Protective effects of Selenium (Se) on Chromium (VI) induced nephrotoxicity in adult rats

Associations Between Individual and Combined Metal Exposures in Whole Blood and Kidney Function in U.S. Adults Aged 40 Years and Older

The effects of metal exposure on kidney function have been reported in previous literature. There is limited and inconsistent information on the associations between individual and combined exposures to metals and kidney function among the middle-aged and older population. The aim of this study was to clarify the associations of exposure to individual metals with kidney function while accounting for potential coexposure to metal mixtures and to evaluate the joint and interactive associations of blood metals with kidney function. A total of 1669 adults aged 40 years and older were enrolled in the present cross-sectional study using the 2015-2016 National Health and Nutrition Examination Survey (NHANES). Single-metal and multimetal multivariable logistic regression models, quantile G-computation, and Bayesian kernel machine regression models (BKMR) were fitted to explore the individual and joint associations of whole blood metals [lead (Pb), cadmium (Cd), mercury (Hg), cobalt (Co), manganese (Mn), and selenium (Se)] with the odds of decreased estimated glomerular filtration rate (eGFR) and albuminuria. A decreased eGFR was defined as an eGFR ≤ 60 mL/min per 1.73 m2, and albuminuria was categorized as a urinary albumin-creatinine ratio (UACR) of ≥ 30.0 mg/g. The results from quantile G-computation and BKMR indicated positive associations between exposure to the metal mixture and the prevalence of decreased eGFR and albuminuria (all P values < 0.05). These positive associations were mainly driven by blood Co, Cd, and Pb. Furthermore, blood Mn was identified as an influential element contributing to an inverse correlation with kidney dysfunction within metal mixtures. Increasing blood Se levels were negatively associated with the prevalence of decreased eGFR and positively associated with albuminuria. In addition, a potential pairwise interaction between Mn-Co on decreased eGFR was identified by BKMR analysis. Findings from our study suggested a positive association between exposure to the whole blood metal mixture and decreased kidney function, with blood Co, Pb, and Cd being the main contributors to this association, while Mn demonstrated an inverse relationship with renal dysfunction. However, as our study was cross-sectional in nature, further prospective studies are warranted to better understand the individual and combined effects of metals on kidney function.

Selenium Alleviates Ammonia-Induced Splenic Cell Apoptosis and Inflammation by Regulating the Interleukin Family/Death Receptor Axis and Nrf2 Signaling Pathway

Ammonia (NH₃) is a harmful gas in livestock houses. So far, many researchers have demonstrated that NH₃ is detrimental to animal and human organs. Selenium (Se) is one of the essential trace elements in the body and has a good antioxidant effect. However, there was little conclusive evidence that Se alleviated NH₃ poisoning. To investigate the toxic mechanism of NH₃ on pig spleen and the antagonistic effect of L-selenomethionine, a porcine NH₃-poisoning model and an L-selenomethionine intervention model were established in this study. Our results showed that NH₃ exposure increased the apoptosis rate, while L-selenomethionine supplementation alleviated the process of excessive apoptosis. Immunofluorescence staining, real-time quantitative polymerase chain reaction (qRT-PCR), and western blot results confirmed that exposure to NH₃ changed the expression levels of interleukin family factors, apoptosis, death receptor, and oxidative stress factors. Our study further confirmed that excessive NH₃ induced inflammatory response and mediated necroptosis leading to cell apoptosis by activating the Nrf2 signaling pathway. Excessive NH₃ could mediate spleen injury through oxidative stress-induced mitochondrial dynamics disorder. L-Selenomethionine could alleviate inflammation and abnormal apoptosis by inhibiting the IL-17/TNF-α/FADD axis. Our study would pave the way for comparative medicine and environmental toxicology.

Combined Exposure to Multiple Metals and Kidney Function in a Midlife and Elderly Population in China: A Prospective Cohort Study

[Background] Metal exposure is suspected to be correlated to kidney function. However, the combined effects of co-exposing to multiple metals, especially both toxic and protective metals, have not been completely evaluated. [Method] A prospective cohort study was conducted with the "135" cohort for the evaluation of how plasma metal levels are correlated to kidney function in a midlife and elderly community in southern China. An amount of 1368 subjects without kidney disease at baseline were enrolled in the final analysis. By using linear regression and logistic regression models, the correlation of individual metal values with renal function parameters was assessed. Measuring of the multiple metal exposure level was performed by principal component analysis (PCA). [Results] Diminished renal function, as evaluated based on fast kidney function decline, or estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m², was positively associated with the plasma concentrations of chromium and potassium, but it was negatively associated with selenium and iron (p < 0.05). In multiple-metal analyses, linear and logistic regression models showed that the iron and chromium exposure pattern had a protective effect on renal function, whereas the sodium and potassium exposure pattern and the cadmium and lead exposure pattern increased the risk for fast kidney function decline, and eGFR < 60 mL/min/1.73 m². [Conclusions] Certain metals, including chromium, potassium, selenium, and iron, were correlated with kidney function in a midlife and elderly community in China. In addition, the potential combined influences of co-exposing to multiple metals were observed.

Insights into the antioxidative mechanisms of melatonin in ameliorating chromium-induced oxidative stress-mediated hepatic and renal tissue injuries in male Wistar rats

Chromium (Cr), a hazardous heavy metal, is toxic to human health and the environment. Severe detrimental effects of Cr on different physiological systems involve oxidative stress. In the current study, sodium dichromate di-hydrate was subcutaneously injected to male Wistar rats at a dose of 5 mg/kg b.w. and experimented up to 14 days to induce alterations in hepatic and renal tissues. Another group of rats was pre-treated with melatonin at three different doses (5, 10, and 20 mg/kg b.w.; orally) and 20 mg/kg b.w. dose was evidenced to provide maximal protection against Cr-induced alterations. The study demonstrated that melatonin efficiently preserved body weight, organ weight, intracellular antioxidant enzymes, and tissue morphology. Furthermore, melatonin was also found to protect organ damage markers, oxidative stress-biomarkers, activities of pro-oxidant enzymes, levels of reactive oxygen species (ROS), nitric oxide (NO), and collagen content through its antioxidative mechanisms. Moreover, melatonin effectively decreased tissue Cr content through its metal-chelating activity. Hence, the present study has established melatonin as a promising antioxidant for conserving the liver and kidney tissues from Cr-induced oxidative damage thereby strengthening the notion that this small indoleamine can act as a future therapeutic against Cr-induced oxidative stress-mediated tissue damage.

Nephroprotective Efficacy of Selenium and Zinc Against Potassium Dichromate-Induced Renal Toxicity in Pregnant Wistar Albino Rats

Hexavalent chromium (CrVI) compounds are potent toxicants commonly used in numerous industries. Thus, potential toxic effects and health hazards are of high relevance. Selenium (Se) and zinc (Zn) are known for their antioxidant and chemoprotective properties. However, little is known about their protective effects against CrVI-induced renal damage during pregnancy. In this context, the present study aimed to investigate the protective efficacy of these two essential elements against potassium dichromate-induced nephrotoxicity in pregnant Wistar Albino rats. Female rats were divided into control and four treated groups of six each receiving subcutaneously on the 3rd day of pregnancy, K₂Cr₂O₇ (10 mg/kg, s.c. single dose) alone, or in association with Se (0.3 mg/kg, s.c. single dose), ZnCl₂ (20 mg/kg, s.c. single dose) or both of them simultaneously. The nephrotoxic effects were monitored by the evaluation of plasma renal parameters, oxidative stress biomarkers, DNA damage, and renal Cr content. The obtained results showed that K₂Cr₂O₇ disturbed renal biochemical markers, induced oxidative stress and DNA fragmentation in kidney tissues, and altered renal histoarchitecture. The co-administration of Se and/or ZnCl₂ has exhibited pronounced chelative, antioxidant, and genoprotective effects against K₂Cr₂O₇-induced renal damage and attenuated partially the histopathological alterations. These results suggest that Se and Zn can be used as efficient nephroprotective agents against K₂Cr₂O₇-induced toxicity in pregnant Wistar Albino rats.

Nephroprotective role of Echinacea purpurea against potassium dichromate-induced oxidative stress, inflammation, and apoptosis in rats

Environmental and occupational exposure to chromium compounds, especially hexavalent chromium [Cr(VI)], is widely recognized as a potential nephrotoxic in humans and animals. Its toxicity is associated with the overproduction of free radicals, which induces oxidative damage. Echinacea purpurea (L.) Moench is an herbaceous perennial plant rich in phenolic components and frequently used for its medicinal benefits. The current work evaluated the effectiveness of E. purpurea (EP) against oxidative stress and nephrotoxicity induced by potassium dichromate in male rats. Male Wistar rats were divided into four groups: control, E. purpurea (EP; 50 mg/kg; once daily for 3 weeks), hexavalent chromium (Cr(VI); 15 mg/kg; single intraperitoneal dose), and EP + Cr(VI) where rats were pretreated with EP for 3 weeks before receiving CrVI, respectively. Results revealed that rats exposed to Cr(VI) showed a significant increase in PC, TBARS, and H₂ O₂ , kidney function biomarkers (Urea, creatinine, and uric acid), lactate dehydrogenase activity (LDH), TNF-α, IL-18, nuclear factor kappa B (NFκB), and IGF-1 (Insulin-like growth factor-1) levels as well as a considerable decline in metallothionein (MT), glutathione (GSH) content, enzymatic antioxidants (SOD, CAT, GPx, GR, and GST), alkaline phosphatase (ALP) activities, and protein content. Cr(VI) induced apoptosis in kidney tissues as revealed by upregulation of Bax and caspase 3 and downregulation of Bcl-2. Furthermore, EP treatment ameliorated the Cr(VI)-induced histopathological and ultrastructure variations of kidney tissue, which was confirmed by the biochemical and molecular data. It is clear from the results of this study that EP exerts nephroprotective effects by improving the redox state, suppressing inflammatory reaction and cell apoptosis as well as ameliorating the performance of kidney tissue architecture, which is eventually reflected by the improvement of kidney function in rats.

Mechanism of chromium-induced toxicity in lungs, liver, and kidney and their ameliorative agents

Heavy metal Chromium (Cr), can adversely affect humans and their health if accumulated in organs of the body, such as the lungs, liver, and kidneys. Cr (VI) is highly toxic and has a higher solubility in water than Cr (III). One of the most common routes for Cr exposure is through inhalation and is associated with liver, lung, kidney damage, widespread dermatitis, GI tract damage, human lung cancer, cardiomyopathies, and cardiovascular disease. The increase in ROS production has been attributed to most of the damage caused by Cr toxicity. Cr-induced ROS-mediated oxidative stress has been seen to cause a redox imbalance affecting the antioxidant system balance in the body. The Nrf2 pathway dysregulation has been implicated in the same. Deregulation of histone acetylation and methylation has been observed, together with gene methylation in genes such as p16, MGMT, APC, hMLH1, and also miR-143 repression. Several ultra-structural changes have been observed following Cr (VI)-toxicity, including rough ER dilation, alteration in the mitochondrial membrane and nuclear membrane, pycnotic nuclei formation, and cytoplasm vacuolization. A significant change was observed in the metabolism of lipid, glucose, and the metabolism of protein after exposure to Cr. Cr-toxicity also leads to immune system dysregulations with changes seen in the expression of IL-8, IL-4, IgM, lymphocytes, and leukocytes among others. P53, as well as pro-and anti-apoptotic proteins, are involved in apoptosis. These Cr-induced damages can be alleviated via agents that restore antioxidant balance, regulate Nrf-2 levels, or increase anti-apoptotic proteins while decreasing pro-apoptotic proteins.

Renal hypoxia-HIF-PHD-EPO signaling in transition metal nephrotoxicity: friend or foe?

The kidney is the main organ that senses changes in systemic oxygen tension, but it is also the key detoxification, transit and excretion site of transition metals (TMs). Pivotal to oxygen sensing are prolyl-hydroxylases (PHDs), which hydroxylate specific residues in hypoxia-inducible factors (HIFs), key transcription factors that orchestrate responses to hypoxia, such as induction of erythropoietin (EPO). The essential TM ion Fe is a key component and regulator of the hypoxia–PHD–HIF–EPO (HPHE) signaling axis, which governs erythropoiesis, angiogenesis, anaerobic metabolism, adaptation, survival and proliferation, and hence cell and body homeostasis. However, inadequate concentrations of essential TMs or entry of non-essential TMs in organisms cause toxicity and disrupt health. Non-essential TMs are toxic because they enter cells and displace essential TMs by ionic and molecular mimicry, e. g. in metalloproteins. Here, we review the molecular mechanisms of HPHE interactions with TMs (Fe, Co, Ni, Cd, Cr, and Pt) as well as their implications in renal physiology, pathophysiology and toxicology. Some TMs, such as Fe and Co, may activate renal HPHE signaling, which may be beneficial under some circumstances, for example, by mitigating renal injuries from other causes, but may also promote pathologies, such as renal cancer development and metastasis. Yet some other TMs appear to disrupt renal HPHE signaling, contributing to the complex picture of TM (nephro-)toxicity. Strikingly, despite a wealth of literature on the topic, current knowledge lacks a deeper molecular understanding of TM interaction with HPHE signaling, in particular in the kidney. This precludes rationale preventive and therapeutic approaches to TM nephrotoxicity, although recently activators of HPHE signaling have become available for therapy.

Occupational exposure to hexavalent chromium. Part I. Hazard assessment of non-cancer health effects

Hexavalent chromium (Cr(VI)) compounds have been studied extensively and several agencies have described their toxicological profile. In the past, personnel of the Dutch Ministry of Defence may have been exposed to Cr(VI) during maintenance activities. To investigate if this exposure may have caused irreversible adverse health effects, the Dutch National Institute for Public Health and the Environment (RIVM) summarized all available knowledge from previous evaluations. This information was complemented with a scoping review to retrieve new scientific literature. All scientific evidence was evaluated in workshops with external experts to come to an overview of irreversible adverse health effects that could be caused by occupational exposure to Cr(VI) compounds. This review focuses on non-cancer health effects. It was concluded that occupational exposure to Cr(VI) can cause perforation of the nasal septum by chromium ulcers, chronic lung diseases, including asthma, rhinitis, pulmonary fibrosis and COPD, skin ulcers and allergic contact dermatitis in humans. It is currently insufficiently clear if Cr(VI) can cause irreversible diseases due to disturbances of the immune system (other than allergic contact eczema, allergic asthma and rhinitis and chronic lung diseases) or adverse effects on fertility or prenatal development in humans.

Protective effects of selenium and zinc against potassium dichromate-induced thyroid disruption, oxidative stress, and DNA damage in pregnant Wistar rats

Hexavalent chromium (CrVI) is an environmental pollutant and an endocrine-disrupting metal. Se and Zn are essential trace elements, known to play a crucial role in thyroid homeostasis. However, there is a lack of data reporting thyrotoxicity during gestation. In this study, we investigated the protective effects of selenium and zinc against potassium dichromate-induced thyrotoxicity in pregnant Wistar rats. Thirty pregnant Wistar rats were divided into control and four treated groups receiving subcutaneously (s.c) on the 3rd day of pregnancy, K2Cr2O7 (10 mg/kg, s.c) alone, or in association with Se (0.3 mg/kg, s.c), ZnCl2 (20 mg/kg, s.c), or both of them simultaneously. The hormonal profile, oxidative stress biomarkers, DNA damage, and histological modifications were evaluated. Our main findings showed that K2Cr2O7 promoted hypothyroidism, oxidative stress, genotoxicity, and histological alterations in the thyroid gland. The co-treatment with Se or ZnCl2 has mitigated K2Cr2O7-induced thyrotoxicity in pregnant Wistar rats by exhibiting antioxidant and genoprotective effects. However, the combined co-treatment of both of them was less thyroprotective, and therefore, further investigations on the synergetic interaction of Se and Zn against CrVI toxicity using different doses and exposure routes are required.

2,4-Dichlorophenoxyacetic acid induced hepatic and renal toxicological perturbations in rat model: Attenuation by selenium supplementation

2,4-Dichlorophenoxyacetic acid (2,4-D) is a commercially used herbicide to manage broadleaf weeds that have various toxicological and ecological effects. In view of ever-escalating use of 2,4-D, risk assessment becomes mandatory to ensure the safety of both human health and the ecosystem. Oxidative injury has been expected as a possible mechanism implicated in 2,4-D toxicity. The present study was planned and conducted to explore the antioxidant potential of selenium (Se) supplementation to moderate the 2,4-D hepatic and renal toxicity in a rat model. The rats were randomly assigned to four equal groups and treated via oral gavage for a period of 4 weeks. Group I: received deionized water as a vehicle, group II: received 2,4-D (150 mg^-1 kg^-1 day^-1), group III: received Se supplement (1 mg^-1 kg^-1 day^-1), and group IV: received 2,4-D (150 mg^-1 kg^-1 day^-1) and Se supplement (1 mg^-1 kg^-1 day^-1) simultaneously. After 4 weeks of administration, 2,4-D induced toxicity was observed, as manifested by disrupted levels of plasma urea, creatinine, alkaline phosphatase (ALP), aspartate aminotransferase (AST), and alanine aminotransferase (ALT). Further, 2,4-D caused a considerable increase in tissue malondialdehyde (MDA) levels and decreased activity of antioxidant enzymes, including superoxide dismutase, catalase, and glutathione reductase. Se supplementation exhibited its antioxidant properties by significantly improving urea, creatinine, ALP, AST, and ALT, and MDA levels and antioxidant enzyme activities. In conclusion, the results suggest that 2,4-D induced hepatic and renal toxicities were attenuated by Se supplementation probably owing to its antioxidant properties.

The Effects of Selenium in Acrylamide-Induced Nephrotoxicity in Rats: Roles of Oxidative Stress, Inflammation, Apoptosis, and DNA Damage

We sought to determine the effects of selenium (Se) on acrylamide (ACR)-induced nephrotoxicity in rats. In our study, 50 adult male Sprague-Dawley rats weighing 200-250 g were randomly divided into five groups. The control group was given intra-gastric (i.g.) saline (1 mL) for 10 days. The ACR group was given i.g. ACR in saline (38.27 mg/kg titrated to 1 mL) for 10 days. The Se0.5 + ACR and Se1 + ACR groups were administered Se in saline (0.5 and 1 mg/kg, respectively) for 10 days and given i.g. ACR (38.27 mg/kg) one hour after the Se injections. The Se1 group was administered i.g. Se (1 mg/kg) for 10 days. On day 11, intracardiac blood samples were obtained from the rats while they were under anesthesia, after which they were euthanized by decapitation. Urea and creatinine concentrations of blood serum samples were analyzed with an autoanalyzer. Enzyme-linked immunosorbence immunosorbent assay (ELISA) was used to quantify malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), glutathione peroxidase (GPx), catalase (CAT), tumor necrosis factor-α (TNF-α), nuclear factor-κB (NF-κB), interleukin (IL)-33, IL-6, IL-1β, cyclooxygenase-2 (COX-2), kidney injury molecule-1 (KIM-1), mitogen-activated protein kinase-1 (MAPK-1), and caspase-3 in kidney tissues. Renal tissues were evaluated by histopathological and immunohistochemical examinations for 8-hydroxylo-2'-deoxyguanosin 8-hydroxy-2'-deoxyguanosine (8-OhDG) and Bax. Serum urea and creatinine levels were higher in the ACR group than in the control, and these ACR-induced increases were prevented by high doses of Se. Additionally, ACR induced the renal oxidative stress, inflammation, apoptosis, and damage to DNA and tissue; likewise, these were prevented by high doses of Se. Taken with ACR, Se confers protection against ACR-induced nephrotoxicity in rats by reducing oxidative stress, inflammation, apoptosis, and DNA damage.

Antagonistic effects of nano-selenium on broilers hepatic injury induced by Cr(VI) poisoning in AMPK pathway

Cr (chromium, with common valence states of III and VI) is one of the common broiler feed additives. Liver injury and metabolic disorders could be caused by Cr_(VI) (hexavalent chromium) poisoning in broilers. Oxidative damage and metabolic disorders of organisms caused by heavy metals could be antagonized by nano-Se (nano-selenium). Nano-Se was chosen to study the antagonism of Cr_(VI) poisoning in broilers. AMPK (Adenosine 5^,-monophosphate-activated protein kinase) is known as a "cell energy regulator" and plays a key regulatory role in carbohydrate and lipid metabolism. AMPK pathway and ACACA/CPT1A two genes were selected to study the prevention and treatment of nano-Se on Cr_(VI) poisoning in broilers and its molecular mechanism. For this purpose, 180 1-day-old AA (Arbor Acres) broilers were selected and randomly divided into 6 groups (n = 30) for further testing. After feeding as planned for 35 days, the livers of such broilers were taken for further examination including histopathological examination, differential gene expression analysis, and further validation on both mRNA and protein levels using related techniques like RT-qPCR, western blot, and immunohistochemistry (IHC). The histopathological examination suggested that the liver cells of the Cr_(VI) poisoning group were more severely injured than the nano-Se addition group. RT-qPCR results showed that the relative expression of ACACA gene in the Cr_(VI) poisoning group was significantly increased (P < 0.05), while the CPT1A gene's expression was significantly decreased (P < 0.01). Those results were reversed in the nano-Se addition group. Western blot results were consistent with RT-qPCR and both suggested antagonism of nano-Se on Cr_(VI). Through morphological and histopathological observation, as well as the measurement of the mRNA and protein expression levels of ACACA and CPT1A genes in AMPK pathway, it was confirmed that nano-Se has certain preventive and protective effects on Cr_(VI) poisoning in broiler chickens. Furthermore, the adverse effects of Cr_(VI) on carbohydrate and lipid metabolism in broilers can be antagonized by nano-Se through AMPK pathway. A new method and experimental basis were provided to the future study of Cr_(VI) poisoning in broilers.

Evaluating toxicity impacts of environmental exposed chromium on small Indian mongoose (Urva auropunctatus) hematological, biochemical and histopathological functioning

Sub-lethal toxic impacts of chromium on hematological, biochemical and histological parameters were analyzed in the female small Indian mongoose (Urva auropuctatus) residing contaminated environment of tannery industry. Chromium bioaccumulation in the blood, liver and kidney tissue of the exposed mongooses was found elevated compared to the control mongooses' tissues. Total body weight (75.7%), liver weight (83.6%) as well as HSI (68.1%), RSI (86.2%) and the platelets counts (59.7%) were found significantly elevated, with significantly reduced RBCs (59.6%), and WBCs (64%). LFT and RFT were also found abnormal, moreover, the histopathological injuries had been distinct inside the kidney (>75%) and hepatic (>75%) tissues of exposed animals. Shrinkage and vacuolization (>75%) inside the hepatocyte expanded sinusoidal spaces and nuclear pyknosis (>75%) was evident within the hepatic tissue. Hypertrophy of epithelial cells of renal tubules and inter-renal cells of the head kidney with a reduction in tubular lumens (>75%) and vacuolization of tubules were witnessed within the kidney section. Atrophy inside the kidney inter-renal cells, glomeruli compression within the Bowman's capsules (>75%) following the necrosis in hematopoietic tissues were found in exposed animals. The present findings indicate that chronic exposure to chromium induces severe anemia, decreased serum protein concentration, hepatic and renal tissue histopathology, impairing the vital capabilities of liver, metabolic regulation, excretion, and stress homeostasis maintenance of which within the long-run may posture a severe risk to animal well-being then distress their inhabitants.

Ameliorative effects of Annona muricata Linn. (Annonaceae) against potassium dichromate-induced hypertension in vivo: involvement of Kim-1/p38 MAPK/Nrf2 signaling

Background Recently, the incidences of hypertension and environmental pollution have increased significantly. This study investigates the antihypertensive effect of Annona muricata extract against K2Cr2O7-induced hypertension. Methods Fifty rats were used for this study, which were divided into five groups of 10 rats each. Rats in Group A received normal saline, and those in Groups B, C, D, and E were treated with A. muricata extract alone at 250 mg/kg, K2Cr2O7 at 30 mg/kg, pretreated with the extract at 250 mg/kg, and pretreated with gallic acid at 60 mg/kg for 14 days, respectively, and thereafter administered with a single intraperitoneal injection of K2Cr2O7 at 30 mg/kg. Results Administration of K2Cr2O7 significantly increased systolic, diastolic, and mean arterial pressure and caused prolonged QT and QTc intervals. Further, pretreatment with the extract at 250 mg/kg and gallic acid at 60 mg/kg significantly reduced high blood pressure to near-normal values. K2Cr2O7 intoxication led to significant increases in serum advanced oxidative protein products, myeloperoxidase, and xanthine oxidase, while serum nitric oxide (NO) also reduced significantly. Immunohistochemistry of the renal kidney injury molecule (Kim-1) and p38 MAPK showed increased expressions following the administration of K2Cr2O7 together with the downregulation of nuclear factor erythroid 2-related factor 2 (Nrf2). Pretreatment with the extract at 250 mg/kg and gallic acid at 60 mg/kg also increased the expressions of Nrf2 and downregulated Kim-1 and p38. Conclusion Together, we found that pretreatment with the extract at 250 mg/kg and gallic acid at 60 mg/kg normalized the blood pressure, reduced the markers of oxidative stress, and improved the antioxidant defense system and serum NO bioavailability.

Phytochemical analysis and nephroprotective effect of cactus (Opuntia ficus-indica) cladodes on sodium dichromate-induced kidney injury in rats

Environmental and occupational exposure to chromium compounds, especially hexavalent chromium, is widely recognized as potentially nephrotoxic in humans and animals. The present study aimed to assess the efficacy of cactus (Opuntia ficus-indica) against sodium dichromate-induced nephrotoxicity, oxidative stress, and genotoxicity. Cactus cladodes extract (CCE) was phytochemically studied and tested in vitro for its potential antioxidant activities. Additionally, the preventive effect of CCE against sodium dichromate-induced renal dysfunction in a Wistar rat model (24 rats) was evaluated. For this purpose, CCE at a dose of 100 mg/kg was orally administered, followed by 10 mg/kg sodium dichromate (intraperitoneal injection). After 40 days of treatment, the rats were sacrificed, and the kidneys were excised for histological, lipid peroxidation, and antioxidant enzyme analyses. The phenol, flavonoid, tannin, ascorbic acid, and carotenoid contents of CCE were considered to be important. Our analyses showed that 1 mL of CCE was equivalent to 982.5 ± 1.79 μg of gallic acid, 294.37 ± 0.84 μg of rutin, 234.78 ± 0.24 μg of catechin, 204.34 ± 1.53 μg of ascorbic acid, and 3.14 ± 0.51 μg of β-carotene. In vivo, pretreatment with CCE was found to provide significant protection against sodium dichromate-induced nephrotoxicity by inhibiting lipid peroxidation, preserving normal antioxidant activities, and protecting renal tissues from lesions and DNA damage. The nephroprotective potential of CCE against sodium dichromate toxicity might be due to its antioxidant properties.

Environmental chromium from the tannery industry induces altered reproductive endpoints in the wild female small Indian mongoose (Urva auropunctatus)

The populations of wild animals are declining in many parts of the world in response to man-made alterations in the environment. Environmental contamination due to heavy metals discharge from industry may contribute to the decline of wild animal populations by impacting their reproduction, growth, and development. In the leather tanning industry, chromium (Cr) is used as a basic component, but it is a potent toxicant that can affect many of the physiological functions of animals. In the current study, we investigated the reproductive toxicity of industrial Cr in female small Indian mongooses inhabiting a tannery area. Adult female specimens were live trapped from February 2015 to January 2016. Blood and other body tissues (ovaries, kidneys and liver) of the captured specimens were collected along with soil and water samples from the environment for analysis. The Cr concentrations were found significantly ( p < 0.0001) increased compared to control in the environment, blood, and all body tissues of the animals. Estradiol and progesterone levels were found to be significantly decreased in comparison with control ( p < 0.0001), along with reduced ovarian weights, while follicle stimulating hormone (FSH) and luteinizing hormone levels were found significantly ( p < 0.0001) elevated. Light microscopy revealed significantly decreased in comparison with control ovarian follicle numbers ( p < 0.0001) and diameters, vacuolization of the oocytes, and a significantly higher percentage of atretic follicles inside the ovary. We conclude that Cr discharged from the tanneries is absorbed by the exposed female small Indian mongoose, leading to ovarian dysfunction with potential impairment of reproductive function.

The role of heavy metals and polychlorinated biphenyls (PCBs) in the oncogenesis of head and neck tumors and thyroid diseases: a pilot study

Previous literature has highlighted the mechanisms of molecular toxicity induced by substances such as arsenic, cadmium, chromium, nickel, lead, barium and PCBs. The research was carried out on 20 volunteers, all the patients gave their consent to the research: the aim of the study was to evaluate the presence of metals and PCBs in these different matrices (blood and hair), correlating the biochemical data to pathological conditions present, and also to the area in which patients resided. Various quantitative determinations were carried out on samples of blood and hair for 14 heavy metals and on blood samples for 12 PCBs. For the 11 patients the results indicated that blood levels for half of the 14 displayed heavy metals measured considerably higher compared to the reference values, whilst the levels measured in hair evidenced some positive values significantly higher than the maximum reference. Of the 12 PCBs assayed in blood some showed higher positive values compared to the maximum tabular reference (although there is no clear reference quantified in the WHO-2005 report). In the 9 healthy patients heavy metals in the blood were within the expected target range, with those showing positive results (≤ 3 out of 14 heavy metals for each patient) having values only slightly higher than the reference maximum. The levels of 14 heavy metals measured in hair were below thresholds, and levels for the 12 PCBs measured in blood showed negativity or positivity with values close to the minimum benchmarks. The analyses carried out on biological matrices have uncovered important and significant differences between healthy and unhealthy subjects, both qualitative and quantitative differences with respect to heavy metals and PCBs. All patients with head and neck cancer enlisted for the study had heavy metal and PCB blood levels at least twice the maximum reference level. The levels of heavy metals in hair were at least double the maximum reference. In contrast, all healthy volunteers enrolled showed no significant levels for either metals or PCBs.

Ameliorative effects of Spirulina platensis against lead-induced nephrotoxicity in newborn rats: Modulation of oxidative stress and histopathological changes

Our experimental work was aimed at evaluating the safety and protective effects of dietary spirulina supplementation on the kidney of newborn rats, the offspring of lead contaminated lactating mothers. Female rats were randomly divided into four groups: group I (control) was given a normal diet, group II (positive control, S) received a diet enriched with spirulina, group III received only lead through drinking water (Pb), and group IV received both a diet enriched with spirulina and lead contaminated water (S Pb). The treatment of pregnant rats with lead administrated in drinking water, from the 5^th day of pregnancy until day 14 after delivery, induced an increased level of renal lipid peroxidation, protein carbonyl, hydrogen peroxide and advanced oxidation protein product, a decreased renal content of glutathione and antioxidant enzyme activities such as superoxide dismutase, catalase and glutathione peroxidase in newborns. A statistically significant increase of renal DNA, mRNA, hematological parameters as well as in plasma urea and creatinine serum levels and lactate dehydrogenase was seen in pups, while those of uric acid declined. Interestingly, these biochemical modifications were accompanied by a significant decrease of lactate dehydrogenase in kidney, plasma alkaline phosphatase and gamma glutamyl-transpeptidase levels, urinary levels of creatinine and urea. Conversely, supplementation of lead-treated mother's with spirulina alleviated hematotoxicity induced by lead as evidenced, by restoring the biochemical markers cited above to near normal levels. Nevertheless, the distorted histoarchitecture in rat kidney attenuated following spirulina supplementation. It can be then concluded that spirulina is an important protective source against kidney impairments.

Association of co-exposure to heavy metals with renal function in a hypertensive population

BACKGROUND

Chronic kidney disease (CKD) is an increasing health problem worldwide. Recent studies have suggested the potential associations between exposure to metals and CKD events, particularly in participants with hypertension. However, relevant studies are limited.

OBJECTIVES

We aimed to explore the associations of metal exposure with renal function in participants with essential hypertension.

METHODS

Nine hundred and thirty-four participants with essential hypertension were recruited at the Department of Cardiology, Union Hospital, Wuhan, China. We measured the levels of chromium, cadmium, thallium and uranium in urine and calculated the estimated glomerular filtration rate (eGFR) for renal function. Multivariable linear regression models adjusted for potential confounders were applied.

RESULTS

After adjusting for potential confounders and other metals, doubling of urinary chromium or uranium levels decreased eGFR by 2.90 (95% confidence interval, 2.04 to 3.76) and 1.87 (0.58 to 3.15) mL/min per 1.73m², respectively. Co-exposure to chromium and uranium was found to greatly decrease eGFR, particularly in women. Compared with those in the low exposure group, women with high exposure to chromium and uranium had a 11.36 (3.66 to 19.07) mL/min per 1.73m² adjusted decline in eGFR. Higher urinary thallium levels were positively related to elevated eGFR in men. The adjusted increase in eGFR with doubling of thallium levels was 3.12 (1.14 to 5.10) mL/min per 1.73m². Sex-difference in the associations of exposure to heavy metals with eGFR was also suggested.

CONCLUSIONS

Our findings suggest that environmental exposure to chromium and uranium might contribute to a decline in eGFR in individuals with hypertension. The associations of exposure to heavy metals with eGFR might be sex-different. Further studies are warranted to confirm our findings and clarify the underlying mechanisms.

A cross-sectional study measuring vanadium and chromium levels in paediatric patients with CKD

OBJECTIVES

Although many secondary effects of high levels of vanadium (V) and chromium (Cr) overlap with symptoms seen in paediatric patients with chronic kidney disease (CKD), their plasma V and Cr levels are understudied.

DESIGN

Ancillary cross-sectional study to a prospective, longitudinal, randomised controlled trial.

SETTING

Children's Hospital of Western Ontario, London Health Sciences Centre, London, Ontario, Canada.

PARTICIPANTS

36 children and adolescents 4-18 years of age with CKD.

INTERVENTIONS

1-6 trace element measurements per patient. Cystatin C (CysC) estimated glomerular filtration rate (eGFR) was calculated using the Filler formula. Plasma V and Cr levels were measured using high-resolution sector field inductively coupled mass spectrometry. Anthropomorphic data and blood parameters were collected from our electronic chart programme. Water Cr and V data were obtained from the Ontario Water (Stream) Quality Monitoring Network.

PRIMARY AND SECONDARY OUTCOME MEASURES

Primary outcomes: plasma Cr and V.

SECONDARY OUTCOMES

age, season, CysC, CysC eGFR, and Cr and V levels in environmental water.

RESULTS

The median (IQR) eGFR was 51 mL/min/1.73 m² (35, 75). The median V level was 0.12 µg/L (0.09, 0.18), which was significantly greater than the 97.5th percentile of the reference interval of 0.088 µg/L; 32 patients had at least one set of V levels above the published reference interval. The median Cr level was 0.43 µg/L (0.36, 0.54), which was also significantly greater than the established reference interval; 34 had at least one set of Cr levels above the published reference interval. V and Cr levels were moderately correlated. Only some patients had high environmental exposure.

CONCLUSIONS

Our study suggests that paediatric patients with CKD have elevated plasma levels of V and Cr. This may be the result of both environmental exposure and a low eGFR. It may be necessary to monitor V and Cr levels in patients with an eGFR <30 mL/min/1.73 m².

TRIAL REGISTRATION NUMBER

NCT02126293; HC#172241.

The decline in kidney function with chromium exposure is exacerbated with co-exposure to lead and cadmium

Environmental factors contribute significantly to the pathogenesis of chronic kidney disease. However, these factors, and particularly the toxic effects of heavy metals, have not been completely evaluated. Chromium is a widespread industrial contaminant that has been linked to nephrotoxicity in animal and occupational population studies. Nevertheless, its role in population renal health and its potential interactions with other nephrotoxic metals, such as lead and cadmium, remain unknown. We assessed the association between exposure to chromium, lead, and cadmium with renal function using estimated glomerular filtration rate (eGFR) in an analysis of 360 Taiwanese adults aged 19-84 years from the National Nutrition and Health Survey in Taiwan (2005-2008). Doubling of urinary chromium or lead decreased the eGFR by -5.99 mL/min/1.73 m² (95% confidence interval -9.70, -2.27) and -6.61 (-9.71, -3.51), respectively, after adjusting for age, sex, body mass index, hypertension, diabetes, cigarette smoking, sodium intake, education, urinary volume, and other metals. For those in the highest tertile of cadmium exposure, the eGFR decreased by -12.68 mL/min/1.73 m² (95% confidence interval -20.44, -4.93) and -11.22 mL/min/1.73 m² (-17.01, -5.44), as urinary chromium or lead levels doubled, respectively. Thus, there is a significant and independent association between chromium exposure and decreased renal function. Furthermore, co-exposure to chromium with lead and cadmium is potentially associated with additional decline in the glomerular filtration rate in Taiwanese adults.

Effect of various selenium doses on chromium(IV)-induced nephrotoxicity in a male chicken model

Our study aimed to explore whether Na₂SeO₃ (Se) can alleviate the nephrotoxicity induced by K₂Cr₂O₇ [Cr(VI)]. One hundred and five male chickens were randomly divided into seven groups with 15 chickens each group: The 6 experimental groups received K₂Cr₂O₇ alone or in combination with 0.31, 0.63, 1.25, 2.50, and 5.00 mg/kg for 42 days, respectively, while control group was treated with equivalent water. Exposure to Cr(VI) significantly increased MDA contents and organ coefficient, whereas decreased T-SOD activities, Ca²⁺-ATPase activities, mitochondrial membrane potential and GSH contents, and histological studies demonstrated renal damage. Above indicators were restored by Se supplement (0.31, 0.63, and 1.25 mg/kg), in which supplement with 0.63 mg/kg Se developed more effectively than the other two groups; on the contrary, in the groups of Se supplement with 2.50 and 5.00 mg/kg, the above indicators were not ameliorated and even exacerbated. This study demonstrated that Cr(VI) can result in kidney oxidative damage in male chickens, and Se of certain dose has the protective effects against Cr(VI)-induced nephrptoxicity.

Selenium Alleviates Oxidative Stress and Lung Damage Induced by Aluminum Chloride in Adult Rats: Biochemical and Histological Approach

Our study pertains to the potential ability of selenium, used as a nutritional supplement, to alleviate oxidative stress induced by aluminum chloride in the lung tissue. Rats have received during 21 days either aluminum chloride (AlCl₃) (400 ppm) via drinking water, AlCl₃ associated with Na₂SeO₃ (0.5 mg/kg of diet), or only Na₂SeO₃. Exposure of rats to AlCl₃ induced lung oxidative stress with an increase of malondialdehyde, hydrogen peroxide, and protein carbonyls levels. An alteration of lactate dehydrogenase activities and antioxidant redox status, enzymatic (catalase, superoxide dismutase, and glutathione peroxidase), and non-enzymatic (non-protein thiols, glutathione, metallothionein, and vitamin C) was also observed. These biochemical modifications were substantiated by histopathological data showing alveolar edema, a large number of hemosiderin-laden macrophages, and emphysema. Se supplementation attenuated the levels of oxidative stress by restoring antioxidant state and improved lung histological damage. Our results revealed that Se, a trace element with antioxidant properties, was effective in preventing lung damage.

Arsenic Induction of Metallothionein and Metallothionein Induction Against Arsenic Cytotoxicity

Human exposure to arsenic (As) can lead to oxidative stress that can become evident in organs such as the skin, liver, kidneys and lungs. Several intracellular antioxidant defense mechanisms including glutathione (GSH) and metallothionein (MT) have been shown to minimize As cytotoxicity. The current review summarizes the involvement of MT as an intracellular defense mechanism against As cytotoxicity, mostly in blood. Zinc (Zn) and selenium (Se) supplements are also proposed as a possible remediation of As cytotoxicity. In vivo and in vitro studies on As toxicity were reviewed to summarize cytotoxic mechanisms of As. Intracellular antioxidant defense mechanisms of MT are linked in relation to As cytotoxicity. Arsenic uses a different route, compared to major metal MT inducers such as Zn, to enter/exit blood cells. A number of in vivo and in vitro studies showed that upregulated MT biosynthesis in blood components are related to toxic levels of As. Despite the cysteine residues in MT that aid to bind As, MT is not the preferred binding protein for As. Nonetheless, intracellular oxidative stress due to As toxicity can be minimized, if not eliminated, by MT. Thus MT induction by essential metals such as Zn and Se supplementation could be beneficial to fight against As toxicity.

Gallic acid attenuates chromium-induced thyroid dysfunction by modulating antioxidant status and inflammatory cytokines

Hexavalent chromium-mediated oxidative stress causes severe organ damage. The present study was designed to investigate the possible thyroprotective effect and underlying mechanisms of gallic acid using rat model of potassium dichromate-induced thyroid dysfunction. Forty adult male albino rats were divided into 4 groups: control, gallic acid (20mg GA/kg b. wt), potassium dichromate (2mg PD/kg b. wt) and the fourth group was co-treated with PD and GA. PD-injection resulted in decreased serum free triiodothyonine (FT3), free thyroxine (FT4) with concomitant significant increase in thyroid stimulating hormone (TSH) levels. Superoxide dismutase (SOD), glutathione-S-transferase (GST) activities and their respective mRNA expression and reduced glutathione (GSH) content were significantly decreased. Thyroid nitrosative stress marker (NO level and iNOS mRNA and protein expression) and pro-inflammatory cytokines (serum TNF-α, IL-6 and thyroid TNF-α, IL-6 and COX-2 gene and protein expression levels) were disturbed. Histopathological changes revealed distended, collapsed and degenerated follicles with vacuolated cytoplasm. GA co-treatment attenuated pro-inflammatory cytokines, the thyroid expression of iNOS, TNF-α, IL-6 and COX-2, decreased the elevated lipid peroxidation biomarkers and NO level and up- regulated SOD and GST mRNA expression levels. In conclusion, GA has shown strong modulatory potential against PD-induced inflammation and oxidative stress in albino rats.

Nephrotoxicity of Kalach 360 SL: biochemical and histopathological findings

Kalach 360 SL (KL) is a commercial herbicide which contains 360 g/l of glyphosate used in both agricultural and urban areas throughout the world including Tunisia. We aimed to evaluate the effects of KL on rats' renal system. Female Wistar rats were divided into three groups: group 1 (n = 6) received a standard diet and served as control, groups 2 and 3 (n = 12 each) received 0.07 ml (D1: 126 mg/kg), and 0.175 ml (D2: 315 mg/kg) of KL, respectively, for 60 d. The chronic exposure to KL induced a significant increase in plasma creatinine, urea, and uric acid levels. Creatinine clearance decreased in KL-treated groups, compared with controls. Several urine parameters, such as urine-specific gravity and urine osmolality, significantly decreased, while dieresis and urinary Na/K + ratio increased in KL-treated groups. These findings suggested a distal tubular damage caused by tubular necrosis. Moreover, the chronic exposure to KL induced an increase in lipid peroxidation (LPO) and a decrease in antioxidant status, enzymatic activities (superoxide dismutase and catalase) and non-enzymatic levels (vitamin C), which led to an oxidative stress. Histopathological studies showed a peritubular inflammatory reaction, nephrose, fragmented glomeruli, necrotic epithelial cells, and tubular dilatation. These results could have significant health implications for animal and human populations. Further data are necessary to investigate the potential consequences of chronic dose exposure during life.

Co-exposure to aluminum and acrylamide disturbs expression of metallothionein, proinflammatory cytokines and induces genotoxicity: Biochemical and histopathological changes in the kidney of adult rats

The individual toxic effects of aluminum and acrylamide are known but there is no data on their combined effects. The present study investigates the toxic effects after combined exposure to these toxicants on: (i) oxidative stress during combined chronic exposure to aluminum and acrylamide on kidney function (ii) correlation of oxidative stress with metallothionein (MT) and inflammatory cytokines expression, DNA damage, and histopathological changes. Rats were exposed to aluminum (50 mg/kg body weight) in drinking water and acrylamide (20 mg/kg body weight) by gavage either individually or in combination for 3 weeks. Exposure rats to aluminum chloride or acrylamide alone and in combination induced nephrotoxicity, as evidenced by a decrease in the 24-h urine volume and uric acid levels in plasma and an increase of plasma creatinine, urea, and blood urea nitrogen levels. Nephrotoxicity was objectified by a significant increase in malondialdehyde level, advanced oxidation protein, and protein carbonyl contents, whereas reduced glutathione, nonprotein thiol, vitamin C levels, catalase, and glutathione peroxidase activities showed a significant decline. Superoxide dismutase activity and its gene expression were increased. Aluminum and acrylamide co-exposure exhibited synergism in various biochemical variables and also in DNA damage. Kidney total MT levels and genes expression of MT1, MT2, and proinflammatory cytokines were increased. All these changes were supported by histopathological observations. Co-exposure to aluminum and acrylamide exhibited synergism and more pronounced toxic effects compared with their individual effects based on various biochemical variables, genotoxic, and histopathological changes. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1044-1058, 2016.

Mercuric chloride induced hepatotoxic and hematologic changes in rats

This study focuses on investigating the possible protective effect of sodium selenite (Na2SeO3) and/or vitamin E against mercuric chloride (HgCl2)-induced hepatotoxicity in rat. Male rats were given HgCl2 (1 mg/kg body weight (bw)) and HgCl2 plus Na2SeO3 (0.25 mg/kg bw) and/or vitamin E (100 mg/kg bw) daily via gavage for 4 weeks. HgCl2-treated groups had significantly higher white blood cell and thrombocyte counts than the control group. Serum activities of alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, γ-glutamyl-transferase, and lactate dehydrogenase significantly increased and serum levels of total protein, albumin, triglyceride, total cholesterol, and low-density lipoprotein cholesterol significantly decreased in the HgCl2-treated groups compared with control group. Malondialdehyde level significantly increased and superoxide dismutase, catalase, and glutathione peroxidase activities decreased in liver tissue of HgCl2-treated rats. Also, HgCl2 exposure resulted in histopathological changes. Supplementation of Na2SeO3 and/or vitamin E provided partial protection in hematological and biochemical parameters that were altered by HgCl2. As a result, Na2SeO3 and/or vitamin E significantly reduced HgCl2-induced hepatotoxicity, but not protected completely.

Cr (VI) induced oxidative stress and toxicity in cultured cerebellar granule neurons at different stages of development and protective effect of Rosmarinic acid

Chromium (Cr) is a widespread metal ion in the workplace, industrial effluent, and water. The toxicity of chromium (VI) on various organs including the liver, kidneys, and lung were studied, but little is known about neurotoxicity. In this study, neurotoxic effects of Cr (VI) have been investigated by cultured cerebellar granule neurons (CGNs). Immature and mature neurons were exposed to different concentrations of potassium dichromate for 24 h and cytotoxicity was measured by MTT assay. In addition, immature neurons were exposed for 5 days as regards cytotoxic effect in development stages. The reactive oxygen species (ROS), mitochondrial membrane potential (MMP) and the protective effect of Rosmarinic acid on mature and immature neurons exposed to potassium dichromate, were measured. Furthermore, lipid peroxidation, glutathione peroxidase (GPx), and acetylcholinesterase activity in mature neurons were assessed following exposure to potassium dichromate. The results indicate that toxicity of Cr (VI) dependent on maturation steps. Cr (VI) was less toxic for immature neurons. Also, Cr (VI) induced MMP reduction and ROS production in both immature and mature neurons. In Cr (VI) treated neurons, increased lipid peroxidation and GPx activity but not acetylcholinesterase activity was observed. Interestingly, Rosmarinic acid, as a natural antioxidant, could protect mature but not immature neurons against Cr (VI) induced toxicity. Our findings revealed vulnerability of mature neurons to Cr (VI) induced toxicity and oxidative stress.

Metal concentrations in hair of patients with various head and neck cancers as a diagnostic aid

Head and neck cancers are one of the most frequent cancers worldwide. This paper attempts to evaluate disturbances of homeostasis of the necessary elements (calcium, magnesium, zinc, copper, iron, manganese) and changes in the levels of toxic metals (lead, cadmium, cobalt, chromium VI) in hair of patients with head and neck cancers, as well as people without a diagnosed neoplastic disease. In order to quantify the necessary elements and toxic metals, a method using ICP-MS and ICP-OES techniques had been developed and validated. The studies have shown that patients with head and neck cancer used to drink alcohol and smoked much more frequently than healthy individuals, both in the past and presently. Statistically significant differences in concentrations of average metal content in the group of patients with head and neck cancers compared to the control group were confirmed. Significant differences in metal content between the group of patients with head and neck cancers and healthy individuals were found which enabled distinguishing between the study groups. To this end, a more advanced statistical tool, i.e. chemometrics, was used. The conducted research analyses and the use of advanced statistical techniques confirm the benefits of using alternative material to distinguish the patients with head and neck cancers from the healthy individuals.

The Remedial Efficacy of Spirulina platensis versus Chromium-Induced Nephrotoxicity in Male Sprague-Dawley Rats

This study was conducted to investigate the possible protective effect of Spirulina platensis against chromium-induced nephrotoxicity. A total of 36 adult male Sprague-Dawley rats were divided into 4 equal groups (Gps). Gp1 served as control, rats of Gps 2, 3, and 4 were exposed to Spirulina platensis (300 mg/kg b.wt per os) and sodium dichromate dihydrate (SDD) via drinking water at concentration of 520 mg /l respectively. Chromium administration caused alterations in the renal function markers as evidenced by significant increase of blood urea and creatinine levels accompanied with significant increase in kidney’s chromium residues and MDA level as well as decreased catalase activity and glutathion content in kidney tissue. Histologically, Cr provoked deleterious changes including: vascular congestion, wide spread tubular epithelium necrobiotic changes, atrophy of glomerular tuft and proliferative hyperplasia. The latter was accompanied with positive PCNA expression in kidney tissues as well as DNA ploidy interpretation of major cellular population of degenerated cells, appearance of tetraploid cells, high proliferation index and high DNA index. Morphometrical measurements revealed marked glomerular and tubular lumen alterations. On contrary, spirulina co-treatment with Cr significantly restored the histopathological changes, antioxidants and renal function markers and all the previously mentioned changes as well.

Effectiveness of (PhSe)2 in protect against the HgCl2 toxicity

This work investigated the preventive effect of diphenyl diselenide [(PhSe)2] on renal and hepatic toxicity biomarkers and oxidative parameters in adult mice exposed to mercury chloride (HgCl2). Selenium (Se) and mercury (Hg) determination was also carried out. Mice received a daily oral dose of (PhSe)2 (5.0mg/kg/day) or canola oil for five consecutive days. During the following five days, the animals were treated with a daily subcutaneous dose of HgCl2 (5.0mg/kg/day) or saline (0.9%). Twenty-four hours after the last HgCl2 administration, the animals were sacrificed and biological material was obtained. Concerning toxicity biomarkers, Hg exposure inhibited blood δ-aminolevulinic acid dehydratase (δ-ALA-D), serum alanine aminotransferase (ALT) activity and also increased serum creatinine levels. (PhSe)2 partially prevented blood δ-ALA-D inhibition and totally prevented the serum creatinine increase. Regarding the oxidative parameters, Hg decreased kidney TBARS levels and increased kidney non-protein thiol levels, while (PhSe)2 pre-treatment partially protected the kidney thiol levels increase. Animals exposed to HgCl2 presented Hg content accumulation in blood, kidney and liver. The (PhSe)2 pre-treatment increased Hg accumulation in kidney and decreased in blood. These results show that (PhSe)2 can be efficient in protecting against these toxic effects presented by this Hg exposure model.

Persistent hexavalent chromium exposure impaired the pubertal development and ovarian histoarchitecture in wistar rat offspring

Hexavalent chromium (CrVI) is a highly toxic metal and a major environmental pollutant. Several studies indicate that CrVI exposure adversely affects reproductive function. We reported that maternal Cr exposure resulted in Cr accumulation in the reproductive organs of female offsprings. CrVI can cross the placental barrier and also can be passed through breastfeeding. The present investigation aimed to determine the persistent (in utero through puberal period) CrVI exposure-induced toxic effects on the reproductive functions of mother and the offspring. Induction of oxidative stress is one of the plausible mechanisms behind Cr-induced cellular deteriorations. Mother rats exposed to CrVI showed reduced reproductive outcome, while the offsprings showed higher accumulation of Cr in ovary, altered steroid, and peptide hormones. Specific activities of antioxidant enzymes were decreased and associated with increased levels of H2 O2 , and lipid peroxidation. CrVI exposure also damaged the ovarian histoarchitecture in various age groups studied. CrVI exposure also delayed the sexual maturation. Results from the present investigation suggest that CrVI exposure from in utero through puberal period significantly damaged the pubertal development through altered antioxidants, anemia, and altered hormone levels. These changes were associated with damaged ovarian histoarchitecture and extended estrous cycle in developing Wistar rats.

Mechanisms of kidney toxicity for chromium- and arsenic-based preservatives: potential involvement of a pro-oxidative pathway

Metals have been extensively used for the preservation of wood. Among metallic conservatives, mixtures of chromated copper arsenate (CCA) were thoroughly used. However, the release and consequent mobilization of such compounds by biota, may culminate in the exertion of toxic chemical effects. The present study intended to show the toxicological effects caused by arsenic (7.2 mg/kg body weight), chromium (10.2 mg/kg Cr body weight) and the commercial mixture CCA (7.2 mg/kg As body weight and 10.2 mg/kg Cr body weight) in mice, namely the oxidative stress response (catalase - CAT, glutathione peroxidase - GPx, and glutathione-S-transferases - GSTs), in kidney tissues. The determination of the tested parameters was performed after exposure; organisms were exposed, and then sacrificed at two distinct periods, namely 14 and 96 h after the administration of toxicants. Exposure to chromium and arsenic induced significant modifications in the redox state of the test organisms, evidenced by significant alterations in GSTs and GPx activities. No alterations were found concerning the activity of catalase. These findings showed that the chemical mixture used as household product may exert significant toxicological outcomes in exposed animals, such as rodents, conditioning their redox homeostasis and antioxidant response.

Proteomic analysis of kidneys from selenoprotein M transgenic rats in response to increased bioability of selenium

BACKGROUND

To characterize changes in global protein expression in kidneys of transgenic rats overexpressing human selenoprotein M (SelM) in response to increased bioabivility of selenium (Sel), total proteins extracted from kidneys of 10-week-old CMV/hSelM Tg and wild-type rats were separated by 2-dimensional gel electrophoresis and measured for changes in expression.

RESULTS

Ten and three proteins showing high antioxidant enzymatic activity were up- and down-regulated, respectively, in SelM-overexpressing CMV/hSelM Tg rats compared to controls based on an arbitrary 2-fold difference. Up-regulated proteins included LAP3, BAIAP2L1, CRP2, CD73 antigen, PDGF D, KIAA143 homolog, PRPPS-AP2, ZFP313, HSP-60, and N-WASP, whereas down-regulated proteins included ALKDH3, rMCP-3, and STC-1. After Sel treatment, five of the up-regulated proteins were significantly increased in expression in wild-type rats, whereas there were no changes in CMV/hSelM Tg rats. Only two of the down-regulated proteins showed reduced expression in wild-type and Tg rats after Sel treatment.

CONCLUSIONS

These results show the primary novel biological evidences that new functional protein groups and individual proteins in kidneys of Tg rats relate to Sel biology including the response to Sel treatment and SelM expression.

Benfotiamine enhances antioxidant defenses and protects against cisplatin-induced DNA damage in nephrotoxic rats

The objective of the present study was to assess superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), paraoxonase (PON1), glutathione reductase (GR), and catalase (CAT) activities ratio and their relationship with DNA oxidative damage in rats treated with cisplatin (3 mg/kg bwt/day) in the presence and absence of benfotiamine (100 mg/kg/day) for 25 days. Cisplatin-induced renal damage was evidenced by renal dysfunction and elevated oxidative stress markers. SOD activity and levels of nitric oxide, protein carbonyl, malondialdehyde, and 8-hydroxy-2'-deoxyguanosine were significantly increased by cisplatin treatment. Moreover, the ratios of GPx/GR, SOD/GPx, SOD/CAT, and SOD/PON1 were significantly increased compared to control. In contrast, glutathione levels were significantly decreased by cisplatin treatment. Simultaneous treatment of rats with cisplatin and benfotiamine ameliorate these variables to values near to those of control rats. This study suggests that benfotiamine can prevent cisplatin-induced nephrotoxicity by inhibiting formation reactive species of oxygen and nitrogen.

Oxidative stress and paraoxonase activity in experimental selenosis: effects of betaine administration

The present study was undertaken on male rats to elucidate the selenosis induced by sodium selenite and the role played by betaine in alleviating selenium toxicity. Rats were treated with sodium selenite (6 mg/kg body weight/day) with or without betaine (240 mg/kg body weight/day). Selenotoxicosis was evident from the elevated plasma levels of total bilirubin, transaminases, and alkaline phosphatase activities. Moreover, the total protein levels decreased, and this decrease associated with a decreased albumin level, whereas the globulin level increased in selenium-intoxicated rats. The development of selenosis corresponded well with the induction of oxidative stress evident from decrease of total thiol level and glutathione content. Furthermore, activities of glutathione reductase, glucose-6-phosphate dehydrogenase, catalase, and paraoxonase-1 were decreased in selenium-treated rats. In contrast, superoxide dismutase and glutathione peroxidase activities were increased by excess selenium administration compared with control animals. As well, malondialdehyde and protein carbonyl were elevated in rats treated with selenium. Supplementation of betaine simultaneously with selenium caused less marked alteration in the investigated parameters. Betaine attenuated the selenotoxicosis by restoring thiol levels that preserve enzymatic antioxidants activity and attenuate the oxidation of lipids and proteins.

The protective and toxic effects of rhubarb tannins and anthraquinones in treating hexavalent chromium-injured rats: the Yin/Yang actions of rhubarb

Chromium nephrotoxicity (CrNT) is thought to occur through the oxidant lesion mechanism. There is still a lack of specific remedies against CrNT. We primarily screened Chinese herbal medicines with a potential protective effect against CrNT, e.g., rhubarb (Rheum palmatum L.). However, the active constituents in rhubarb and its mechanisms remain unclear. In this study, the total rhubarb extract (TR) was successively separated into three parts: total anthraquinone extract (TA), total tannin extract (TT) and remaining component extract (RC). The effects of each extract on the potassium dichromate (K(2)Cr(2)O(7))-induced nephrotoxicity in rats were comparatively assessed. The results showed that only the administration of TT protected the kidney function in K(2)Cr(2)O(7)-injured rats. Besides, TT showed significant activity to scavenge hydroxyl radicals, which is considered to be the dominant lesion product generated by hexavalent chromium. TT also showed a reduced ability to transform toxic high valence chromium ions into non-toxic low valence ions. And TT was able to further precipitate chromium ions. These results suggested that rhubarb tannins treat CrNT as a free radical scavenger, reductant, and metal precipitant. The multiple protective routes of the plant tannins reveal a superior option for development into a promising natural remedy against CrNT. In addition, the opposite effects of rhubarb anthraquinones in treating CrNT were observed compared to rhubarb tannins, which suggested the duo-directional effects (Yin and Yang) of herbal medicines should be addressed.

Effect of selenium on methimazole-induced liver damage and oxidative stress in adult rats and their offspring

This study aimed to investigate the protective effect of selenium (Se) on methimazole (MMI; an antithyroid drug)-induced hepatotoxicity in adult rats and their progeny. Female Wistar rats were randomly divided into four groups of six rats in each group: group I served as controls that received standard diet; group II received MMI in drinking water as 250 mg L−1 and standard diet; group III received both MMI (250 mg L−1, orally) and Se (0.5 mg kg−1 of diet); group IV received Se (0.5 mg kg−1 of diet) as sodium selenite. Treatments were started from the 14th day of pregnancy until day 14 after delivery. Exposure of rats to MMI promoted oxidative stress with an increase in liver malondialdehyde levels, advanced oxidation protein products and protein carbonyl contents and a decrease in the levels of glutathione, nonprotein thiols and vitamin C. A decrease in the activities of liver glutathione peroxidase, superoxide dismutase, catalase and lactate dehydrogenase and in the levels of plasma total protein and albumin was also observed. Plasma transaminase activities and total, direct and indirect bilirubin levels increased. Coadministration of Se through diet improved all biochemical parameters. The histopathological changes confirmed the biochemical results. Therefore, our investigation revealed that Se, a trace element with antioxidant properties, was effective in preventing MMI-induced liver damage.

The influence of selenium on root growth and oxidative stress induced by lead in Vicia faba L. minor plants

The effect of selenium (Se) on Vicia faba L. minor roots subjected to lead (Pb) stress was studied by investigating root growth, root viability, and antioxidant enzyme activity. The experiments were carried out on plants grown for 2 weeks on Hoagland medium supplied with 50 μM Pb in the form of lead nitrate Pb(NO(3))(2) and/or Se concentrations of 1.5 and 6 μM in the form of sodium selenite Na(2)SeO(3). It was shown that Pb reduced the root growth and caused serious damage in the roots, which was accompanied by metal accumulation in these tissues. The exposition of roots to Pb led to significant changes in the biochemical parameters: the MDA and T-SH content and glutathione peroxidase (GSH-Px) activity increased but the guaiacol peroxidase (GPOX) activity decreased. Moreover, Pb intensified O(2)(·-) production in the roots. Selenium at a lower concentration alleviated Pb toxicity which was accompanied by a decreased O(2)(·-) production in the apical parts of roots and increased the T-SH content and GPOX activity. However, higher Se concentration intensified MDA and T-SH accumulation and GPOX and GSH-Px activity in Pb-treated plant roots. At low concentration, Se improved cell viability whereas at high concentration it was pro-oxidant and enhanced the lipid peroxidation and cell membrane injury.