Cadmium-induced apoptosis in mouse liver

Chemoprotective effect of monoisoamyl 2, 3-dimercaptosuccinate (MiADMS) on cytokines expression in cadmium chloride treated human lung cells

Cadmium is commercially profitable element, but it causes toxicity in humans and animals leading to diseases in various organs. The main route of cadmium exposure to humans is through inhalation. Lungs respond to insult through secretion of cytokines. In this study, the chemoprotective effect of monoisoamyl 2, 3-dimercaptosuccinate (MiADMS) was evaluated on viability and cytokines expression in CdCl2 treated human lung A549 cells by cytokine array. Cells were treated with 0, 50, 75, and 100 µM CdCl2 alone, 300 µM MiADMS alone, and co-treated with 300 µM MiADMS and 75 µM CdCl2 for 24 h. The viability was measured by crystal violet dye. The level of cytokines in the cells' lysate and cell culture medium was measured using Ray Biotech's Human Cytokine Array 6 in control cells, 75 µM CdCl2 alone and MiADMS co-treated cells. Array results were validated by ELISA kit. The CdCl2 caused a dose dependent decrease in cell viability, while MiADMS co-treatment resulted in a significant increase in viability of CdCl2 treated cells. Morphology of the cells treated with CdCl2 was destroyed, while MiADMS restored the lost shape in CdCl2 treated cells. In addition, the cells co-treated with MiADMS and CdCl2 showed modulation of cytokines expression in comparison to the CdCl2 alone treated cells. The ELISA results showed the similar pattern of cytokine expression as Human Cytokine Array and validated the array results. These results clearly show the chemoprotective effect of MiADMS and suggest that MiADMS can be used as antidote at moderate dose against CdCl2 toxicity.

Hepatoprotective activity of Moringa oleifera against cadmium toxicity in rats

Aim:

The present investigation has been conducted to evaluate the hepatoprotective activity of Moringa oleifera against cadmium-induced toxicity in rats.

Materials and Methods:

For this study, 18 Wistar albino rats were taken. Control group, Group I rats were given cadmium chloride @ 200 ppm per kg and Group II rats were treated with M. oleifera extract @ 500 mg/kg along with cadmium chloride @ 200 ppm per kg (daily oral for 28 days). On 29^th day, animals were slaughtered and various parameters were determined. Serum biomarkers, oxidative stress parameters, histomorphological examination were carried out with estimation of cadmium concentration in liver tissues.

Results:

Oral administration of cadmium chloride @ 200 ppm/kg for 28 days resulted in a significant increase in aspartate aminotransferase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), significant (p≤0.01) increase of lipid peroxidation (LPO) and decrease in superoxide dismutase (SOD), and increase in cadmium accumulation in liver. Treatment with M. oleifera @ 500 mg/kg significantly (p<0.01) decreased the elevated ALP, AST, ALT, LPO levels and increase in SOD levels, and as compared to cadmium chloride treated group. However, there was no significant difference in cadmium concentration in liver when compared with cadmium chloride treated group.

Conclusion:

The study conclude that supplementation of M. oleifera (500 mg/kg), daily oral for 28 days has shown protection against cadmium-induced hepatotoxicity.

Effects of cadmium on cell proliferation, apoptosis, and proto-oncogene expression in zebrafish liver cells

Cadmium (Cd) is one of the major transitional metal that has toxic effects in aquatic organisms and their associated ecosystem; however, its hepatic toxicity and carcinogenicity are not very well characterized. We used a zebrafish liver (ZFL) cell line as a model to investigate the mechanism of Cd-induced toxicity on hepatocytes. Our results showed that Cd can be effectively accumulated in ZFL cells in our exposure experiments. Cell cytotoxicity assays and flow cytometer measurements revealed that Cd(2+) stimulated ZFL cell proliferation with decreasing apoptotic cell numbers indicating potentially tumorigenic effects of Cd in ZFL cells. Gene expression profiles also indicated that Cd downregulated oncogenes p53 and rad51 and upregulated immediate response oncogenes, growth arrest and DNA damage-inducible (gadd45) genes, and growth factors. We also found dramatic changes in the gene expression of c-jun and igf1rb at different exposure time points, supporting the notion that potentially tumorigenic of Cd-is involved in the activation of immediate early genes or genes related to apoptosis in cancer promotion.

Research advances on apoptosis caused by quantum dots

Recently, quantum dots (QDs) have been widely applied in biological and biomedical fields such as cell labeling, living tissue imaging, and photodynamic therapy because of their superior optical properties. Meanwhile, the potential biological negative effects and/or toxic effects of QDs have become increasingly important, especially the cytotoxicity caused by QDs. One of the common cytotoxicity when living organisms are treated with QD is apoptosis, where many attempts have been made to explain the mechanisms of apoptosis caused by QDs' use. One of the mechanisms is the production of cadmium ion (Cd(2+)) and reactive oxygen species (ROS). Excess generation of ROS will result in oxidative stress that would mediate apoptosis. Furthermore, the activation of cell death receptors and mitochondria-dependent such as B cell lymphoma 2 (Bcl-2) family and the caspase family could onset apoptosis. Signal transduction such as some classical signal pathways of PI3K-AKT, NF-E2-related factor 2 (Nrf2)-antioxidant response element (ARE), mitogen-activated protein kinases (MAPKs), and nuclear factor kappa B (NF-κB) also plays an important role in the regulation of apoptosis. Several ways to reduce the apoptotic rate have been introduced, such as surface modification, controlling, the dose, size, and exposure time of QDs as well as using antioxidants or inhibitors. In this review, we attempted to review the most recent findings associated with apoptosis caused by QDs so as to provide some guidelines for a safer QD application in the future.

Humoral and haemocytic responses of Litopenaeus vannamei to Cd exposure

White shrimp, Litopenaeus vannamei, subadults were exposed to four dilutions of the 96 h cadmium LC50 reported for postlarvae (PL12) of this species, and the effects were evaluated after 5, 48, and 96 h of exposure. While treatments did not affect survival and hemolymph clotting time increased with time, but not as a response to Cd exposure, the intensity of other responses was related to concentration, to time of exposure, and to their interaction. Hemocyanin decreased with time in all metal concentrations but increased in the control treatment, and an almost similar trend was observed with hemocyte numbers. As an initial response, phenoloxidase activity decreased with all metal concentrations, but it increased later to values similar or higher than the control treatment.

Protective effect of curcumin against heavy metals-induced liver damage

Occupational or environmental exposures to heavy metals produce several adverse health effects. The common mechanism determining their toxicity and carcinogenicity is the generation of oxidative stress that leads to hepatic damage. In addition, oxidative stress induced by metal exposure leads to the activation of the nuclear factor (erythroid-derived 2)-like 2/Kelch-like ECH-associated protein 1/antioxidant response elements (Nrf2/Keap1/ARE) pathway. Since antioxidant and chelating agents are generally used for the treatment of heavy metals poisoning, this review is focused on the protective role of curcumin against liver injury induced by heavy metals. Curcumin has shown, in clinical and preclinical studies, numerous biological activities including therapeutic efficacy against various human diseases and anti-hepatotoxic effects against environmental or occupational toxins. Curcumin reduces the hepatotoxicity induced by arsenic, cadmium, chromium, copper, lead and mercury, prevents histological injury, lipid peroxidation and glutathione (GSH) depletion, maintains the liver antioxidant enzyme status and protects against mitochondrial dysfunction. The preventive effect of curcumin on the noxious effects induced by heavy metals has been attributed to its scavenging and chelating properties, and/or to the ability to induce the Nrf2/Keap1/ARE pathway. However, additional research is needed in order to propose curcumin as a potential protective agent against liver damage induced by heavy metals.

In vitro effect of cadmium and copper on separated blood leukocytes of Dicentrarchus labrax

The immunotoxic effects of heavy metals on blood leukocytes of sea bass (Dicentrarchus labrax) were examined. The cells, separated by a discontinuous Percoll-gradients, were exposed in vitro to various sublethal concentrations of cadmium and copper (10(-7)M, 10(-5)M, and 10(-3)M) and their immunotoxic effect was then evaluated by measuring neutral red uptake, MTT assay, DNA fragmentation and Hsp70 gene expression. First of all, we demonstrated that the cells treated in vitro could incorporate Cd and Cu. A relationship between heavy metal exposure and dose-time-dependent alterations in responses of leukocytes from blood was found for both metals, but copper was more immunotoxic than cadmium in all assays performed. A significant reduction in the cells׳ ability to uptake neutral red and viability by MTT assay was recorded, indicating that both cadmium and copper could change the membrane permeability, inducing cellular apoptosis when the concentration of metals reached 10(-3)M. The apoptotic effect may also explain the high level of cytotoxicity found when the leukocytes were exposed to higher concentration of metals. These results demonstrated that toxic effect of copper and cadmium affect on the mechanisms of cell-mediated immunity reducing the immune defences of the organism.

Apoptotic and necrotic changes in the midgut glands of the wolf spider Xerolycosa nemoralis (Lycosidae) in response to starvation and dimethoate exposure

In the present study, the intensity of degenerative changes (apoptosis, necrosis) in the cells of the midgut glands of male and female wolf spiders, Xerolycosa nemoralis (Lycosidae), exposed to natural (starvation) and anthropogenic (the organophosphorous pesticide dimethoate) stressors under laboratory conditions were compared. The spiders were collected from two differentially polluted sites, both located in southern Poland: Katowice-Welnowiec, which is heavily polluted with metals, and Pilica, the reference site. Starvation and dimethoate treatment resulted in enhancement of apoptotic and necrotic changes in the midgut glands of the spiders. The frequency of degenerative changes in starving individuals was twice as high as in the specimens intoxicated with dimethoate. The percentage of apoptotic and necrotic cells was higher in starving males than in starving females. A high intensity of necrotic changes, together with increased Cas-3 like activity and a greater percentage of cells with depolarized mitochondria, were typical of starving males from the polluted site. The cell death indices observed in females depended more strongly on the type of stressor than on previous preexposure to pollutants.

EGCG inhibits Cd(2+)-induced apoptosis through scavenging ROS rather than chelating Cd(2+) in HL-7702 cells

CONTEXT AND OBJECTIVE

Epigallocatechin-3-gallat (EGCG), the major catechin in green tea, shows a potential protective effect against heavy metal toxicity to humans. Apoptosis is one of the key events in cadmium (Cd(2+))-induced cytotoxicity. Nevertheless, the study of EGCG on Cd(2+)-induced apoptosis is rarely reported. The objective of this study was to clarify the effect and detailed mechanism of EGCG on Cd(2+)-induced apoptosis.

METHODS

Normal human liver cells (HL-7702) were treated with Cd(2+) for 21 h, and then co-treated with EGCG for 3 h. Cell viability, apoptosis, intracellular reactive oxygen species (ROS), malondialdehyde (MDA), mitochondrial membrane potential (MMP) and caspase-3 activity were detected. On the other hand, the chelation of Cd(2+) with EGCG was tested by UV-Vis spectroscopy analysis and Nuclear Magnetic Resonance ((1)H NMR) spectroscopy under neutral condition (pH 7.2).

RESULTS AND CONCLUSION

Cd(2+) significantly decreased the cell viability and induced apoptosis in HL-7702 cells. Conversely, EGCG co-treatment resulted in significant inhibition of Cd(2+)-induced reduction of cell viability and apoptosis, implying a rescue effect of EGCG against Cd(2+) poisoning. The protective effect most likely arises from scavenging ROS and maintaining redox homeostasis, as the generation of intracellular ROS and MDA is significantly reduced by EGCG, which further prevents MMP collapse and suppresses caspase-3 activity. However, no evidence is observed for the chelation of EGCG with Cd(2+) under neutral condition. Therefore, a clear conclusion from this work can be made that EGCG could inhibit Cd(2+)-induced apoptosis by acting as a ROS scavenger rather than a metal chelating agent.

The protective effect of clay minerals against damage to adsorbed DNA induced by cadmium and mercury

The adsorption of Salmon Sperm DNA on three kinds of raw clay (rectorite, montmorillonite and sericite) was investigated as a function of pH, ionic strength and the concentrations of DNA and phosphate ions in solution. The DNA adsorption was reduced in the following order: rectorite>montmorillonite>sericite. Based on these findings, there is a strong evidence that the mechanisms for DNA adsorption on clay involve electrostatic forces, cation bridging and ligand exchange. Cyclic voltammetry (CV) and UV-vis absorption and fluorescence spectroscopy were used to compare the properties of unbound DNA and the absorbed DNA on rectorite, both in the absence and presence of Cd(2+) and Hg(2+) inaqueous solutions. The interaction of heavy metals with the unbound DNA was evidenced by the disappearance of reduction peaks in CV, a small bathochromic shift in UV-vis spectroscopy and an incomplete quenching in the emission spectra. Such changes were not observed in the DNA-rectorite hybrids, which is evidence that adsorption on the clay can reduce the extent of the DNA damage caused by heavy metals. Therefore, in these experience the rectorite played an important role in protecting DNA against Cd(2+) and Hg(2+) induced damage.

Cadmium induced hepatotoxicity in chickens (Gallus domesticus) and ameliorative effect by selenium

Cadmium (Cd) is one of the most toxic metal compounds released into the environment. It was well known that Cd induced hepatotoxicity in animal models. However, little is known about the negative effects of Cd toxicity in the liver of birds. To investigate the Cd hepatotoxicity in birds and the protective effects of selenium (Se) against subchronic exposure to dietary Cd, 100-day-old cocks received either Se (as 10mg Na2SeO3 per kg of diet), Cd (as 150mg CdCl2 per kg of diet) or Cd+Se in their diets for 60 days. Histological and ultrastructural changes in the liver, the concentrations of Cd and Se, the lipid peroxidation (LPO) and nitric oxide (NO) production, the activities of the antioxidants superoxide dismutase (SOD) and glutathione peroxidase (GPx), nitric oxide synthase (NOS) activities and apoptosis were determined. Exposure to Cd significantly reduced SOD and GPx activity, Se content in the liver tissue. It increased the LPO and NO production, the numbers of apoptotic cells and Cd concentration and caused obvious histopathological changes in the liver. Concurrent treatment with Se reduced the Cd-induced liver histopathological changes, oxidative stress, overexpression of NO and apoptosis, suggesting that the toxic effects of Cd on the liver is partly ameliorated by inorganic Se. Se supplementation also modified the distribution of Cd in the liver.

In vivo biodistribution and synergistic toxicity of silica nanoparticles and cadmium chloride in mice

Silica nanoparticles (SiNPs) are now in daily use due to their low intrinsic toxicity. Cadmium is a ubiquitous environmental pollutant. In spite of real risk of humans' co-exposure to SiNPs and cadmium, their synergistic toxicity is still unclear. Here, we report the synergistic effects of SiNPs and CdCl₂ on their biodistribution and subacute toxicity in mice. The biodistributions, histopathological changes, serum biochemical parameters and oxidative stress responses were determined after intraperitoneal injection of SiNPs and/or CdCl₂ to mice. SiNPs and CdCl₂ have a positive synergistic toxicity in mice. Although SiNPs were low toxic to mice, co-exposure of SiNPs and CdCl₂ significantly enhanced CdCl₂-induced oxidative damage in the liver as indicated by the severe liver dysfunction and histopathological abnormalities. Co-exposure to SiNPs and CdCl₂ markedly increased the cadmium accumulation in the liver, which induced significant hepatic oxidative stress. In vitro binding assays indicated that serum albumin and Cd(2+) mutually enhanced the binding of each other to SiNPs via the interaction of serum albumin and Cd(2+). The uptake of serum albumin- and Cd(2+)-bound SiNPs by the macrophages significantly increased cadmium accumulation in mice. These results demonstrate that serum albumins play an important role in the positive synergistic toxicity of SiNPs and CdCl₂.

Cadmium and cellular signaling cascades: interactions between cell death and survival pathways

Cellular stress elicited by the toxic metal Cd(2+) does not coerce the cell into committing to die from the onset. Rather, detoxification and adaptive processes are triggered concurrently, allowing survival until normal function is restored. With high Cd(2+), death pathways predominate. However, if sublethal stress levels affect cells for prolonged periods, as in chronic low Cd(2+) exposure, adaptive and survival mechanisms may deregulate, such that tumorigenesis ensues. Hence, death and malignancy are the two ends of a continuum of cellular responses to Cd(2+), determined by magnitude and duration of Cd(2+) stress. Signaling cascades are the key factors affecting cellular reactions to Cd(2+). This review critically surveys recent literature to outline major features of death and survival signaling pathways as well as their activation, interactions and cross talk in cells exposed to Cd(2+). Under physiological conditions, receptor activation generates 2nd messengers, which are short-lived and act specifically on effectors through their spatial and temporal dynamics to transiently alter effector activity. Cd(2+) recruits physiological 2nd messenger systems, in particular Ca(2+) and reactive oxygen species (ROS), which control key Ca(2+)- and redox-sensitive molecular switches dictating cell function and fate. Severe ROS/Ca(2+) signals activate cell death effectors (ceramides, ASK1-JNK/p38, calpains, caspases) and/or cause irreversible damage to vital organelles, such as mitochondria and endoplasmic reticulum (ER), whereas low localized ROS/Ca(2+) levels act as 2nd messengers promoting cellular adaptation and survival through signal transduction (ERK1/2, PI3K/Akt-PKB) and transcriptional regulators (Ref1-Nrf2, NF-κB, Wnt, AP-1, bestrophin-3). Other cellular proteins and processes targeted by ROS/Ca(2+) (metallothioneins, Bcl-2 proteins, ubiquitin-proteasome system, ER stress-associated unfolded protein response, autophagy, cell cycle) can evoke death or survival. Hence, temporary or permanent disruptions of ROS/Ca(2+) induced by Cd(2+) play a crucial role in eliciting, modulating and linking downstream cell death and adaptive and survival signaling cascades.

Cadmium and copper reduce hematopoietic potential in common carp (Cyprinus carpio L.) head kidney

The effects of cadmium and copper on activity of common carp head kidney hematopoietic tissue were evaluated. The fish were subjected to short-term (3 h, Cd-s and Cu-s) or long-term (4 weeks, Cd-l and Cu-l) exposures to 100% 96hLC₅₀ or 10% 96hLC₅₀, respectively. Head kidneys were isolated weekly from 5 fish of each group for 4 weeks (post-short-term exposure and during long-term exposure). Percentage of early blast cells among the hematopoietic precursors was calculated. Proliferative and apoptotic activity were evaluated using immunocytochemical staining for proliferating cell nuclear antigen (PCNA) and caspase 3, respectively. Hematopoietic activity was calculated as the ratio of proliferating to apoptotic cells. All metal exposures induced an increase in frequency of early blast cells. The frequency of proliferating (PCNA-positive) cells also significantly increased. A considerable and significant increase in the frequency of apoptotic cells was the most pronounced effect of metal exposures. Both short-term and long-term treatments caused similar effects, but in case of Cd exposures, the reaction was more pronounced. All metal exposures reduced hematopoietic potential of fish measured as the ratio of proliferating to apoptotic precursor cell frequency. However, in all cases, hematopoietic activity was higher than 1 showing that the rate of repair of hematopoietic tissue prevailed over destruction.

Effects of the heavy metal Cu2+ on growth, development, and population dynamics of Spodoptera litura (Lepidoptera: Noctuidae)

Spodoptera litura (F.) larvae were fed with artificial food containing four different concentrations of copper (25, 50, 100, and 200 mg/kg). Copper affected growth, development, and population dynamics of late instar larvae. Our results indicate that the fourth and fifth instar survival rates were significantly reduced at 50-200 mg/kg copper (Cu2+). Moreover, all the Cu2+ treatments significantly reduced pupation and moth emergence rates in a dose-dependent manner. Larvae fed 25 or 50 mg/kg Cu2+ showed significant reductions in development period compared with non-Cu controls, and the pupation duration of animals fed 200 mg/kg was significantly longer than in non-Cu controls. All Cu2+ concentrations significantly reduced individual pupal weights compared with controls. In addition, Cu2+ at some concentrations significantly affected fertility parameters, such as doubling population time (DT), the net reproduction rate (R(o)), the mean generation time (T), the intrinsic rate of increase (r(m)), and the finite increase rate (A). Our study demonstrates that low concentrations of Cu2+ in the diet (25 and 50 mg/kg) shorten the generation time by 4-5 d, whereas higher Cu2+ concentrations (100 and 200 mg/kg) increase DT for 1-2 d.

Protective effect of Piper betle leaf extract against cadmium-induced oxidative stress and hepatic dysfunction in rats

The present study was undertaken to examine the attenuative effect of Piper betle leaf extract (PBE) against cadmium (Cd) induced oxidative hepatic dysfunction in the liver of rats. Pre-oral supplementation of PBE (200 mg/kg BW) treated rats showed the protective efficacy against Cd induced hepatic oxidative stress. Oral administration of Cd (5 mg/kg BW) for four weeks to rats significantly (P > 0.05) elevated the level of serum hepatic markers such as serum aspartate transaminase (AST), serum alanine transaminase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), gamma-glutamyl transpeptidase (GGT), bilirubin (TBRNs), oxidative stress markers viz., thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides (LOOH), protein carbonyls (PC) and conjugated dienes (CD) and significantly (P > 0.05) reduced the enzymatic antioxidants viz., superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), glutathione reductase (GR) and glucose-6-phosphate dehydrogenase (G6PD) and non-enzymatic antioxidants Viz., reduced glutathione (GSH), total sulfhydryls (TSH), vitamin C and vitamin E in the liver. Pre-oral supplementation of PBE (200 mg/kg BW) in Cd intoxicated rats, the altered biochemical indices and pathological changes were recovered significantly (P > 0.05) which showed ameliorative effect of PBE against Cd induced hepatic oxidative stress. From the above findings, we suggested that the pre-administration of P. betle leaf extract exhibited remarkable protective effects against cadmium-induced oxidative hepatic injury in rats.

IN-AIR MICRO-PIXE ANALYSIS FOR METAL ELEMENTS IN RAT HEPATOCYTES TREATED WITH FUCOIDAN

This study was undertaken to elucidate physiological properties of fucoidan extracted from Cladosiphon okamuranus TOKITA (C. okamuranus) and Fucus vesiculosus (F.vesilurosus). According to the data on MTT assay and TUNEL staining, F. vesiculosus possessed more anti-proliferate activity than C. okamuranus through apoptosis induction. We determined the metal contents of fucoidan to evaluate the relevance of metal elements in its biological effects. Al , Fe and Zn levels were significantly increased in F. vesiculosus than in C. okamuranus. The intracellular changes of metal elements following the administration of fucoidan was analyzed by in-air micro-PIXE in TRL1215 cells (normal rat liver cell line). At 24 h after 5-bromo-2'-deoxyuridine ( BrdU ) dosing, TRL1215 cells were treated with 1.0 mg/mL of each fucoidan for 9 h. The X-ray spectra showed that F. vesiculosus-treated cells markedly increased the yield of aluminum ( Al ) compared to those of C. okamuranus -treated cells and the control. In F. vesiculosus -treated cells, the focal accumulation of Br was spatially correlated with Al map, suggesting that Al was localized within the nucleus. These findings suggest that F. vesiculosus fucoidan increases the accumulations of Al in rat hepatocytes, which may participate in anti-proliferate activity of this fucoidan.

Metallothioneins and energy budget indices in cadmium and copper exposed spiders Agelena labyrinthica in relation to their developmental stage, gender and origin

The aim of our studies was to explain the role of metallothioneins (MTs) in the neutralization of excessive amounts of metals (essential: copper (Cu) and toxic: cadmium (Cd)) and to describe the energy status in metal-exposed spiders Agelena labyrinthica in relation to its developmental stage, gender and origin. Juvenile, female and male spiders were collected from three variously polluted habitats, transferred to the laboratory and exposed to the metals in their diet. Cu and Cd accumulation in the body and exuviae, bioaccumulation factor, percentage of metallothionein positive cells, MT concentration, percentage of cells with depolarized mitochondria, ATP concentration and ADP/ATP ratio were measured and calculated. Cu appeared to be regulated and its excess is eliminated via, among others, the molting process, while Cd was rather accumulated by the spiders. The level of MTs increased significantly mainly in females exposed to both metals, irrespectively of the pollution degree of their site of origin, indicating a defensive role of the proteins. In general, even if both the MT level and the energy status indices were positively correlated with Cd and Cu concentrations in the spider body, the energy status of A. labyrinthica did not seem disturbed.

Low doses of cadmium chloride and methallothionein-1-bound cadmium display different accumulation kinetics and induce different genes in cells of the human nephron

Background/Aims

The present study was conducted to investigate the renal tubular handling of inorganic cadmium (Cd²⁺) by exposing primary human tubular cell cultures to physiologically relevant doses of cadmium chloride (CdCl₂). Furthermore, the cellular accumulation of Cd²⁺ was compared to that of metallothionein-1-bound Cd (Cd7MT-1). Finally, this study aimed to investigate the effect of the accumulation of Cd (both Cd²⁺ and Cd7MT-1) in renal cells on the expression of genes relevant to nephrotoxic processes.

Methods

Cd concentration was measured using atomic absorption spectrometry. mRNA expression was evaluated by quantitative real-time RT-PCR.

Results

Cd²⁺ accumulated into human tubular cells in a concentration- and time-dependent way. Furthermore, cellular accumulation of Cd²⁺ was different from the cellular accumulation of Cd7MT-1, indicative for different uptake routes. Finally, mRNA expression of the genes encoding the anti-oxidative proteins metallothionein-1 (MT-1) and heme-oxygenase-1 (HO-1) as well as the pro-apoptotic Bcl-2-associated X protein (Bax) were upregulated by CdCl₂ and not by Cd7MT1.

Conclusion

In the presence of physiologically relevant Cd concentrations, tubular accumulation of the element in its inorganic form is different from that of Cd7MT-1. Furthermore, the tubular accumulation of inorganic Cd induces mRNA expression of genes of which the protein products may play a role in Cd-associated renal toxicity.

Metabolic and osmoregulatory changes and cell proliferation in gilthead sea bream (Sparus aurata) exposed to cadmium

The impact of cadmium on metabolism and osmoregulation was assessed in gilthead sea bream (Sparus aurata). Seawater acclimated fish were injected intraperitoneally with a sublethal dose of cadmium (1.25 mg Cd/kg body wt). After 7 days, half of the injected fish were sampled. The remaining fish were transferred to hypersaline water and sampled 4 days later. Gill and kidney Na(+)/K(+)-ATPase activities, plasma levels of cortisol, several metabolites and osmolytes, as well as osmolality were measured. Hepatosomatic index and condition factor were calculated. The expression levels of Na(+)/K(+)-ATPase, heat shock proteins (HSP70, HSP90) and proliferating cell nuclear antigen was assessed by western blotting. Cadmium treatment adversely affected the Na(+)/K(+)-ATPase activity, although, there was no perturbation in ion homeostasis and the animals were not compromised following transfer to hypersaline water. Increased cell proliferation and Hsp90 expression likely contributed to the attenuation of the deleterious effects of cadmium exposure.

Antioxidant Activities of Hydroalcoholic Extract of Ocimum sanctum Against Cadmium Induced Toxicity in Rats

The present study was undertaken to analyze the antioxidant (both enzymic and nonenzymic) activities of leaves of Ocimum sanctum hydroalcoholic extract against cadmium induced damage in albino rats. Oral administration of cadmium as CdCl(2) (6.0 mg/kg body weight) led to significant elevation of lipid peroxidation (LPO) levels and significantly decreased Superoxide Dismutase (SOD), Catalase (CAT), Glutathione Peroxidase (GPx), Reduced Glutathione (GSH) and Vitamin C (Ascorbate) levels. Administration of Ocimum sanctum extract (100 mg/kg body weight, po) and (200 mg/kg body weight, po) before and after cadmium intoxication showed a significant decrease in LPO levels and significant increase in SOD, CAT, GPx, GSH and Ascorbate levels. The results suggest that oral administration of Ocimum sanctum extract provides significant protection against cadmium induced toxicity in Wistar albino rats.

Apoptosis and necroptosis are induced in rainbow trout cell lines exposed to cadmium

Cadmium is an important environmental toxicant that can kill cells. A number of studies have implicated apoptosis as well as necrosis and, most recently, a form of programmed necrosis termed necroptosis in the process of cadmium-mediated toxicity, but the exact mechanism remains ill-defined and may depend on the affected cell type. This study investigated which mode of cell death may be responsible for cell death induction in cadmium-exposed trout cell lines from gill and liver and if this cell death was sensitive to inhibitors of necroptosis or apoptosis, respectively. It was observed that intermediate levels of cadmium that killed approximately 50% of the cells over 96-120h of exposure caused cell death that morphologically resembled apoptosis and was associated with an increase of apoptotic markers such as the number of cells with diminished DNA content (sub-G1 cells), condensed or fragmented nuclei, and elevation of caspase-3 activity. At the same time, however, cells also lost plasma membrane integrity, as indicated by uptake of propidium iodide, showed a decrease of ATP levels and mitochondrial membrane potential, and displayed cell swelling, signs associated with secondary necrosis, or equally possible, necroptotic cell death. Importantly, many of these alterations were at least partly inhibited by the necroptosis inhibitor necrostatin-1 and were to a lesser extent also sensitive to the pan-caspase inhibitor zVAD-fmk, indicating that multiple modes of cell death are concurrently induced in cadmium-exposed trout cells, including necroptosis and apoptosis. Cell death appeared to lack concurrent radical formation, consistent with genetically regulated necroptotic cell death, but was characterized by the rapid induction of DNA damage markers, and the early onset of disintegration of the Golgi complex. Comparative experiments evaluating copper-toxicity indicated that in comparison to cadmium much higher concentrations of this metal were required to induce cell death and that neither necrostatin-1 nor a pan-caspase inhibitor conferred protection, suggesting that additional modes of cell death can be triggered in response to poisoning with heavy metals.

High-mobility group box-1 protein promotes angiogenesis after peripheral ischemia in diabetic mice through a VEGF-dependent mechanism

OBJECTIVE

High-mobility group box-1 (HMGB1) protein is a nuclear DNA-binding protein released from necrotic cells, inducing inflammatory responses and promoting tissue repair and angiogenesis. Diabetic human and mouse tissues contain lower levels of HMGB1 than their normoglycemic counterparts. Deficient angiogenesis after ischemia contributes to worse outcomes of peripheral arterial disease in patients with diabetes. To test the hypothesis that HMGB1 enhances ischemia-induced angiogenesis in diabetes, we administered HMGB1 protein in a mouse hind limb ischemia model using diabetic mice.

RESEARCH DESIGN AND METHODS

After the induction of diabetes by streptozotocin, we studied ischemia-induced neovascularization in the ischemic hind limb of normoglycemic, diabetic, and HMGB1-treated diabetic mice.

RESULTS

We found that the perfusion recovery was significantly attenuated in diabetic mice compared with normoglycemic control mice. Interestingly, HMGB1 protein expression was lower in the ischemic tissue of diabetic mice than in normoglycemic mice. Furthermore, we observed that HMGB1 administration restored the blood flow recovery and capillary density in the ischemic muscle of diabetic mice, that this process was associated with the increased expression of vascular endothelial growth factor (VEGF), and that HMGB1-induced angiogenesis was significantly reduced by inhibiting VEGF activity.

CONCLUSIONS

The results of this study show that endogenous HMGB1 is crucial for ischemia-induced angiogenesis in diabetic mice and that HMGB1 protein administration enhances collateral blood flow in the ischemic hind limbs of diabetic mice through a VEGF-dependent mechanism.

Protective and damaging effects of platelets in acute cholestatic liver injury revealed by depletion and inhibition strategies

Alpha-naphthylisothiocyanate (ANIT) causes cholestatic hepatitis characterized by intrahepatic bile duct epithelial cell injury and periportal hepatocellular necrosis. The progression of ANIT-induced hepatocyte injury is reported to involve extrahepatic cells including platelets. We showed recently that the procoagulant protein tissue factor (TF) is essential for ANIT-induced coagulation and contributes to ANIT-induced liver necrosis. Platelets have been shown to express TF and can contribute to coagulation cascade activation. To this end, we tested the hypothesis that platelet-dependent coagulation contributes to ANIT-induced liver injury. In ANIT (60 mg/kg)-treated mice, activation of the coagulation cascade occurred prior to a decrease of platelets in the blood. Immunostaining for glycoprotein IIb (CD41) revealed platelet accumulation along the borders of necrotic foci in livers of ANIT-treated mice. Antibody-mediated platelet depletion did not affect coagulation but markedly affected liver histopathology in ANIT-treated mice. Platelet depletion induced marked pooling of blood within necrotic lesions consistent with parenchymal-type peliosis as early as 24 h after ANIT treatment. In contrast, treatment with the P2Y(12) inhibitor clopidogrel significantly reduced ANIT-induced hepatocyte necrosis and serum alanine aminotransferase activity but did not exaggerate bleeding into necrotic foci. Clopidogrel also reduced hepatic neutrophil accumulation but did not affect induction of Intercellular adhesion molecule-1 or chemokine CxC motif ligand-1 messenger RNA expression in liver. The data indicate that ANIT-induced coagulation is platelet independent and that platelets contribute to ANIT-induced hepatocyte necrosis by promoting neutrophil accumulation. In contrast, severe thrombocytopenia induces parenchymal-type peliosis in the livers of ANIT-treated mice, a rare hepatic lesion associated with pooling of blood in the liver.

Cd-induced apoptosis was mediated by the release of Ca2+ from intracellular Ca storage

Previous studies found that cadmium (Cd) could induce apoptosis via interfering with the intracellular calcium (Ca) ions homeostasis. But the detailed mechanisms remain poorly understood. In the present study two cell lines (normal human liver cell HL-7702, and tumor cell Raji cell) were exposed to Cd along or co-incubated with ethylene glycol-bis (2-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA) and 1,2-bis (2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester (BAPTA-AM), respectively. After the incubation, the apoptosis and intracellular Ca(2+) ([Ca(2+)](i)) were measured. Excessive apoptosis was observed both in HL-7702 and Raji cells treated with Cd. Significant elevation of [Ca(2+)](i) was also detected in the cells with higher levels of apoptosis. EGTA (the extracellular Ca(2+) chelator) decreased Cd-elicited [Ca(2+)](i) (22% in HL-7702 and 41% in Raji cells; p<0.05) significantly except for apoptosis. However, BAMTA-AM (the [Ca(2+)](i) chelator) attenuated the Cd-elevated [Ca(2+)](i) (78% in HL-7702 and 59% in Raji cells; p<0.05) and inhibited Cd-induced apoptosis significantly (p<0.05). These results suggest that (1) Ca(2+) was primarily generated intracellularly and only a small portion was generated extracellularly; (2) Cd-induced apoptosis was mediated by the release of Ca(2+) from intracellular Ca storage but not an influx of extracellular Ca(2+).

Immunomodulatory role of piperine in cadmium induced thymic atrophy and splenomegaly in mice

Cadmium being a potent immunotoxicant, affects both humoral and cell mediated immunity. In rodents, it is primarily characterized by marked thymic atrophy and splenomegaly. Cadmium induces apoptosis in mice and suppresses the immune functions. Piperine, major alkaloid of Piper longum Linn. and Piper nigrum Linn. with a long history of medicinal value, has shown anti-apoptotic activity in vitro. Thus, to delineate its role in vivo, piperine (2.5mg/kg/day, oral, 7 days) treated Balb/C mice were administered Cd as CdCl(2) (1.8mg/kg, i.p., once, 4th day). The various biochemical indexes of cell damage such as cytotoxicity (MTT assay), oxidative stress (glutathione, reactive oxygen species), apoptosis (mitochondrial membrane potential, caspase-3 activity, phosphatidylserine externalization, apoptotic DNA, intranucleosomal DNA fragmentation) along with lymphocyte phenotyping, cell proliferative response and cytokine secretion (IL-2 and IFNγ) were assessed in thymic and splenic single cell suspensions. Lowering of body weight gain and cellularity and a loss in cell viability seen in Cd group, were abrogated by piperine treatment. Similarly, oxidative stress and apoptotic markers altered by Cd were also modulated by this alkaloid. In addition, a pronounced inhibition of cell proliferative response, alterations in T- and B-cell phenotypes, cytokine release and morphological changes were restored to normalcy. The present in vivo data corroborating with our previous in vitro findings, provide confirmatory evidence of the immuno-protective efficacy of piperine.

Prevention of cadmium-induced toxicity in liver-derived cells by the combination preparation Hepeel(®)

Cadmium is a heavy metal of considerable environmental concern that causes liver damage. This study examined the possible prevention of cadmium toxicity in human HepG2 cells and primary rat hepatocytes by Hepeel(®), a combined preparation of tinctures from seven different plants. Hepeel(®) prevented cadmium chloride (CdCl(2))-induced cell death in both HepG2 cells and hepatocytes, and also reduced the loss of glutathione, lipid peroxidation, nuclear fragmentation, caspase activation and release of mitochondrial cytochrome C. To compare their relative efficacy, the seven constituent plant tinctures of Hepeel(®) were also separately tested. The tinctures China and Nux moschata, which exert solely anti-oxidative effects, failed to reduce cytotoxicity, and only protected against loss of glutathione and lipid peroxidation. In contrast, the tinctures Carduus marianus and Chelidonium, demonstrated anti-apoptotic effects, and protected HepG2 cells and primary hepatocytes against CdCl(2)-induced cell death. These results demonstrate how the effectiveness of Hepeel(®) is determined by the synergistic features of its constituent tinctures. Furthermore, we conclude that cadmium toxicity in the liver is mainly due to stimulation of the intrinsic apoptotic pathway, but may be intensified by increased oxidative stress.

The Effects of Chronic Cadmium Toxicity on the Hemostatic System

Cadmium, a highly toxic heavy metal, is distributed widely in the general environment. The characteristic clinical manifestations of chronic cadmium intoxication include renal proximal tubular dysfunction, osteomalacia and anemia. Accumulating evidence suggests that cadmium toxicity may also affect various organs such as the liver, lung, testis and hematopoietic system. The aim of this study was to determine the effect of chronic cadmium exposure on the anticoagulant system in rats. Fourty-five adult Wistar albino rats were randomly allocated into 2 groups. While the control group was given tap water, the animals in the cadmium group were treated with 15 ppm CdCl(2) for 4 weeks. Blood cadmium concentration, prothrombin time, activated partial thromboplastin time, plasma protein C and antithrombin activity, and platelet count were determined in the rats. Blood cadmium concentrations increased in the experiment group compared to the control group (p < 0.001). Results also show that cadmium exposure shortened prothrombin time (p < 0.05) and activated partial thromboplastin time (p < 0.01) in rats. Protein C (p < 0.001) and antithrombin (p < 0.001) decreased to statistically significantly lower levels in rat plasma after cadmium exposure when compared to the control group. When the number of thrombocytes was compared between 2 groups, a decrease was observed in the group treated with CdCl(2), which was, however, not statistically significant (p > 0.05). In conclusion, when the parameters of the hemolytic system are considered, the decrease in protein C and antithrombin activities and the shortening of prothrombin time and activated partial thromboplastin time suggests the presence of a hypercoagulable state during chronic cadmium intoxication. Therefore, it may be stated that chronic cadmium toxicity sets the stage for hypercoagulation and hence increases the risk of thrombosis.

Cadmium- and lead-induced apoptosis in mallard erythrocytes (Anas platyrhynchos)

Cadmium, lead and cadmium-lead (1:10) induced apoptosis were studied using mallard blood cells. The allowable range in concentrations were: 0.01-0.5, 0.1-5.0, and 0.01:0.10-0.50:5.00 mM, for cadmium, lead and cadmium-lead, respectively. The lowest EC(50) achieved was for cadmium (0.22+/-0.04 mM). Two doses from each treatment group were chosen to study apoptosis and the presence of metals in cells. The percentage of apoptotic cells increased as the concentration of metals increased. The percentage of cells with intracellular metals was high for both exposure levels and the quantity of intracellular metal was greater for exposure to high concentrations. Morphological alterations for all types of exposure were related to the diverse range of effects that these metals have on membranes. We suggest that the decrease in the number of erythrocytes observed in specimens suffering from lead and cadmium poisoning is related to the induction of apoptosis.

Taurine protects the antioxidant defense system in the erythrocytes of cadmium treated mice

The present study was undertaken to investigate the protective role of taurine (2-aminoethanesulfonic acid) against cadmium (Cd) induced oxidative stress in murine erythrocytes. Cadmium chloride (CdCl(2)) was chosen as the source of Cd. Experimental animals were treated with either CdCl(2) alone or taurine, followed by Cd exposure. Cd intoxication reduced hemoglobin content and the intracellular Ferric Reducing/Antioxidant Power of erythrocytes, along with the activities of antioxidant enzymes, glutathione content, and total thiols. Conversely, intracellular Cd content, lipid peroxidation, protein carbonylation, and glutathione disulphides were significantly enhanced in these cells. Treatment with taurine before Cd intoxication prevented the toxin-induced oxidative impairments in the erythrocytes of the experimental animals. Overall, the results suggest that Cd could cause oxidative damage in murine erythrocytes and that taurine may play a protective role in reducing the toxic effects of this particular metal.

Endomorphin 1 effectively protects cadmium chloride-induced hepatic damage in mice

The antioxidative capacity of endomorphin 1 (EM1), an endogenous mu-opioid receptor agonist, has been demonstrated by in vivo assays. The present study reports the effect of EM1 on hepatic damage induced by cadmium chloride (Cd(II)) in adult male mouse. Mouse were given intraperitoneally (i.p.) a single dose of Cd(II) (1mg/kg body weight per day) and the animals were co-administrated with a dose of EM1 (50 microM/kg body weight per day) for 6 days. Since hepatic damage induced by Cd(II) is related to oxidative stress, lipid peroxidation (LPO), protein carbonyl (PCO), superoxide dismutase (SOD), catalase (CAT) and reduced glutathione (GSH) were evaluated. The parameter indicating tissue damage such as liver histopathology was also determined. In addition, the concentrations of Cd and zinc (Zn) in the liver were analyzed. The intoxication of Cd(II) lead to the enhanced production of LPO and PCO, treatment with EM1 can effectively ameliorate the increase of LPO and PCO compared to the Cd(II) group. The increased activities of CAT, SOD and the elevated GSH induced by Cd(II) may relate to an adaptive-response to the oxidative damage, the effect of EM1 can restore the elevated antioxidant defense. Our results suggested that the structure features and the ability of chelating metal of EM1 may play a major role in the antioxidant effect of EM1 in vivo and opioid receptors may be involved in the protection of hepatic damage induced by Cd(II).

Cadmium generates reactive oxygen- and carbon-centered radical species in rats: insights from in vivo spin-trapping studies

Cadmium (Cd) is a known industrial and environmental pollutant. In the present work, an in vivo spin-trapping technique was used in conjunction with electron spin resonance (ESR) spectroscopy to investigate free radical generation in rats following administration of cadmium chloride (CdCl2, 40 micromol/kg) and the spin trapping agent alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (POBN, 1 g/kg). In Cd-treated rats, POBN radical adducts were formed in the liver, were excreted into the bile, and exhibited an ESR spectrum consistent with a carbon-centered radical species probably derived from endogenous lipids. Isotope substitution of dimethyl sulfoxide [(CH3)2SO] with 13C demonstrated methyl radical formation (POBN/*13CH3). This adduct indicated the production of hydroxyl radical, which reacted with [(13CH3)2SO] to form *13CH3, which then reacted with POBN to form POBN/*13CH3. Depletion of hepatic glutathione by diethyl maleate significantly increased free radical production, whereas inactivation of Kupffer cells by gadolinium chloride and chelation of iron by desferal inhibited it. Treatment with the xanthine oxidase inhibitor allopurinol, the catalase inhibitor aminobenzotriazole, or the cytochrome P450 inhibitor 3-amino-1,2,4-triazole had no effect. This is the first study to show Cd generation of reactive oxygen- and carbon-centered radical species by involvement of both iron mediation through iron-catalyzed reactions and activation of Kupffer cells, the resident liver macrophages.

Study on the relationship between cadmium chloride-induced adrenocortical cell of guinea pig apoptosis and stress-activated protein kinase activity

Heavy metals are important environmental pollutants that affect many cellular functions. The signaling pathways that lead to apoptosis of adrenocortical cells following exposure to cadmium chloride (CdCl2) have not yet been fully clarified. We developed a primary culture of guinea pig adrenocortical cells and treated it with various concentrations of CdCl2 for different time periods. The apoptosis induced by CdCl2 was detected by fluorescein isothiocyanate-labeled annexin V and propidium iodide staining using a flow cytometer. Stress-activated protein kinase (SAPK) activities were measured by immunoprecipitation and chemiluminescence assay. After 2h of treatment, the apoptotic cell rate increased in a dose-dependent manner. The difference between the high-dose group and the control group was significant (P<0.01). The apoptosis was also found to increase in a time-dependent manner in cells treated with 50micromol/L CdCl2. Among the various treatment period groups, the difference between more than 1h-treated groups and the control group was significant (P<0.01). The SAPK activity increased with an increase in CdCl2 dose after 5min of exposure. However, after 15min of exposure to CdCl2, the SAPK activity decreased with an increase in exposure time. Our findings suggest that the SAPK signaling pathway might play an important role in CdCl2-induced apoptosis of adrenocortical cells.

Environmentally relevant cadmium concentrations affect development and induce apoptosis of Paracentrotus lividus larvae cultured in vitro

Sea urchin embryos and larvae represent suitable model systems on where to investigate the effects of heavy metals on development and cell viability. Here, we tested the toxic effects of low (10(-12 )M), medium (10(-9 )M), and high (10(-6 )M) cadmium chloride concentrations, mimicking unpolluted, moderately and highly polluted seawaters, respectively, on Paracentrotus lividus sea urchins offspring. Larvae were continuously treated from fertilization and inspected at time intervals comprised between 10 and 30 days of development. Delays and/or morphological abnormalities were firstly evident in larvae treated for 15 days with high cadmium (10(-6 )M) and for 25 days with medium cadmium (10(-9 )M). Major defects consisted in the reduction and lack of arms and skeleton elongation. No obvious differences with respect to controls were observed in embryos/larvae exposed to low cadmium (10(-12) M), even after 30 days of exposure. Using in situ terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay (TUNEL) assay on larvae whole mounts, we detected apoptosis after 10 days of treatment with 10(-6) and 10(-9) M CdCl(2,) when no morphological abnormalities were recognizable yet. Supernumerary apoptotic cells were found in arm buds, ciliary bands, and apex. In conclusion, echinoderm embryos and larvae represent candidates of choice for the study of stress and defense mechanisms activated by cadmium exposure.

Metals and apoptosis: recent developments

Apoptosis, also known as programmed cell death is a highly regulated and crucial process found in all multicellular organisms. It is not only implicated in regulatory mechanisms of cells, but has been attributed to a number of diseases, i.e. inflammation, malignancy, autoimmunity and neurodegeneration. A variety of toxins can induce apoptosis. Carcinogenic transition metals, viz. cadmium, chromium and nickel promote apoptosis along with DNA base modifications, strand breaks and rearrangements. Generation of reactive oxygen species, accumulation of Ca(2+), upregulation of caspase-3, down regulation of bcl-2, and deficiency of p-53 lead to arsenic-induced apoptosis. In the case of cadmium, metallothionein expression determines the choice between apoptosis and necrosis. Reactive oxygen species (ROS) and p53 contribute in apoptosis caused by chromium. Immuno suppressive mechanisms contribute in lead-induced apoptosis whereas in the case of mercury, p38 mediated caspase activation regulate apoptosis. Nickel kills the cells by apoptotic pathways. Copper induces apoptosis by p53 dependent and independent pathways. Beryllium stimulates the formation of ROS that play a role in Be-induced macrophage apoptosis. Selenium induces apoptosis by producing superoxide that activates p53. Thus, disorders of apoptosis may play a critical role in some of the most debilitating metal-induced afflictions including hepatotoxicity, renal toxicity, neurotoxicity, autoimmunity and carcinogenesis. An understanding of metal-induced apoptosis will be helpful in the development of preventive molecular strategies.

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.

Role of α-tocopherol in cadmium-induced oxidative stress in Wistar rat's blood, liver and brain

Cadmium (Cd) a highly toxic metal is considered to be a multitarget toxicant, and it accumulates principally in the liver and kidney after absorption. In vivo studies of mouse and rat liver have shown that apoptosis plays a primary role in Cd-induced hepatotoxicity. However, the detailed mechanisms by which toxic metals such as Cd produce their effects are still largely unknown. The present study aimed at investigating the consequences of exposure to Cd, alpha-tocopherol and their combination on stress biochemical parameters (lipoperoxidation and protein carbonyls levels). Male albino Wistar rats (1 month old) were treated intravenously with cadmium (2 mg CdCl(2)/kg body weight/day), and alpha-tocopherol (100 mg/kg body weight/day), or with alpha-tocopherol+Cd (100 mg Vit E/kg body weight, 2 mg CdCl(2)/kg). The lipoperoxidation was measured by the thiobarbituric acid reactive substances (TBARS) method and oxidatively generated damage to proteins by determining carbonyl (DNPH) levels. Among the hematological parameters measured the haematocrit value and haemoglobin concentration were significantly decreased in the blood of Cd-treated rats. A significant increase was observed in the level of malondialdehyde (MDA) and protein carbonyls in the cadmium exposed group compared to control group (p<0.001), and these values were decreased after administration of alpha-tocopherol (group 4). The activity of lactate dehydrogenase in rat liver and brain showed a significant increase as compared to that found in the control group and significant decrease of catalase and superoxide dismutase activities. In the liver of the Cd-treated group the contents of reduced glutathione were decreased. Our results suggest that cadmium induces an oxidation of cellular lipids and proteins and that administration of alpha-tocopherol can reduce Cd-induced oxidative stress and improve the glutathione level together with other biochemical parameters.

Effect of 5-HT(2) receptor blockade on cadmium-induced acute toxicity

The protective effect of 5-HT(2) receptor blockade with ketanserin or ritanserin against cadmium liver injury was investigated. Male Wistar rats were injected intraperitoneally with a sublethal dose of cadmium (3.5 mg/kg body weight). Rats were treated with normal saline (group I), ketanserin (3 mg/kg body weight; group II), or ritanserin (3 mg/kg body weight; group III) 2 hr prior and 4 hr after cadmium administration and killed at different time points. Hematoxylin/eosin-stained liver sections were assessed for necrosis, apoptosis, peliosis, mitoses, and inflammatory infiltration. Apoptosis was also quantified by the TUNEL assay. Nonparenchymal liver cells and activated Kupffer cells were identified histochemically. Necrosis, hepatocyte apoptosis, nonparenchymal cell apoptosis, and macroscopic and microscopic peliosis were markedly reduced or minimized in ketanserin- or ritanserin-treated rats. The observed protective effect was almost identical for both ketanserin and ritanserin administration. 5-HT(2) receptor blockade exerts a protective effect against acute cadmium-induced hepatotoxicity.

Cadmium-Induced Germline Apoptosis in Caenorhabditis elegans: The Roles of HUS1, p53, and MAPK Signaling Pathways

The transition metal cadmium (Cd) has been shown to induce apoptosis in a variety of cell lines and tissues. Caspase activation of the tumor suppressor gene p53 and mitogen-activated protein kinase (MAPK) signaling cascades have been reported to be involved in Cd-induced apoptosis. However, the underlying pathways of Cd-induced apoptosis have not been clearly elucidated in the in vivo systems, primarily for the lack of appropriate animal models. The nematode Caenorhabditis elegans has been shown to be a good model to study basic biological processes, including apoptosis. In this study, we used the mutated alleles of C. elegans homologs of known mammalian genes that are involved in regulation of apoptosis. Sublethal doses of Cd exposure increased C. elegans germline apoptosis in a dose- and time-dependent manner. The loss-of-function mutations of DNA damage response (DDR) genes HUS1 and p53 exhibited significant increase in germline apoptosis under Cd exposure, and the depletion of p53 antagonist ABL1 significantly enhanced apoptosis. Cd-induced apoptosis was blocked in the loss-of-function alleles of both c-Jun N-terminal kinase (JNK) and p38 MAPK cascades, which behaved normally under gamma-irradiation. Our findings implicate that both JNK and p38 MAPK cascades participate in Cd-induced apoptosis. Together, the results of this study suggest the nonessential roles of the DDR genes hus1 and p53 in Cd-induced germline apoptosis and that the apoptosis occurs through the ASK1/2-MKK7-JNK and ASK1/2-MKK3/6-p38 signaling pathways in a caspase-dependent manner. Finally, our study demonstrates that C. elegans is a mammalian in vivo substitute model to study the mechanisms of Cd-induced apoptosis.

Apoptosis, metallothionein, and bioavailable metals in domestic mice (Mus musculus L.) from a human-inhabited volcanic area

The influence of extreme environments of volcanic origin over vertebrates and the cellular responses that these may give are almost unknown. The main objectives were to evaluate the exposure of mice to metals in the interior of houses of a small village settled inside a volcanic crater (Furnas, Azores), and the levels of apoptosis and metallothionein in the organs (lung, liver, and kidney) of those animals. Adult mice (Mus musculus) were captured in two areas, one with volcanic activity and the other without it over the last three centuries. In the excised organs, analysis of metals (Al, Cd, Pb, Zn), TUNEL assay for apoptosis, and immunohistochemistry for metallothionein were undertook. Mice from the area with volcanic activity presented higher levels of apoptosis and metallothionein than those from the area without volcanic activity. Such results were in agreement with the differences in metal burdens of the three organs, and interestingly these concentrations were similar to or higher than others found in heavily polluted areas outside the Azores. Thus, there may be a high risk of harmful effects for organisms, including humans, inhabiting areas with volcanism, where hazardous gases and metals in the air are very common during the entire day or even all year round.