Influence of static magnetic field on cadmium toxicity: study of oxidative stress and DNA damage in rat tissues

The detoxification of cadmium in Japanese quail by pomegranate peel powder

Environmental pollution and exposure to toxic metals such as cadmium (Cd) can cause severe and chronic diseases and have significant side effects on vital organs. The present study aimed to evaluate the effect of pomegranate peel on biochemical factors and lipid peroxidation in intoxication by Cd in Japanese quail. Two hundred seventy quails in different groups were fed diets containing Cd and pomegranate peel from 6 to 35 days old. Then, serum biochemical parameters were assessed, including liver enzymes, urea, and thiobarbituric acid. In the quails, Cd significantly increased MDA, urea, and AST (P < 0.05). Adding pomegranate peel at 1.5 and 2% levels decreased these parameters significantly (P < 0.05). In conclusion, dietary enrichment using pomegranate peel reduced the adverse effects of Cd by improving lipid peroxidation, aspartate aminotransferase (AST), and urea in Japanese quail.

Magnetic field effects in biology from the perspective of the radical pair mechanism

Hundreds of studies have found that weak magnetic fields can significantly influence various biological systems. However, the underlying mechanisms behind these phenomena remain elusive. Remarkably, the magnetic energies implicated in these effects are much smaller than thermal energies. Here, we review these observations, and we suggest an explanation based on the radical pair mechanism, which involves the quantum dynamics of the electron and nuclear spins of transient radical molecules. While the radical pair mechanism has been studied in detail in the context of avian magnetoreception, the studies reviewed here show that magnetosensitivity is widespread throughout biology. We review magnetic field effects on various physiological functions, discussing static, hypomagnetic and oscillating magnetic fields, as well as isotope effects. We then review the radical pair mechanism as a potential unifying model for the described magnetic field effects, and we discuss plausible candidate molecules for the radical pairs. We review recent studies proposing that the radical pair mechanism provides explanations for isotope effects in xenon anaesthesia and lithium treatment of hyperactivity, magnetic field effects on the circadian clock, and hypomagnetic field effects on neurogenesis and microtubule assembly. We conclude by discussing future lines of investigation in this exciting new area of quantum biology.

Magnetic Fields and Cancer: Epidemiology, Cellular Biology, and Theranostics

Humans are exposed to a complex mix of man-made electric and magnetic fields (MFs) at many different frequencies, at home and at work. Epidemiological studies indicate that there is a positive relationship between residential/domestic and occupational exposure to extremely low frequency electromagnetic fields and some types of cancer, although some other studies indicate no relationship. In this review, after an introduction on the MF definition and a description of natural/anthropogenic sources, the epidemiology of residential/domestic and occupational exposure to MFs and cancer is reviewed, with reference to leukemia, brain, and breast cancer. The in vivo and in vitro effects of MFs on cancer are reviewed considering both human and animal cells, with particular reference to the involvement of reactive oxygen species (ROS). MF application on cancer diagnostic and therapy (theranostic) are also reviewed by describing the use of different magnetic resonance imaging (MRI) applications for the detection of several cancers. Finally, the use of magnetic nanoparticles is described in terms of treatment of cancer by nanomedical applications for the precise delivery of anticancer drugs, nanosurgery by magnetomechanic methods, and selective killing of cancer cells by magnetic hyperthermia. The supplementary tables provide quantitative data and methodologies in epidemiological and cell biology studies. Although scientists do not generally agree that there is a cause-effect relationship between exposure to MF and cancer, MFs might not be the direct cause of cancer but may contribute to produce ROS and generate oxidative stress, which could trigger or enhance the expression of oncogenes.

Coenzyme Q10 ameliorates cadmium induced reproductive toxicity in male rats

This study aimed at investigating the protective role of CoQ10 against cadmium (Cd)-induced reproductive toxicity in male rats. Adult male Wistar rats were exposed to an acute dose of Cd (25 mg/kg bwt; Cd group), Cd+CoQ10 (25 mg/kg bwt Cd+10 mg CoQ10; Cd-Q10 group) and distilled water (control) in vivo for 15 consecutive days and semen quality was assessed. A significant reduction was noted in sperm concentration, progressive motility, morphology and DNA integrity in both Cd- and Cd-Q10 groups in comparison to control indicating Cd-induced testicular lipid per oxidation (LPO) and decline in indigenous antioxidant defense system as measured by total antioxidant capacity (TAC) (p<0.05). However, simultaneous co-administration of CoQ10 along with Cd (Cd-Q10 group) was able to improve sperm concentration, motility, progressive motility, morphology, DNA integrity, and testicular TAC as well as lower LPO compared to Cd group (p<0.05). Results indicate that used dose of CoQ10 is capable of moderately ameliorating reproductive toxicity of Cd by improving semen quality and reducing testicular oxidative stress.

Ascorbic acid inhibits cadmium-induced disruption of the blood-testis barrier by regulating oxidative stress-mediated p38 MAPK pathways

Ascorbic acid (AA), one of the best-known reactive oxygen species (ROS) scavengers, exhibits numerous functions such as antioxidant, anti-cancer, and anti-inflammatory effects. Increasing evidence demonstrates that oxidative stress plays an important role in testicular toxicity. In the present study, we investigated the protective effect of AA against cadmium (Cd)-induced blood-testis barrier (BTB) disruption. Sprague-Dawley (SD) rats were divided into four groups: the Cd-treated group received a single dose (s.c.) of 2 mg/kg BW cadmium chloride; the AA antagonism group received an injection of AA at a dose of 400 mg/kg BW (200 mg 24 h prior to Cd treatment and 200 mg 24 h following Cd treatment); and the control groups received an equal volume of saline or an equal dose of AA. As expected, ROS expression was upregulated in the Cd-treated rats, accompanied by an increase in malondialdehyde (MDA). Interestingly, AA suppressed Cd-induced oxidative stress by decreasing the levels of ROS and MDA and increasing the activity of superoxide dismutase (SOD) and catalase (CAT). In addition, AA also reduced BTB disruption by inhibiting TGF-β3 activation and p38 MAPK phosphorylation. Significant decreases in occludin and claudin-11 expression were observed in the Cd-treated rats, whereas AA administration attenuated this effect. Moreover, testicular histopathology and transmission electron microscopy further demonstrated the protective effects of AA against Cd-induced BTB damage. In conclusion, the results of the present study suggest that AA protects BTB destruction via the inhibition of oxidative stress and the TGF-β3/p38 MAPK signalling pathway in the testis of Cd-exposed rats.

l-Theanine attenuates cadmium-induced neurotoxicity through the inhibition of oxidative damage and tau hyperphosphorylation

Cadmium (Cd) has long been known to induce neurological degenerative disorders. We studied effects of l-theanine, one of the major amino acid components in green tea, on Cd-induced brain injury in mice. Male ICR mice were intraperitoneally injected with l-theanine (100 or 200mg/kg/day) or saline and after one hour these mice were orally administrated with CdCl₂ (3.75-6mg/kg). The treatment was conducted for 8 weeks. l-Theanine significantly reduced Cd level in the mouse brain and plasma. Cd-induced neuronal cell death in the mouse cortex and hippocampus were apparently inhibited by l-theanine treatment. l-Theanine also decreased the levels of malondialdehyde (MDA) and ROS, and obviously elevated the levels of glutathione (GSH) and activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) in the mouse brain. Hyperphosphorylation of tau protein is proposed to be an early event for the evolution of tau pathology, and may play an important role in Cd-induced neurodegeneration. Our results showed that l-theanine significantly suppressed Cd-induced tau protein hyperphosphorylation at Ser199, Ser202, and Ser396. Mechanism study showed that l-theanine inhibited the activation of glycogen synthase kinase-3β (GSK-3β) which contributed to the hyperphosphorylation of tau and Cd-induced cytotoxicity. Furthermore, l-theanine reduced Cd-induced cytotoxicity possibly by interfering with the Akt/mTOR signaling pathway. In conclusion, our study indicated that l-theanine protected mice against Cd-induced neurotoxicity through reducing brain Cd level and relieved oxidative damage and tau hyperphosphorylation. Our foundings provide a novel insight into the potential use of l-theanine as prophylactic and therapeutic agents for Cd-induced neurodegenerative diseases.

Calcium, zinc and vitamin E ameliorate cadmium-induced renal oxidative damage in albino Wistar rats

This study was aimed to examine the protective effects of supplementation with calcium + zinc (Ca + Zn) or vitamin E (Vit-E) on Cd-induced renal oxidative damage. Young albino Wistar rats (180 ± 10 g) (n = 6) control rats, Cd, Cd + Ca + Zn, and Cd + Vit-E experimental groups and the experimental period was 30 days. Rats were exposed to Cd (20 mg/kg body weight) alone treated as Cd treated group and the absence or presence of Ca + Zn (2 mg/kg each) or Vit-E (20 mg/kg body weight) supplementation treated as two separate groups. The activities of the stress marker enzymes superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and lipid peroxidase (LPx) were determined in renal mitochondrial fractions of experimental rats. We observed quantitative changes in SOD isoenzymatic patterns by non-denaturing PAGE analysis, and quantified band densities. These results showed that Cd exposure leads to decreases in SOD, CAT, GR, and GPx activities and a concomitant increase in LPx and GST activities. Ca + Zn and Vit-E administration with Cd significantly reversed Cd-induced perturbations in oxidative stress marker enzymes. However, Vit-E showed more inhibitory activity against Cd than did Ca + Zn, and it protected against Cd-induced nephrotoxicity.

Evaluation of oxidative response and tissular damage in rat lungs exposed to silica-coated gold nanoparticles under static magnetic fields

The purpose of our study was the evaluation of toxicological effects of silica-coated gold nanoparticles (GNPs) and static magnetic fields (SMFs; 128 mT) exposure in rat lungs. Animals received a single injection of GNPs (1,100 µg/kg, 100 nm, intraperitoneally) and were exposed to SMFs, over 14 days (1 h/day). Results showed that GNPs treatment induced a hyperplasia of bronchus-associated lymphoid tissue. Fluorescence microscopy images showed that red fluorescence signal was detected in rat lungs after 2 weeks from the single injection of GNPs. Oxidative response study showed that GNPs exposure increased malondialdehyde level and decreased CuZn-superoxide dismutase, catalase, and glutathione peroxidase activities in rat lungs. Furthermore, the histopathological study showed that combined effects of GNPs and SMFs led to more tissular damages in rat lungs in comparison with GNPs-treated rats. Interestingly, intensity of red fluorescence signal was enhanced after exposure to SMFs indicating a higher accumulation of GNPs in rat lungs under magnetic environment. Moreover, rats coexposed to GNPs and SMFs showed an increased malondialdehyde level, a fall of CuZn-superoxide dismutase, catalase, and glutathione peroxidase activities in comparison with GNPs-treated group. Hence, SMFs exposure increased the accumulation of GNPs in rat lungs and led to more toxic effects of these nanocomplexes.

Synergistic health effects between chemical pollutants and electromagnetic fields

Humans and ecosystems are exposed to highly variable and unknown cocktail of chemicals and radiations. Although individual chemicals are typically present at low concentrations, they can interact with each other resulting in additive or potentially synergistic mixture effects. This was also observed with products obtained by radiation actions such as sunlight or electromagnetic fields that can change the effects of chemicals, such as pesticides, and metal trace elements on health. Concomitant presence of various pesticides and their transformation products adds further complexity to chemical risk assessment since chronic inflammation is a key step for cancer promotion. Degradation of a parent molecule can produce several by-products which can trigger various toxic effects with different impacts on health and environment. For instance, the cocktail of sunlight irradiated sulcotrione pesticide has a greater cytotoxicity and genotoxicity than parent molecule, sulcotrione, and questions about the impact of photochemical process on environment. Adjuvants were shown to modify the biological features of pesticides. Addition of other elements, metals or biological products, can differently enhance cell toxicity of pesticides or electromagnetic radiations suggesting a synergy in living organisms. Electromagnetic fields spreading, pesticide by-products and mixtures monitoring become greater for environmental contamination evaluations.

Cadmium supplement triggers endoplasmic reticulum stress response and cytotoxicity in primary chicken hepatocytes

Cadmium (Cd), a potent hepatotoxin, has been reported to induce endoplasmic reticulum (ER) stress in various cell types. However, whether such effect exists in bird is still unclear. To delineate the effects of Cd exposure on ER stress response, we examined the expression of 78-kDa glucose-regulated protein (GRP78) and alteration in calcium homeostasis in primary chicken hepatocytes treated with 2-22 µM Cd for 24 h. A significant decrease of cell viability was observed in chicken hepatocytes following Cd administration. In cells treated with Cd, GRP78 protein levels increased in a dose-dependent manner. In addition, GRP78 and GRP94mRNA levels were elevated in response to Cd exposure. The increase of the intracellular Ca(2+) concentration in chicken hepatocytes was found during Cd exposure. Cd significantly decreased the CaM mRNA levels in hepatocytes. These results show that Cd regulates the expression of GRP78 and calcium homeostasis in chicken hepatocytes, suggesting that ER stress induced by Cd plays an important role in the mechanisms of Cd cytotoxicity to the bird hepatocytes.

Effect of Physalis peruviana L. on cadmium-induced testicular toxicity in rats

Cadmium (Cd) stimulates the production of reactive oxygen species and causes tissue damage. We investigated here the protective effect of Physalis peruviana L. (family Solanaceae) against cadmium-induced testes toxicity in rats. Twenty-eight Wistar albino rats were used. They were divided into four groups (n=7). Group 1 was used as control. Group 2 was intraperitoneally injected with 6.5 mg/kg body weight (bwt) of cadmium chloride for 5 days. Group 3 was orally treated with 200 mg/kg bwt of methanolic extract of physalis (MEPh). Group 4 was pretreated with MEPh before cadmium for 5 days. Changes in body and testes weights were determined. Oxidative stress markers, antioxidant enzymes, and testosterone level were measured. Histopathological changes of testes were examined, and the immunohistochemical staining for the proapoptotic (caspase-3) protein was performed. The injection of cadmium caused a significant decrease in body weight, while a significant increase in testes weight and testes weight index was observed. Pretreatment with MEPh was associated with significant reduction in the toxic effects of Cd as shown by reduced testicular levels of malondialdehyde, nitric oxide, and caspase-3 expression and increased glutathione content, and the activities of superoxide dismutase, catalase, glutathione reductase, glutathione peroxidase, and testosterone were also increased. Testicular histopathology showed that Cd produced an extensive germ cell apoptosis, and the pretreatment of MEPh in Cd-treated rats significantly reduced Cd-induced testicular damage. On the basis of the above results, it can be hypothesized that P. peruviana L. has a protective effect against cadmium-induced testicular oxidative stress and apoptosis in the rat.

Static magnetic fields modulate X-ray-induced DNA damage in human glioblastoma primary cells

Although static magnetic fields (SMFs) are used extensively in the occupational and medical fields, few comprehensive studies have investigated their possible genotoxic effect and the findings are controversial. With the advent of magnetic resonance imaging-guided radiation therapy, the potential effects of SMFs on ionizing radiation (IR) have become increasingly important. In this study we focused on the genotoxic effect of 80 mT SMFs, both alone and in combination with (i.e. preceding or following) X-ray (XR) irradiation, on primary glioblastoma cells in culture. The cells were exposed to: (i) SMFs alone; (ii) XRs alone; (iii) XR, with SMFs applied during recovery; (iv) SMFs both before and after XR irradiation. XR-induced DNA damage was analyzed by Single Cell Gel Electrophoresis assay (comet assay) using statistical tools designed to assess the tail DNA (TD) and tail length (TL) as indicators of DNA fragmentation. Mitochondrial membrane potential, known to be affected by IR, was assessed using the JC-1 mitochondrial probe. Our results showed that exposure of cells to 5 Gy of XR irradiation alone led to extensive DNA damage, which was significantly reduced by post-irradiation exposure to SMFs. The XR-induced loss of mitochondrial membrane potential was to a large extent averted by exposure to SMFs. These data suggest that SMFs modulate DNA damage and/or damage repair, possibly through a mechanism that affects mitochondria.

Effect of Cadmium on Lipid Peroxidation and on Some Antioxidants in the Liver, Kidneys and Testes of Rats Given Diet Containing Cadmium-polluted Radish Bulbs

The aim of this study was to examine the effects of cadmium (Cd), incorporated in radish bulbs, on malondialdehyde and glutathione levels and on superoxide dismutase activity in the liver, kidneys and testes of male rats. The control animals were given diet containing ordinary radish bulbs for 4, 8 and 12 weeks, while contaminated animals were given diet containing Cd-polluted radish bulbs (1.1 mg Cd/g of diet) for the same periods as in the controls. At each time point, rats were euthanized and the liver, kidneys and testes were removed. The results indicated that the body weight gain of contaminated rats was identical to that of the control rats. Cd concentrations in the liver, kidneys and testes increased significantly and gradually from the 4th to 12th week of treatment. Malondialdehyde concentrations decreased significantly in the liver and increased significantly in the kidneys and testes after 12 weeks of treatment, while glutathione levels increased significantly in the liver, and decreased significantly in the kidneys and testes at the same time. No changes were observed in SOD activity in the liver, while in the kidneys and testes, this activity was increased after 12 weeks of treatment as compared with the control rats.

Nanotoxicological evaluation of oxidative responses in rat nephrocytes induced by cadmium

The aim of this study was to investigate the interaction of cadmium chloride with mineral elements in rat nephrocytes in terms of the biosynthesis of nanocomplexes. The results show that selenium supplementation enhanced cadmium accumulation in kidneys. Analysis of the fluorescence revealed an increase in red fluorescence in the kidneys of rats co-exposed to cadmium and selenium. Interestingly, X-ray diffraction measurements carried out on kidney fractions of co-exposed rats point to the biosynthesis of cadmium selenide and/or sulfide nanoparticles (about 62 nm in size). Oxidative stress assays showed the ability of selenium to reduce lipid peroxidation and to restore glutathione peroxidase and superoxide dismutase activity in kidneys. Hence, cadmium complexation with selenium and sulfur at a nanoscale level could reduce oxidative stress induced by cadmium in kidneys.

Subacute toxicity of cadmium on hepatocytes and nephrocytes in the rat could be considered as a green biosynthesis of nanoparticles

The purpose was to study the toxicity of cadmium (Cd) and to explore its potential to generate nanoparticles during detoxification. In order to demonstrate this, in vivo fluorescence imaging, X-ray diffraction, and flow cytometry were performed. The in vivo imaging showed a fluorescence signal after Cd treatment (CdCl2, 1.50 mg/Kg, intraperitoneally). By contrast, the control-rat fluorescence was negative. The fluorescence was divided into three colors, red, yellow, and green, and probably indicates the presence of quantum dots. X-ray diffraction results revealed the presence of Cd sulfide (CdS) and/or Cd selenide (CdSe) nanoparticles following Cd injection in the liver (6.52 nm) and kidneys (56.30 nm). Interestingly, flow cytometry revealed a heterogeneous size distribution and a homogeneous granularity of synthesized nanoparticles. Using the green fluorescence channel and the red fluorescence channel, a narrow green emission spectrum and a broad red emission spectrum were detected, respectively, by cytometric analysis.

Assessment of genotoxic and cytotoxic hazards in brain and bone marrow cells of newborn rats exposed to extremely low-frequency magnetic field

The present study aimed to evaluate the association between whole body exposure to extremely low frequency magnetic field (ELF-MF) and genotoxic , cytotoxic hazards in brain and bone marrow cells of newborn rats. Newborn rats (10 days after delivery) were exposed continuously to 50 Hz, 0.5 mT for 30 days. The control group was treated as the exposed one with the sole difference that the rats were not exposed to magnetic field. Comet assay was used to quantify the level of DNA damage in isolated brain cells. Also bone marrow cells were flushed out to assess micronucleus induction and mitotic index. Spectrophotometric methods were used to measure the level of malondialdehyde (MDA) and the activity of glutathione (GSH) and superoxide dismutase (SOD). The results showed a significant increase in the mean tail moment indicating DNA damage in exposed group (P < 0.01, 0.001, 0.0001). Moreover ELF-MF exposure induced a significant (P < 0.01, 0.001) four folds increase in the induction of micronucleus and about three folds increase in mitotic index (P < 0.0001). Additionally newborn rats exposed to ELF-MF showed significant higher levels of MDA and SOD (P < 0.05). Meanwhile ELF-MF failed to alter the activity of GSH. In conclusion, the present study suggests an association between DNA damage and ELF-MF exposure in newborn rats.

A combination of ascorbic acid and α-tocopherol or a combination of Mg and Zn are both able to reduce the adverse effects of lindane-poisoning on rat brain and liver

The purpose of this study, carried out on male Wistar rats, was to evaluate the beneficial effects of supplementation with ascorbic acid (Vit C) and α-tocopherol (Vit E) or with Mg and Zn upon lindane-induced damages in liver and brain. Under our experimental conditions, lindane poisoning (5mg/kg body weight per day for 3 days) resulted in (1) an increased level of plasma glucose, cholesterol and triglycerides, (2) an increased activity of LDH, ALP, AST, ALT, (3) an oxidative stress in liver and brain as revealed by an increased level of lipids peroxidation (TBARS) and a decrease of glutathione-peroxidase, superoxide dismutase and catalase activities in liver and brain. In conclusion, both Vit C+E or Mg+Zn treatments display beneficial effects upon oxidative stress induced by lindane treatment in liver and brain.

Effects of static magnetic fields on growth and membrane lipid composition of Salmonella typhimurium wild-type and dam mutant strains

This study was carried out to explore the adaptive mechanisms of S. typhimurium particularly, the implication of the Dam methyltransferase in the remodelling of membrane lipid composition to overcome magnetic field stress. With this aim, we focused our analyses on the increase in viable numbers and membrane lipid modifications of S. typhimurium wild-type and dam mutant cells exposed for 10h to static magnetic fields (SMF; 200 mT). For the wild-type strain, exposure to SMF induced a significant decrease (p<0.05) of CFU at 6h, followed by an increase between 8 and 10h. Growth of the dam mutant was significantly affected (p<0.05) after 6h and no recovery was observed until 10h, highlighting a different behavior of SMF stressed wild-type and dam mutant strains. SMF significantly affected the phospholipid proportions in the two strains. The most affected were those of the acidic phospholipids, cardiolipins (CL). In the dam strain the phospholipid response to SMF followed a globally similar trend as in the wild-type with however lower effects, leading mainly to an unusual accumulation of CL. This would in part explain the different behavior of the wild-type and the dam strain. Results showed a significant increase of membrane cyclic fatty acids Cyc17 and Cyc19 in the wild-type strain but only the Cyc17 in the dam strain and a meaningful increase of the total unsaturated fatty acids (UFAs) to total saturated fatty acids (SFAs) ratios of the exposed cells compared to controls from 3 to 9h (p<0.05) for both strains. The net increase of the total UFAs to total SFAs ratios seemed to result mainly from the increase of (C18:1) proportion (p<0.05) and to a lower extent from that of (C16:1) (p<0.05). These modifications of cyclic and unsaturated fatty acid proportions constitute an adaptive response to SMF stress in S. typhimurium wild-type and dam mutants to maintain an optimum level of membrane fluidity under SMF.

The late and persistent pathogenic effects of cadmium at very low levels on the kidney of rats

Cadmium (Cd) is an important nephrotoxic pollutant. To examine late effects on the kidney of individuals previously exposed to chronic Cd at very low levels, male Wistar rats were given 20 nmol/kg i.p. injections of Cd every other day for 4 weeks. At the 20(th), 28(th), 36(th), 44(th) and 52(nd) week of the study, renal metal accumulation, morphology and function were examined. Immunochemical staining was performed to detect renal 3-nitrotyrosine (3-NT) accumulation, metallothionein (MT) expression, cell proliferation and global DNA methylation. Results showed that renal Cd concentration and MT expression along with 3-NT accumulation were significantly higher in the Cd group than that in the control. Histopathologically renal tubule damage at the early stage and hyperplasia at the late stage were observed in the Cd group. Renal fibrosis in glomeruli was evident in the Cd group, particularly at the late stage of the study. Immunoreactivity of global DNA methylation was markedly diminished in the Cd group at both 20(th) and 52(nd) weeks. These results suggest that previous exposure to chronic Cd at very low level induced persistent damaging effects on the kidney along with increases in cell proliferation and global DNA hypomethylation.

Differential liver proteome mapping of control and cadmium-fed rats

A comparative study of proteome maps from control and Cd-exposed rat liver was performed using a new technology of two-dimensional liquid chromatography separation method (PF-2D system, Beckman Coulter). Rats were fed for one month 0 or 100 μg Cd g(-1). The between-replicate and between-sample variations showed good repeatability and suitable reproducibility for the two dimensions of separation of proteins. In this complex mixture, PF-2D led to the separation of two major peaks which differed between control and Cd-exposed rat livers, one being identified by mass spectrometry as Cu/Zn superoxide dismutase (SOD), a well-known biomarker of Cd exposure, the other as phosphatidylethanolamine binding protein (PEBP). SOD content was decreased in Cd-exposed rat liver, compared to the control group which was corroborated by a significant decrease of SOD activity. PEBP content also tended to be decreased after Cd exposure. Present results demonstrate interest but also limitations of proteomic approach using PF-2D system to analyze effects of chemicals on organisms.

Effects of static magnetic field and cadmium on oxidative stress and DNA damage in rat cortex brain and hippocampus

The present study was undertaken to determine the effect of co-exposure to static magnetic field (SMF) and cadmium (Cd) on the antioxidant enzymes activity and DNA integrity in rat brain. Sub-chronic exposure to CdCl (CdCl(2), 40 mg/L, per os) for 30 days resulted in a significant reduction in antioxidant enzyme activity such as the glutathione peroxidase (GPx), catalase (CAT) and superoxide dismutase (SOD) in frontal cortex and hippocampus. Total GSH were decreased in the frontal cortex of the Cd-exposed group. Cd exposure induced an increase in malondialdehyde (MDA) concentration in the frontal cortex and hippocampus. Moreover, the same exposure increased 8-oxo-7,8-dihydro-2-desoxyguanosine (8-oxodGuo) level in rat brain. Interestingly, the combined effect of SMF (128 mT, 1 hour/day for 30 consecutive days) and CdCl (40 mg/L, per os) decreased the SOD activity and glutathione level in frontal cortex as compared with the Cd group. Moreover, the association between SMF and Cd increased MDA concentration in frontal cortex as compared with Cd-exposed rats. DNA analysis revealed that SMF exposure failed to alter 8-oxodGuo concentration in Cd-exposed rats. Our data showed that Cd exposure altered the antioxidant enzymes activity and induced oxidative DNA lesions in rat brain. The combined effect of SMF and Cd increased oxidative damage in rat brain as compared with Cd-exposed rats.

Changes in antioxidant status and biochemical parameters after orally cadmium administration in females rats

The research was conducted to investigate the toxic effects of cadmium chloride (CdCl2), administered during gestation period on female Wistar rats. Pregnant rats received CdCl2 (20 mg/l, orally) from Day 6 to Day 19 of pregnancy. Results showed that Cd treatment induced a decrease in body weight gain. The relative liver weight increased significantly, with a marked decrease of glycogen and total lipids content. The administration of Cd induced hepatotoxicity as indicated by elevations in plasma alanine aminotransferase (ALT), aspartate aminotransferase and lactate dehydrogenase (LDH) activities (p < 0.05). Treatment with CdCl2 caused a significant (p < 0.05) increase in glucose. A significant increase was observed in the level of MDA and 8-oxodGuo tissues in the cadmium-exposed group compared to the control group (p < 0.05). Results showed that cadmium given to dams led to an oxidative stress and DNA damage in tissues of pregnant rats.

Preventive effect of zinc against cadmium-induced oxidative stress in the rat testis

The aim of this study was to investigate the antioxidant role of zinc (Zn) in the Cd-exposed testes of Wistar rats. Subchronic exposure to Cd (CdCl(2), 40 mg/l, per os) for 30 days resulted in a significant reduction in growth rate (-11%) and relative weights of testes (-36%) and seminal vesicles (-80%). Treated rats displayed a decrease in testicular and plasma testosterone levels, respectively (-70%, P<0.05; -48%, P<0.05), epididymal sperm count (-22%, P<0.05), and spermatozoa motility (-35%, P<0.05). In contrast, Cd increased the malondialdehyde (+46%, P<0.05), metallothionein (+200%, P<0.05), and 8-oxodGuo concentrations (+71%, P<0.05) in the testis. In the gonad, Cd decreased the GPx (-30%, P<0.05), CAT (-32%, P<0.05), mitochondrial Mn-SOD (-34%, P<0.05), and cytosolic CuZn-SOD (-32%, P<0.05) activities. Zinc supplementation (ZnCl(2), 40 mg/l, per os) in the Cd-exposed rats restored the activities of GPx, CuZn-SOD, and Mn-SOD in the testes to the levels of the control group. Moreover, zinc administration was capable of reducing the elevated levels of malondialdehyde in the testis. Interestingly, zinc supplementation attenuated DNA oxidation induced by Cd in the gonad and restored the testosterone level and sperm count to the levels of the control group. Zinc administration minimized oxidative damage and reversed the impairment of spermatogenesis and testosterone production induced by Cd in the rat testis.

Midkine secretion protects Hep3B cells from cadmium induced cellular damage

AIM: To evaluate role of midkine secretion during Cadmium (Cd) exposure in the human hepatocyte cell line Hep3B cells.

METHODS: Different dosages of Cd (0.5-1-5-10 &mgr;g/mL) were applied to Hep3B cells and their effects to apoptosis, lactate dehydrogenase (LDH) leakage and midkine secretion were evaluated as time dependent manner. Same experiments were repeated with exogenously applied midkine (250-5000 pg/mL) and/or 5 &mgr;g/mL Cd.

RESULTS: Cd exposure induced prominent apoptosis and LDH leakage beginning from lower dosages at the 48^th h. Cd induced midkine secretion with higher dosages (P < 0.001), (control, Cd 0.5-1-5-10 &mgr;g/mL respectively: 1123 ± 73, 1157 ± 63, 1242 ± 90, 1886 ± 175, 1712 ± 166 pg/mL). Exogenous 500-5000 pg/mL midkine application during 5 &mgr;g/mL Cd toxicity prevented caspase-3 activation (control, Cd toxicity, 250, 500, 1000, 2500, 5000 pg/mL midkine+ Cd toxicity, respectively: 374 ± 64, 1786 ± 156, 1545 ± 179, 1203 ± 113, 974 ± 116, 646 ± 56, 556 ± 63 cfu) LDH leakage and cell death in Hep3B cells (P < 0.001).

CONCLUSION: Our results showed that midkine secretion from Hep3B cells during Cd exposure protects liver cells from Cd induced cellular damage. Midkine has anti-apoptotic and cytoprotective role during Cd toxicity. Further studies are needed to explain the mechanism of midkine secretion and cytoprotective role of midkine during Cd exposure. Midkine may be a promising therapeutic agent in different toxic hepatic diseases.