Subchronic dietary exposure of rats to cadmium alters the metabolism of metals essential to bone health

Changes in Endogenous Essential Metal Homeostasis in the Liver and Kidneys during a Six-Month Follow-Up Period after Subchronic Cadmium Exposure

Cadmium (Cd) is one of the most dangerous environmental pollutants. Its mechanism of action is multidirectional; among other things, it disrupts the balance of key essential elements. The aim of this study was to assess how cumulative exposure to Cd influences its interaction with selected essential elements (Cu, Zn, Ca, and Mg) in the kidney and liver during long-term observation (90 and 180 days) after subchronic exposure of rats (90 days) to Cd at common environmental (0.09 and 0.9 mg Cd/kg b.w.) and higher (1.8 and 4.5 mg Cd/kg b.w.) doses. Cd and essential elements were analyzed using the F-AAS and GF-AAS techniques. It was shown that the highest bioaccumulation of Cd in the kidney occurred six months after the end of exposure, and importantly, the highest accumulation was found after the lowest Cd dose (i.e., environmental exposure). Organ bioaccumulation of Cd (>21 μgCd/g w.w. in the kidney and >6 μgCd/g w.w. in the liver) was accompanied by changes in the other studied essential elements, particularly Cu in both the kidney and liver and Zn in the liver; these persisted for as long as six months after the end of the exposure. The results suggest that the critical concentration in human kidneys (40 μgCd/g w.w.), currently considered safe, may be too high and should be reviewed, as the observed long-term imbalance of Cu/Zn in the kidneys may lead to renal dysfunction.

An Assessment of Metallothionein-Cadmium Binding in Rat Uterus after Subchronic Exposure Using a Long-Term Observation Model

Cadmium (Cd) is an environmental pollutant known to pose a public health issue. The mechanism of Cd toxicity on the uterus, including the protective role of metallothionein (MT), is still not fully understood. The aim of the study was to evaluate the degree of MT-Cd binding in the uterus of rats exposed per os to Cd at daily doses of 0.09, 0.9, 1.8 and 4.5 mg Cd/kg b.w. for 90 days. To assess the permanence of the bond, the rats were observed over long observation periods: 90 and 180 days after termination of exposure. Additionally, uterine concentration of Zn, Cu, Ca, Mg was determined. Cd leads immediately after exposure to a max. 30-fold increase in the concentration of Cd in the uterus, with only small amounts being bound to MT. After 90 days following termination of exposure, and especially after 180 days, an increase in MT-Cd concentration was noted for the three highest doses; even so, the degree of Cd binding by MT was still small. Additionally, the accumulation of Cd in the uterus disturbs the homeostasis of determined essential elements, manifested by a significant increase in Cu concentration and a decrease in Zn, Mg and Ca, especially 180 days after termination of exposure. The obtained results indicate that MT has only a slight protective role in the uterus and that Cd ions may have harmful effects not related to MT: directly on the uterine tissue, and indirectly by disturbing the homeostasis of its essential elements.

A systematic review of adverse health effects associated with oral cadmium exposure

Scientific data characterizing the adverse health effects associated with dietary cadmium (Cd) exposure were identified in order to make informed decisions about the most appropriate toxicological reference value (TRV) for use in assessing dietary Cd exposure. Several TRVs are available for Cd and regulatory organizations have used epidemiologic studies to derive these reference values; however, risk of bias (RoB) evaluations were not included in the assessments. We performed a systematic review by conducting a thorough literature search (through January 4, 2020). There were 1714 references identified by the search strings and 328 studies identified in regulatory assessments. After applying the specific inclusion and exclusion criteria, 208 studies (Human: 105, Animal: 103) were considered eligible for further review and data extraction. For the epidemiologic and animal studies, the critical effects identified for oral Cd exposure from the eligible studies were a decrease in bone mineral density (BMD) and renal tubular degeneration. A RoB analysis was completed for 49 studies (30 epidemiological and 19 animal) investigating these endpoints. The studies identified through the SR that were considered high quality and low RoB (2 human and 5 animal) can be used to characterize dose-response relationships and inform the derivation of a Cd TRV.

Bioaccumulation of total mercury, copper, cadmium, silver, and selenium in green turtles (Chelonia mydas) stranded along the Potiguar Basin, northeastern Brazil

Sea turtles face several threats and pollution has become a major concern for their conservation worldwide. We analyzed samples of the liver, muscles, and kidneys of 38 Chelonia mydas stranded along the Potiguar Basin, northeastern Brazil, between 2015 and 2018 to determine the total Hg concentration (THg), as well as the concentrations of Cu, Cd, Ag, and Se. The relation between turtle size and element concentrations revealed a negative correlation for THg and Se (liver, muscles, and kidneys), Cu and Cd (liver and kidneys) and a positive correlation for Ag in the three organs analyzed. Concentrations of THg, Cu, Ag, and Se were high in the liver, highlighting the Cu concentration (median = 25.1150 μg g^-1 w.w.), while the kidneys had the highest Cd levels (median = 12.2200 μg g^-1 w.w.). There was significant difference between element concentrations and the three organs analyzed, except for Ag and Se concentrations in the muscle and kidney samples. Our study showed that green turtles found in Potiguar Basin, northeastern Brasil, have bioaccumulated inorganic elements which indicate the need of further investigations on the environmental quality of the region.

Survival of Embryos and Fry of Sea Trout (Salmo trutta m. trutta) Growing from Eggs Exposed to Different Concentrations of Selenium during Egg Swelling

Adequate selenium (Se) availability enhances the health and growth of organisms, but overdose of it can be harmful and pathogenic. The study's objective was to analyse the impact of short-term exposure of sea trout fertilised eggs to inorganic selenium (SeO₂) at concentrations from 0 to 32 mg Se L^-1 to find the optimal and toxic dose of Se on early fish development. Se accumulated in the body, embryos' survival rate, and growth in the first four months of life was examined. Swelling of fertilised eggs in water supplemented with Se at a concentration from 0.5 to 8 mg Se L^-1 was associated with a slightly positive impact on the hatching rate. At higher Se concentration, a harmful effect on the survival of the embryo was observed. The survival of fry was similar in all groups, while the fry length and weight correlated positively with Se concentration in its body. Immersion of fertilised eggs in water enriched with Se during egg swelling can constitute a method to supplement the element to non-feeding stages of fish. In selenium-poor areas, this innovative method can be implemented in aquaculture to improve breeding outcomes. Se concentration should be adjusted to the chemical compound, fish species, and Se's content in the yolk.

Comparison of nanoparticle-selenium, selenium-enriched yeast and sodium selenite on the alleviation of cadmium-induced inflammation via NF-kB/IκB pathway in heart

Cadmium (Cd) has been confirmed as an environmental contaminant, which potential threats health impacts to humans and animals. Selenium (Se) as a beneficial element that alleviates the negative effects of Cd toxicity. Se mainly exists in two forms in food nutrients including organic Se usually as (Se-enriched yeast (SeY)) and inorganic Se (sodium selenite (SSe)). Nanoparticle of Se (Nano-Se), a new form Se, which is synthesized by the bioreduction of Se species, which attracted significant attention recently. However, compared the superiority alleviation effects of Nano-Se, SeY or SSe on Cd-induced toxicity and related mechanisms are still poorly understood. The purpose of this study was to compare the superiority antagonism effects of Nano-Se, SeY and SSe on Cd-induced inflammation response via NF-kB/IκB pathway in the heart. The present study demonstrated that exposed to Cd obviously increased the accumulation of Cd, disruption of ion homeostasis and depressed the ratios of K⁺/Na⁺ and Mg²⁺/Ca²⁺ via ion chromatography mass spectrometry (ICP-MS) detecting the heart specimens. In the results of histological and ultrastructure observation, typical inflammatory infiltrate characteristics and mitochondria and nuclear structure alterations in the hearts of Cd group were confirmed. Cd treatment enhanced the inducible nitric oxide synthase (iNOS) activities and NOS isoforms expression via NF-kB/IκB pathway to promote inflammation response. However, the combined treatment of Cd-exposed animals with Nano-Se was more effective than SeY and SSe in reversing Cd-induced histopathological changes and iNOS activities increased, reducing Cd accumulation and antagonizing Cd-triggered inflammation response via NF-kB/IκB pathway in chicken hearts. Overall, Se applications, especially Nano-Se, can be most efficiently used for relieving cardiotoxicity by exposed to Cd compared to other Se compound.

Transcriptome analysis of cadmium exposure in kidney fibroblast cells of the North Atlantic Right Whale (Eubalaena glacialis)

An 8X15k oligonucleotide microarray was developed consisting of 2334 Eubalaena glacialis probes and 2166 Tursiops truncatus probes and used to measure the effects, at transcriptomic level, of cadmium exposure in right whale kidney fibroblast cells. Cells were exposed to three concentrations (1 μM, 0.1 μM, and 0.01 μM) of cadmium chloride (CdCl₂) for three exposure times (1, 4, and 24 h). Cells exposed to 1 μM CdCl₂ for 4 h and 24 h showed upregulated genes involved in protection from metal toxicity and oxidative stress, protein renaturation, apoptosis inhibition, as well as several regulators of cellular processes. Downregulated genes represented a suite of functions including cell proliferation, transcription regulation, actin polymerization, and stress fiber synthesis. The collection of differentially expressed genes in this study support proposed mechanisms of cadmium-induced apoptosis such as ubiquitin proteasome system disruption, Ca²⁺ homeostasis interference, mitochondrial membrane potential collapse, reactive oxygen species (ROS) production, and cell cycle arrest. The results also have confirmed the right whale microarray as a reproducible tool in measuring differentiated gene expression that could be a valuable asset for transcriptome analysis of other baleen whales and potential health assessment protocols.

The effects of pretreatment with lithium metaborate dihydrate on lipid peroxidation and Ca, Fe, Mg, and K levels in serum of Wistar albino male rats exposed to Cd

Boron and boron compounds have beneficial biological effects. Lithium metaborate dihydrate (LMBDH) is used in many branches of industry. Despite its wide industrial use, there is limited information about its biological effects on antioxidant defense system and trace element homeostasis. Therefore, the aim of this study was to evaluate the in vivo protective effects of LMBDH against CdCl₂-induced oxidative stress and imbalance of some bioelements for the first time. In the study, totally 20 Wistar albino male rats were used. The rats were fed with pellet food and water ad libitum and divided into four groups including five rats in each. Group I was control group (standard pellet food + water + normal saline), Group II was CdCl₂ (4.58 mg/kg/body weight/intraperitoneally/single dose), Group III was LMBDH (15 mg/kg/body weight/day orally, for 5 days), Group IV was CdCl₂ (4.58 mg/kg/body weight/intraperitoneally/single dose in fifth day), and LMBDH (15 mg/kg/body weight/day orally for 5 days). The results showed that CdCl₂ treatment increased blood MDA level and decreased antioxidant enzyme activities and the level of blood GSH compared to control group. Pretreatment with LMBDH significantly decreased MDA levels and increased SOD activity (p < 0.05). In addition, Ca, Fe, and K levels decreased in LMBDH pretreatment group in different statistically levels. However, Mg levels showed an increase in LMBDH pretreatment group. As a result, LMBDH pretreatment decreased MDA status and supported antioxidant system by increasing SOD activity. In addition, it did not exhibit an ameliorative effect on measured bioelement homeostasis.

Cadmium exposure triggers mitochondrial dysfunction and oxidative stress in chicken (Gallus gallus) kidney via mitochondrial UPR inhibition and Nrf2-mediated antioxidant defense activation

Cadmium (Cd) is a widespread environmental pollutant that accumulates in living systems and represents a significant global health hazard. Cd poses a toxicity threat to both human and animal health, including that of birds. Further knowledge of Cd toxicology pathways will allow for a better understanding of Cd-induced nephrotoxicity. To evaluate Cd-induced nephrotoxicity through potential oxidative damage, male chickens were treated with 0 mg/kg, 35 mg/kg or 70 mg/kg CdCl₂ in diet for 90 days. Markedly, histopathology indicated renal tubular epithelial cell swelling, renal function CREA content abnormalities, biochemical and morphologic indices indicative of Cd-induced kidney injury. Cd toxicity induced the up-regulation of Nrf2 and downstream target genes that relieve oxidative stress. Meanwhile, Cd disrupted the homeostasis of trace elements and promoted oxidative damage. Cd interfered with mitochondrial unfolded protein response (UPR^mt)-related factors (SIRT1, SIRT3, PGC-1α, TFAM, Nrf1, and HTRA2) and disrupted the homeostasis of mitochondrial dynamics (OPA1, MFN1, MFN2, Fis1 and MFF), thereby exacerbating mitochondrial structural damage and mitochondrial dysfunction. In conclusion, our study demonstrated that the nephrotoxicity of Cd exposure results in oxidative stress and mitochondrial dysfunction by activating the Nrf2 signaling pathway and inhibiting UPR^mt in the kidneys.

Cadmium and High-Fat Diet Disrupt Renal, Cardiac and Hepatic Essential Metals

Exposure to the environmental toxicant cadmium (Cd) contributes to the development of obesity-associated diseases. Obesity is a risk factor for a spectrum of unhealthy conditions including systemic metabolic dyshomeostasis. In the present study, the effects of whole-life exposure to environmentally-relevant concentrations of Cd on systemic essential metal distribution in adult mice fed a high-fat diet (HFD) were examined. For these studies, male and female mice were exposed to Cd-containing drinking water for >2 weeks before breeding. Pregnant mice and dams with offspring were exposed to Cd-containing drinking water. After weaning, offspring were continuously exposed to the same Cd concentration as their parents, and divided into HFD and normal (low) fat diet (LFD) groups. At 10 and 24 weeks, mice were sacrificed and blood, liver, kidney and heart harvested for metal analyses. There were significant concentration dependent increases in Cd levels in offspring with kidney > liver > heart. Sex significantly affected Cd levels in kidney and liver, with female animals accumulating more metal than males. Mice fed the HFD showed > 2-fold increase in Cd levels in the three organs compared to similarly treated LFD mice. Cadmium significantly affected essential metals levels in blood, kidney and liver. Additionally, HFD affected essential metal levels in these three organs. These findings suggest that Cd interacts with HFD to affect essential metal homeostasis, a phenomenon that may contribute to the underlying mechanism responsible for the development of obesity-associated pathologies.

Comparative effects of meso-2,3-dimercaptosuccinic acid, monensin and salinomycin on the concentrations of cadmium and some essential elements in skeletal muscles of Cd-exposed mice

Cadmium (Cd) is an environmental pollutant shown to induce multi organ dysfunction. In this study we present novel data about the effects of meso-2,3-dimercaptosuccinic acid (DMSA), monensin and salinomycin on the concentration of Cd in skeletal muscles of mice exposed to Cd (II) acetate treatment for 14 days. The impact of Cd and the chelating agents on the endogenous concentrations of calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), phosphorous (P), selenium (Se) and zinc (Zn) was also investigated. Subacute exposure of mice to Cd (II) acetate resulted in a significant accumulation of the toxic metal ion in the skeletal muscles compared to the untreated controls. Salinomycin most effectively mobilized Cd from the muscles compared to DMSA and monensin. The Cd exposure and the tested chelating agents did not significantly alter the endogenous concentrations of the selected essential elements in mouse muscles. The presented results confirmed that among the tested chelating agents salinomycin is superior as a potential antidote to Cd poisoning.

The protective role of selenium against cadmium-induced hepatotoxicity in laying hens: Expression of Hsps and inflammation-related genes and modulation of elements homeostasis

The purpose of this study was to examine the potential role of high selenium (Se) diets in alleviating chronic cadmium (Cd) hepatic toxicity in laying hens. In the present study, 128 healthy 31-week-old laying hens were fed a diet supplemented with Se (Na₂SeO₃, 2 mg/kg), Cd (CdCl₂, 150 mg/kg), or both Se and Cd (150 mg/kg of CdCl₂ and 2 mg/kg of Na₂SeO₃) for 90 days. The expression levels of heat shock proteins (Hsps, including Hsp60, Hsp70 and Hsp90) and inflammation-related factors, including nuclear factor-kappa B p50 (NF-κB), cyclooxygenase-2 (COX-2), prostaglandin E synthases (PTGES), interleukin 1-beta (IL-1β), and tumor necrosis factor-α (TNF-α) were investigated. The concentrations of 28 elements were also determined. The results indicated that Cd treatment significantly increased the mRNA and protein expression levels of Hsps and significantly improved the expression of inflammation-related genes. Moreover, Cd addition to the diets resulted in disturbances in the systemic balance of 13 elements, leading to decrease in the concentrations of Cr, Mn, Sr, Ba, and Hg and increase in Li, B, Ca, Ti, Fe, Cu, Mo, and Cd concentrations. Treatment with Se significantly alleviated Cd-induced hepatic toxicity, as evidenced by a reduction in Hsp60, Hsp70, Hsp90, NF-κB, COX-2, PTGES, TNF-α, and IL-1β expression. Additionally, Se and Cd co-treatment alleviated the changes in Li, B, Ca, Fe, Ti, Cu, Mo, Cd, Cr, Se, Sr, Ba, and Hg concentrations, which was in contrast to that upon Cd induction. The study indicated that Se could help against the negative effects of Cd and may be related to the alleviation of Cd-induced Hsps stress and the inflammatory responses along with modulating the element homeostasis.

Biochemical and transcriptional analyses of cadmium-induced mitochondrial dysfunction and oxidative stress in human osteoblasts

Cadmium (Cd) accumulation is known to occur predominantly in kidney and liver; however, low-level long-term exposure to Cd may also result in bone damage. Few studies have addressed Cd-induced toxicity in osteoblasts, particularly upon cell mitochondrial energy processing and putative associations with oxidative stress in bone. To assess the influence of Cd treatment on mitochondrial function and oxidative status in osteoblast cells, human MG-63 cells were treated with Cd (up to 65 μM) for 24 or 48 h. Intracellular reactive oxygen species (ROS), lipid and protein oxidation and antioxidant defense mechanisms such as total antioxidant activity (TAA) and gene expression of antioxidant enzymes were analyzed. In addition, Cd-induced effects on mitochondrial function were assessed by analyzing the activity of enzymes involved in mitochondrial respiration, membrane potential (ΔΨm), mitochondrial morphology and adenylate energy charge. Treatment with Cd increased oxidative stress, concomitantly with lipid and protein oxidation. Real-time polymerase chain reaction (qRT-PCR) analyses of antioxidant genes catalase (CAT), glutathione peroxidase 1 (GPX1), glutathione S-reductase (GSR), and superoxide dismutase (SOD1 and SOD2) exhibited a trend toward decrease in transcripts in Cd-stressed cells, particularly a downregulation of GSR. Longer treatment with Cd (48 h) resulted in energy charge states significantly below those commonly observed in living cells. Mitochondrial function was affected by ΔΨm reduction. Inhibition of mitochondrial respiratory chain enzymes and citrate synthase also occurred following Cd treatment. In conclusion, Cd induced mitochondrial dysfunction which appeared to be associated with oxidative stress in human osteoblasts.

Effect of an Extract from Aronia melanocarpa L. Berries on the Body Status of Zinc and Copper under Chronic Exposure to Cadmium: An In Vivo Experimental Study

In an experimental model of low-level and moderate environmental human exposure to cadmium (Cd), it was investigated whether the consumption of a polyphenol-rich Aronia melanocarpa L. berries (chokeberries) extract (AE) may influence the body status of zinc (Zn) and copper (Cu). The bioelements' apparent absorption, body retention, serum and tissue concentrations, total pool in internal organs, excretion, and the degree of binding to metallothionein were evaluated in female rats administered 0.1% aqueous AE or/and Cd in their diet (1 and 5 mg/kg) for 3-24 months. The consumption of AE alone had no influence on the body status of Zn and Cu. The extract administration at both levels of Cd treatment significantly (completely or partially) protected against most of the changes in the metabolism of Zn and Cu caused by this xenobiotic; however, it increased or decreased some of the Cd-unchanged indices of their body status. Based on the findings, it seems that rational amounts of chokeberry products may be included in the daily diet without the risk of destroying Zn and Cu metabolisms; however, their potential prophylactic use under exposure to Cd needs further study to exclude any unfavourable impact of these essential elements on the metabolism.

Trace elements in loggerhead turtles (Caretta caretta) stranded in mainland Portugal: Bioaccumulation and tissue distribution

Pollution is among the most significant threats that endanger sea turtles worldwide. Waters off the Portuguese mainland are acknowledged as important feeding grounds for juvenile loggerheads. However, there is no data on trace element concentrations in marine turtles occurring in these waters. We present the first assessment of trace element concentrations in loggerhead turtles (Caretta caretta) occurring off the coast of mainland Portugal. Also, we compare our results with those from other areas and discuss parameters that may affect element concentrations. Trace element concentrations (As, Cd, Cu, Pb, Mn, Hg, Ni, Se, Zn) were determined in kidney, liver and muscle samples from 38 loggerheads stranded between 2011 and 2013. As was the only element with higher concentrations in muscle (14.78 μg g^-1 ww) than in liver or kidney. Considering non-essential elements, Cd presented the highest concentrations in kidney (34.67 μg g^-1) and liver (5.03 μg g^-1). Only a weak positive link was found between renal Cd and turtle size. Inter-elemental correlations were observed in both liver and kidney tissues. Hepatic Hg values (0.30 ± 0.03 μg g^-1) were higher than values reported in loggerheads in the Canary Islands but lower than in Mediterranean loggerheads. Cd concentrations in the present study were only exceeded by values found in turtles from the Pacific. Although many endogenous and exogenous parameters related with complex life cycle changes and wide geographic range may influence trace element accumulation, the concentrations of Cd are probably related to the importance of crustaceans in loggerhead diet in the Portuguese coast.

Ameliorative Effects of Dietary Selenium Against Cadmium Toxicity Is Related to Changes in Trace Elements in Chicken Kidneys

The ameliorative effects of selenium (Se) against cadmium (Cd)-induced toxicity have been reported extensively. However, few studies have assessed the effects of multiple ions simultaneously on the variations of elements. In this study, the changes in Se, Cd, and 26 other element concentrations were investigated in chicken kidneys. One hundred and twenty-eight 31-week-old laying hens were fed a diet supplemented with either Se, Cd, or both Se and Cd for 90 days. The ion content was analyzed by inductively coupled plasma mass spectrometry (ICP-MS). We found that the Se, Cd, and combined Se and Cd treatments significantly affected the trace elements in the chicken kidneys. The Cd supplement caused ion profile disorders, including reduced concentrations of V, Cr, Mn, Mo, As, Ba, Hg, Ti, and Pb and increased Si, Cu, Li, Cd, and Sb. The Se supplement reduced the contents of Co, Mo, and Pb and increased the contents of Cr, Fe, and Se. Moreover, Se also increased the concentrations of Cr, Mn, Zn, and Se and decreased those of Li and Pb, which in contrast were induced by Cd. Complex interactions between elements were analyzed, and both positive and negative correlations among these elements are presented. The present study indicated that Se can help against the negative effects of Cd and may be related to the homeostasis of the trace elements in chicken kidneys.

Remarkable differences in the biochemical fate of Cd2+, Hg2+, CH3Hg+ and thimerosal in red blood cell lysate

The application of a metallomics method revealed that all investigated Hg species bound to hemoglobin and that these interactions are of toxicological significance.

Effects of Selenium and Cadmium on Ion Profiles in the Brains of Chickens

Antagonistic effects of selenium (Se) in cadmium (Cd)-induced toxicity have been frequently reported in previous studies. However, little was known about the interactions of Se and Cd on ion profiles in the brains of poultry. The aim of this study was to investigate the interaction between Se and Cd in the ion profile of the chicken brain. In the present study, a total of 128 laying hens were fed a Se-, Cd-, or Se + Cd-supplemented diet for 90 days. Levels of 28 ions were detected in chicken brains using ICP-MS. We found that Cd exposure significantly increased the content of Cd in the brain; furthermore, the content of lithium (Li), stannum (Sn), and stibium (Sb) increased, but the content of kalium (K) decreased. The content of Se in the brain was not altered by Se supplementation; however, Se reduced the concentrations of Sn and Sb, which in contrast were increased by Cd exposure. Complex interactions between ions were analyzed by principal component analysis, and both positive and negative correlations between different ions were found after prolonged exposure to Se and Cd. These findings suggest that Se and Cd supplementation influences the ion profiles in the chicken brain, and moreover, Se may have an antagonistic effect under longer exposure to Cd.

Effects of thirty elements on bone metabolism

The human skeleton, made of 206 bones, plays vital roles including supporting the body, protecting organs, enabling movement, and storing minerals. Bones are made of organic structures, intimately connected with an inorganic matrix produced by bone cells. Many elements are ubiquitous in our environment, and many impact bone metabolism. Most elements have antagonistic actions depending on concentration. Indeed, some elements are essential, others are deleterious, and many can be both. Several pathways mediate effects of element deficiencies or excesses on bone metabolism. This paper aims to identify all elements that impact bone health and explore the mechanisms by which they act. To date, this is the first time that the effects of thirty minerals on bone metabolism have been summarized.

Can the Hyperaccumulating Plant Arabidopsis halleri in Feed Influence a Given Consumer Organism (Rattus norvegicus var. alba)?

Zinc and cadmium concentrations in rat (Rattus norvegicus var. alba) tissues were analyzed by inductively coupled plasma optical emission spectrometry. Rats were fed the zinc and cadmium hyperaccumulating plant, Arabidopsis halleri. When compared to the control group, a Cd increase in all tissues (liver, kidneys, small intestine, spleen, testes, muscle), with the exception of bone tissue was observed. In comparison to the control group, the kidneys, liver and small intestine contained 375, 162, and 80 times more Cd, respectively. Differences between zinc concentrations in rats fed with A. halleri and those of the control group were significant only in the small intestine and kidney tissues. Results suggest using the hyperaccumulating plant A. halleri as a feed stresses the consumer organism not through its Zn content, but through its Cd content.

Changes in compact bone microstructure of rats subchronically exposed to cadmium

Background

Chronic exposure to cadmium (Cd), even at low concentrations, has an adverse impact on the skeletal system. Histologically, primary and secondary osteons as basic structural elements of compact bone can also be affected by several toxicants leading to changes in bone vascularization and mechanical properties of the bone. The current study was designed to investigate the effect of subchronic peroral exposure to Cd on femoral bone structure including histomorphometry of the osteons in adult male rats.

In our study, 20 one-month-old male Wistar rats were randomly divided into two experimental groups. In the first group, young males received a drinking water containing 30 mg of CdCl₂/L, for 90 days. Ten one-month-old males without Cd intoxication served as a control group. After 90 days of daily peroral exposure, body weight, femoral weight, femoral length, cortical bone thickness and histological structure of the femora were analysed.

Results

We found that subchronic peroral application of Cd had no significant effect on body weight, femoral length and cortical bone thickness in adult rats. On the other hand, femoral weight was significantly increased (P < 0.05) in Cd-intoxicated rats. These rats also displayed different microstructure in the middle part of the compact bone where vascular canals expanded into central area of substantia compacta and supplied primary and secondary osteons. Additionally, a few resorption lacunae which are connected with an early stage of osteoporosis were identified in these individuals. Histomorphometrical evaluations showed that all variables (area, perimeter, maximum and minimum diameter) of the primary osteons’ vascular canals, Haversian canals and secondary osteons were significantly decreased (P < 0.05) in the Cd group rats. This fact points to alterations in bone vascularization.

Conclusions

Subchronic peroral exposure to Cd significantly influences femoral weight and histological structure of compact bone in adult male rats. It induces an early stage of osteoporosis and causes reduced bone vascularization. Histomorphometrical changes of primary and secondary osteons allow for the conclusion that the bone mechanical properties could be weakened in the Cd group rats. The current study significantly expands the knowledge on damaging action of Cd on the bone.

Bone adaptation to simultaneous cadmium and diazinon toxicity in adult male rats

Food contamination from natural or anthropogenic sources poses severe risks to health of human and animals. Bone is a metabolically active organ, which can be affected by various toxic substances, such as cadmium (Cd) and diazinon (DZN), leading to disruption in bone metabolic processes. The present study was designed to investigate the effect of simultaneous peroral administration to Cd and DZN on femoral compact bone structure in adult male rats. A total of twenty 1-month-old male Wistar rats were randomized into two experimental groups. In the first group (EG), young males were dosed with a combination of 30 mg CdCl2/L and 40 mg DZN/L in drinking water, for 90 days. Ten 1-month-old males without Cd-DZN intoxication served as a control group (CG). After 90 days of daily peroral exposure, evaluations of femoral bonemacro- and micro-structure were performed in each group. We found no significant differences in body weight, femoral weight, femoral length and cortical bone thickness between both groups (EG and CG). However, rats from the group EG displayed different microstructure in the middle part of the substantia compacta where primary vascular radial bone tissue appeared. In some cases, vascular expansion was so enormous that canals were also present near the periost. On the other hand, they occurred only near endosteal surfaces in rats from the control group. Moreover, a smaller number of primary and secondary osteons was identified in Cd-DZN-exposed rats. This fact signalizes reduced mechanical properties of their bones. Anyway, our results suggest an adaptive response of compact bone tissue to Cd-DZN-induced toxicity in adult male rats in order to prevent osteonecrosis.

Monensin ameliorates cadmium-induced hepatic injury in mice, subjected to subacute cadmium intoxication

This study was designed to evaluate the potential application of monensin as an oral drug for the treatment of cadmium-induced hepatic dysfunction. The study was performed using ICR mouse model. Twenty-seven adult ICR male mice were divided into three groups of nine animals each: control (received distilled water and food ad libitum for 28 days); Cd-intoxicated (treated orally with 20 mg/kg b.w. Cd(II) acetate from the 1st to the 14th day of the experimental protocol); and monensin treated group (intoxicated with Cd(II) acetate as described for the Cd-intoxicated group followed by an oral treatment with 16 mg/kg b.w. tetraethylammonium salt of monensic acid for two weeks). The obtained results demonstrated that the treatment of Cd-intoxicated animals with monensin restored the liver weight/body weight index to normal values, decreased the concentration of the toxic metal ion by 50% compared to the Cd-treated controls, and recovered the homeostasis of Cu and Zn. Monensin reduced the activity of aspartate aminotransferase, alanine aminotrasnferase and alkaline phosphatase in the plasma of Cd-treated animals to the normal control levels and ameliorated the Cd-induced inflammation in the liver. Taken together, these data demonstrated that monensin could be an effective chelating agent for the treatment of Cd-induced hepatotoxicity.

Combined effects of fluoride and cadmium on liver and kidney function in male rats

It has been shown that cadmium and fluoride may both have adverse effects on liver and kidney functions, but most studies focus on a single agent. In this study, we observed the effects of cadmium and fluoride on liver and kidney functions using a rat model. Total of 24 Sprague-Dawley male rats were divided into four groups, one control group and three exposure groups that were given cadmium (50 mg/L) and fluoride (100 mg/L) alone or in combination via drinking water. At the 12th week, urine, blood, and kidney tissues were collected. Aspartate transaminase, alanine transaminase (ALT), urinary β2-microglobulin, and albumin were determined. Contents of malondialdehyde (MDA) and superoxide dismutase (SOD) in liver and kidney homogenates were measured to evaluate oxidative stress. There was a significant increase in serum ALT and urinary β2-microglobulin of rats in exposure groups compared with control. Serum ALT and urinary β2-microglobulin of rats exposed to cadmium and fluoride in combination was significantly higher than those treated with cadmium alone and fluoride alone. SOD declined significantly and MDA increased in combination group compared with control and those treated with cadmium and fluoride alone. Cadmium and fluoride co-exposure increase the liver and kidney damage compared with that exposed to cadmium or fluoride alone.

The liver in itai-itai disease (chronic cadmium poisoning): pathological features and metallothionein expression

Cadmium (Cd) is a highly hepatotoxic heavy metal, which is widely dispersed in the environment. Acute Cd hepatotoxicity has been well studied in experimental animals; however, effects of prolonged exposure to Cd doses on the liver remain unclear. In the present study, to evaluate chronic Cd hepatotoxicity, we examined specimens from cases of itai-itai disease, the most severe form of chronic Cd poisoning. We compared 89 cases of itai-itai disease with 27 control cases to assess Cd concentration in organs. We also examined 80 cases of itai-itai disease and 70 control cases for histopathological evaluation. In addition, we performed immunohistochemistry for metallothionein, which binds and detoxifies Cd. Hepatic Cd concentration was higher than Cd concentration in all other organs measured in the itai-itai disease group, whereas it was second highest following renal concentration in the control group. In the liver in the itai-itai disease group, fibrosis was observed at a significantly higher rate than that in the control group. Metallothionein expression was significantly higher in the itai-itai disease group than that in the control group. Prolonged exposure to low doses of Cd leads to high hepatic accumulation, which can then cause fibrosis; however, it also causes high expression of metallothionein, which is thought to reduce Cd hepatotoxicity.

The association between blood pressure and blood cadmium in a Chinese population living in cadmium polluted area

Cadmium exposure may be associated with high risk of hypertension. But inconsistent results have been reported. In this study, the association of blood pressure (BP) with blood cadmium (BCd) and the possible influencing factors were investigated. A total of 181 persons (71 men and 110 women) living near a cadmium smelter participated in this study. The participants completed a questionnaire and BP, BCd and related biochemical indicators were measured. The geometric mean of BCd was 3.84μg/L and 3.32μg/L for women and men. The systolic blood pressure (SBP) and diastolic blood pressure both increased with the increasing of BCd. The BP in women was positively correlated with BCd (p<0.05). The BCd level of participants with hypertension was obvious higher (+28%) than those with normal BP. The prevalence of hypertension was increased with the increasing of BCd, in particular to women (χ(2)=3.896, p=0.048). Cadmium level in blood was associated with elevation in blood pressure, especially for women.

The tetraethylammonium salt of monensic acid-An antidote for subacute cadmium intoxication: a study using an ICR mouse model

In this study, the ability of the chelating agent monensic acid (administered as the tetraethylammonium salt) to reduce the cadmium (Cd) concentration in the kidneys, liver, heart, lungs, spleen and testes of Cd-intoxicated mice was investigated. Chelation therapy with the tetraethylammonium salt of monensic acid led to a significant decrease of the Cd concentration in all of the organs of the Cd-treated mice. This effect varied from 50% in the kidneys to 90% in the hearts of the sacrificed animals (compared to the Cd-treated controls). No redistribution of the toxic metal ions to the brain of the animals as a result of the detoxification with the chelating agent was observed. The detoxification of the animals with the antibiotic salt did not perturb the endogenous levels of copper (Cu) or zinc (Zn). The tetraethylammonium salt of monensic acid significantly ameliorated the Cd-induced total iron (Fe) depletion in the liver and spleen of Cd-treated mice. It also restored to control levels the values of transferrin-bound Fe and the total iron binding capacity (TIBC) of the plasma. These results imply that the tetraethylammonium salt of monensic acid could be an efficient antidote in cases of Cd-intoxication.

Cadmium toxicokinetics and bioaccumulation in turtles: trophic exposure of Trachemys scripta elegans

Ecotoxicological data in reptiles are mainly represented by field studies reporting the tissue burden of wild-captured individuals but much less is known regarding the processes of uptake, depuration, accumulation and the effects of inorganic contaminants in these species. In the present study, the accumulation, the path and the effects of exposure to cadmium (Cd) through diet intake were investigated in female red eared slider turtles, Trachemys scripta elegans. In the first phase of the experiment, turtles underwent an acclimatization period during which they were fed a control diet. In the second phase, the turtles were exposed to cadmium through a CdCl(2) supplemented-diet with increased environmentally relevant concentrations for a period of 13 weeks. Following this, the turtles went through a third phase, a recovery phase of 3 weeks, during which they were fed uncontaminated food. Blood and feces were collected during the three phases of the experiment. The turtles were euthanized at the end of the experiment and organ samples collected. The Cd-concentrations in blood remained stable over the course of the experiment while Cd-concentrations in feces increased with time and with the amount of Cd ingested. The proportional accumulation in liver and kidney together was comprised between 0.7 and 6.1% and they represented the main organs of accumulation. Cd accumulated in the organs in the following order of concentration: kidney > liver > pancreas > muscle. In terms of burden in organs, the Cd-burden was the highest in liver followed by kidney and pancreas. The proportional accumulation decreased as Cd ingestion increased, suggesting that at a higher dose of Cd, assimilation decreased. Mineral content of the liver and pancreas became modified according to Cd level; increasing dietary Cd exposure increased concentrations of zinc and iron in liver and copper in pancreas in a dose-dependent manner. Accumulation of Cd had no effect on survival, food consumption, growth, weight or length suggesting no effect of the treatment on female turtle body condition.

Effect of zinc supplementation on glutathione peroxidase activity and selenium concentration in the serum, liver and kidney of rats chronically exposed to cadmium

It was investigated whether the ability of zinc (Zn) to prevent cadmium (Cd)-induced lipid peroxidation may be connected with its impact on glutathione peroxidase (GPx) activity and selenium (Se) concentration. GPx and Se were determined in the serum, liver and kidney of the rats that received Cd (5 or 50 mg/L) or/and Zn (30 mg/L) in drinking water for 6 months in whose the protective Zn impact was noted (Rogalska J, Brzóska MM, Roszczenko A, Moniuszko-Jakoniuk J. Enhanced zinc consumption prevents cadmium-induced alterations in lipid metabolism in male rats. Chem Biol Interact 2009;177:142-52). Moreover, dependences between these parameters, and indices of lipid peroxidation (F(2)-isoprostane, lipid peroxides, oxidized low density lipoprotein cholesterol) as well as concentrations of Cd and Zn were estimated. The supplementation with Zn during the exposure to 5 mg Cd/L entirely antagonized the Cd-induced increase in GPx activity and Se concentration in the liver and kidney, but not in the serum. Zn administration during the treatment with 50 mg Cd/L totally or partially prevented from the Cd-caused decrease in GPx activity and Se concentration in the serum, liver and kidney. At the higher level of Cd exposure, GPx activity in the serum and tissues positively correlated with Se concentration. Moreover, numerous correlations were noted between GPx and/or Se and the indices of lipid peroxidation. The results indicate that the protective impact of Zn against the Cd-induced lipid peroxidation during the relatively high exposure might be connected with its beneficial influence on Se concentration and GPx activity in the serum and tissues, whereas this bioelement influence at the moderate exposure seems to be independent of GPx and Se.

Interrelationships between cadmium, zinc and antioxidants in the liver of the rat exposed orally to relatively high doses of cadmium and zinc

Zinc (Zn) reduces cadmium (Cd)-induced toxicity in the liver although it increases Cd tissue burden in some conditions; hence, the present study is designed to study the relationships between Cd, Zn and antioxidants in the liver of rats exposed to Cd. Livers of male rats which received orally relatively high doses of Cd (200 mg Cd/L as Cd chloride or Cd (200 mg/L)+Zn (500 mg Zn as Zn chloride) during five weeks, were investigated. Cd induced an accumulation of Cd and Zn in parallel to depletion in important variables (GSH, GSH/GSSG, CuZn-SOD and GPx activities) and to elevation in others (Cd/Zn and GSSG). Cd, did not affect CuZn SOD/GPx, nor Mn-SOD in the liver. Cd accumulation, Cd/Zn, CuZn SOD activity and CuZn SOD/GPx, was increased remarkably under Zn action. Zn supply ameliorated GSH level and partially reversed the decrease in GSH/GSSG, but it did not ameliorate GPx activity. Analysis showed high correlations between Cd and the majority of the variables, while Zn was positively correlated with only GSSG. We suggest from our results that Zn has indirect ameliorative effects on Cd-induced toxicity in the liver and that the increase in Cd retention is probably the key mechanism modulating, in the case of relatively high doses of Cd, the antioxidant response during exposure to Cd and Zn.

Effects of a single intraperitoneal administration of cadmium on femoral bone structure in male rats

BACKGROUND

Exposure to cadmium (Cd) is considered a risk factor for various bone diseases in humans and experimental animals. This study investigated the acute effects of Cd on femoral bone structure of adult male rats after a single intraperitoneal administration.

METHODS

Ten 4-month-old male Wistar rats were injected intraperitoneally with a single dose of 2 mg CdCl2/kg body weight and killed 36 h after the Cd had been injected. Ten 4-month-old males served as a control group. Differences in body weight, femoral weight, femoral length and histological structure of the femur were evaluated between the two groups of rats. The unpaired Student's t-test was used for establishment of statistical significance.

RESULTS

A single intraperitoneal administration of Cd had no significant effect on the body weight, femoral weight or femoral length. On the other hand, histological changes were significant. Rats exposed to Cd had significantly higher values of area, perimeter, maximum and minimum diameters of the primary osteons' vascular canals and Haversian canals. In contrast, a significant decrease in all variables of the secondary osteons was observed in these rats.

CONCLUSIONS

The results indicate that, as expected, a single intraperitoneal administration of 2 mg CdCl2/kg body weight had no impact on macroscopic structure of rat's femora; however, it affected the size of vascular canals of primary osteons, Haversian canals, and secondary osteons.

Aging effects of major and trace elements in rat bones and their mutual correlations

The concentrations of 29 major to trace elements in rat bones (femur) aging from 5 to 113 weeks old were determined. The samples were decomposed by high purity nitric acid and hydrogen peroxide. Nine elements (Na, Mg, P, K, Ca, Fe, Ni, Zn, and Sr) were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) and 20 elements (Li, B, Al, V, Cr, Mn, Cu, As, Se, Rb, Mo, Ag, Cd, Sb, Cs, Ba, W, Tl, Pb, and U) were determined by inductively coupled plasma mass spectrometry (ICP-MS). Aging effects on these elements and mutual elemental correlations were investigated. The concentrations of Ca, P and Na increased in the initial stage of 5-17 weeks and then maintained constant values, whereas those of Mg, K, Mn, Sr and Ba showed decreasing trends of differing patterns. Furthermore, Cu, Zn and Mo showed increasing trends for a whole range of ages. Selenium showed a remarkable increasing trend with a factor of 10. The values of Na, Mg, P, K, Ca, Mn, Cu, Zn, Se and Mo in the age-matched rats distributed narrow ranges, indicating that the metabolism of these elements in bone was well-established. By contrast, those of Al, V, Ni, Ag, Cd, Sb, W, Tl, and U were distributed across a broad range. The metabolism of these elements was not well-established. A cluster analysis was performed using an elemental correlation matrix.

Effect of wheat bran and flaxseed on cadmium effects and retention in rats

Dietary fiber can affect cadmium (Cd) absorption and toxicity, but the effect appears to depend on the type of dietary fiber. The aim of the present study was to compare the effect of dietary sources containing distinct amounts of soluble and insoluble fiber on Cd absorption, accumulation and toxicity in growing rats. The absorption of essential macrominerals (Ca, P and Mg) was also evaluated. Animals received a nutritionally balanced diet with cellulose (cel - control), wheat bran or flaxseed as the fiber source with 0 or 50 mg Cd kg(-1) diet, during 30 days. Cd exposure reduced body weight gain, feed efficiency ratio, epididymal fat relative weight and liver relative weight, and increased plasma alanine aminotransferase activity in all fiber groups. The apparent Cd absorption was similar among Cd-groups, but the flax-Cd group had a higher hepatic and renal Cd concentration. Cd decreased the absorption of Ca and P, and increased Mg absorption in the wheat bran and flaxseed groups, but not in the cel group. Although the different fiber sources investigated had no effect on Cd toxicity, the major soluble fiber source, flaxseed, increased Cd retention. Thus, caution should be taken in the intake of flaxseed by Cd-exposed populations.

Influence of cereal bran supplement on cadmium effects in growing rats

Strategies to diminish cadmium (Cd) absorption are highly desirable especially where Cd exposure due to environmental contamination is still inevitable. Cd toxicity may be influenced by dietary components, such as fiber and minerals. Multimixtures are low-cost cereal bran supplements used in Brazil and in other countries to counteract malnutrition in low-income populations. This study was aimed at evaluating whether multimixture would reduce Cd effects in young rats. Animals received a diet with or without the multimixture plus 0, 5, or 25 mg Cd/kg (control, Cd-5, and Cd-25 groups) during 30 days. The Cd-5 groups were similar to control groups in all parameters analyzed, except in the higher renal Cd concentration. However, the Cd-25 groups had lower biological growth parameters and renal delta-aminolevulinate dehydratase activity, besides higher renal Cd concentration and plasma alanine aminotransferase activity compared to the controls. The multimixture did not prevent Cd effects in the Cd-25 group, but caused a small reduction in renal Cd concentration in the Cd-5 group. Although this multimixture was ineffective to prevent Cd effects at the higher concentration, it seemed to reduce Cd accumulation at the lower Cd dietary concentration, which is similar to levels of human exposure in some polluted areas.

Cadmium availability to freshwater mussel (Unio tumidus) in the presence of organic matter and UV radiation

The influence of ultraviolet radiation (UV) on cadmium availability to freshwater mussel (Unio tumidus) in the presence of organic matter was investigated. Water solutions containing 1000, 500, and 250 microg x L(-1) of cadmium and 28.8 mg x L(-1) of total organic carbon (TOC) were exposed to ecologically relevant biologically effective UV-A and UV-B irradiances of 1.73 x 10(-6) W x cm(-2) and 1.50 x 10(-5) W x cm(-2) respectively for 12 h. The availability of cadmium was measured directly as Cd concentration in gills, mantle, digestive gland and foot, and indirectly as its impact on the content of essential cations. The concentration of cadmium ions, soluble forms of cadmium, pH and conductivity in UV irradiated solutions were also measured. UV exposures resulted in a decrease of the TOC to 25.9 mg x L(-1), followed by a decrease in the total concentration of Cd soluble forms, increase in the concentration of cadmium bound to particulate matter, and increase in the concentration of free cadmium ions in comparison to non-irradiated mixtures. Mussels from mixtures exposed to UV accumulated more cadmium than specimens from non-irradiated mixtures. This was confirmed by the fluctuations of essential cations, i.e. decreases in the contents of Zn, Ca, Fe and increase of the Cu content. Na/K molar ratios in gills were negatively correlated with cadmium content, while a positive trend occurred in other organs. We suggest that in UV-exposed water more ionic forms of cadmium occur. On the other hand more cadmium is also bound to particulate matter. Our research indicate that the increase of cadmium accumulation in mussels grown in humic acid solutions exposed to UV were most probably related to the increase in the concentration of cadmium bound to particulate matter.

Blood and urine cadmium and bioelements profile in nickel-cadmium battery workers in Serbia

Although cadmium (Cd) is extensively used for nickel-cadmium battery production, few recent reports are available on the effect of this toxic metal on the imbalance of biometals in occupational exposure. The current study was carried out to determine the Cd level and its effect on the content of bioelements: zinc, cooper, magnesium, and iron in blood and urine of workers exposed to Cd during nickel-cadmium battery production. β2-microglobulins (β2-MG), as indicators of kidney damage, were determined in urine.

The study group comprised 32 male nickel-cadmium battery workers, and the control group had 15 male construction workers with no history of Cd exposure. Levels of Cd and bioelements were determined in blood and urine by atomic absorption spectrophotometry.

Cd concentration in blood of exposed workers was around 10 μg/L and in urine ranged from 1.93 to 8.76 μg/g creatinine (cr). Urine Cd concentration was significantly higher in exposed workers than in the controls, although no statistical difference in β2-MG content was observed in urine between the two groups. Blood Zn and Mg level were significantly reduced and urine Zn level was increased in Cd-exposed group when compared with controls.

The mean Cd concentrations in blood and urine did not exceed the recommended reference values of 10 μg/L in blood and 10 μg/g cr in urine. Cd exposure resulted in disturbances of Zn in blood and urine and Mg in blood but had no effect on Cu and Fe content in biological fluids.

Cadmium dietary intake and biomarker data in French high seafood consumers

Seafood and especially mollusks are known to be a rich source of cadmium (Cd), but little data are available concerning French seafood contamination and Cd exposure of French populations. The objective was then to assess food intake and biological level of Cd in high consumers of seafood, and to determine the impact of the consumption of self-fished mollusks on urinary Cd. Seafood consumption levels of 80 products were assessed for 1011 high consumers aged 18 and over in four French coastal areas, thanks to a validated food frequency questionnaire (FFQ). According to a total diet study approach, seafood samples were collected taking into account preservation methods and supply habits. Food samples were analyzed for Cd. Exposure was assessed by crossing consumption data with contamination data. Total blood and urine samples were collected from 380 subjects of the cohort and analyzed for Cd. The impact of the self-collected mollusks consumption on the Cd biological level adjusted for creatinine was assessed by a multivariate linear regression model. The mean dietary intake of Cd is 2.44+/-3.34 microg/kg bw/wk and the mean urinary Cd (U-Cd) level is 0.65+/-0.45 microg/g creatinine, and is significantly higher in women than in men (P<0.05). The consumption of self-fished mollusks is significantly negatively associated with U-Cd (r=-0.11 [-0.185, -0.009], P=0.03). The results of this study indicate that the biological Cd levels remain below the standards, and also suggest a protective effect of self-fishing, which inspires confidence about the high consumer health safety in terms of Cd exposure.

Changes in levels of essential elements in suckling rats exposed to zinc and mercury

The effect of mercury and its interaction with zinc on the content of essential metals in tissues from neonate rats was investigated. Three-day-old Wistar rats were treated with saline or 27 mg kg(-1)d(-1) ZnCl2 (s.c.) for five consecutive days. From the 8th to the 12th day of life, the rats received one daily dose of saline or 5.0 mg kg(-1) HgCl2 (s.c). Twenty-four hours after the last injection liver, kidneys and blood were collected for metal quantification. The HgCl(2) exposure induced alterations on metal levels, such as increase of Fe, Hg and Zn in liver, decrease of Fe and Mg and increase of Cu and Hg contents in kidneys. The Hg exposure also increased Hg levels in the blood. The treatment with ZnCl2, administered previously to HgCl2, partially prevented the increase of Fe in the liver, and not only prevented the decrease of renal Mg but also increased it to levels higher than those found in control group. The Zn-Hg rats also presented higher renal Cu levels, and showed partially lower blood and hepatic Hg levels and higher renal Hg levels. The pre-administration of Zn caused no severe alterations in levels of essential metals (Cu, Fe, Mg and Mn). In short, Zn appears to be an alternative treatment of Hg poisoning in young animals in comparison to chelating drugs since these have low metal selectivity.

Relation between lipid peroxidation and iron concentration in mouse liver after acute and subacute cadmium intoxication

In this study the effect of acute and subacute cadmium (Cd) intoxication on iron (Fe) concentration and lipid peroxidation (LPO) was investigated in the livers of Swiss mice. Animals were divided into two groups: the Cd group--mice intoxicated with Cd and controls. In acute time-response studies, Fe and malondialdehyde (MDA) levels were determined at 4, 6, 12, 24 and 48 h after a single oral dose of Cd (20 mg Cd/kg b.w.). In the subacute experiment, mice were given 10 mg Cd/kg b.w. orally every day for 14 days; Fe and MDA contents were determined in liver after 1 and 2 weeks. Acute Cd intoxication induced a significantly increased hepatic Fe content after 4 and 6h, and a statistically significant increase in MDA 6, 12 and 24h after Cd administration, although a significantly decreased MDA level was observed after 48 h. The results suggest development of early oxidative stress in livers of mice after acute intoxication with Cd. The decreased MDA observed after 48 h occurred presumably due to the adaptive response of the organism. Subacute Cd intoxication induced a significant decrease of hepatic Fe and MDA levels at both investigated time intervals compared with control. These results indicate a positive correlation between hepatic Fe and MDA content and suggest that prolonged Cd intoxication decreases hepatic LPO indirectly, by reducing the Fe content of mouse liver.

Cadmium accumulation in deer tongue grass (Panicum clandestinum L.) and potential for trophic transfer to microtine rodents

Site 36 at the Crab Orchard National Wildlife Refuge includes a Cd-contaminated soil dominated by deer tongue grass (Panicum clandestinum L.). Analysis of deer tongue grass from this site indicated that biomass and leaf surface area were reduced and that there was a linear relationship between both plant bioavailable soil Cd and total soil Zn and tissue Cd concentration. The Cd concentrations in stems and leaves were also used to estimate the dietary Cd exposures that might be experienced by prairie voles (Microtus ochrogaster) and pine voles (M. pinetorum) consuming deer tongue grass. Renal and hepatic Cd burdens predicted from exclusive consumption of deer tongue grass would be comparable to those that have resulted in chronic toxicity in rodents. The results suggest that for the contaminated soil at Site 36, conditions could allow for the accumulation of Cd in deer tongue grass to concentrations that may pose an ecological risk.

Effect of zinc supplementation on bone metabolism in male rats chronically exposed to cadmium

The aim of the present study is to investigate, based on the rat model of moderate and relatively high human exposure to cadmium (Cd), whether zinc (Zn) supplementation may prevent Cd-induced disorders in bone metabolism. For this purpose, male Wistar rats received Cd (5 and 50mg/l) or/and Zn (30 and 60mg/l) in drinking water for 6 and 12 months. Bone densitometry and biochemical markers of bone turnover were used to assess the effects of Cd or/and Zn. Bone mineral content (BMC) and density (BMD) were measured in the femur. Serum osteocalcin (OC) and alkaline phosphatase in trabecular (bT-ALP) and cortical (bC-ALP) bone were determined as bone formation markers, and carboxy-terminal cross-linking telopeptides of type I collagen (CTX) in serum were measured as bone resorption marker. Serum concentration of calcium (Ca) and its renal handling, as well as Zn and Cd concentrations in the serum/blood, urine and femur were evaluated as well. The exposure to 5 and 50mg Cd/l (0.340+/-0.026 and 2.498+/-0.093mg Cd/kg body wt/24h, respectively), in a dose and duration dependent manner, affected bone turnover (inhibited bone formation and stimulated its resorption) and disturbed bone mineralization (decreased BMC, BMD and Zn concentration). Zn supply at the concentration of 30 and 60mg/l (1.904+/-0.123 and 3.699+/-0.213mg/kg body wt/24h, respectively) during Cd exposure influenced the Cd-induced disorders in bone metabolism. Zn administration to the Cd-exposed rats enhanced the bone ALP activity and prevented Cd-induced bone resorption, but had no statistically significant effect on BMC and BMD; however, mean values of the densitometric parameters in the rats receiving both Cd and Zn were higher than in those treated with Cd alone. Moreover, Zn supplementation at both levels of Cd exposure was found to prevent Cd accumulation in the femur and the Cd-induced decrease in bone Zn concentration. The results of the present study allow the conclusion that Zn supplementation during Cd exposure may partly protect from disorders in bone metabolism. The influence of Zn may be accompanied by its ability to prevent Cd-induced Zn deficiency and to decrease Cd accumulation in bone tissue. The findings seem to indicate that enhanced dietary intake of Zn in subjects chronically exposed to moderate and relatively high Cd levels may have a protective influence on the skeleton.

Subcellular changes of essential metal shown by in-air micro-PIXE in oral cadmium-exposed mice

To clarify the relation of essential metals to cadmium (Cd) toxicity, we evaluated metallothionein expression and analyzed the subcellular distribution of essential metals using in-air micro-Particle-Induced X-ray Emission (PIXE). Four mice were dosed orally with 100 mg/L of Cd in drinking water for 1.5 or 2 years. Frozen samples of organs were used for micro-PIXE analysis and formalin-fixed samples were used for metallothionein staining. Immunohistochemically, metallothionein induction by 1.5y-Cd exposure was higher in the renal cortex than in the liver. Metallothionein expression was reduced after 2y-Cd administration compared to the 1.5y-Cd-exposed mice. Cd-induced tissue damage became marked in the 2y-Cd-exposed mice compared to the 1.5y-Cd-exposed mice, in which nephrotoxicity was more prominent than hepatotoxicity. Cd yield was higher in the renal cortex of the 2y-Cd-exposed mouse than in that of the 1.5y-Cd-exposed mouse, whereas no such increasing tendency was found in the liver. Compared to the control, the Cd-exposed mice markedly accumulated zinc in the liver and renal cortex. In the Cd-exposed mice, iron was mildly accumulated in the renal cortex and was slightly deprived in the liver. Elemental maps showed that a large amount of Cd was spatially combined with zinc in the 1.5y-Cd mouse. Free Cd became abundant in the 2y-Cd-exposed mouse. In addition, a small amount of Cd was colocalized with iron. The data suggest that zinc may contribute to protect against oral-administrated Cd toxicity, and impaired induction of MT may participate in hepato-nephrotoxicity of the 2y-Cd-exposed mouse.