly enhanced. Although the pathophysiological role for higher Cu levels in patients with HD and in experimental models of the disease is not fully understood, results in the present study suggest that Cu oral intake stimulates anti-oxidant defenses, an effect that may be a potential factor for reducing the progression of HD.

Copper and copper proteins in Parkinson's disease

Copper is a transition metal that has been linked to pathological and beneficial effects in neurodegenerative diseases. In Parkinson's disease, free copper is related to increased oxidative stress, alpha-synuclein oligomerization, and Lewy body formation. Decreased copper along with increased iron has been found in substantia nigra and caudate nucleus of Parkinson's disease patients. Copper influences iron content in the brain through ferroxidase ceruloplasmin activity; therefore decreased protein-bound copper in brain may enhance iron accumulation and the associated oxidative stress. The function of other copper-binding proteins such as Cu/Zn-SOD and metallothioneins is also beneficial to prevent neurodegeneration. Copper may regulate neurotransmission since it is released after neuronal stimulus and the metal is able to modulate the function of NMDA and GABA A receptors. Some of the proteins involved in copper transport are the transporters CTR1, ATP7A, and ATP7B and the chaperone ATOX1. There is limited information about the role of those biomolecules in the pathophysiology of Parkinson's disease; for instance, it is known that CTR1 is decreased in substantia nigra pars compacta in Parkinson's disease and that a mutation in ATP7B could be associated with Parkinson's disease. Regarding copper-related therapies, copper supplementation can represent a plausible alternative, while copper chelation may even aggravate the pathology.

Rapid copper acquisition by developing murine mesothelioma: decreasing bioavailable copper slows tumor growth, normalizes vessels and promotes T cell infiltration

Copper, an essential trace element acquired through nutrition, is an important co-factor for pro-angiogenic factors including vascular endothelial growth factor (VEGF). Decreasing bioavailable copper has been used as an anti-angiogenic and anti-cancer strategy with promising results. However, the role of copper and its potential as a therapy in mesothelioma is not yet well understood. Therefore, we monitored copper levels in progressing murine mesothelioma tumors and analyzed the effects of lowering bioavailable copper. Copper levels in tumors and organs were assayed using atomic absorption spectrophotometry. Mesothelioma tumors rapidly sequestered copper at early stages of development, the copper was then dispersed throughout growing tumor tissues. These data imply that copper uptake may play an important role in early tumor development. Lowering bioavailable copper using the copper chelators, penicillamine, trientine or tetrathiomolybdate, slowed in vivo mesothelioma growth but did not provide any cures similar to using cisplatin chemotherapy or anti-VEGF receptor antibody therapy. The impact of copper lowering on tumor blood vessels and tumor infiltrating T cells was measured using flow cytometry and confocal microscopy. Copper lowering was associated with reduced tumor vessel diameter, reduced endothelial cell proliferation (reduced Ki67 expression) and lower surface ICAM/CD54 expression implying reduced endothelial cell activation, in a process similar to endothelial normalization. Copper lowering was also associated with a CD4(+) T cell infiltrate. In conclusion, these data suggest copper lowering is a potentially useful anti-mesothelioma treatment strategy that slows tumor growth to provide a window of opportunity for inclusion of other treatment modalities to improve patient outcomes.

Intranasal deferoxamine reverses iron-induced memory deficits and inhibits amyloidogenic APP processing in a transgenic mouse model of Alzheimer's disease

Increasing evidence indicates that a disturbance of normal iron homeostasis and an amyloid-β (Aβ)-iron interaction may contribute to the pathology of Alzheimer's disease (AD), whereas iron chelation could be an effective therapeutic intervention. In the present study, transgenic mice expressing amyloid precursor protein (APP) and presenilin 1 and watered with high-dose iron served as a model of AD. We evaluated the effects of intranasal administration of the high-affinity iron chelator deferoxamine (DFO) on Aβ neuropathology and spatial learning and memory deficits created in this AD model. The effects of Fe, DFO, and combined treatments were also evaluated in vitro using SHSY-5Y cells overexpressing the human APP Swedish mutation. In vivo, no significant differences in the brain concentrations of iron, copper, or zinc were found among the treatment groups. We found that high-dose iron (deionized water containing 10 mg/mL FeCl(3)) administered to transgenic mice increased protein expression and phosphorylation of APP695, enhanced amyloidogenic APP cleavage and Aβ deposition, and impaired spatial learning and memory. Chelation of iron via intranasal administration of DFO (200 mg/kg once every other day for 90 days) inhibited iron-induced amyloidogenic APP processing and reversed behavioral alterations. DFO treatment reduced the expression and phosphorylation of APP protein by shifting the processing of APP to the nonamyloidogenic pathway, and the reduction was accompanied by attenuating the Aβ burden, and then significantly promoted memory retention in APP/PS1 mice. The effects of DFO on iron-induced amyloidogenic APP cleavage were further confirmed in vitro. Collectively, the present data suggest that intranasal DFO treatment may be useful in AD, and amelioration of iron homeostasis is a potential strategy for prevention and treatment of this disease.

Regulation of brain iron and copper homeostasis by brain barrier systems: implication in neurodegenerative diseases

Iron (Fe) and copper (Cu) are essential to neuronal function; excess or deficiency of either is known to underlie the pathoetiology of several commonly known neurodegenerative disorders. This delicate balance of Fe and Cu in the central milieu is maintained by the brain barrier systems, i.e., the blood-brain barrier (BBB) between the blood and brain interstitial fluid and the blood-cerebrospinal fluid barrier (BCB) between the blood and cerebrospinal fluid (CSF). This review provides a concise description on the structural and functional characteristics of the brain barrier systems. Current understanding of Fe and Cu transport across the brain barriers is thoroughly examined, with major focuses on whether the BBB and BCB coordinate the direction of Fe and Cu fluxes between the blood and brain/CSF. In particular, the mechanism by which pertinent metal transporters in the barriers, such as the transferrin receptor (TfR), divalent metal transporter (DMT1), copper transporter (CTR1), ATP7A/B, and ferroportin (FPN), regulate metal movement across the barriers is explored. Finally, the detrimental consequences of dysfunctional metal transport by brain barriers, as a result of endogenous disorders or exogenous insults, are discussed. Understanding the regulation of Fe and Cu homeostasis in the central nervous system aids in the design of new drugs targeted on the regulatory proteins at the brain barriers for the treatment of metal's deficiency or overload-related neurological diseases.

Regulation of brain copper homeostasis by the brain barrier systems: effects of Fe-overload and Fe-deficiency

Maintaining brain Cu homeostasis is vital for normal brain function. The role of systemic Fe deficiency (FeD) or overload (FeO) due to metabolic diseases or environmental insults in Cu homeostasis in the cerebrospinal fluid (CSF) and brain tissues remains unknown. This study was designed to investigate how blood-brain barrier (BBB) and blood-SCF barrier (BCB) regulated Cu transport and how FeO or FeD altered brain Cu homeostasis. Rats received an Fe-enriched or Fe-depleted diet for 4 weeks. FeD and FeO treatment resulted in a significant increase (+55%) and decrease (-56%) in CSF Cu levels (p<0.05), respectively; however, neither treatment had any effect on CSF Fe levels. The FeD, but not FeO, led to significant increases in Cu levels in brain parenchyma and the choroid plexus. In situ brain perfusion studies demonstrated that the rate of Cu transport into the brain parenchyma was significantly faster in FeD rats (+92%) and significantly slower (-53%) in FeO rats than in controls. In vitro two chamber Transwell transepithelial transport studies using primary choroidal epithelial cells revealed a predominant efflux of Cu from the CSF to blood compartment by the BCB. Further ventriculo-cisternal perfusion studies showed that Cu clearance by the choroid plexus in FeD animals was significantly greater than control (p<0.05). Taken together, our results demonstrate that both the BBB and BCB contribute to maintain a stable Cu homeostasis in the brain and CSF. Cu appears to enter the brain primarily via the BBB and is subsequently removed from the CSF by the BCB. FeD has a more profound effect on brain Cu levels than FeO. FeD increases Cu transport at the brain barriers and prompts Cu overload in the CNS. The BCB plays a key role in removing the excess Cu from the CSF.

Metabolic crossroads of iron and copper

Interactions between the essential dietary metals, iron and copper, have been known for many years. This review highlights recent advances in iron-copper interactions with a focus on tissues and cell types important for regulating whole-body iron and copper homeostasis. Cells that mediate dietary assimilation (enterocytes) and storage and distribution (hepatocytes) of iron and copper are considered, along with the principal users (erythroid cells) and recyclers of red cell iron (reticuloendothelial macrophages). Interactions between iron and copper in the brain are also discussed. Many unanswered questions regarding the role of these metals and their interactions in health and disease emerge from this synopsis, highlighting extensive future research opportunities.

Copper blocks quinolinic acid neurotoxicity in rats: contribution of antioxidant systems

Reactive oxygen species and oxidative stress are involved in quinolinic acid (QUIN)-induced neurotoxicity. QUIN, a N-methyl-D-aspartate receptor (NMDAr) agonist and prooxidant molecule, produces NMDAr overactivation, excitotoxic events, and direct reactive oxygen species formation. Copper is an essential metal exhibiting both modulatory effects on neuronal excitatory activity and antioxidant properties. To investigate whether this metal is able to counteract the neurotoxic and oxidative actions of QUIN, we administered copper (as CuSO(4)) intraperitoneally to rats (2.5, 5.0, 7.5, and 10.0 mg/kg) 30 min before the striatal infusion of 1 microliter of QUIN (240 nmol). A 5.0 mg/kg CuSO(4) dose significantly increased the copper content in the striatum, reduced the neurotoxicity measured both as circling behavior and striatal gamma-aminobutyric acid (GABA) depletion, and blocked the oxidative injury evaluated as striatal lipid peroxidation (LP). In addition, copper reduced the QUIN-induced decreased striatal activity of Cu,Zn-dependent superoxide dismutase, and increased the ferroxidase activity of ceruloplasmin in cerebrospinal fluid from QUIN-treated rats. However, copper also produced significant increases of plasma lactate dehydrogenase activity and mortality at the highest doses employed (7.5 and 10.0 mg/kg). These results show that at low doses, copper exerts a protective effect on in vivo QUIN neurotoxicity.

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.

Neuroprotective effect of acute and chronic administration of copper (II) sulfate against MPP+ neurotoxicity in mice

Neurodegenerative effects of MPP+, the main metabolite of MPTP include dopamine (DA) depletion and enhanced lipid peroxidation (LPO) in mice striata, both associated to free radicals overproduction. Since copper is related to several antioxidant enzymes, we tested its neuroprotective effect against MPP+-induced neurotoxicity (20 microg/3 microl). CuSO4 pretreatment was administrated by either acute (2.5 mg/kg, i.p.) or chronic (350 or 700 mg/l doses through drinking water, for 30 days) schemes. Acute administration blocked MPP+-induced striatal LPO only when administered 16 or 24 hours before MPP+, and prevented the DA-depleting effect only at 24 hours. Chronic CuSO4 prevented the LPO increase, and blocked the DA depletion only at the higher dose used (700 mg/l). Neuroprotective effect of CuSO4 was dependent on the dose and the time of pretreatment, which suggest that this lag could be related with mechanisms of activation or synthesis of copper-dependent proteins responsible of cellular defense against MPP+.

Dietary iron reduces the anti-convulsion activity of phenytoin in electroconvulsion via inhibition of brain penetration

We determined the anti-convulsion activity of phenytoin (PHT) using the maximum electron shock method in mice fed diets containing various concentrations of iron for 18 weeks. Dietary iron reduces the anti-convulsion activity of PHT in a dose-dependent manner (0-6100 ppm). High concentrations of PHT are detected in the plasma of mice fed a high iron diet compared with those fed normal and low iron diets, in contrast to the pharmacological effect. However, the concentration of PHT in the brains of mice fed high amounts of dietary iron decreased significantly 3 h after treatment with PHT, consistent with the anti-convulsion effect of PHT. The relationship between brain and plasma-unbound concentrations of PHT indicates that the penetration of PHT into brain is significantly inhibited by dietary iron.

Maze learning and motor activity deficits in adult mice induced by iron exposure during a critical postnatal period

Newborn mice were administered Fe(2+) (iron succinate: 7.5 mg/kg, b. wt) on either Days 3-5, 10-12 or 19-21, or vehicle (saline) at the same times, postnatally. Spontaneous motor behaviour and radial arm maze learning were tested at the age of 3 months. It was found that mice treated with Fe(2+) during postnatal Days 10-12 were markedly hypokinetic during the 1st 20-min test period and hyperkinetic during the 3rd and final 20-min test period. These mice showed an almost complete lack of habituation of spontaneous motor activity parameters to the test chambers. In the radial arm maze, the Days 10-12 treatment group evidenced significantly both more errors in arm choices and longer latencies to acquire all eight pellets; these mice showed also a severe trial-to-trial retention deficit as indexed by retention quotients. These behavioural deficits were observed also in animals treated with Fe(2+) during postnatal Days 3-5, but the effects were less pronounced, indicating the higher susceptibility of the brain for Fe(2+)-induced damage during Days 10-12 postpartum. Treatment with Fe(2+) on Days 19-21 did not induce behavioural alterations in comparison with its respective control (vehicle) group. Analysis of total brain iron content indicated significantly more iron (microg/g) accumulation in the basal ganglia, but not frontal cortex, of mice from the Days 3-5 and 10-12 Fe(2+) (7.5 mg/kg) treatment groups. The contribution of iron overload during the immediate postnatal to later functional deficits seems to implicate symptoms of Parkinsonism but the kinetics of iron uptake to the brain and its regional distribution at this critical period of development awaits elucidation.

Reduced ferroxidase activity in the cerebrospinal fluid from patients with Parkinson's disease

Recent evidence suggest the implication of transition metals leading to overproduction of free radicals as a possible causal factor in the death of nigral cells associated to Parkinson's disease (PD). Iron depots in the basal ganglia of PD patients have been described; in addition, contents of nigral copper have been found decreased, while its concentration in cerebrospinal fluid (CSF) is raised, particularly the free form of the metal. To search for a possible link between altered copper concentrations and PD, we advanced the hypothesis that ferroxidase activity of ceruloplasmin is decreased in the CSF of PD patients. We studied 35 untreated PD patients, 14 L-3,4-dihydroxyphenylalanine (L-DOPA)-treated PD patients and 26 controls. Both CSF ferroxidase activity and CSF copper content were measured and correlated with the clinical stage of the disease. We found that untreated PD patients had a significant reduction of 40% in CSF ferroxidase while CSF copper was slightly increased as compared with both the values in L-DOPA-treated PD patients and controls. We also found that the fraction of copper linked to ferroxidase in untreated PD is inversely related to the clinical stage of the disease.

Desferrioxamine and vitamin E protect against iron and MPTP-induced neurodegeneration in mice

To elucidate the neuroprotective effects of the iron chelator desferrioxamine (DFO) and the antioxidant vitamin E on excessive iron-induced free radical damage, a chronic iron-loaded mice model was established. The relationship between striatal iron content, oxidized to reduced glutathione ratio, hydroxyl radical (.OH) levels and dopamine concentrations were observed in DFO or vitamin E pretreated iron-loaded/1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated C57BL/6 mice. The results demonstrated that both DFO and vitamin E inhibit the iron accumulation and thus reverses the increase in oxidized glutathione (GSSG), oxidized to reduced glutathione ratios, .OH and lipid peroxidation levels. The striatal dopamine concentration was elevated to normal value. Our data suggested that: (1) iron may induce neuronal damage and thus excessive iron in the brain may contribute to the neuronal loss in PD; (2) iron chelators and antioxidants may serve as potential therapeutic agents in retarding the progression of neurodegeneration.