Beneficial effect of zinc supplementation on biomechanical properties of femoral distal end and femoral diaphysis of male rats chronically exposed to cadmium

Role of Nutraceuticals in Treating Erectile Dysfunction via Inhibition of Phosphodiesterase-5 Enzyme: A Mini Review

Erectile Dysfunction (ED) is a prevalent sexual health condition affecting a significant portion of the male population worldwide. The conventional therapeutic approaches for ED often involve the use of pharmaceutical agents targeting the phosphodiesterase-5 (PDE5) enzyme. Currently, treatment with PDE-5 inhibitors is the standard approach for ED, and four PDE-5 inhibitors, namely sildenafil, vardenafil, tadalafil, and avanafil, are in use. However, these pharmaceutical interventions may be associated with adverse effects and limitations. As a result, there has been a growing interest in exploring alternative and complementary treatment options for ED, such as nutraceuticals, which are bioactive compounds derived from natural sources. Nutraceuticals, which include vitamins, minerals, herbs, and other dietary supplements, have gained popularity for their potential health benefits. Certain nutraceuticals have demonstrated the ability to modulate various physiological pathways, including those involved in erectile function. A notable mechanism of action is the inhibition of the PDE5 enzyme, which plays a pivotal role in the regulation of cGMP levels. By inhibiting PDE5, nutraceuticals can promote the accumulation of cGMP, leading to enhanced penile blood flow and improved erectile function. A comprehensive analysis of the literature showcases various nutraceutical agents, including plant-derived compounds like flavonoids, polyphenols, and amino acids which have exhibited PDE5 inhibitory effects. Mechanistic insights into their action involve modulation of NO release, cGMP elevation, and relaxation of penile smooth muscles, all critical factors for achieving and sustaining erections. This review focuses on elucidating the role of nutraceuticals in treating erectile dysfunction through the inhibition of the PDE5 enzyme.

The Abundance of Trace Elements in Human Bone Relative to Bone Type and Bone Pathology

As the global population ages and the proportion of individuals afflicted with musculoskeletal disease spirals upward, there is an increasing interest in understanding and preventing bone-related diseases. Bone diseases, such as osteoporosis and osteoarthritis, are known to be influenced by a variety of factors including age, gender, nutrition, and genetics, but are also inherently linked to the human body's ability to produce biominerals of suitable quality. Because the crystal lattice structure and mineralogy of bone hydroxyapatite is surprisingly analogous to geological hydroxyapatite, trace element levels and exposure have long been proposed to influence the structure of biominerals as they do geological minerals (e.g., strontium substitution changes the crystal lattice of bone minerals, while toxic lead disrupt bone cellular processes leading to bone disease). Here, we explore the distribution of trace elements in human bones to evaluate the distribution of these elements with respect to bone type (cortical vs. trabecular) and bone disease (osteoarthritis vs. osteoporosis). We find higher concentrations of many metabolically active transition metals, as well as lead, in cortical bone compared to trabecular bone. When compared to patients who have osteoarthritis, and thus presumably normal bone minerals, osteoporosis patients have higher concentrations of scandium and chromium (Cr) in trabecular bone, and Cr and lead in cortical bone. Lower concentrations of barium and titanium are associated with osteoporotic trabecular bone. This survey is an exploratory cross-sectional geochemical examination of several trace element concentrations previously understudied in human bone minerals.

Interference with zinc homeostasis and oxidative stress induction as probable mechanisms for cadmium-induced embryo-toxicity in zebrafish

The present study was conducted to provide new insights into the mechanisms that may be responsible for cadmium (Cd)-induced toxicity in zebrafish larvae as well as the role of the trace element zinc (Zn) in reversing Cd harmful effects. For this purpose, zebrafish eggs were exposed to Cd or/and Zn for 96 h. The effects on morphological aspect; mortality rate; Cd, Zn, and metallothionein (MT) levels; oxidative stress biomarkers; as well as molecular expression of some genes involved in Zn metabolism (Zn-MT, ZIP10, and ZnT1) and in antioxidant defense system (Cu/Zn-SOD, CAT and GPx) were examined. Our results showed that Cd toxicity was exerted, initially, by an interference with Zn metabolism. Thus, Cd was able to modify the expression of the corresponding genes so as to ensure its intracellular accumulation at the expense of Zn, causing its depletion. An oxidative stress was then generated, representing the second mode of Cd action which resulted in developmental anomalies and subsequently mortality. Interestingly, significant corrections have been noted following Zn supplementation based, essentially, on its ability to interact with the toxic metal. The increases of Zn bioavailability, the improvement of the oxidative status, as well as changes in Zn transporter expression profile are part of the protection mechanisms. The decrease of Cd-induced MTs after Zn supplement, both at the protein and the mRNA level, suggests that the protection provided by Zn is ensured through mechanisms not involving MT expression but which rather depend on the oxidative status.

Zinc as a countermeasure for cadmium toxicity

Cadmium (Cd) is an important environmental pollutant and long-term Cd exposure is closely related to autoimmune diseases, cancer, cardiovascular diseases (CVD), and hepatic dysfunction. Zinc (Zn) is an essential metal that plays key roles in protein structure, catalysis, and regulation of their function. Numerous studies have shown that Zn can reduce Cd toxicity; however, the underlying mechanisms have not been extensively explored. Preclinical studies have revealed direct competition for sarcolemmal uptake between these two metals. Multiple sarcolemmal transporters participate in Cd uptake, including Zn transporters, calcium channels, and DMT1 (divalent metal transporter 1). Zn also induces several protective mechanisms, including MT (metallothionein) induction and favorable redox homeostasis. This review summarizes current knowledge related to the role of Zn and metal transporters in reducing Cd toxicity and discusses potential future directions of related research.

Sea urchin chronicles. The effect of oxygen super-saturation and marine polluted sediments from Bagnoli-Coroglio Bay on different life stages of the sea urchin Paracentrotus lividus

In marinas and harbours, the accumulation of pollutants in sediments, combined with poor exchange of water with the open sea, poses a major environmental threat. The presence of photosynthetic organisms and the related oxygen production, however, may alleviate the negative effects of environmental contamination on heterotrophic organisms, enhancing their physiological defences. Furthermore, possible transgenerational buffer effects may increase the ability of natural populations to face environmental stress. Here we tested the occurrence of transgenerational effects on larvae of the sea urchin Paracentrotus lividus, whose parents were exposed, during the gametogenesis, to contaminated sediments subject to two temporal patterns of water re-suspension events and normal- (90%) vs. super-saturated (200%) levels of O₂. The study site was Bagnoli-Coroglio (Gulf of Naples, southern Tyrrhenian Sea), a historically polluted brownfield and Site of National Interest for which environmental restoration options are currently under exploration. Larvae from different adult populations were significantly, although not linearly, affected by the interaction of all factors to which parents were exposed, at both 24h and 48h post fertilization. Specifically, the exposure of larvae to elutriates from contaminated sediments determined a developmental delay, a reduction in size and an increased percentage of abnormalities in all larval populations independently of their parental exposure. On the contrary, larvae from parents exposed to contaminated sediments, when reared in clean filtered sea water, succeeded in developing until the echinopluteus stage after 48h, with size and abundance comparable to those of larvae from control parents. Pre-exposure of parents to contaminated sediments did not successfully buffer the negative effects of elutriates on their offspring, and no positive effects of 'super-saturated' levels of O₂ in response to contaminants were observed, suggesting that the Bagnoli-Coroglio area is currently not suitable for the re-stocking or re-introduction of this species.

Zinc protects against cadmium-induced toxicity in neonatal murine engineered cardiac tissues via metallothionein-dependent and independent mechanisms

Cadmium (Cd) is a nonessential heavy metal and a prevalent environmental toxin that has been shown to induce significant cardiomyocyte apoptosis in neonatal murine engineered cardiac tissues (ECTs). In contrast, zinc (Zn) is a potent metallothionein (MT) inducer, which plays an important role in protection against Cd toxicity. In this study, we investigated the protective effects of Zn against Cd toxicity in ECTs and explore the underlying mechanisms. ECTs were constructed from neonatal ventricular cells of wild-type (WT) mice and mice with global MT gene deletion (MT-KO). In WT-ECTs, Cd (5-20 μM) caused a dose-dependent toxicity that was detected within 8 h evidenced by suppressed beating, apoptosis, and LDH release; Zn (50-200 μM) dose-dependently induced MT expression in ECTs without causing ECT toxicity; co-treatment of ECT with Zn (50 µM) prevented Cd-induced toxicity. In MT-KO ECTs, Cd toxicity was enhanced; but unexpectedly, cotreatment with Zn provided partial protection against Cd toxicity. Furthermore, Cd, but not Zn, significantly activated Nrf2 and its downstream targets, including HO-1; inhibition of HO-1 by a specific HO-1 inhibitor, ZnPP (10 µM), significantly increased Cd-induced toxicity, but did not inhibit Zn protection against Cd injury, suggesting that Nrf2-mediated HO-1 activation was not required for Zn protective effect. Finally, the ability of Zn to reduce Cd uptake provided an additional MT-independent mechanism for reducing Cd toxicity. Thus, Zn exerts protective effects against Cd toxicity for murine ECTs that are partially MT-mediated. Further studies are required to translate these findings towards clinical trials.

Biochemical Effects of the Toxic Interaction of Copper, Lead and Cadmium on Clarias gariepinus

BACKGROUND

The presence of heavy metals in the aquatic environment is a concern because of potential toxicity and threats to plant and animal life.

OBJECTIVE

The present study evaluated the joint action toxicity and biochemical effects of sublethal concentrations of copper (Cu), lead (Pb) and cadmium (Cd) against Clarias gariepinus over a period of 28 days.

METHODS

We procured fingerlings (weight: 5-8 g; length: 4.5-6.0 cm) and juveniles (weight: 20-25 g; length: 14.5-17.5 cm) from a commercial fish farm in Bariga, Lagos state, Nigeria. Test toxicants were selected from the analyzed heavy metals in the field based on their deviation from World Health Organization, Federal Environmental Protection Agency and United States Environmental Protection Agency standards. Fish were randomly loaded into a 4-L glass aquaria for the bioassay per toxicant concentration of two replicates and untreated control (dechlorinated tap water).

RESULTS

The derived 96 hour lethal concentration 50 (LC50) value of Cu (2.11 mg/L) was the most toxic followed by Cd (24.18 mg/L) and Pb (34.48 mg/L), which was the least toxic of the singly tested pollutants. The analysis of dose-response data of the joint action toxicity of Cu and Cd, and Cu and Pb determined 96 hour LC50 values of 1.804 mg/L and 2.15 mg/L, respectively. The interactions between the mixture of Cu:Cd conformed with the model of synergism (synergistic ratio (SR)>1 and relative toxic units (RTU)>1), while the interaction between Cu:Pb was found to be antagonistic (SR<1), with an SR value of 0.98. The biochemical effects study revealed that malondialdehyde (MDA) levels decreased significantly (P<0.05) in the exposed fish, reduced glutathione was not significant at (P<0.05), and levels of superoxide dismutase (SOD), catalase, glucose and cholesterol were significantly different (P<0.05).

DISCUSSION

The observed increased in the glutathione level in the Cu:Cd mixture and a corresponding decrease in MDA concentration in the liver of test animals revealed the ability of fish to overcome the effects of lipid peroxidation in this group because the Cu ion is displaced by Cd, and the fish were able to catalyze the breakdown of hydrogen peroxide via the Fenton reaction.

CONCLUSIONS

Further studies on the joint action toxicity of heavy metals are needed in order to further determine their concentration in the local environment.

ETHICS APPROVAL

Study protocols were approved by the Health Research Ethics Committee of the University of Lagos.

Can zinc supplementation ameliorate cadmium-induced alterations in the bioelement content in rabbits?

The study was designed to investigate the influence of zinc (Zn) supplementation on cadmium-induced alterations in zinc, copper (Cu), and magnesium (Mg) status in rabbits. For this purpose, the concentrations of cadmium (Cd), Zn, Cu, and Mg were estimated in the blood, liver, kidney, and bone. The rabbits were divided in a control group, a Cd group-animals intoxicated orally with Cd (10 mg kg-1 bw, as aqueous solution of Cd-chloride), and a Cd+Zn group-animals intoxicated with the same dose of Cd and co-treated with Zn (20 mg kg-1 bw, as aqueous solution of Zn-sulphate). Solutions were administered orally, every day for 28 days. Sample mineralisation was performed with concentrated nitric acid (HNO3) and perchloric acid (HClO4) (4:1) and metal concentrations were determined by atomic absorption spectrophotometry (AAS). Zinc supplementation improved some of Cd-induced disturbances in bioelement levels in the investigated tissues. Beneficial effects of Zn on Zn and Cu levels were observed in blood, as well as on the Cu kidney level. The calculated values for Cu/Zn, Mg/Zn, and Mg/Cu ratios in blood suggest that Zn co-treatment reduces Cd-induced changes in bioelement ratios in blood.

Cadmium-induced toxicity is rescued by curcumin: A review

Cadmium (Cd) is one of the most common environmental and occupational heavy metals with extended distribution. Exposure to Cd may be associated with several deleterious consequences on the liver, bones, kidneys, lungs, testes, brain, immunological, and cardiovascular systems. Overproduction of reactive oxygen species (ROS) as the main mechanism behind its toxicity causes oxidative stress and subsequent damages to lipids, proteins, and DNA. Therefore, antioxidants along with chelating agents have shown promising outcomes against Cd-induced toxicity. Curcumin with various beneficial effects and medical efficacy has been evaluated for its inhibitory activities against biological impairments caused by Cd. Thus, this article is intended to address the effectiveness of curcumin against toxicity following Cd entry. Curcumin can afford to attenuate lipid peroxidation, glutathione depletion, alterations in antioxidant enzyme, and so forth through scavenging and chelating activities or Nrf2/Keap1/ARE pathway induction. © 2017 BioFactors, 43(5):645-661, 2017.

Protective Effect of Chokeberry (Aronia melanocarpa L.) Extract against Cadmium Impact on the Biomechanical Properties of the Femur: A Study in a Rat Model of Low and Moderate Lifetime Women Exposure to This Heavy Metal

The hypothesis that the consumption of Aronia melanocarpa berries (chokeberries) extract, recently reported by us to improve bone metabolism in female rats at low-level and moderate chronic exposure to cadmium (1 and 5 mg Cd/kg diet for up to 24 months), may increase the bone resistance to fracture was investigated. Biomechanical properties of the neck (bending test with vertical head loading) and diaphysis (three-point bending test) of the femur of rats administered 0.1% aqueous chokeberry extract (65.74% of polyphenols) or/and Cd in the diet (1 and 5 mg Cd/kg) for 3, 10, 17, and 24 months were evaluated. Moreover, procollagen I was assayed in the bone tissue. The low-level and moderate exposure to Cd decreased the procollagen I concentration in the bone tissue and weakened the biomechanical properties of the femoral neck and diaphysis. Chokeberry extract administration under the exposure to Cd improved the bone collagen biosynthesis and femur biomechanical properties. The results allow for the conclusion that the consumption of chokeberry products under exposure to Cd may improve the bone biomechanical properties and protect from fracture. This study provides support for Aronia melanocarpa berries being a promising natural agent for skeletal protection under low-level and moderate chronic exposure to Cd.

Effect of supplementary zinc on orthodontic tooth movement in a rat model

INTRODUCTION

Osteoclasts and osteoblasts are responsible for regulating bone homeostasis during which the trace element zinc has been shown to exert a cumulative effect on bone mass by stimulating osteoblastic bone formation and inhibiting osteoclastic bone resorption.

OBJECTIVE

The aim of the present study was to investigate the effects of zinc (Zn) on orthodontic tooth movement (OTM) in a rat model.

MATERIAL AND METHODS

A total of 44 male Wistar rats were divided into four groups of 11 animals each and received 0, 1.5, 20 and 50 ppm Zn in distilled water for 60 days. In the last 21 days of the study, nickel-titanium closed coil springs were ligated between maxillary right incisors and first molars of all rats, and tooth movement was measured at the end of this period. Histological analysis of hematoxylin/eosin slides was performed to assess root resorption lacunae, osteoclast number and periodontal ligament (PDL) width.

RESULTS

Mean OTM was calculated as 51.8, 49.1, 35.5 and 45 µm in the 0, 1.5, 20 and 50 ppm zinc-receiving groups, respectively. There were no significant differences in neither OTM nor histological parameters among the study groups (p > 0.05).

CONCLUSION

According to the results obtained in the current investigation, increase in supplementary zinc up to 50 ppm does not affect the rate of OTM neither bone and root resorption in rats.

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.

The Content of the 14 Metals in Cancellous and Cortical Bone of the Hip Joint Affected by Osteoarthritis

The aim of the study was to determine the content of particular elements Ca, Mg, P, Na, K, Zn, Cu, Fe, Mo, Cr, Ni, Ba, Sr, and Pb in the proximal femur bone tissue (cancellous and cortical bone) of 96 patients undergoing total hip replacement for osteoarthritis using ICP-AES and FAAS analytical techniques. The interdependencies among these elements and their correlations depended on factors including age, gender, place of residence, tobacco consumption, alcohol consumption, exposure to environmental pollution, physical activity, and type of degenerative change which were examined by statistical and chemometric methods. The factors that exerted the greatest influence on the elements in the femoral head and neck were tobacco smoking (higher Cr and Ni content in smokers), alcohol consumption (higher concentrations of Ni, Cu in people who consume alcohol), and gender (higher Cu, Zn, and Ni concentrations in men). The factors influencing Pb accumulation in bone tissue were tobacco, alcohol, gender, and age. In primary and secondary osteoarthritis of the hip, the content and interactions of elements are different (mainly those of Fe and Pb). There were no significant differences in the concentrations of elements in the femoral head and neck that could be attributed to residence or physical activity.

Protection against T1DM-Induced Bone Loss by Zinc Supplementation: Biomechanical, Histomorphometric, and Molecular Analyses in STZ-Induced Diabetic Rats

Several studies have established an association between diabetes and alterations in bone metabolism; however, the underlying mechanism is not well established. Although zinc is recognized as a potential preventive agent against diabetes-induced bone loss, there is no evidence demonstrating its effect in chronic diabetic conditions. This study evaluated the effects of zinc supplementation in a chronic (90 days) type 1 diabetes-induced bone-loss model. Male Wistar rats were distributed in three groups: control, type 1 diabetes mellitus (T1DM), and T1DM plus zinc supplementation (T1DMS). Serum biochemical analysis; tibia histomorphometric, biomechanical, and collagen-content analyses; and femur mRNA expression were evaluated. Relative to T1DM, the zinc-supplemented group showed increased histomorphometric parameters such as TbWi and BAr and decreased TbSp, increased biomechanical parameters (maximum load, stiffness, ultimate strain, and Young's modulus), and increased type I collagen content. Interestingly, similar values for these parameters were observed between the T1DMS and control groups. These results demonstrate the protective effect of zinc on the maintenance of bone strength and flexibility. In addition, downregulation of OPG, COL1A, and MMP-9 genes was observed in T1DMS, and the anabolic effects of zinc were evidenced by increased OC expression and serum ALP activity, both related to osteoblastogenesis, demonstrating a positive effect on bone formation. In contrast, T1DM showed excessive bone loss, observed through reduced histomorphometric and biomechanical parameters, characterizing diabetes-associated bone loss. The bone loss was also observed through upregulation of OPG, COL1A, and MMP-9 genes. In conclusion, zinc showed a positive effect on the maintenance of bone architecture and biomechanical parameters. Indeed, OC upregulation and control of expression of OPG, COL1A, and MMP-9 mRNAs, even in chronic hyperglycemia, support an anabolic and protective effect of zinc under chronic diabetic conditions. Furthermore, these results indicate that zinc supplementation could act as a complementary therapy in chronic T1DM.

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.

Protective effect of zinc supplementation against cadmium-induced oxidative stress and the RANK/RANKL/OPG system imbalance in the bone tissue of rats

It was investigated whether protective influence of zinc (Zn) against cadmium (Cd)-induced disorders in bone metabolism may be related to its antioxidative properties and impact on the receptor activator of nuclear factor (NF)-κΒ (RANK)/RANK ligand (RANKL)/osteoprotegerin (OPG) system. Numerous indices of oxidative/antioxidative status, and Cd and Zn were determined in the distal femur of the rats administered Zn (30 and 60mg/l) or/and Cd (5 and 50mg/l) for 6months. Soluble RANKL (sRANKL) and OPG were measured in the bone and serum. Zn supplementation importantly protected from Cd-induced oxidative stress preventing protein, DNA, and lipid oxidation in the bone. Moreover, Zn protected from the Cd-induced increase in sRANKL concentration and the sRANKL/OPG ratio, and decrease in OPG concentration in the bone and serum. Numerous correlations were noted between indices of the oxidative/antioxidative bone status, concentrations of sRANKL and OPG in the bone and serum, as well as the bone concentrations of Zn and Cd, and previously reported by us in these animals (Brzóska et al., 2007) indices of bone turnover and bone mineral density. The results allow us to conclude that the ability of Zn to prevent from oxidative stress and the RANK/RANKL/OPG system imbalance may be implicated in the mechanisms of its protective impact against Cd-induced bone damage. This paper is the first report from an in vivo study providing evidence that beneficial Zn impact on the skeleton under exposure to Cd is related to the improvement of the bone tissue oxidative/antioxidative status and mediating the RANK/RANKL/OPG system.

Excessive ethanol consumption under exposure to lead intensifies disorders in bone metabolism: a study in a rat model

It was investigated whether ethanol (Et) modifies the damaging impact of lead (Pb) on bone metabolism in a rat model reflecting excessive alcohol consumption by humans exposed to relatively high levels of this metal. For this purpose, markers of bone formation (osteocalcin, procollagen I, osteoprotegerin, alkaline phosphatase) and resorption (telopeptides of collagen I, soluble receptor activator of nuclear factor-κB ligand), calciotropic hormones (parathormone, calcitonin, 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D) in the serum, and the femur content of mineral (including calcium - Ca and inorganic phosphorus - P(i)) and organic components were estimated in the rats exposed to 500 mg Pb/l (in drinking water) or/and Et (5 g/kg b.wt./24 h, by oral gavage) for 12 weeks. Moreover, Ca and P(i) in the serum and urine, alkaline phosphatase in the bone tissue and Pb in the blood and femur were determined. The exposure to Pb or/and Et decreased bone formation and increased its resorption resulting in the bone demineralization. These effects were accompanied by destroying the hormonal regulation of mineral metabolism, and Ca and P(i) imbalance. The co-exposure to Pb and Et-induced disorders in bone metabolism were more advanced than those caused by Pb alone. Et co-administration increased Pb concentration in the blood and decreased its accumulation in the bone. This paper is the first report providing evidence that consumption of Et under exposure to Pb intensifies disorders in bone metabolism and that destroying of the receptor activator nuclear factor-κB (RANK)/RANK ligand/osteoprotegerin system is involved in the mechanisms of interactive action of these xenobiotics on the skeleton. The modifying impact of Et may be an effect of its independent osteotropic action and interaction with Pb. Based on the results it can be concluded that alcohol abuse by subjects excessively exposed to Pb considerably increases the risk of bone damage.

Effects of sub-chronic exposure to cadmium on some parameters of calcium and iodine metabolisms in the Shaw's jird Meriones shawi

In the present work we determined effects of a sub-chronic exposure to cadmium on some parameters of calcium and iodine metabolisms in Meriones shawi, a desert rodent species occupying the arid steppes of Tunisia and other countries. Fourteen jirds of both sex were equally divided into a control group receiving diet without cadmium and a treated group receiving cadmium in the diet during 30, 45, 60 and 90 days. At the end of each period, 5 jirds from each group were sacrificed. In cadmium-treated group, cadmium accumulation and total metallothioneins synthesis in the liver and kidneys were high and dependant on the duration of treatment. Cadmium caused significant modifications in the body weight and in the relative weights of the liver, femur and thyroids, in parallel to a decrease in calcium content in serum and in femur. Cadmium also decreased iodine content in serum and in the thyroids. Several impairments were dependant on the duration of exposure and were more pronounced at the end of the experiment. In conclusion, a sub-chronic exposure to cadmium induces perturbations in calcium and iodine metabolisms in Meriones shawi. However, effects on calcium seem to be more evident. We can conclude also that Meriones shawi is an indicator of cadmium presence in arid environments.

Effect of magnesium supplementation on the distribution patterns of zinc, copper, and magnesium in rabbits exposed to prolonged cadmium intoxication

The present study is designed to investigate whether magnesium (Mg) supplementation may prevent Cd-induced alterations in zinc (Zn), copper (Cu), and magnesium (Mg) status in rabbits. For this purpose, the concentrations of Zn, Cu, and Mg were estimated in blood, urine, and organs (brain, heart, lungs, liver, kidney, spleen, pancreas, skeletal muscle, and bone) of rabbits given Cd (10 mg/kg b.w.) and rabbits cotreated with Mg (40 mg/kg b.w.) orally, as aqueous solutions of Cd chloride and Mg acetate every day for 4 weeks. Samples were mineralized with conc. HNO₃ and HClO₄ (4:1) and metals concentrations were determined by atomic absorption spectrophotometry (AAS). Magnesium supplementation succeeded to overcome Cd-induced disbalance of investigated bioelements. Beneficial effects of Mg were observed on Zn levels in blood and urine, on Cu levels in urine, and on Mg levels in blood. Magnesium pretreatment also managed to counteract or reduce all Cd-induced changes in levels of Cu and Mg in organs, while it did not exert this effect on Zn levels. These findings suggest that enhanced dietary Mg intake during Cd exposure can have at least partly beneficial effect on Cd-induced alterations in homeostasis of zinc, copper, and magnesium.

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.

Protective effect of zinc against cadmium hepatotoxicity depends on this bioelement intake and level of cadmium exposure: a study in a rat model

It was estimated, in a rat model of moderate and relatively high chronic human exposure to cadmium (Cd), whether enhanced zinc (Zn) consumption may prevent Cd-induced liver injury and if the possible protective effect of this bioelement depends on its intake. For this purpose, the structure and function of the liver of the rats that received Zn (30 and 60mg/l) or/and Cd (5 and 50mg/l) for 6months were evaluated. The treatment with Cd led to, dependent on the exposure level, pathological changes in the liver, including enhanced apoptosis and induction of inflammatory and necrotic processes. Moreover, the serum activities of hepatic marker enzymes (alanine transaminase and aspartate transaminase) and the concentration of proinflammatory cytokine - tumor necrosis factor α were increased. The supplementation with 30 and 60mg Zn/l (enhancing daily Zn intake by 79% and 151%, respectively) partially or totally prevented from some of the Cd-induced changes in the liver structure and function; however, it provided no protection from necrosis, and the administration of 60mg Zn/l during the higher Cd exposure even intensified this process. At both levels of Cd treatment, the use of 30mg Zn/l was more effective in preventing liver injury than that of 60mg Zn/l. The hepatoprotective impact of Zn may be explained, at least partly, by its antioxidative, antiapoptotic and anti-inflammatory action, ability to stimulate regenerative processes in the liver tissue, and indirect action resulting in a decrease in the liver pool of the non-metallothionein-bound Cd(2+) ions able to exert toxic action. The results provide strong evidence that enhanced Zn consumption may be beneficial in protection from Cd hepatotoxicity; however, its excessive intake at relatively high exposure to Cd may intensify liver injury.

Cadmium Toxicity Revisited: Focus on Oxidative Stress Induction and Interactions with Zinc and Magnesium

Discovered in late 1817, cadmium is currently one of the most important occupational and environmental pollutants. It is associated with renal, neurological, skeletal and other toxic effects, including reproductive toxicity, genotoxicity, and carcinogenicity. There is still much to find out about its mechanisms of action, biomarkers of critical effects, and ways to reduce health risks. At present, there is no clinically efficient agent to treat cadmium poisoning due to predominantly intracellular location of cadmium ions. This article gives a brief review of cadmium-induced oxidative stress and its interactions with essential elements zinc and magnesium as relevant mechanisms of cadmium toxicity. It draws on available literature data and our own results, which indicate that dietary supplementation of either essential element has beneficial effect under condition of cadmium exposure. We have also tackled the reasons why magnesium addition prevails over zinc and discussed the protective role of magnesium during cadmium exposure. These findings could help to solve the problem of prophylaxis and therapy of increased cadmium body burden.

The involvement of oxidative stress in the mechanisms of damaging cadmium action in bone tissue: a study in a rat model of moderate and relatively high human exposure

It was investigated whether cadmium (Cd) may induce oxidative stress in the bone tissue in vivo and in this way contribute to skeleton damage. Total antioxidative status (TAS), antioxidative enzymes (glutathione peroxidase, superoxide dismutase, catalase), total oxidative status (TOS), hydrogen peroxide (H(2)O(2)), lipid peroxides (LPO), total thiol groups (TSH) and protein carbonyl groups (PC) as well as Cd in the bone tissue at the distal femoral epiphysis and femoral diaphysis of the male rats that received drinking water containing 0, 5, or 50mg Cd/l for 6 months were measured. Cd, depending on the level of exposure and bone location, decreased the bone antioxidative capacity and enhanced its oxidative status resulting in oxidative stress and oxidative protein and/or lipid modification. The treatment with 5 and 50mg Cd/l decreased TAS and activities of antioxidative enzymes as well as increased TOS and concentrations of H(2)O(2) and PC at the distal femur. Moreover, at the higher exposure, the concentration of LPO increased and that of TSH decreased. The Cd-induced changes in the oxidative/antioxidative balance of the femoral diaphysis, abundant in cortical bone, were less advanced than at the distal femur, where trabecular bone predominates. The results provide evidence that, even moderate, exposure to Cd induces oxidative stress and oxidative modifications in the bone tissue. Numerous correlations noted between the indices of oxidative/antioxidative bone status, and Cd accumulation in the bone tissue as well as indices of bone turnover and bone mineral status, recently reported by us (Toxicology 2007, 237, 89-103) in these rats, allow for the hypothesis that oxidative stress is involved in the mechanisms of damaging Cd action in the skeleton. The paper is the first report from an in vivo study indicating that Cd may affect bone tissue through disorders in its oxidative/antioxidative balance resulting in oxidative stress.

Metallothionein gene expression in liver of rats exposed to cadmium and supplemented with zinc and selenium

Cadmium (Cd), one of the most widely distributed heavy metals, is highly toxic to humans and animals. It is well known that zinc (Zn) and selenium (Se) administration reduce the Cd-induced toxicity and that metallothioneins can have a protective effect to mitigate Cd toxicity in biological systems. In this study we report the expression analysis of the two metallothioneines gene classes MT-1 and MT-2 as well as the total metalloprotein content in the liver of rats exposed to Cd (200 ppm), Cd + Zn (200 ppm + 500 ppm), Cd + Se (200 ppm + 0.1 ppm) or Cd + Zn + Se (200 ppm + 500 ppm + 0.1 ppm) in their drinking water for 35 days. Metals accumulation was quantified in rat liver. Cd decreased significantly the hepatic concentrations of Se and increased those of Zn. The treatment of Cd-exposed rats with Se alone or combined with Zn reversed the Cd-induced depletion of Se concentrations in the liver. However, Zn or Zn + Se administration significantly increased the liver Cd uptake and had no effect on the Cd-induced increase in hepatic concentrations of Zn. The molecular assay showed a decreasing trend of MT-1 relative gene expression levels in animals supplemented with Zn (6.87-fold), Se (3.58-fold), and their combination (1.69-fold) when compared to Cd-treated animals (16.22-fold). Upregulation of the MT-2 expression were recorded in all conditions, although fold induction levels were less pronounced than MT-1 expressions. Our data suggest that the well-established protective effect of Zn and Se against Cd-induced toxicity passes through non-MT gene expression mechanisms, being more dependent on the oxidative stress status of the cell.

Protective effects of selenium, zinc, or their combination on cadmium-induced oxidative stress in rat kidney

The present study was conducted to investigate whether the combined treatment with Se and Zn offers more beneficial effects than that provided by either of them alone in reversing Cd-induced oxidative stress in the kidney of rat. For this purpose, 30 adult male Wistar albino rats, equally divided into control and four treated groups, received either 200 ppm Cd (as CdCl(2)), 200 ppm Cd + 500 ppm Zn (as ZnCl(2)), 200 ppm Cd + 0.1 ppm Se (as Na(2)SeO(3)), or 200 ppm Cd + 500 ppm Zn + 0.1 ppm Se in their drinking water for 35 days. The results showed that Cd treatment decreased significantly the catalase (CAT) and glutathione peroxidase (GSH-Px) activities, whereas the superoxide dismutase (SOD) activity and the renal levels of lipid peroxidation (as malondialdehyde, MDA) were increased compared to control rats. The treatment of Cd-exposed rats with Se alone had no significant effect on the Cd-induced increase in the MDA concentrations but increased significantly the CAT activities and reversed Cd-induced increase in SOD activity. It also partially prevented Cd-induced decrease in GSH-Px activity. The treatment of Cd-exposed animals with Zn alone increased significantly the CAT activity and partially protected against Cd-induced increase in the MDA concentrations, whereas it had no significant effect on the Cd-induced increase in SOD activity and decrease in GSH-Px activity. The combined treatment of Cd-exposed animals with Se and Zn was more effective than that with either of them alone in reversing Cd-induced decrease in CAT and GSH-Px activities and Cd-induced increase in MDA concentrations. Results demonstrated beneficial effects of combined Se and Zn treatment in Cd-induced oxidative stress in kidney and suggest that Se and Zn can have a synergistic role against Cd toxicity.

Protective effects of selenium (Se) and zinc (Zn) on cadmium (Cd) toxicity in the liver of the rat: effects on the oxidative stress

Cadmium (Cd) is a very harmful environmental pollutant that transfers between various levels of the food chain. To study the protective effect of Se and Zn on Cd-induced oxidative stress in livers, male rats received either, tap water, Cd, Cd+Zn, Cd+Se or Cd+Zn+Se in their drinking water, for 35 days. The activities of total superoxide dismutase (SOD), copper, zinc-superoxide dismutase (CuZn SOD), glutathione peroxidase (GPx) and catalase (CAT), malondialdehyde (MDA) level and the ratio of CuZn SOD to GPx activity, were determined in the liver. Exposure to Cd lowered total SOD, CuZn SOD, GPx and CAT activities, while it increased MDA level and the ratio of CuZn SOD to GPx activity, in the organ studied. With Se or Zn administration during exposure to Cd, only partial corrective effects on Cd-induced oxidative stress in the liver have been observed, while Se and Zn together assured a more efficient protection of the organ against the observed oxidative stress.

Cadmium osteotoxicity in experimental animals: mechanisms and relationship to human exposures

Extensive epidemiological studies have recently demonstrated increased cadmium exposure correlating significantly with decreased bone mineral density and increased fracture incidence in humans at lower exposure levels than ever before evaluated. Studies in experimental animals have addressed whether very low concentrations of dietary cadmium can negatively impact the skeleton. This overview evaluates results in experimental animals regarding mechanisms of action on bone and the application of these results to humans. Results demonstrate that long-term dietary exposures in rats, at levels corresponding to environmental exposures in humans, result in increased skeletal fragility and decreased mineral density. Cadmium-induced demineralization begins soon after exposure, within 24 h of an oral dose to mice. In bone culture systems, cadmium at low concentrations acts directly on bone cells to cause both decreases in bone formation and increases in bone resorption, independent of its effects on kidney, intestine, or circulating hormone concentrations. Results from gene expression microarray and gene knock-out mouse models provide insight into mechanisms by which cadmium may affect bone. Application of the results to humans is considered with respect to cigarette smoke exposure pathways and direct vs. indirect effects of cadmium. Clearly, understanding the mechanism(s) by which cadmium causes bone loss in experimental animals will provide insight into its diverse effects in humans. Preventing bone loss is critical to maintaining an active, independent lifestyle, particularly among elderly persons. Identifying environmental factors such as cadmium that contribute to increased fractures in humans is an important undertaking and a first step to prevention.

Involvement of cd bioaccumulation in spinal deformities occurrence in natural populations of Mediterranean killifish

The aim of this study was to investigate the possible influence of environmental exposure to cadmium (Cd) on the spinal deformities occurrence in the Mediterranean killifish, Aphanius fasciatus (Pisces: Cyprinodontidae). For this purpose, some indicators of skeletal bone mineralization, Cd, and calcium (Ca) concentrations in spinal column as well as bioaccumulation of Cd from the water and the sediment have been compared in normal and deformed fish collected from polluted (S1) and nonpolluted (S2) areas in the Gulf of Gabès in Tunisia. When compared to the normal fish, the deformed fish showed signs of spinal column demineralization such as significant decrease in the ash weight/dry weight ratio, percentage of nonorganic components content, and Ca concentration. Cd concentrations in spinal column and liver were significantly higher in deformed fish than in normal fish. A highly significant negative correlation (r = -0.915, p < 0.01) between Cd and Ca concentrations was noted in spinal column of deformed fish. Bioaccumulation factors of Cd in the liver from the water and the sediment in deformed fish were also significantly higher (p < 0.0001) than in normal fish from S1 and S2. These findings suggest that the ability to accumulate large amount of Cd may represent a potential risk to induce spinal deformities in natural populations of Mediterranean killifish.

Reversal of cadmium-induced thyroid dysfunction by selenium, zinc, or their combination in rat

The aim of this study was to evaluate the potential benefit of combined treatment with zinc (Zn) and selenium (Se) in reversing cadmium (Cd)-induced thyroid dysfunction compared to Se or Zn treatment alone in rats exposed to Cd. For this purpose, 30 adult male Wistar albino rats were equally divided into control and four treated groups receiving either 200 ppm Cd (as CdCl2), 200 ppm Cd + 500 ppm Zn (as ZnCl2), 200 ppm Cd + 0.1 ppm Se (as Na2SeO3), or 200 ppm Cd + 500 ppm Zn + 0.1 ppm Se in their drinking water for 35 days. The results showed that Cd exposure increased significantly the relative thyroid weight (RTW), the thyroid Cd concentration, and the serum thyroid stimulating hormone (TSH) level, whereas the serum thyroxine (T4) level was decreased compared to control rats. The treatment of Cd-exposed rats with Se alone only partially protected from the Cd-induced decrease in serum T4 level. The treatment of Cd-exposed animals with Zn alone partially protected against Cd-induced thyroid dysfunction by maintaining normal RTW and by decreasing Cd concentration in the thyroid. It also partially prevents Cd-induced decrease in serum T4 level. The combined treatment of Cd-exposed animals with Se and Zn induced a more significant decrease in the thyroid Cd concentration than the Zn supplement and a total correction of the RTW. This treatment was also more effective than that with Se or Zn alone in reversing Cd-induced decrease in serum T4 level and Cd-induced increase in serum TSH level. Se and Zn can have a synergistic role against Cd-induced thyroid dysfunction.