Cadmium stress: an oxidative challenge. Biometals. 2010;23:927-940. [PMID: 20361350 DOI: 10.1007/s10534-010-9329-x]

Bioactive phytochemicals from Salvia officinalis attenuate cadmium-induced oxidative damage and genotoxicity in rats

This study was conducted to identify the bioactive phytochemicals in Salvia officinalis essential oil, to determine the polyphenols in the aqueous extract (SOE), and to evaluate their protective role against cadmium (Cd)-induced oxidative damage and genotoxicity in rats. Six groups of female rats were treated orally for 2 weeks including the control group, CdCl₂-treated group, SOE-treated groups at low or high dose (100 and 200 mg/kg b.w), and CdCl₂ plus SOE-treated groups at the two doses. The GC-MS analysis identified 39 compounds; the main compounds were 9-octadecenamide, eucalyptol, palmitic acid, and oleic acid. However, the HPLC analysis showed 12 polyphenolic compounds and the majority were coumaric acid, chlorogenic acid, coffeic acid, catechin, vanillin, gallic acid, ellagic acid, and rutin. In the biological study, rats received CdCl₂ displayed severe disturbances in liver and kidney indices alanine aminotransferase (ALT), aspartate aminotransferase (AST), albumin (Alb), total protein (TP), total bilirubin (T. Bil), direct bilirubin (D. Bil), creatinine, uric acid, and urea, lipid profile, tumor necrosis factor-alpha (TNF-α), alpha-fetoprotein (AFP) and CEA), glutathione (GSH), glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase (CAT), malondialdehyde (MDA), nitric oxide (NO), gene expressions, DNA fragmentation, and histological alterations in the liver and kidney tissue. SOE showed a potent antioxidant and mitigated these alterations in serum and tissue. Moreover, the high dose succeeded to normalize most of the tested parameters and histological features. It could be concluded that S. officinalis is a promising source for bioactive compounds with therapeutic benefits against environmental toxicants.

External application of nitrogen alleviates toxicity of cadmium on poplars via starch and sucrose metabolism

Phytoremediation technology can help achieve moderate cost and considerable effect with respect to the remediation of heavy metal (HM) pollution in soil and water. Many previous studies have suggested the role of nitrogen (N) in the alleviation of effects of HM on plants. Herein, we sought to determine the molecular mechanisms by which additional N supplementation mitigates cadmium (Cd) toxicity in poplars using a combination of physiological, transcriptomic and phosphoproteomic analyses. The application of N can alleviate the toxicity of Cd to Populus by reducing chlorophyll degradation, maintaining the stability of ions inside and outside the cell membrane and increasing the soluble sugar content. Plant samples from the control, Cd stress and Cd_N treatments were used for an integrated analysis of the transcriptome, as well as for phosphoproteomics analysis. Moreover, 1314 differentially expressed genes and 119 differentially expressed kinase genes were discovered. Application of additional N under Cd stress promoted the phosphorylation process. Furthermore, 51 significantly enriched phosphorylated protein sites and 23 differentially expressed kinases were identified using phosphoproteomic and proteomic analyses. Importantly, transcriptomic and phosphoproteomic analyses jointly determined that the application of N could activate corresponding gene expression [UDP-glucose-dehydrogenase (UGD), GAUT, PME, pectin lyase, UDP-glucose-pyrophosphorylase 2 (UGP2), sucrose phosphate synthase (SPS), SUS and SPP2] and protein phosphorylation (UGP2 and SPS) in the sugar and starch synthesis pathways, which promoted the synthesis of sucrose and soluble sugar and subsequently alleviated the damage caused by Cd.

Effects of coenzyme Q10 on reproductive performance of laying Japanese quail (Coturnix japonica) under cadmium challenge

Japanese quail is an increasingly important bird of economic importance for commercial egg and meat production, particularly in developing countries. There is a need for research aimed at improving efficiency of these birds during stressful challenges, such as oxidative stress. Coenzyme Q10 (CoQ10), a highly functional antioxidant, protects cells against oxidative stress. This study was conducted to determine the effects of CoQ10 on reproductive performance of Japanese quail under cadmium (Cd) challenge. A total of 216 six-wk-old Japanese quail were randomly allocated into 3 groups for an 8 wk experimental trial. The treatments include a negative control (NC): feeding basal diet; a positive control (PC): feeding basal diet and cadmium administration (1 mg/100 g BW, at 10 and 11 wk of age), and (CdQ10): feeding CoQ10 supplemented (900 mg/kg diet) basal diet and Cd administration. At 11 and 13 wk of age, egg production, body weight, mortality, oviduct, and ovarian biometry, were recorded. Histology and histopathology of isthmus and magnum, fertility, hatchability, hatchling quality, and HSP70 mRNA transcript abundance in the utero-vaginal junction (UVJ) were evaluated. Positive control and CdQ10 group had no significant effect on live body weight, stroma weight, follicle size, hatchability, and fertility; however, Cd administration increased (P < 0.01) mortality rate in the PC group compared to the NC and CdQ10 groups. CdQ10 quail produced more eggs and had a higher hatchling quality compared to the PC group (P < 0.01). The thickness and height of isthmus and magnum folds in the CdQ10 group was increased compared to the PC group (P < 0.01) and overall oviduct weight was increased with CoQ10 supplementation (P < 0.01). Compared to PC, the CdQ10 group had a reduction in infiltration of inflammatory cells. Relative abundance of HSP70 mRNA in UVJ was influenced by interactive effect of treatment × time (P < 0.05). In conclusion, dietary supplementation of CoQ10 showed beneficial effects on some reproduction characteristics of female Japanese quail under Cd-induced oxidative stress.

Detoxification and recovery after cadmium exposure in the freshwater crab Sinopotamon henanense

Cadmium (Cd) is a common pollutant in the aquatic environment, which puts the health and safety of aquatic organisms and humans at risk. In the present study, the freshwater crab Sinopotamon henanense was exposed to Cd (0, 50, 100, and 500 μg·L^-1) for 14 d (0-14th d), followed by 21 d (14-35th d) of depuration. The changes in Cd bioaccumulation, microstructure, biomacromolecules (polysaccharides, neutral lipids, DNA and total proteins), and biochemical parameters (SOD, CAT, GR, TrxR, MDA and AChE) in the gills and hepatopancreas were tested. The injured microstructure, activated antioxidant system, increased MDA, and inhibited AChE of the gills and hepatopancreas responded with progressive bioaccumulation of Cd. Meanwhile, the polysaccharides and neutral lipids in the hepatopancreas reduced and DNA synthesis enhanced. During depuration, more than 58.80 ± 8.53% and 13.84 ± 12.11% of Cd was excreted from the gills and hepatopancreas, respectively. Recovery of microstructure and biomacromolecules as well as alleviated oxidative damage and neurotoxicity were also found in these two organs. Additionally, based on PCA, I_his, GR and MDA were identified as the optimal biomarkers indicating the health status of crabs. In conclusion, S. henanense could resist Cd stress through antioxidant defence and self-detoxification.

Antioxidant and antigenotoxic potential of Morinda tinctoria Roxb. leaf extract succeeding cadmium exposure in Asian catfish, Pangasius sutchi

The present study investigated the protective effect of methanolic leaf extract of Morinda tinctoria. Roxb (MEMT) (200 mg/kg) via feed in supplementation with standard compound silymarin (400 mg/kg). M. tinctoria (Roxb.) belonging to Rubiaceae, is an evergreen shrub indigenous to unfarmed lands of tropical countries. It is considered as an essential traditional medicine attributing for the potential antioxidant and anti-inflammatory properties. The enhancements of antioxidant and antigenotoxic status in different tissues of cadmium (Cd) intoxicated Pangasius sutchi were evaluated by using various antioxidant assays (superoxide dismutase (SOD) and catalase (CAT) and lipid peroxidation) in addition to micronuclei (MN), binuclei (BN) and comet assay. The cadmium toxicated fish showed a significant (p < 0.001) increase in lipid peroxidation (LPO) activities in liver, gills, muscle and kidney whereas significant (p < 0.001) decline were observed in superoxide dismutase (SOD) and catalase (CAT) contents in all fish tissues. The results also revealed that, Cd exposure induced the formation of genotoxic endpoints like MN, BN, notched nuclei, kidney shaped nuclei and DNA damage in the fish erythrocytes. Maximum of 26.8% MN frequencies and maximum of 66.74% tail DNA damage were observed on the 7th day of Cd exposure. A time-dependent significant increase (p < 0.001) in the frequencies of MN, BN and tail DNA damage were observed in all treated groups against the control which started to decline from 14th day onwards. There was a decline in the LPO content, frequencies of MN, BN and percentage of tail DNA in contrast to significant elevation in SOD and CAT content in all tissues due to the combined treatment of M. tinctoria feed and water borne Cd exposure. It can be concluded from our observations that, supplementation of M. tinctoria leaf extract through feed alone produced enhanced antioxidant and antigenotoxic status in cadmium treated fish by diminishing oxidative stress and genotoxicity effects in a time dependent manner.

The Molecular Basis of Acinetobacter baumannii Cadmium Toxicity and Resistance

Acinetobacter species are ubiquitous Gram-negative bacteria that can be found in water, in soil, and as commensals of the human skin. The successful inhabitation of Acinetobacter species in diverse environments is primarily attributable to the expression of an arsenal of stress resistance determinants, which includes an extensive repertoire of metal ion efflux systems. Metal ion homeostasis in the hospital pathogen Acinetobacter baumannii contributes to pathogenesis; however, insights into its metal ion transporters for environmental persistence are lacking. Here, we studied the impact of cadmium stress on A. baumannii. Our functional genomics and independent mutant analyses revealed a primary role for CzcE, a member of the cation diffusion facilitator (CDF) superfamily, in resisting cadmium stress. We also show that the CzcCBA heavy metal efflux system contributes to cadmium efflux. Collectively, these systems provide A. baumannii with a comprehensive cadmium translocation pathway from the cytoplasm to the periplasm and subsequently the extracellular space. Furthermore, analysis of the A. baumannii metallome under cadmium stress showed zinc depletion, as well as copper enrichment, both of which are likely to influence cellular fitness. Overall, this work provides new knowledge on the role of a broad arsenal of membrane transporters in A. baumannii metal ion homeostasis. IMPORTANCE Cadmium toxicity is a widespread problem, yet the interaction of this heavy metal with biological systems is poorly understood. Some microbes have evolved traits to proactively counteract cadmium toxicity, including Acinetobacter baumannii, which is notorious for persisting in harsh environments. Here, we show that A. baumannii utilizes a dedicated cadmium efflux protein in concert with a system that is primarily attuned to zinc efflux to efficiently overcome cadmium stress. The molecular characterization of A. baumannii under cadmium stress revealed how active cadmium efflux plays a key role in preventing the dysregulation of bacterial metal ion homeostasis, which appeared to be a primary means by which cadmium exerts toxicity upon the bacterium.

Immunomodulation by heavy metals as a contributing factor to inflammatory diseases and autoimmune reactions: Cadmium as an example

Cadmium (Cd) represents a unique hazard because of the long biological half-life in humans (20-30 years). This metal accumulates in organs causing a continuum of responses, with organ disease/failure as extreme outcome. Some of the cellular and molecular alterations in target tissues can be related to immune-modulating potential of Cd. This metal may cause adverse responses in which components of the immune system function as both mediators and effectors of Cd tissue toxicity, which, in combination with Cd-induced alterations in homeostatic reparative activities may contribute to tissue dysfunction. In this work, current knowledge concerning inflammatory/autoimmune disease manifestations found to be related with cadmium exposure are summarized. Along with epidemiological evidence, animal and in vitro data are presented, with focus on cellular and molecular immune mechanisms potentially relevant for the disease susceptibility, disease promotion, or facilitating development of pre-existing pathologies.

Comparative physiological and transcriptomic analyses reveal ascorbate and glutathione coregulation of cadmium toxicity resistance in wheat genotypes

BACKGROUND

Cadmium (Cd) is a heavy metal with high toxicity that severely inhibits wheat growth and development. Cd easily accumulates in wheat kernels and enters the human food chain. Genetic variation in the resistance to Cd toxicity found in wheat genotypes emphasizes the complex response architecture. Understanding the Cd resistance mechanisms is crucial for combating Cd phytotoxicity and meeting the increasing daily food demand.

RESULTS

Using two wheat genotypes (Cd resistant and sensitive genotypes T207 and S276, respectively) with differing root growth responses to Cd, we conducted comparative physiological and transcriptomic analyses and exogenous application tests to evaluate Cd detoxification mechanisms. S276 accumulated more H₂O₂, O₂^-, and MDA than T207 under Cd toxicity. Catalase activity and levels of ascorbic acid (AsA) and glutathione (GSH) were greater, whereas superoxide dismutase (SOD) and peroxidase (POD) activities were lower in T207 than in S276. Transcriptomic analysis showed that the expression of RBOHA, RBOHC, and RBOHE was significantly increased under Cd toxicity, and two-thirds (22 genes) of the differentially expressed RBOH genes had higher expression levels in S276 than inT207. Cd toxicity reshaped the transcriptional profiling of the genes involving the AsA-GSH cycle, and a larger proportion (74.25%) of the corresponding differentially expressed genes showed higher expression in T207 than S276. The combined exogenous application of AsA and GSH alleviated Cd toxicity by scavenging excess ROS and coordinately promoting root length and branching, especially in S276.

CONCLUSIONS

The results indicated that the ROS homeostasis plays a key role in differential Cd resistance in wheat genotypes, and the AsA-GSH cycle fundamentally and vigorously influences wheat defense against Cd toxicity, providing insight into the physiological and transcriptional mechanisms underlying Cd detoxification.

The modulatory potential of herbal antioxidants against oxidative stress and heavy metal pollution: plants against environmental oxidative stress

Free radicals, principally reactive oxygen species (ROS), contribute to oxidative stress in human beings. Free radicals have different mechanisms of action and affect lipids, proteins, and DNA. Heavy metals including cadmium (Cd), lead (Pb), and arsenic are environmental pollutants that may induce oxidative stress and produce ROS, leading to harmful effects on different body systems such as the liver and brain. On the other side, antioxidants can have protective effects against oxidative stress and decrease their toxicity. Herbal antioxidants have potential antioxidative effects. These antioxidants positively affect neurodegenerative diseases, atherosclerotic diseases, lung fibrosis, kidney injuries, and liver toxicities induced by oxidative agents, including heavy metals. In this manuscript, we explained the mechanisms of oxidative stress, and also discussed heavy metals which contribute to human oxidative stress. We further discussed different herbal antioxidants, their mechanisms of action, and their clinical use for various diseases.

Combined toxic effects of aflatoxin B2 and the protective role of resveratrol in Swiss albino mice

In this study, the toxic effects of aflatoxin B₂ (AFB₂) on Swiss albino mice and the protective effects of resveratrol were investigated. Physiological (body weight, liver and kidney weight), biochemical (aspartate aminotransferase-AST, alanine transaminase-ALT, blood urea nitrogen-BUN, creatinine, malondialdehyde-MDA and glutathione-GSH) and cytogenetic parameters (micronucleus-MN in buccal epithelium, erythrocyte and leukocyte cells and chromosomal aberrations-CAs) were used to determine the toxic effects. Additionally, scavenging effects of resveratrol against superoxide, hydrogen peroxide (H₂O₂) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals were also investigated. In experimental period, mice were divided into six groups and the groups were treated with tap water, 10 mg/kg b.w resveratrol, 20 mg/kg b.w resveratrol, 20 µg/kg b.w. AFB₂, 10 mg/kg b.w resveratrol + 20 µg/kg b.w AFB₂, 20 mg/kg b.w resveratrol + 20 µg/kg b.w AFB₂, respectively. As a result, the scavenging effects of resveratrol increased with increasing dose and the superoxide, H₂O₂ and DPPH radical scavenging activity of resveratrol were 74.9%, 79.1% and 49.2%, respectively. AFB₂ administration caused a significant decrease in physiological parameters, and these decreases regressed in AFB₂ + resveratrol treated groups. Serum ALT and AST activities, BUN and creatinine levels were higher in the AFB₂ treated group compared to the control group and serious abnormalities were found in MDA and GSH levels in the kidney and liver. In the group treated with AFB₂ + 20 mg/kg resveratrol, ALT, AST, BUN and creatinine levels decreased significantly and GSH levels increased compared to only-AFB₂ treated group. AFB₂ triggered MN formation in buccal epithelium, erythrocyte and leukocyte cells and CAs in bone marrow cells. The application of 20 mg/kg resveratrol together with AFB₂ was decreased the MN and CAs frequency. Resveratrol exhibited a recovery effect in the range of 40.9-80.5% against AFB₂ toxicity in all tested parameters. In this study, it was determined that AFB₂ caused serious changes in selected physiological, biochemical and cytogenetic parameters while resveratrol displayed a protective role against these toxic effects.

Improved physiological defense responses by application of sodium nitroprusside in Isatis cappadocica Desv. under cadmium stress

Isatis cappadocica is a well-known arsenic-hyperaccumulator, but there are no reports of its responses to cadmium (Cd). Nitric oxide (NO) is a signaling molecule, which induces cross-stress tolerance and mediates several physio-biochemical processes related to heavy metal toxicity. In this study, the effects of Cd and sodium nitroprusside (SNP as NO donor) on the growth, defense responses and Cd accumulation in I. cappadocica were investigated. When I. cappadocica was treated with 100 and 200 μM Cd, there was an insignificant inhibition of shoot growth. However, Cd stress at Cd400 treatment decreased significantly the dry weight of root and shoot by 73 and 38%, respectively, as compared to control. The application of SNP significantly improved the growth parameters and mitigated Cd toxicity. In addition, SNP decreased reactive oxygen species (ROS) production induced by Cd. The increased total thiol and glutathione (GSH) concentrations after SNP application may play a decisive role in maintaining cellular redox homeostasis, thereby protecting plants against oxidative damage under Cd stress. Bovine hemoglobin (Hb as NO scavenger) reduced the protective role of SNP, suggesting a major role of NO in the defensive effect of SNP. Furthermore, the reduction in shoot growth and the increase of oxidative damage were more severe after the addition of Hb, which confirms the protective role of NO against Cd-induced oxidative stress. The protective role of SNP in decreasing Cd-induced oxidative stress may be related to NO production, which can lead to stimulation of the thiols synthesis and improve defense system.

Protective Effect of Tubotaiwine on Cadmium-Induced Hypertension in Rats through Reduction in Arterial Stiffness and Vascular Remodeling

Humans are adversely affected by exposure to cadmium (Cd) as it induces oxidative stress which damages kidneys, bones pulmonary tissues, liver, cardiovascular, immune, reproductive systems and influences endocrine secretions. In the present study tubotaiwine treatment regulated systolic, diastolic and mean arterial blood pressure of the Cd exposed rats. Tubotaiwine significantly promoted vascular responsiveness to Phe, ACh and SNP and reversed Cd mediated decrease in eNOS and increase in iNOS expression. Treatment of the Cd exposed rats with tubotaiwine reduced number of smooth muscle cells, decreased collagen content and promoted content of elastin in aortic artery walls. Tubotaiwine treatment significantly suppressed Cd-induced increase in MMP-2 and MMP-9 in rat aortic artery tissues. Increase in O2-, urinary nitrate/nitrite, MDA, carbonyl level and decrease in GSH production in rat blood and thoracic aorta tissues were effectively reversed by tubotaiwine treatment. Tubotaiwine treatment of the rats significantly reduced Cd-induced increase in blood, liver, heart and kidney tissue Cd content in dose dependent manner. Thus, tubotaiwine suppresses Cd induced hypertension in rats by reducing arterial stiffness, inhibition of oxidative stress and increasing vascular remodeling. Therefore, tubotaiwine has beneficial effect on Cd induced hypertension in rats and may be developed as a potential candidate for treatment of hypertension.

Resolvin D1 protects against cadmium chloride-induced memory loss and hippocampal damage in rats: A comparison with docosahexaenoic acid

BACKGROUND

Intoxication with cadmium (Cd) ions leads to hippocampal damage and cognitive impairment. However, omega-3 polyunsaturated fatty acids (n-3 PUFAs) exert neuroprotective effects in different animal models of neurodegeneration.

PURPOSE

This study compared the neuroprotective effect of the n-3 PUFA, docosahexaenoic acid (DHA), and its downstream metabolite, resolvin D1 (RVD1), on hippocampal damage and memory deficits in cadmium chloride (CdCl₂)-treated rats.

RESEARCH DESIGN

Control or CdCl₂ (0.5 mg/kg)-treated rats were subdivided into three groups (n = 18/each) and treated for 6 weeks as follows: (1) fed control diet, (2) fed DHA-rich diets (0.7 g/100 g), or (3) treated with RVD1 (0.2 μg/kg, i.p).

RESULTS

Treatment with a DHA-rich diet or RVD1 significantly increased the levels of docosahexaenoic acid and RVD1, respectively, in the hippocampal of CdCl₂-treated rats without affecting the reduction in the expression of the 15-lipooxygenase-1 (ALOX15). These effects were associated with improvements in rats' memory function and hippocampal structure, as well as a redction in the hippocampal levels of reactive oxygen species (ROS), malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), nuclear localization of the nuclear factor-kappa beta p65 (NF-κB p65), and expression of cleaved caspase-3. Concomitantly, hippocampi of both groups of rats showed significantly higher levels of Bcl-2, superoxide dismutase (SOD), and glutathione (GSH), as well as enhanced nuclear levels of the nuclear factor erythroid 2-related factor 2 (Nrf-2). The effects of RVD1 on all these markers in the CdCl₂-induced rats were more profound than those of DHA. Also, the increase in the nuclear protein levels of Nrf-2 and the decrease in the levels of Bax and nuclear protein levels of NF-κB p65 were only seen in the hippocampal of CdCl₂ + RVD1-treated rats.

CONCLUSION

RVD1 is more powerful than DHA in preventing CdCl₂-induced memory loss and hippocampal damage in rats.

GSH and Zinc Supplementation Attenuate Cadmium-Induced Cellular Stress and Stimulation of Choline Uptake in Cultured Neonatal Rat Choroid Plexus Epithelia

Choroid plexus (CP) sequesters cadmium and other metals, protecting the brain from these neurotoxins. These metals can induce cellular stress and modulate homeostatic functions of CP, such as solute transport. We previously showed in primary cultured neonatal rat CP epithelial cells (CPECs) that cadmium induced cellular stress and stimulated choline uptake at the apical membrane, which interfaces with cerebrospinal fluid in situ. Here, in CPECs, we characterized the roles of glutathione (GSH) and Zinc supplementation in the adaptive stress response to cadmium. Cadmium increased GSH and decreased the reduced GSH-to-oxidized GSH (GSSG) ratio. Heat shock protein-70 (Hsp70), heme oxygenase (HO-1), and metallothionein (Mt-1) were induced along with the catalytic and modifier subunits of glutamate cysteine ligase (GCL), the rate-limiting enzyme in GSH synthesis. Inhibition of GCL by l-buthionine sulfoximine (BSO) enhanced stress protein induction and stimulation of choline uptake by cadmium. Zinc alone did not induce Hsp70, HO-1, or GCL subunits, or modulate choline uptake. Zinc supplementation during cadmium exposure attenuated stress protein induction and stimulation of choline uptake; this effect persisted despite inhibition of GSH synthesis. These data indicated up-regulation of GSH synthesis promotes adaptation to cadmium-induced cellular stress in CP, but Zinc may confer cytoprotection independent of GSH.

Gestational Cd Exposure in the CD-1 Mouse Induces Sex-Specific Hepatic Insulin Insensitivity, Obesity, and Metabolic Syndrome in Adult Female Offspring

There is compelling evidence that developmental exposure to toxic metals increases risk for obesity and obesity-related morbidity including cardiovascular disease and type 2 diabetes. To explore the hypothesis that developmental Cd exposure increases risk of obesity later in life, male, and female CD-1 mice were maternally exposed to 500 ppb CdCl2 in drinking water during a human gestational equivalent period (gestational day 0-postnatal day 10 [GD0-PND10]). Hallmark indicators of metabolic disruption, hepatic steatosis, and metabolic syndrome were evaluated prior to birth through adulthood. Maternal blood Cd levels were similar to those observed in human pregnancy cohorts, and Cd was undetected in adult offspring. There were no observed impacts of exposure on dams or pregnancy-related outcomes. Results of glucose and insulin tolerance testing revealed that Cd exposure impaired offspring glucose homeostasis on PND42. Exposure-related increases in circulating triglycerides and hepatic steatosis were apparent only in females. By PND120, Cd-exposed females were 30% heavier with 700% more perigonadal fat than unexposed control females. There was no evidence of dyslipidemia, steatosis, increased weight gain, nor increased adiposity in Cd-exposed male offspring. Hepatic transcriptome analysis on PND1, PND21, and PND42 revealed evidence for female-specific increases in oxidative stress and mitochondrial dysfunction with significant early disruption of retinoic acid signaling and altered insulin receptor signaling consistent with hepatic insulin sensitivity in adult females. The observed steatosis and metabolic syndrome-like phenotypes resulting from exposure to 500 ppb CdCl2 during the pre- and perinatal period of development equivalent to human gestation indicate that Cd acts developmentally as a sex-specific delayed obesogen.

Co-exposures of TiO2 nanoparticles and cadmium ions at non-lethal doses aggravates liver injury in mice with ConA-induced hepatitis

The wide applications of titanium dioxide nanoparticles (TNP) and ubiquitous cadmium (Cd) pollution increase the chances of their co-existence in the environment and also pose potential health risks to humans. However, toxicological understanding of effects of co-exposures of TNP and Cd to mammals is still lacking. In this study, non-lethal doses of TNP and CdCl2 were intravenously co-administered to healthy or Concanavalin A (ConA)-induced acute hepatitis mice. Co-exposures of TNP and CdCl2 increased the accumulation of Cd2+ in the liver of hepatitis mice, which was 1.42-fold higher than that of healthy mice. Co-exposures also caused liver damage only in hepatitis mice on the basis of histopathological and biochemical evidence. Further study showed that co-exposure upregulated hepatic oxidative stress, which further induced autophagy and apoptosis only in the liver of hepatitis mice. This finding underlines the potential toxicological consequences of co-exposures of TNP and CdCl2 in hepatitis sufferers.

Role of dietary curcumin against waterborne lead toxicity in common carp Cyprinus carpio

Curcumin exhibited numerous key activities including antioxidant, anti-inflammatory, and immunostimulatory effects in fish. This study evaluated the protective effects of curcumin (CUR) against lead (Pb)-induced toxicities in fish. Healthy Cyprinus carpio L. individuals were segregated into control, Pb only, Pb+CUR, and CUR only groups. Pb groups were exposed to 1 mg L ^-1 of Pb, and CUR groups were fed a basal diet supplemented with 15 g kg^-1 of CUR. After eight weeks, growth performance, Pb accumulation in tissues, various haemato-biochemical parameters, immune responses, and cytokine gene expression were measured. Dietary CUR effectively decreased Pb accumulation in tissues and increased the survival of Pb-exposed fish. Co-treatment with Pb and CUR reversed alterations in haemato-biochemical parameters, ameliorated Pb-induced oxidative stress, enhanced immune responses, and restored intestinal enzymatic activities. Dietary CUR reversed changes in intestinal microbiota in Pb-exposed fish. Pb-induced upregulation of NF-κBp65 and HSP70 was inhibited by dietary CUR. CUR supplementation upregulated the mRNA levels of SOD, Nrf2, IL-10, and CYP450 1A and attenuated Pb-induced degradation of I κB-α mRNA levels. Overall, CUR antagonizes Pb-induced negative impacts in fish. Thus, dietary CUR had several beneficial effects on immune responses, decreased Pb accumulation in tissues, and reversed Pb-induced oxidative stress in fish. Therefore, CUR plays a protective role in Pb-induced immune toxicity in fish, and, as such, may be suitable as an aqua feed additive for use in carp aquaculture.

Physiological and Molecular Alterations of Phycobionts of Genus Trebouxia and Coccomyxa Exposed to Cadmium

Several studies on aeroterrestrial microalgae are unravelling their resistance mechanisms to different abiotic stressors, including hazardous metals, pointing to their future role as bioremediation microorganisms. In the present study, physiological and molecular alterations of four phycobionts of genus Trebouxia (T. TR1 and T. TR9) and Coccomyxa (C. subellipsoidea and C. simplex) exposed to Cd were studied. Cd accumulation and subcellular distribution, cell wall structure, production of biothiols (GSH and phytochelatins), reactive oxygen species (ROS) formation, expression of key antioxidant genes and ROS-related enzymes were evaluated to determine the physiological differences among the four microalgae, with the aim to identify the most suitable microorganism for further biotechnological applications. After 7 days of Cd exposure, Coccomyxa algae showed higher capacity of Cd intake than Trebouxia species, with C. subellipsoidea being the highest Cd accumulator at both intracellular and, especially, cell wall level. Cd induced ROS formation in the four microalgae, but to a greater extent in both Coccomyxa algae. Trebouxia TR9 showed the lowest Cd-dependent oxidative stress probably due to glutathione reductase induction. All microalgae synthetized phytochelatins in response to Cd but in a species-specific and a dose-dependent manner. Results from this study agree with the notion that each microalga has evolved a distinct strategy to detoxify hazardous metals like Cd and to cope with oxidative stress associated with them. Coccomyxa subellipsoidea and Trebouxia TR9 appear as the most interesting candidates for further applications.

Role of hepcidin in oxidative stress and cell death of cultured mouse renal collecting duct cells: protection against iron and sensitization to cadmium

The liver hormone hepcidin regulates systemic iron homeostasis. Hepcidin is also expressed by the kidney, but exclusively in distal nephron segments. Several studies suggest hepcidin protects against kidney damage involving Fe2+ overload. The nephrotoxic non-essential metal ion Cd2+ can displace Fe2+ from cellular biomolecules, causing oxidative stress and cell death. The role of hepcidin in Fe2+ and Cd2+ toxicity was assessed in mouse renal cortical [mCCD(cl.1)] and inner medullary [mIMCD3] collecting duct cell lines. Cells were exposed to equipotent Cd2+ (0.5-5 μmol/l) and/or Fe2+ (50-100 μmol/l) for 4-24 h. Hepcidin (Hamp1) was transiently silenced by RNAi or overexpressed by plasmid transfection. Hepcidin or catalase expression were evaluated by RT-PCR, qPCR, immunoblotting or immunofluorescence microscopy, and cell fate by MTT, apoptosis and necrosis assays. Reactive oxygen species (ROS) were detected using CellROX™ Green and catalase activity by fluorometry. Hepcidin upregulation protected against Fe2+-induced mIMCD3 cell death by increasing catalase activity and reducing ROS, but exacerbated Cd2+-induced catalase dysfunction, increasing ROS and cell death. Opposite effects were observed with Hamp1 siRNA. Similar to Hamp1 silencing, increased intracellular Fe2+ prevented Cd2+ damage, ROS formation and catalase disruption whereas chelation of intracellular Fe2+ with desferrioxamine augmented Cd2+ damage, corresponding to hepcidin upregulation. Comparable effects were observed in mCCD(cl.1) cells, indicating equivalent functions of renal hepcidin in different collecting duct segments. In conclusion, hepcidin likely binds Fe2+, but not Cd2+. Because Fe2+ and Cd2+ compete for functional binding sites in proteins, hepcidin affects their free metal ion pools and differentially impacts downstream processes and cell fate.

Construction of Mode of Action for Cadmium-Induced Renal Tubular Dysfunction Based on a Toxicity Pathway-Oriented Approach

Although it is recognized that cadmium (Cd) causes renal tubular dysfunction, the mechanism of Cd-induced nephrotoxicity is not yet fully understood. Mode of action (MOA) is a developing tool for chemical risk assessment. To establish the mechanistic MOA of Cd-induced renal tubular dysfunction, the Comparative Toxicogenomics Database (CTD) was used to obtain genomics data of Cd-induced nephrotoxicity, and Ingenuity^® Pathway Analysis (IPA) software was applied for bioinformatics analysis. Based on the perturbed toxicity pathways during the process of Cd-induced nephrotoxicity, we established the MOA of Cd-induced renal tubular dysfunction and assessed its confidence with the tailored Bradford Hill criteria. Bioinformatics analysis showed that oxidative stress, DNA damage, cell cycle arrest, and cell death were the probable key events (KEs). Assessment of the overall MOA of Cd-induced renal tubular dysfunction indicated a moderate confidence, and there are still some evidence gaps to be filled by rational experimental designs.

Cadmium promotes glycolysis upregulation and glutamine dependency in human neuronal cells

Cadmium is a widespread pollutant, which easily accumulates inside the human body with an estimated half-life of 25-30 years. Many data strongly suggest that it may play a role in the pathogenesis of neurodegenerative diseases. In this paper we investigated cadmium effect on human SH-SY5Y neuroblastoma cells metabolism. Results showed that, although SH-SY5Y cells already showed hyperactivated glycolysis, cadmium further increased basal glycolytic rate. Both glycolytic capacity and reserve were also increased following cadmium administration, endowing the cells with a higher compensatory glycolysis when oxidative phosphorylation was inhibited. Cadmium administration also led to an increase in glycolytic ATP production rate, paralleled by a decrease in ATP production by oxidative phosphorylation, due to an impairment of mitochondrial respiration. Moreover, following cadmium administration, mitochondria increased their dependency on glutamine, while decreasing lipids oxidation. On the whole, our data show that cadmium exacerbates the Warburg effect and promotes the use of glutamine as a substrate for lipid biosynthesis. Although increased glutamine consumption leads to an increase in glutathione level, this cannot efficiently counteract cadmium-induced oxidative stress, leading to membrane lipid peroxidation. Oxidative stress represents a serious threat for neuronal cells and our data confirm glutathione as a key defense mechanism.

Aptamer-Modified Cu2+-Functionalized C-Dots: Versatile Means to Improve Nanozyme Activities-"Aptananozymes"

The covalent linkage of aptamer binding sites to nanoparticle nanozymes is introduced as a versatile method to improve the catalytic activity of nanozymes by concentrating the reaction substrates at the catalytic nanozyme core, thereby emulating the binding and catalytic active-site functions of native enzymes. The concept is exemplified with the synthesis of Cu²⁺ ion-functionalized carbon dots (C-dots), modified with the dopamine binding aptamer (DBA) or the tyrosinamide binding aptamer (TBA), for the catalyzed oxidation of dopamine to aminochrome by H₂O₂ or the oxygenation of l-tyrosinamide to the catechol product, which is subsequently oxidized to amidodopachrome, in the presence of H₂O₂/ascorbate mixture. Sets of structurally functionalized DBA-modified Cu²⁺ ion-functionalized C-dots or sets of structurally functionalized TBA-modified Cu²⁺ ion-functionalized C-dots are introduced as nanozymes of superior catalytic activities (aptananozymes) toward the oxidation of dopamine or the oxygenation of l-tyrosinamide, respectively. The aptananozymes reveal enhanced catalytic activities as compared to the separated catalyst and respective aptamer constituents. The catalytic functions of the aptananozymes are controlled by the structure of the aptamer units linked to the Cu²⁺ ion-functionalized C-dots. In addition, the aptananozyme shows chiroselective catalytic functions demonstrated by the chiroselective-catalyzed oxidation of l/d-DOPA to l/d-dopachrome. Binding studies of the substrates to the different aptananozymes and mechanistic studies associated with the catalytic transformations are discussed.

Long-Term Lime and Phosphogypsum Amended-Soils Alleviates the Field Drought Effects on Carbon and Antioxidative Metabolism of Maize by Improving Soil Fertility and Root Growth

Long-term surface application of lime (L) and/or phosphogypsum (PG) in no-till (NT) systems can improve plant growth and physiological and biochemical processes. Although numerous studies have examined the effects of L on biomass and plant growth, comprehensive evaluations of the effects of this practice on net CO2 assimilation, antioxidant enzyme activities and sucrose synthesis are lacking. Accordingly, this study examined the effects of long-term surface applications of L and PG on soil fertility and the resulting impacts on root growth, plant nutrition, photosynthesis, carbon and antioxidant metabolism, and grain yield (GY) of maize established in a dry winter region. At the study site, the last soil amendment occurred in 2016, with the following four treatments: control (no soil amendments), L (13 Mg ha-1), PG (10 Mg ha-1), and L and PG combined (LPG). The long-term effects of surface liming included reduced soil acidity and increased the availability of P, Ca2+, and Mg2+ throughout the soil profile. Combining L with PG strengthened these effects and also increased SO4 2--S. Amendment with LPG increased root development at greater depths and improved maize plant nutrition. These combined effects increased the concentrations of photosynthetic pigments and gas exchange even under low water availability. Furthermore, the activities of Rubisco, sucrose synthase and antioxidative enzymes were improved, thereby reducing oxidative stress. These improvements in the physiological performance of maize plants led to higher GY. Overall, the findings support combining soil amendments as an important strategy to increase soil fertility and ensure crop yield in regions where periods of drought occur during the cultivation cycle.

Metallomic profile in non-cirrhotic hepatocellular carcinoma supports a phenomenon of metal metabolism adaptation in tumor cells

We have previously described a form of hepatocellular carcinoma (HCC) in non-cirrhotic liver (HCC-NC) developed by Peruvian patients. We analyzed the metallomic profile in hepatic tissues from two independent cohorts exhibiting HCC-NC. Clinical, histopathological data, and HCC and non-tumoral liver (NTL) samples of 38 Peruvian and 38 French HCC-NC patients, were studied. Twelve metals were quantified using ICP/MS: Mn, Fe, Cu, Co, Zn, As, Se, Rb, Mo, Cd, Pb, and Sn. Associations between metals and survival were assessed. Our data showed significant differences between cohorts. Mean ages were 40.6 ± 20, 67.5 ± 9 years old for Peruvians and French, respectively. Fifty percent of the Peruvian patients were positive for the HBsAg, versus 3% in French patients. Mn, Cu, Zn, As, Se, Rb, Mo, Cd, Sn metal concentrations were higher in NTL of Peruvians. Importantly, metal concentrations were lower in HCC areas compared to NTL tissues in both cohorts, except for Cu for which mean concentration was higher in HCC (p < 0.05). Se concentration in HCC was associated with extended survival only in Peruvians. Our data, obtained in Peruvian and French HCC-NC cohorts, highlights similarity in the metallomic profile of HCC compared to NTL during the hepatic tumorigenesis in these specific groups of patients.

Quercetin alleviates cadmium chloride-induced renal damage in rats by suppressing endoplasmic reticulum stress through SIRT1-dependent deacetylation of Xbp-1s and eIF2α

Endoplasmic reticulum (ER) stress plays a key role in cadmium chloride (CdCl2)-induced nephrotoxicity. Sirtuin-1 (SIRT1) is a potent inhibitor of ER stress. In this study, we examined whether the protective effect of quercetin (QUR) against CdCl₂-induced nephrotoxicity in rats involved modulation of SIRT1 and/or ER stress. Adult male rats were divided into five groups (n = 8, each) and treated for eight weeks as follows: control, control + QUR, CdCl₂, CdCl₂ + QUR, and CdCl₂ + QUR + EX-527 (a SIRT1 inhibitor). Treatment of rats with QUR preserved the glomerulus and tubule structure, attenuated interstitial fibrosis, increased creatinine excretion, and reduced urinary levels of albumin, N-acetyl-β-D-glucosaminidase, and β2-microglobulin in CdCl₂-treated rats. Concomitantly, QUR increased renal levels of Bcl-2, reduced mRNA levels of CHOP, and protein levels of Bax, caspase-3, and cleaved caspase-3, but failed to reduce the mRNA levels of GRP78, PERK, eIf2α, ATF-6, and xbp-1. QUR also reduced the renal levels of reactive oxygen species, tumour necrosis factor, and interleukin-6 and the nuclear activity of NF-κB in the control and CdCl₂-treated rats but increased the nuclear activity of Nrf2 and levels of glutathione and manganese superoxide dismutase. Additionally, QUR increased the total levels and nuclear activity of SIRT1 and reduced the acetylation of eIf2α and xbp-1. The nephroprotective effects of QUR were abrogated by treatment with EX-527. Thus, QUR ameliorated CdCl₂-induced nephrotoxicity through antioxidant and anti-inflammatory effects and suppressed ER stress mediated by the upregulation or activation of SIRT1-induced deacetylation of Nrf2, NF-κB p65, eIF2α, and xbp-1.

Characterisation of Neurospheres-Derived Cells from Human Olfactory Epithelium

A major problem in psychiatric research is a deficit of relevant cell material of neuronal origin, especially in large quantities from living individuals. One of the promising options is cells from the olfactory neuroepithelium, which contains neuronal progenitors that ensure the regeneration of olfactory receptors. These cells are easy to obtain with nasal biopsies and it is possible to grow and cultivate them in vitro. In this work, we used RNAseq expression profiling and immunofluorescence microscopy to characterise neurospheres-derived cells (NDC), that simply and reliably grow from neurospheres (NS) obtained from nasal biopsies. We utilized differential expression analysis to explore the molecular changes that occur during transition from NS to NDC. We found that processes associated with neuronal and vascular cells are downregulated in NDC. A comparison with public transcriptomes revealed a depletion of neuronal and glial components in NDC. We also discovered that NDC have several metabolic features specific to neuronal progenitors treated with the fungicide maneb. Thus, while NDC retain some neuronal/glial identity, additional protocol alterations are needed to use NDC for mass sample collection in psychiatric research.

Involvement of different hemoprotein thiol groups of Oncorhynchus mykiss in cadmium toxicity

BACKGROUND

Cadmium is considered the seventh most toxic heavy metal as per ATSDR ranking but its mechanism of toxicity is debated. Recently, we evaluated the effects of this metal on the erythrocyte of teleost fish (Oncorhynchus mykiss) leading us to hypothesize that the pro-oxidant activity of cadmium is not linked to mitochondria but more likely to haemoglobin. In this context, the main aim of this work was to detect the ability of Cd to induce structural perturbation in haemoproteins that present different structures and thus different functional properties and to identify what sites of interaction are mainly involved.

METHODS

The effect of Cd on the structural destabilization of the different haemoproteins was followed spectrophometrically through their precipitation. In addition, the sites of interaction between the different haemoproteins and bivalent cadmium ions were identified by MIB server followed by molecular docking/molecular dynamics simulations both in the dimeric and tetrameric associations.

RESULTS

Cadmium does not influence the autoxidation rate of Mb, HbA and trout HbI. However, the presence of this metal accelerates the precipitation process in trout HbIV in a dose-dependent manner. Moreover, the presence of 1-10-50-250-500-1000 μM GSH, a chelating agent, reduces the ability of cadmium to accelerate the denaturation process although it is not able to completely prevent it. In order to explain the experimental results, a computational investigations was carried out to identify the cadmium cation affinity for the studied haemoglobins and myoglobin, both in their dimeric and tetrameric forms. As a result, the highest affinity cadmium binding sites for fish HbIV are located at the interface between tetramer-tetramer association, indicating that the cation can assist supramolecular protein aggregations and induce complex precipitation. For mammalian Hb, Mb and fish HbI computational investigation did not detect any site where Cd could to induce such aggregation, in line with the experimental results.

CONCLUSION

The present study provides new information on the mechanisms of toxicity of cadmium by specific interaction with trout O. mykiss haemoglobin component.

Calcium and ethylene glycol tetraacetic acid mitigate toxicity and alteration of gene expression associated with cadmium stress in chickpea (Cicer arietinum L.) shoots

In the aim to estimate the protective role of calcium (Ca) and ethylene glycol tetraacetic acid (EGTA) against cadmium (Cd)-induced damage, chickpea (Cicer arietinum L.) seeds were exposed to 200 μM Cd stress for 6 days or 3 days then subjected to co-treatment of the metal with either 100 mM CaCl₂ or 100 μM EGTA for 3 additional days. The addition of Ca and EGTA improved seedling growth. This protecting effect was correlated to the alleviation of the metal-induced oxidative stress, exemplified by the reduction of hydrogen peroxide (H₂O₂) contents. Besides, Ca and EGTA stimulated thioredoxin (Trx) and thioredoxin reductase (NTR) activities (2.75- and 1.75-fold increase when compared to Cd-stressed, respectively) protecting, thereby, protein -SH groups from the Cd-mediated oxidation, and modulated ferredoxin (Fdx) activity to a control level. Moreover, Ca and EGTA reinstated the glutathione redox steady state, mainly via preserving a high level of glutathione reduced form (GSH). This effect coincided with the maintaining of the Cd-stimulated glutathione reductase (GR) activity and the decline of glutathione peroxidase (GPX, 43% lower than Cd-stressed shoots) activity. Ca and EGTA counteracted the inhibitory effect of Cd on the activity and gene expression of Cu/Zn-superoxide dismutase (Cu/Zn-SOD) isoenzyme and modulated the activities of catalase (CAT) and ascorbate peroxidase (APX). Overall, our results provided evidence that Ca and EGTA supplement could be a promising approach in the remediation of Cd-contaminated environment.

Protective effect of eugenol on hepatic inflammation and oxidative stress induced by cadmium in male rats

BACKGROUND

Cadmium is one of the most toxic heavy metals. The prolonged exposure of it can lead to severe alterations and damage in different tissues including blood, liver, kidney and brain. Eugenol, a phenolic compound, is present in various aromatic plants. It acts as a natural antioxidant and anti-inflammatory agent. The aim of this study was to investigate whether the treatment of eugenol is beneficial against the hepatic oxidative stress and inflammation induced by Cd.

METHODS

To study the effect of eugenol in reversal of Cd toxicity, 24 albino rats were equally divided into four different groups: G1 Control (saline), G2 Eugenol (3 mg kg-1), G3 CdCl2 (5 mg kg-1) and G4 CdCl2 + Eugenol (5 mg kg-1 + 3 mg kg-1). All the groups were treated with gavage orally for the period of 21 days. After this treatment period, rats were sacrificed and liver tissues were removed. The hepatic antioxidant status was evaluated by measuring the activities of SOD, Catalase and GST enzymes. The reduced glutathione, lipid peroxidation, protein carbonyl oxidation (PCO) and thiol contents were measured in hepatic tissues. The activities of liver marker enzymes such as ALT, AST, GGT, ALP, TP, albumin, Bilirubin content and LDH were determined to assess the hepatic damage in different groups. Cd induced hepatic inflammation was determined by evaluating the levels of TNF-a, IL-6 and NO.

RESULTS

Oral intoxication of Cd for 21 days significantly elevated the level of hepatic markers including activities of LDH, GGT, ALP, ALT, AST and Bilirubin level. The albumin content, reduced GSH level, and activities of antioxidant enzymes were significantly reduced in Cd treated group. The levels of inflammatory markers were significantly elevated in Cd treated group. The eugenol treatment was very effective and it significantly reversed the Cd induced biochemical alterations almost similar to that of control.

CONCLUSION

The results demonstrated that the eugenol possessed very strong anti-oxidative and anti-inflammatory potential. The co-treatment of eugenol with Cd exhibited protective potential of eugenol against Cd induced toxicity. Eugenol was able to improve the cellular redox system in rats treated with Cd.

Effects of cadmium alone and in combination with pH on bioaccumulation, tissue structure, and enzyme activity of the Chinese mitten crab, Eriocheir sinensis

In this study, Chinese mitten crabs (Eriocheir sinensis) were exposed to various combinations of reduced pH (7.8, 7.3, and 6.5) and cadmium (Cd; 0 and 1 mg·L^-1) for 7, 14, and 21 days. The reduced pH and 1 mg·L^-1 Cd treatment significantly decreased the Cd concentration in crab tissues in the order of pH 7.8 > pH 7.3 > pH 6.5. The exposure to Cd resulted in edema, tubular vacuolization in epithelial cells, and hepatic duct degeneration in the hepatopancreas and indistinct cellular structure and disconnected epithelial layer in the gills. However, low pH alleviated the toxic effects of Cd on the tissues. In gill and hepatopancreas tissues, low pH and Cd exposure caused a significant increase in superoxide dismutase and catalase activities and oxidized glutathione content, but metallothionein activity was not affected. In contrast, the activity of glutathione-S-transferase decreased. Thus, indirect effects of pH on metal accumulation and antagonistic toxicities were observed in E. sinensis, and reduced pH and Cd exposure modulated the oxidative balance via different mechanisms.

Environmental pollution and diabetes mellitus

Diabetes mellitus (DM) is a chromic metabolic disease that affects a large segment of the population worldwide. Physical inactivity, poor nutrition, and genetic predisposition are main risk factors for disease development. In the last decade, it was clear to the scientific community that DM development is linked to a novel disease inducer that was later defined as diabetogenic factors of pollution and endocrine disrupting agents. Environmental pollution is exponentially increasing in uncontrolled manner in several countries. Environmental pollutants are of diverse nature and toxicities, including polyaromatic hydrocarbons (PAHs), pesticides, and heavy metals. In the current review, we shed light on the impact of each class of these pollutants and the underlined molecular mechanism of diabetes induction and biological toxicities. Finally, a brief overview about the connection between coronavirus disease 2019 and diabetes pandemics is presented.

N-acetylcysteine restores the cadmium toxicity of Caenorhabditis elegans

Cadmium is a well-known environmental toxicant. At the cellular level, exposure to cadmium results in cytotoxic effects through the elevation of reactive oxygen species (ROS) production. Although cadmium exposure leads to the dysfunction of various organs, the underlying mechanisms of the toxic effects of cadmium in vivo are still largely unknown. Caenorhabditis elegans (C. elegans) is a useful model animal and exhibits unique biological reactions in response to environmental toxicants. In this study, the toxic mechanisms of cadmium exposure in C. elegans were investigated using N-acetylcysteine (NAC), which has dual functions, i.e., as a chelator of metals and as an antioxidant. NAC did not inhibit the uptake of cadmium into nematodes, suggesting that NAC did not function as a chelator of cadmium under these experimental conditions. Based on this finding, we investigated the effect of NAC as an antioxidant on representative phenotypic traits caused by cadmium exposure-reduced body length, aversion behavior, and shortened lifespan. NAC did not reverse the decreased body size but did clearly restore the aversion behavior and the shortened lifespan. These data suggest that aversion behavior and shortened lifespan are mediated by oxidative stress in C. elegans.

Research on the Mechanisms of Plant Enrichment and Detoxification of Cadmium

The heavy metal cadmium (Cd), as one of the major environmentally toxic pollutants, has serious impacts on the growth, development, and physiological functions of plants and animals, leading to deterioration of environmental quality and threats to human health. Research on how plants absorb and transport Cd, as well as its enrichment and detoxification mechanisms, is of great significance to the development of phytoremediation technologies for ecological and environmental management. This article summarises the research progress on the enrichment of heavy metal cadmium in plants in recent years, including the uptake, transport, and accumulation of Cd in plants. The role of plant roots, compartmentalisation, chelation, antioxidation, stress, and osmotic adjustment in the process of plant Cd enrichment are discussed. Finally, problems are proposed to provide a more comprehensive theoretical basis for the further application of phytoremediation technology in the field of heavy metal pollution.

Reproductive toxicity of cadmium in pubertal male rats induced by cell apoptosis

Cadmium (Cd) is a heavy metal that is widely present in modern industrial production. It is a known, highly toxic environmental endocrine disruptor. Long-term exposure to Cd can cause varying degrees of damage to the liver, kidney, and reproductive system of organisms, especially the male reproductive system. This study aimed to explore the mechanism of Cd toxicity in the male reproductive system during puberty. Eighteen healthy 6-week-old male Sprague-Dawley rats were randomly divided into three groups (control group, low-dose group, and high-dose group) according to their body weight, with six in each group. Cd (0, 1, and 3 mg/kg/day) was given by gavage for 28 consecutive days. The results showed that Cd exposure to each dose group caused a decrease in the testicular organ coefficient and sperm count, compared with the control group. Cd exposure resulted in significant changes in testicular morphology in the 3 mg/kg/day Cd group. In the 1 and 3 mg/kg/day Cd groups, serum testosterone decreased and apoptosis of testicular cells increased significantly (p < 0.05). In addition, compared with the control group, the activity of glutathione peroxidase and superoxide dismutase in each Cd exposure dose group decreased, but the content of malondialdehyde in the high-dose, 3 mg/kg/day Cd treatment group significantly increased (p < 0.05). Although Cd exposure caused an increase in the messenger RNA (mRNA) levels of Bcl-2, Caspase-3 and Caspase-9 in the testicular tissues (p < 0.05), Bcl-2 expression was unchanged (p > 0.05). The expression level of Akt mRNA in testicular tissue of rats in the high-dose 3 mg/kg/day Cd group was increased (p < 0.05). Our data suggest that Cd affected testosterone levels, and apoptosis was observed in spermatids.

The protective effect of nnano-selenium against cadmium-induced cerebellar injury via the heat shock protein pathway in chicken

Cadmium (Cd) is one of the toxic environmental heavy metals that poses health hazard to animals due to its toxicity. Nano-Selenium (Nano-Se) is a Nano-composite form of Se, which has emerged as a promising therapeutic agent for its protective roles against heavy metals-induced toxicity. Heat shock proteins (HSPs) play a critical role in cellular homeostasis. However, the potential protective effects of Nano-Se against Cd-induced cerebellar toxicity remain to be illustrated. To investigate the toxic effects of Cd on chicken's cerebellum, and the protective effects of Nano-Se against Cd-induced cerebellar toxicity, a total of 80 male chicks were divided into four groups and treated as follows: (A) 0 mg/kg Cd, (B) 1 mg/kg Nano-Se (C) 140 mg/kg Cd + 1 mg/kg Nano-Se (D) 140 mg/kg Cd for 90 days. We tested heat shock protein pathway-related factors including heat shock factors (HSFs) HSF1, HSF2, HSF3 and heat shock proteins (HSPs) HSP10, HSP25, HSP27, HSP40, HSP60, HSP70 and HSP90 expressions. Histopathological results showed that Cd treatment caused degradation of Purkinje cells. In addition, HSFs and HSPs expression decreased significantly in the Cd group. Nano-Se co-treatment with Cd enhanced the expression of HSFs and HSPs. In summary, our findings explicated a potential protective effect of Nano-Se against Cd-induced cerebellar injury in chicken, suggesting that Nano-Se is a promising therapeutic agent for the treatment of Cd toxicity.

Biomarkers of effect as determined in human biomonitoring studies on hexavalent chromium and cadmium in the period 2008-2020

A number of human biomonitoring (HBM) studies have presented data on exposure to hexavalent chromium [Cr(VI)] and cadmium (Cd), but comparatively few include results on effect biomarkers. The latter are needed to identify associations between exposure and adverse outcomes (AOs) in order to assess public health implications. To support improved derivation of EU regulation and policy making, it is of great importance to identify the most reliable effect biomarkers for these heavy metals that can be used in HBM studies. In the framework of the Human Biomonitoring for Europe (HBM4EU) initiative, our study aim was to identify effect biomarkers linking Cr(VI) and Cd exposure to selected AOs including cancer, immunotoxicity, oxidative stress, and omics/epigenetics. A comprehensive PubMed search identified recent HBM studies, in which effect biomarkers were examined. Validity and applicability of the markers in HBM studies are discussed. The most frequently analysed effect biomarkers regarding Cr(VI) exposure and its association with cancer were those indicating oxidative stress (e.g., 8-hydroxy-2'-deoxyguanosine (8-OHdG), malondialdehyde (MDA), glutathione (GSH)) and DNA or chromosomal damage (comet and micronucleus assays). With respect to Cd and to some extent Cr, β-2-microglobulin (B2-MG) and N-acetyl-β-D-glucosaminidase (NAG) are well-established, sensitive, and the most common effect biomarkers to relate Cd or Cr exposure to renal tubular dysfunction. Neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule (KIM)-1 could serve as sensitive biomarkers of acute kidney injury in response to both metals, but need further investigation in HBM studies. Omics-based biomarkers, i.e., changes in the (epi-)genome, transcriptome, proteome, and metabolome associated with Cr and/or Cd exposure, are promising effect biomarkers, but more HBM data are needed to confirm their significance. The combination of established effect markers and omics biomarkers may represent the strongest approach, especially if based on knowledge of mechanistic principles. To this aim, also mechanistic data were collected to provide guidance on the use of more sensitive and specific effect biomarkers. This also led to the identification of knowledge gaps relevant to the direction of future research.

Low-level exposure to lead, mercury, arsenic, and cadmium, and blood pressure among 8-17-year-old participants of the 2009-2016 National Health and Nutrition Examination Survey

BACKGROUND

Dysregulation of systolic, diastolic blood pressure (SBP, DBP), and pulse pressure (PP) in children may predict elevated blood pressure (BP) in adulthood. Toxicant exposure is widely studied as a risk factor for high BP in adults, but not in children. We assessed the joint associations between lead (Pb), mercury (Hg), arsenic (As), and cadmium (Cd) exposure and SBP, DBP, and PP among 8-17 year-old participants (n = 1642) of the 2009-2016 National Health and Nutrition Examination Survey (NHANES).

METHODS

Participants with at least two BP measures were included. Urinary As and Cd were adjusted for urinary creatinine concentrations. Blood Pb, Hg, and urinary As, Cd were natural log-transformed. Bayesian Kernel Machine Regression (BKMR) analyses were conducted to assess the associations between the toxicant mixture and BP measures. Multivariable regression models assessed the associations between individual toxicants, and the four toxicants simultaneously with each of the outcomes. Interactions with sodium intake were tested.

RESULTS

Exposure to all toxicants was low, with median (5%, 95%) level: Pb, 0.57 (0.26, 1.60) μg/dL; Hg, 0.37 (0.19, 2.12) μg/L; As, 5.61 (1.37, 33.2) μg/g creatinine, Cd, 0.06 (0.03, 0.23) μg/g creatinine. Toxicant mixture showed a statistically significant, inverse association with DBP, but not other BP measures. Linear regressions revealed no association between toxicants, individually or together, and BP measures. No evidence of interaction of sodium intake with any of the toxicants was observed.

CONCLUSIONS

In a nationally representative sample of 8-17 year-olds, we found suggestive inverse association of the mixture of low-level Pb, Hg, As, and Cd, with DBP. Longitudinal studies with multiple toxicants are needed to understand the interactive effects of toxicants on children's BP.

Efficient regulation of copper homeostasis underlies accession-specific sensitivities to excess copper and cadmium in roots of Arabidopsis thaliana

The commonly used Arabidopsis thaliana natural accessions Columbia (Col-0) and Wassilewskija (Ws) are known to differ in their metal sensitivity, with Col-0 being more sensitive to copper (Cu) and cadmium (Cd) than Ws. As both Cu and Cd are known to affect Cu homeostasis, it was investigated whether this process is part of an accession-specific mechanism underlying their difference in metal sensitivity. As roots are the first contact point during metal exposure, responses were compared between roots of both accessions of hydroponically grown plants exposed to excess Cu or Cd for 24 and 72 h. Root Cu levels increased in both accessions under Cu and Cd exposure. However, under Cu exposure, the downregulation of Cu transporter (COPT) genes in combination with a more pronounced upregulation of metallothionein gene MT2b indicated that Ws plants coped better with the elevated Cu concentrations. The Cd-induced disturbance in Cu homeostasis was more efficiently counteracted in roots of Ws plants than in Col-0 plants. This was indicated by a higher upregulation of the SPL7-mediated pathway, crucial in the regulation of the Cu homeostasis response. In conclusion, maintaining the Cu homeostasis response in roots is key to accession-specific differences in Cu and Cd sensitivity.

Modulatory effects of carvacrol against cadmium-induced hepatotoxicity and nephrotoxicity by molecular targeting regulation

AIM

Cadmium (Cd) is a toxic heavy metal that causes severe toxic effects on different tissues including liver and kidney. Therefore the research for alternatives to reduce the damage caused by Cd has substantial importance. This study was performed to examine the possible modulatory effects of carvacrol (CRV) against Cd-induced hepatorenal toxicities and the possible mechanisms underlying these effects.

MATERIALS AND METHODS

In the present study, 35 male Wistar rats were randomly divided into 5 groups. The rats were treated with Cd (25 mg/kg) and treated with CRV (25 and 50 mg/kg body weight) for 7 consecutive days.

KEY FINDINGS

CRV could modulate Cd-induced elevations of ALT, ALP, AST, urea, creatinine, MDA and enhance antioxidant enzymes' activities such as SOD, CAT, and GPx, and GSH's level. CRV also reversed the changes in levels of inflammatory biomarker and apoptotic genes that include NF-κB, Bcl-3, MAPK-14, iNOS, COX-2, MPO, PGE2, Bax, Bcl-2, P53, Caspase-9, Caspase-6 and Caspase-3 in both tissues. The levels of 8-OHdG in the Cd-induced liver and kidney tissues were modulated after CRV treatment. Furthermore, CRV treatment considerably lowered Cd, Na, Fe, and Zn content while increased K, Ca, Mg and Cu contents in both tissues as compared to the Cd-exposed rats.

SIGNIFICANCE

The results of the present study revealed that CRV supplementation could be a promising strategy to protect the liver and kidney tissues against Cd-induced oxidative damage, inflammation and apoptosis.

Effects of Moringa oleifera leaf extracts and its bioactive compound gallic acid on reducing toxicities of heavy metals and metalloid in Saccharomyces cerevisiae

Moringa oleifera leaf extract is rich in antioxidants and has high potential for use to alleviate metal toxicity. Previously, we have reported the roles of aqueous M. oleifera leaf extract in mitigating intracellular cadmium (Cd) accumulation and Cd-induced oxidative stress. In this study, we investigated the protective role of aqueous and/or ethanolic M. oleifera leaf extracts (AMOLE and/or EMOLE) against other metal(loid)s in the eukaryotic model Saccharomyces cerevisiae. Our results show that only the AMOLE remarkably promoted the growth of yeast cells grown in the presence of arsenite (As(III)), Cd, nickel (Ni), and lead (Pb). Although the AMOLE contained lower amount of total phenolic and flavonoid contents and displayed lower DPPH scavenging capacity than the EMOLE, both AMOLE and EMOLE had the same capacity for reducing intracellular ROS levels in yeast cells exposed to As(III), Cd, Ni, and Pb. Moreover, the AMOLE was more effective than the EMOLE in inhibiting intracellular accumulation of these toxic metal(loid)s. In addition, we found that gallic acid, one of important phenolic constituents present in both extracts, could protect yeast cells against As(III) toxicity, likely through its role in decreasing As(III) accumulation and As(III)-induced ROS production. Furthermore, the hydroxyl and carboxyl groups of gallic acid appear to play a critical role in chelating As(III). The present study suggests the promising applications of the AMOLE (and also gallic acid) as protective agents against hazardous metal(loid)s.

Intestinal response characteristic and potential microbial dysbiosis in digestive tract of Bufo gargarizans after exposure to cadmium and lead, alone or combined

The gastrointestinal tract is the largest immune organ in the body and meanwhile, accommodates a large number of microorganisms. Heavy metals could disturb the intestinal homeostasis and change the gut microbial composition. However, the information regarding the links between dysbiosis of gut microbiota and imbalance of host intestinal homeostasis induced by the mixture of heavy metals is insufficient. The present study investigates the effects of Cd/Pb, both single and combination exposure, on the growth performance, intestinal histology, digestive enzymes activity, oxidative stress and immune parameters, and intestinal microbiota in Bufo gargarizans tadpoles. Our results revealed that co-exposure of Cd-Pb induced more severe impacts not only on the host, but the intestinal microbiota. On the one hand, co-exposure of Cd-Pb significantly induced growth retardation, intestinal histological injury, decreased activities of digestive enzymes. On the other hand, Cd and Pb exposure, especially in mixed form, changed the diversity and richness, structure of microbiota. Also, the intestinal microbial composition was altered by Cd/Pb exposure (alone and combination) both at the different levels. Proteobacteria, act as front-line responder, was significantly increased in tadpoles under the exposure of metals. Finally, the functional prediction revealed that the disorders of metabolism and immune responses of intestinal microbiota was increased in tadpoles exposed to Cd/Pb (especially the mixture of Cd and Pb). Our research complements the understanding of links between changes in host fitness loss and intestinal microbiota and will add a new dimension of knowledge to the ecological risks of mixed heavy metals in amphibian.

Cadmium-induced toxicity to amphibian tadpoles might be exacerbated by alkaline not acidic pH level

Heavy metal pollution in natural water bodies generally interacting with other environmental stressors produces toxic effects on aquatic organisms. However, toxicological studies exploring interactive effects of these stressors are still limited. Here, tadpoles of the Zhenhai brown frog (Rana zhenhaiensis) were exposed to a 3 × 3 factorial combination, with three cadmium (Cd) concentrations (0, 10 and 100 μg/L) and three pH levels (5.0, 7.23 and 9.0) throughout the developmental period to assess combined toxic effects of Cd × pH on tadpole growth, development and physiology. Nearly all measured traits [including survival, metamorphosis and abnormality rate, metamorphosis time, post-metamorphic size, hepatic metal content, locomotor performance, antioxidant enzyme activity, and erythrocytic nuclear abnormality (ENA) frequency] were affected by Cd exposure, indicating notable Cd-induced toxicity to R. zhenhaiensis tadpoles. The pH level and its interaction with Cd also had significant impacts on most measured traits, such as survival rate, metamorphosis time, froglet jumping distance, hepatic Cd content, ENA frequency. Acidic (or alkaline) environment itself was toxic to tadpoles. However, high pH (but not low pH) level appeared to exacerbate Cd-induced toxicity to tadpoles. Excess free hydrogen ions under acidic environments might inhibit Cd2+ ions binding to cell surface, which reduced Cd accumulation in tissues. Under alkaline environments, other forms of Cd complexes in the aqueous phase probably contributed to promoting Cd accumulation. Our results indicated that Cd exposure could interact with different pH levels, producing diverse combined toxicities to amphibian larvae.

Macro and Trace Elements in Hemp (Cannabis sativa L.) Cultivated in Greece: Risk Assessment of Toxic Elements

The accumulation of hazardous contaminants in Cannabis sativa L. raises warning signs regarding possible adverse effects on human health due to the consumption of herbal medicines and/or other herbal edible products made from cannabis. Thus, there is an urge to investigate the levels of hazardous contaminants, such as heavy metals, in cannabis plant. In the present study, 29 macro and trace elements, including both beneficial and toxic elements (heavy metals and metalloids), were investigated in 90 samples of Cannabis sativa L. collected from Greece. According to the results, the detected concentrations of macro elements in the leaves/flowers of cannabis ranged between 28 and 138,378 ppm, and of trace elements between 0.002 and 1352.904 ppm. Although the concentrations of elements varied among the samples, their accumulation pattern was found to be similar, with the contribution of toxic elements to the total concentration of trace elements being below 1%. The detected levels of the most toxic elements were below the prescribed limits established by the WHO, while the calculated THQ and CR values showed no risk (non-carcinogenic and carcinogenic) for the population exposed to the current cannabis samples. Positive correlation between the concentration of elements and cannabis geographical origin and variety was observed. Cannabis leaves/flowers were more contaminated with trace and macro elements than seeds.

The global research trend on cadmium in freshwater: a bibliometric review

Cadmium pollution turns out to be a global environmental problem. This study conducted a quantitative and qualitative bibliometric analysis based on 9188 research items from the Web of Science Core Collection published in the last 20 years (2000-2020), presenting an in-depth statistical investigation of global freshwater cadmium research progress and developing trend. Our results demonstrated that the researchers from China, the USA, and India contribute the most to this field. The primary sources of cadmium are mining, industry, wastewater, sedimentation, and agricultural activities. In developing countries, cadmium exposure occurs mainly through the air, freshwater, and food. Fish and vegetables are the main food sources of cadmium for humans because of their high accumulation capability. Source evaluation, detection, and remediation represent the main technologies used to clean up cadmium-contaminated sites. To mitigate the risk of cadmium contamination in freshwater, biomarker-based cadmium monitoring methods and integrated policies/strategies to reduce cadmium exposure merit further concern.

Health Beneficial Properties of Grapevine Seed Extract and Its Influence on Selected Biochemical Markers in the Blood, Liver and Kidneys of Rattus norvegicus

Cadmium (Cd) is a heavy metal that occurs in all areas of the environment, including the food chain. In the body, it causes oxidative stress by producing free radicals that are harmful to the cells. Grape seed extract (GSE) contains a wide range of biologically active components that help to neutralize the adverse effects of free radicals. In this study, the effects of GSE prepared form semi-resistant grapevine cultivar Cerason, which is rich in phenolics, on biochemical markers of brown rats exposed to the effects of cadmium were monitored. GSE increased the plasma antioxidant activity and, in the kidneys and the liver, Cd content was significantly lowered by GSE co-administration. Accordingly, the increase in creatinine content and alanine aminotransferase activity and the decrease of catalase and superoxide dismutase activities caused by cadmium were slowed down by GSE co-administration. The results of this work reveal that grape seed extract offers a protective effect against the intake of heavy metals into the organism.

Cadmium-Tolerant and -Sensitive Cultivars Identified by Screening of Medicago truncatula Germplasm Display Contrasting Responses to Cadmium Stress

Cadmium (Cd) pollution in soils is an increasing problem worldwide, and it affects crop production and safety. We identified Cd-tolerant and -sensitive cultivars by testing 258 accessions of Medicago truncatula at seedling stage, using the relative root growth (RRG) as an indicator of Cd tolerance. The factorial analysis (principal component analysis method) of the different growth parameters analyzed revealed a clear differentiation between accessions depending on the trait (tolerant or sensitive). We obtained a normalized index of Cd tolerance, which further supported the suitability of RRG to assess Cd tolerance at seedling stage. Cd and elements contents were analyzed, but no correlations with the tolerance trait were found. The responses to Cd stress of two accessions which had similar growth in the absence of Cd, different sensitivity to the metal but similar Cd accumulation capacity, were analyzed during germination, seedling stage, and in mature plants. The results showed that the Cd-tolerant accession (CdT) displayed a higher tolerance than the sensitive cultivar (CdS) in all the studied stages. The increased gene expression of the three main NADPH recycling enzymes in CdT might be key for this tolerance. In CdS, Cd stress produced strong expression of most of the genes that encode enzymes involved in glutathione and phytochelatin biosynthesis (MtCYS, MtγECS, and MtGSHS), as well as GR, but it was not enough to avoid a redox status imbalance and oxidative damages. Our results on gene expression, enzyme activity, antioxidant content, and lipid peroxidation indicate different strategies to cope with Cd stress between CdS and CdT, and provide new insights on Cd tolerance and Cd toxicity mechanisms in M. truncatula.

Transcriptional and Catalytic Responsiveness of the Antarctic Fish Trematomus bernacchii Antioxidant System toward Multiple Stressors

Ocean-warming and acidification jeopardize Antarctic marine species, adapted to cold and constant conditions and naturally exposed to high pro-oxidant pressures and cadmium (Cd) bioavailability. The aim of this study was to investigate if projected temperature increase and pH reduction may affect the accumulation and the effects of Cd in the rockcod Trematomus bernacchii. Organisms were exposed for 14 days to six scenarios, combining environmental or increased temperature (−1 °C, +1 °C) and control or reduced pH (8.05, 7.60), either with or without Cd (40 µg/L). Responses in liver and gills were analyzed at different levels, including mRNA and functional measurements of metallothioneins and of a wide battery of antioxidants, integrated with the evaluation of the total antioxidant capacity and onset of oxidative damages. In the gills, metallothioneins and mRNA of antioxidant genes (nrf2, keap1, cat, gpx1) increased after Cd exposure, but such effects were softened by warming and acidification. Antioxidants showed slighter variations at the enzymatic level, while Cd caused glutathione increase under warming and acidified scenarios. In the liver, due to higher basal antioxidant protection, limited effects were observed. Genotoxic damage increased under the combined stressors scenario. Overall results highlighted the modulation of the oxidative stress response to Cd by multiple stressors, suggesting the vulnerability of T. bernacchii under predicted ocean change scenarios.