Cd-induced Nephrotoxicity Research Articles

Ligustrazine modulates renal cysteine biosynthesis in rats exposed to cadmium

The objective of this study was to determine the effect of ligustrazine (TMP) on cadmium (Cd)-induced nephrotoxicity and its relevant mechanism. TMP (50mg/kg) was injected intraperitoneally (i.p.) into rats 1h prior to CdCl2 exposure (at a Cd dose of 0.6mg/kg). TMP reversed Cd-induced nephrotoxicity, evidenced by the relatively normal architecture of the renal cortex. Additionally, TMP alleviated renal oxidative stress of rats that were exposed to Cd, evidenced by the decreased levels of malondialdehyde (MDA), 4-hydroxynonenal (4-HNE), elevated levels of glutathione (GSH) and GSH/GSSG (glutathione disulfide) ratios. Furthermore, TMP also raised the decreased levels of S-adenosylmethionine (SAM) and cystathionine involved in cysteine biosynthesis in rats exposed to Cd. Further analysis revealed that TMP treatment upregulated expression of several proteins involved in cysteine biosynthesis including methionine adenosyltransferases (MATs) and cystathionine-beta-synthase (CBS). Taken together, these results suggest that TMP remodeled metabolomics of cysteine biosynthesis in rat kidneys and attenuated Cd-induced nephrotoxicity.

Effect of exogenous TGF-β1 on the cadmium-induced nephrotoxicity by inhibiting apoptosis of proximal tubular cells through PI3K-AKT-mTOR signaling pathway

Heavy metal polluted soils have been a serious problem for the global ecological balance and people's health. Cadmium (Cd), one of the heavy metals, could induce apoptosis of proximal tubular cells in many experimental models and lead to damage the human kidney. Here, we reported a potent chemokine TGF-β1 which could ameliorate cadmium-induced nephrotoxicity. Interestingly, western blotting and TUNEL staining assays indicated that PI3K-AKT-mTOR signaling pathway was involved in the protective mechanism of TGF-β1 in vitro and in vivo. Moreover, TGF-β1 could alleviate Cd-induced nephrotoxicity by inhibiting apoptosis of proximal tubular cells through detecting the level of caspase 3, 8 and 9. Therefore, up-regulation of exogenous TGF-β1 may be a potential strategy to reverse cadumium-induced nephrotoxicity.

Resveratrol rescues cadmium-induced mitochondrial injury by enhancing transcriptional regulation of PGC-1α and SOD2 via the Sirt3/FoxO3a pathway in TCMK-1 cells

Resveratrol has been reported to ameliorate Cd-induced nephrotoxicity. However, the beneficial effects of resveratrol on Cd-induced nephrotoxicity and the underlying mechanisms of this protection remain unclear. Here, we showed that mouse renal tubular epithelial (TCMK-1) cells exposed to Cd experienced significantly increased mitochondrial reactive oxygen species (mROS) production, as well as decreased mitochondrial biogenesis and function. Cd exposure dramatically decreased Sirt3 protein expression and activity and promoted the acetylation of forkhead box O3 (FoxO3a). Moreover, Cd exposure led to a decreased binding affinity of FoxO3a to the promoters of both peroxisome proliferator-activated receptor-gamma coactivator (PGC)-1α and superoxide dismutase 2 (SOD2), powerful and broad regulators of mitochondrial biogenesis and mROS metabolism. Meanwhile, resveratrol remarkably reduced mROS generation by promoting Sirt3 enrichment within the mitochondria and subsequent upregulation of FoxO3a-mediated mitochondria gene expression of PGC-1α and SOD2. Importantly, mechanistic study revealed that ERK1/2 activation was associated with increased apoptosis induced by Cd, resveratrol suppressed Cd-induced apoptosis in mice kidney. Taken together, our data suggest a novel mechanism of action for resveratrol-attenuated Cd-induced cellular damage, which, in part, was mediated through the activation of the Sirt3/FoxO3a signaling pathway.

Sinapic acid ameliorate cadmium-induced nephrotoxicity: In vivo possible involvement of oxidative stress, apoptosis, and inflammation via NF-κB downregulation.

Cadmium (CD), an environmental and industrial pollutant, generates reactive oxygen species (ROS) and NOS responsible for oxidative and nitrosative stress that can lead to nephrotoxic injury, including proximal tubule and glomerulus dysfunction. Sinapic acid (SA) has been found to possess potent antioxidant and anti-inflammatory effects in vitro and in vivo. We aimed to examine the nephroprotective, anti-oxidant, anti-inflammatory, and anti-apoptotic effects of SA against CD-induced nephrotoxicity and its underlying mechanism. Kidney functional markers (serum urea, uric acid, creatinine, LDH, and calcium) and histopathological examinations of the kidney were used to evaluate CD-induced nephrotoxicity. Oxidative stress markers (lipid peroxidation and total protein), renal nitrosative stress (nitric oxide), antioxidant enzymes (catalase and NP-SH), inflammation markers (NF-κB [p65], TNF-α, IL-6, and myeloperoxidase [MPO]), and apoptotic markers (caspase 3, Bax, and Bcl-2) were also assessed. SA (10 and 20mg/kg) pretreatment restored kidney function, upregulated antioxidant levels, and prevented the elevation of lipid peroxidation and nitric oxide levels, significantly reducing oxidative and nitrosative stress. CD upregulated renal cytokine levels (TNF-α, IL-6), nuclear NF-κB (p65) expression, NF-κB-DNA-binding activity, and MPO activity, which were significantly downregulated upon SA pretreatment. Furthermore, SA treatment prevented the upregulation of caspase 3 and Bax protein expression and upregulated Bcl-2 protein expression. SA pretreatment also alleviated the magnitude of histological injuries and reduced neutrophil infiltration in renal tubules. We conclude that the nephroprotective potential of SA in CD-induced nephrotoxicity might be due to its antioxidant, anti-inflammatory, and anti-apoptotic potential via downregulation of oxidative/nitrosative stress, inflammation, and apoptosis in the kidney.

Pomegranate peel Extract Protects Cadmium-induced nephrotoxicity in albino mice.

Cadmium chloride (CdCl2) is a toxicant heavy metal displays adverse properties in humans creating public health risks. Pomegranate (Punica granatum L.) is widely known as antimicrobial and antioxidant. This study investigated the cadmium-induced structural effects in mice and evaluated the beneficial effect of alcoholic extract of P. granatum fruit peel (PPE) to protective CdCl2 nephrotoxicity. Animals were divided into 4 groups; group 1: control, group 2: given 25ml/kg PPE, group 3: given CdCl2 at a dose level of 2mg/kg, and Group 4: given CdCl2 and PPE. The animals were given the previous treatment daily for 14days. CdCl2 intoxication led to obvious many histopathological alterations in kidney glomeruli accompanied with wide and congested blood vessels, renal tubules missed their distinct form with cytoplasmic vacuolation of their epithelial cells and pyknotic nuclei and leucocytes cells infiltration in the intertubular spaces. On the other hand, the immunohistochemical staining of antiapoptotic Bcl-2 and α-smooth muscle actin (α-SMA) expressions were positive after CdCl2 exposure compared with the control group. Ultrastructure observations revealed thickening of the glomerular basement membrane and fusion of the podocytes foot processes, tubular epithelial cells vacoulation with pyknotic nuclei, perforation and vacoulation of mitochondria, deterioration of endoplasmic reticulum, and increase of lysosomes. CdCl2-exposure accompanied by increased level of serum urea, creatinine and blood urea nitrogen (BUN) as well as significant increase in malondialdehyde (MDA) besides decreased of the total antioxidant capacity (TAC) level. In contrast, co-administration of PPE plus CdCl2 ameliorated these parameters around the normal levels. It contributed the improvement by the histological, ultrastructure, and decreased Bcl-2 and α smooth muscle protein expression, and kidney function through a significant decrease in urea, creatinine, and BUN, reduced the level of serum MDA as lipid peroxidation marker and restored the altered antioxidant system activity. It was concluded that Cd-induced nephrotoxicity at a dose level 2 mg/kg b.w. in mice. The PPE may be involved in the protection of toxicity displayed by CdCl2 induction attributed to the high antioxidant capacity.

Endoplasmic reticulum stress eIF2α-ATF4 pathway-mediated cyclooxygenase-2 induction regulates cadmium-induced autophagy in kidney.

The heavy metal cadmium (Cd) is nephrotoxic. Recent studies show that autophagy plays an essential role in Cd-induced kidney injury. However, the mechanisms of Cd-induced kidney injury accompanied by autophagy are still obscure. In the present study, we first confirmed that Cd induced kidney damage and dysfunction, along with autophagy, both in vivo and in vitro. Then, we observed that cyclooxygenase-2 (COX-2) and the eIF2α–ATF4 pathway of endoplasmic reticulum (ER) stress were induced by Cd in both kidney tissues and cultured cells. Further studies showed that inhibition of COX-2 with celecoxib or RNA interference (RNAi) inhibited the Cd-induced autophagy in kidney cells. In addition, blocking ER stress with 4-phenylbutyrate or RNAi partially counteracted COX-2 overexpression and autophagy induced by Cd, which suggested that ER stress was required for Cd-induced kidney autophagy. Significantly, our results showed that Cd activated ATF4 and induced its translocation to the nucleus. Knockdown of ATF4 inhibited Cd-induced COX-2 overexpression. While COX-2 overexpression is involved in renal dysfunction, there is no prior report on the role of COX-2 in autophagy regulation. The results of the current study suggest a novel molecular mechanism that the ER stress eIF2α–ATF4 pathway-mediated COX-2 overexpression contributes to Cd-induced kidney autophagy and injury. The present study implies that COX-2 may be a potential target for therapy against Cd-induced nephrotoxicity.

Modulatory effect of Tinospora cordifolia extract on Cd-induced oxidative stress in Wistar rats

BackgroundCadmium (Cd), a nonessential heavy metal, is a major environmental and public health concern. Oxidative stress plays an important role in Cd-induced kidney dysfunction. Tinospora cordifolia, a medicinal plant rich in phytochemicals, possesses antioxidant activity. The objective of the present study was to assess the protective effect of Tinospora cordifolia-stem methanolic extract (TCE) on Cd-induced nephrotoxicity in Wistar rats. MethodsMale Wistar rats were administered ∼5mg/kg body weight Cd orally and 100mg/kg body weight TCE for 28 days. At the end of Cd and TCE treatment, biochemical assays were performed in serum and tissue homogenate. ResultsCd-induced oxidative stress in the kidney resulted in increased levels of lipid peroxidation and protein carbonyl content with a significant decrease in cellular antioxidants, such as reduced GSH, SOD, CAT, GPX, and GST. Cd-induced nephrotoxicity was further confirmed by marked changes in the histology of the kidney and increased levels of kidney markers. Additionally, Cd-treated rats showed alterations in membrane-bound ATPase activity and decreased levels of tissue glycoproteins. Cotreatment with TCE considerably reduced the biochemical alterations in serum and renal tissue induced by Cd, and also restored ATPase activity and glycoproteins to near normal levels. ConclusionOur results suggested that TCE with its antioxidant effect offered cytoprotection against Cd-induced toxicity in kidneys by restoring the altered cellular antioxidants and renal markers. TCE treatment for 28 days reversed ATPase activity and tissue glycoprotein levels. These results revealed the protective effect of TCE on Cd-induced toxicity in kidneys and oxidative stress.

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

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

An Assessment of Renal Function Parameters on the Ameliorative Properties of <i>Ginkgo Biloba</i> Extract in Cadmium-Induced Nephrotoxicity in Adult Wistar Rats Model

Renal failure is a growing concern in the modern society and the increasing rate of exposure to toxic substances has contributed a lot to renal diseases. As a result of this, there is a great need for agents that can serve as nephroprotective. The present study assessed some parameters of renal function on the ameliorative properties of <i>Ginkgo biloba</i> extract (GBE) in cadmium (Cd) - induced nephrotoxicity in adult wistar rats model. The study was performed on twenty four (24) male Wistar rats divided into four groups: Group A (Control), Group B (Cd), Group C (Cd + 100mg/kg BW of GBE) and Group D (Cd + 300mg/kg BW of GBE). The Cd and GBE were administered orally through oro-gastric cannula. The results showed changes in the renal function chemical parameters (creatinine, urea, and total protein) in the treated groups compared to the control group. Exposure to Cd lowered the activities of the kidney by increasing the plasma level of creatinine and urea, and decreasing the plasma level of total protein. The creatinine concentration decreased significantly (p<0.05) in groups C and D while the urea concentration increased on GBE administration. A significant decrease was observed in the plasma total protein level in the Cd group when compared with the control and on administration of GBE there was an increase in the plasma total protein concentration in groups C and D. The results showed that <i>Ginkgo biloba</i> treatment ameliorated the effects of Cd-induced nephrotoxicity in all parameters except urea which is to be further investigated. These may be explained by the oxidative and anti-oxidative properties of the Cd and GBE respectively and their mechanisms of action.

Regulatory role of miR-125a/b in the suppression by selenium of cadmium-induced apoptosis via the mitochondrial pathway in LLC-PK1 cells

Cadmium (Cd), a toxic heavy metal, is known to induce kidney damage and renal tubular dysfunction. Our previous studies have indicated that selenium (Se), as an essential trace element, protects against Cd-induced nephrotoxicity via the mitochondrial apoptotic pathway in vivo and in vitro. The available evidence suggests that the expression of miRNAs is altered after Cd exposure. However, the regulatory effects of miRNAs on Cd-induced apoptosis and on the suppression by Se of Cd-induced apoptosis remain unclear. The present study aimed to explore the effects of miRNAs on the suppression by Se of Cd-induced apoptosis in LLC-PK1 cells. miR-125a and miR-125b were downregulated in response to Cd exposure but were upregulated in the Se pretreatment group. Over-expression and low expression of miR-125a/b were simulated by their mimics and inhibitors, respectively. Both Se and over-expression of miR-125a/b attenuated Cd-induced apoptosis through significant enhancement of the anti-apoptotic protein Bcl-2, reduction of the pro-apoptotic proteins Bax and Bak, the release of cytochrome c and the inactivation of caspase-9 and caspase-3. The effects of downregulation of miR-125a/b on apoptosis were similar to those of Cd treatment, and both effects were inhibited by Se. Moreover, miR-125a/b were observed to target Bak and caspase-3 directly. In summary, miR-125a/b play an important role in the suppression of Cd-induced apoptosis by Se via the mitochondrial pathway in LLC-PK1 cells.

Thymoquinone Ameliorates Cadmium-Induced Nephrotoxicity, Apoptosis, and Oxidative Stress in Rats is Based on its Anti-Apoptotic and Anti-Oxidant Properties.

Cadmium (Cd), an environmental and industrial pollutant, generates free radicals responsible for oxidative stress. Cd can also lead to various renal toxic damage such as the proximal tubules and glomerulus dysfunction. Thymoquinone (TQ) is the main constituent of the essential oil obtained from black seeds (Nigella sativa) and has various pharmacological effects. The aim of the present study was to examine the nephroprotective, anti-oxidant, and anti-apoptotic effect of the TQ against Cd-induced nephrotoxicity. A total of 24 male Wistar albino rats were divided into three groups: control, Cd-treated, and Cd-treated with TQ; each group contain eight animals. The Cd-treated group was injected subcutaneously with CdCl2 dissolved in saline in the amount of 2ml/kg/day for 30days, resulting in a dosage of 1mg/kg Cd. The rats in TQ-treated groups were given TQ (50mg/kg body weight) once a day orally together with first Cd injection during the study period. The histopathological studies in the kidney of rats also showed that TQ markedly reduced the toxicity of Cd and preserved the normal histological architecture of the renal tissue. Immunohistochemical analysis revealed that TQ significantly decreased the Cd-induced over expression of nuclear factor-κB in renal tissue. Furthermore, TQ treatment resulted in decreased the number of apoptotic cells. TQ significantly suppressed lipid peroxidation, compensated deficits in the anti-oxidant defenses (reduced superoxide dismutase, glutathione peroxidase and catalase activities) in renal tissue resulted from Cd administration. These findings suggest that the nephroprotective potential of TQ in Cd toxicity might be due to its anti-oxidant and anti-apoptotic properties, which could be useful for achieving optimum effects in Cd-induced nephrotoxicity.

Ameliorative Effects of Selenium on Cadmium-Induced Oxidative Stress and Endoplasmic Reticulum Stress in the Chicken Kidney.

The harmful influences of dietary cadmium (Cd) on the chicken kidney and the protective role of selenium (Se) against Cd-induced nephrotoxicity in the chicken are relatively unexplored subjects. The aim of this study was to investigate the ameliorative role of Se on the effects of Cd-induced oxidative stress, endoplasmic reticulum stress, and apoptosis in chicken kidneys. For this study, 100-day-old chickens received Se (as 10 mg Na2SeO3/kg dry weight of diet), Cd (as 150 mg CdCl2/kg dry weight of diet), or Cd + Se in their diets for 60 days. Then, the histopathological changes, Cd and Se contents, levels of oxidative stress, inducible nitric oxide synthase-nitric oxide (iNOS-NO) system activity, levels of endoplasmic reticulum (ER) stress, results of the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay of apoptosis, and expression levels of Bcl-2 and caspase 3 in the kidney were examined. The results showed that Cd exposure caused histopathological and ultrastructural damage and apoptosis of the kidneys. Cd administration significantly increased the accumulation of Cd, the malondialdehyde (MDA) content, NO production, iNOS activity, iNOS expression levels, expression levels of ER stress-related genes (GRP78, GRP94, ATF4, ATF6, and IRE) and the pro-apoptosis gene caspase 3, and the rate of apoptosis. Cd administration markedly decreased the Se content, superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities, and anti-apoptosis gene Bcl-2 expression levels. Co-treatment with Se and Cd obviously reduced the accumulation of Cd, Cd-induced histopathological and ultrastructural changes, oxidative stress, iNOS-NO system activity, ER stress, caspase 3 expression levels, and the rate of apoptosis in the kidneys. These results suggested that Cd exposure caused renal injury and that Se ameliorated Cd-induced nephrotoxicity in chickens.

Protective effect of Irvingia gabonensis stem bark extract on cadmium-induced nephrotoxicity in rats.

Cadmium has been considered a risk factor for humans as it accumulates in body tissues, such as the liver, lungs, kidneys, bones, and reproductive organs. The aim of the present study was to evaluate the effect of Irvingia gabonensis (IG) against cadmium (Cd)-induced nephrotoxicity. The study was performed on twenty (20) male rats divided into four groups: control group, cadmium group (4 mg/kg/day, intraperitoneally), cadmium + extract (200 mg/kg body weight by oral gavage) and cadmium + extract (400 mg/kg body weight by oral gavage). Changes in the kidney biochemical markers, namely glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), aminotransferase (ALT), aspartate aminotransferase (AST) activities and levels of malondialdehyde (MDA), urea, and creatinine were determined in serum. Histological examinations were monitored. Exposure to Cd lowered the activities of kidney antioxidants, while it increased LPO levels. Levels of all disrupted parameters were alleviated by co-administration of IG extract. The malondialdehyde concentration of the rats treated with 200 and 400 mg/kg body weight of the extract significantly decreased (p<0.05) compared with the untreated cadmium rats. Yet the creatinine concentration decreased significantly (p<0.05) when the cadmium animals treated with 200 and 400 mg/kg body weight of the extract were compared with the cadmium control. Furthermore, histological alterations in the kidney were observed in cadmium untreated rats and these were ameliorated in cadmium treated rats by co-administration of IG extract. IG showed apparent protective and curative effect on Cd-induced nephrotoxicity.

Evaluation of Cadmium-Induced Nephrotoxicity Using Urinary Metabolomic Profiles in Sprague-Dawley Male Rats

The aim of this study was to investigate urinary metabolomic profiles associated with cadmium (Cd)-induced nephrotoxicity and their potential mechanisms. Metabolomic profiles were measured by high-resolution 1H-nuclear magnetic resonance (NMR) spectroscopy in the urine of rats after oral exposure to CdCl2 (1, 5, or 25 mg/kg) for 6 wk. The spectral data were further analyzed by a multivariate analysis to identify specific urinary metabolites. Urinary excretion levels of protein biomarkers were also measured and CdCl2 accumulated dose-dependently in the kidney. High-dose (25 mg/kg) CdCl2 exposure significantly increased serum blood urea nitrogen (BUN), but serum creatinine (sCr) levels were unchanged. High-dose CdCl2 (25 mg/kg) exposure also significantly elevated protein-based urinary biomarkers including osteopontin, monocyte chemoattractant protein-1 (MCP-1), kidney injury molecules-1 (Kim-1), and selenium-binding protein 1 (SBP1) in rat urine. Under these conditions, six urinary metabolites (citrate, serine, 3-hydroxyisovalerate, 4-hydroxyphenyllactate, dimethylamine, and betaine) were involved in mitochondrial energy metabolism. In addition, a few number of amino acids such as glycine, glutamate, tyrosine, proline, or phenylalanine and carbohydrate (glucose) were altered in urine after CdCl2 exposure. In particular, the metabolites involved in the glutathione biosynthesis pathway, including cysteine, serine, methionine, and glutamate, were markedly decreased compared to the control. Thus, these metabolites are potential biomarkers for detection of Cd-induced nephrotoxicity. Our results further indicate that redox metabolomics pathways may be associated with Cd-mediated chronic kidney injury. These findings provide a biochemical pathway for better understanding of cellular mechanism underlying Cd-induced renal injury in humans.

Protective Effects of Zinc Supplementation on Renal Toxicity in Rats Exposed to Cadmium

Background: Cadmium (Cd) is a nonessential element with many industrial applications and is one of the most toxic pollutants in the environment. The ultimate goal of occupational health is prevention of health hazards on workplace; hence, is as a hazardous chemical contaminant in the workplace, Cd needs special attention. Objectives: The object of this study was to determine the effect of ZnCl 2 on Cd-induced nephrotoxicity in rats. Materials and Methods: Adult male rats were given CdCl 2 at doses of 0, 1, 2, and 3 mg/kg. Another series of rats were pretreated with 4 mg/ kg of ZnCl 2 30 minutes prior to administration of various doses of CdCl 2 . The experiment was repeated for seven consecutive days. Twentyfour hours after administering the latest dose, animals were sacrificed. Blood samples were analyzed for blood urea nitrogen (BUN) and creatinine levels. Kidney tissues were excised for measuring malondialdehyde (MDA) concentration. Results: In contrast to the animals that received ZnCl2, CdCl 2 induced a dose-dependent elevation in BUN, creatinine, and MDA in those without ZnCl2 pretreatment. Zinc chloride had significantly decreased all biochemical parameters and protected kidney cells against Cdinduced toxicity. Conclusions: The results of this study supported the potential protective effects of ZnCl 2 on rat kidney tissues against CdCl 2 toxicity.

Ligustrazine attenuates elevated levels of indoxyl sulfate, kidney injury molecule-1 and clusterin in rats exposed to cadmium

In this study, we aimed at evaluating the effect of ligustrazine, a major constituent of Ligusticum wallichii from traditional Chinese medicine, on Cd-induced changes in nephrotoxicity indices. Rats were divided into four experimental groups: control; ligustrazine; Cd and ligustrazine+Cd. Cd treated alone group showed significant decreases (P<0.05) in body weight, renal levels of superoxide dismutase (SOD) and glutathione reductase (GR); and significant increases (P<0.05) in urine volume (24h), pH values, serum blood urea nitrogen (BUN), serum uric acid, kidney malondialdehyde (MDA), urinary total protein, urinary glucose, urinary lactate dehydrogenase (LDH) and urinary alkaline phosphatase (ALP). Apart from indoxyl sulfate (a uremic toxin), two newly accepted nephrotoxicity biomarkers including kidney injury molecule-1 (kim-1) and clusterin were also found to be increased. Nonetheless, all these effects induced by Cd were reversed upon treatment by ligustrazine although it failed in decreasing the concentrations of Cd in kidney and urine. Histopathological studies in Cd-treated rats exhibited renal tubule damage, which was also ameliorated by ligustrazine pretreatment. These results suggest that ligustrazine exhibits protective effects on Cd-induced nephrotoxicity. Additionally, this study also demonstrates Cd exposure induces elevated levels of indoxyl sulfate in serum and kidney, and clusterin in urine.

Quercetin protects against oxidative stress-related renal dysfunction by cadmium in rats

The aim of this study was to investigate the possible protective role of the dietary flavonoid quercetin on cadmium (Cd)-induced nephrotoxicity using biochemical and histopathological approaches. In experimental rats oral administration of CdCl 2 (5 mg/kg) for 4 weeks significantly induced renal damage which was evident from the increased levels of serum urea, uric acid and creatinine with a significant ( p<0.05) decrease in creatinine clearance. Cd also significantly ( p<0.05) decreased the levels of urea, uric acid and creatinine in urine. Cd-induced oxidative stress in kidney tissue was indicated by the increased levels of renal lipid peroxidation markers (thiobarbituric acid reactive substances and lipid hydroperoxides) and protein carbonyl content with a significant ( p<0.05) decrease in non-enzymatic (total sulphydryl group, reduced glutathione, vitamin C and vitamin E) and enzymatic antioxidants (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), glutathione reductase (GR) and glucose 6-phosphate dehydrogenase (G6PD)). Moreover the kidneys of Cd-treated rats showed tubular necrosis, degeneration, dilation, desquamation, thickening of basement membrane and luminal cast formation. Quercetin treatment markedly attenuated the Cd-induced biochemical alterations in serum, urine and renal tissue. Quercetin also ameliorated the Cd-induced pathological changes when compared with Cd-alone-treated group. These data indicate that the natural dietary antioxidant quercetin might have protective effect against Cd-induced nephrotoxicity and oxidative stress in rats.

The role of endoplasmic reticulum in cadmium-induced mesangial cell apoptosis

Cd is an industrial and environmental pollutant that affects many organs in humans and other mammals. However, the molecular mechanisms of Cd-induced nephrotoxicity are unclear. In this study, we show that endoplasmic reticula (ER) played a pivotal role in Cd-induced apoptosis in mesangial cells. Using Fluo-3 AM, the intracellular concentration of calcium ([Ca 2+] i) was detected as being elevated as time elapsed after Cd treatment. Co-treatment with BAPTA-AM, a calcium chelator, was able to significantly suppress Cd-induced apoptosis. Calcineurin is a cytosolic phosphatase, which was able to dephosphorylate the inositol-1,4,5-triphosphate receptor (IP 3R) calcium channel to prevent the release of calcium from ER. Cyclosporine A, a calcineurin inhibitor, increased both [Ca 2+] i and the percentage of Cd-induced apoptosis. However, EGTA and the IP 3R inhibitor, 2-APB, were able to partially modulate Cd cytotoxicity. These results led us to suggest that the extracellular and ER-released calcium plays a crucial role in Cd-induced apoptosis in mesangial cells. Following this line, we further detected the ER stress after Cd treatment since ER is one of the major calcium storage organelles. After Cd exposure, GADD153, a hallmark of ER stress, was upregulated (at 4 h of exposure), followed by activation of ER-specific caspase-12 and its downstream molecule caspase-3 (at 16 h of exposure). The pan caspase inhibitor, Z-VAD, and BAPTA-AM were able to reverse the Cd-induced cell death and ER stress, respectively. Furthermore, the mitochondrial membrane potential (Δ Ψ m) was depolarized significantly and cytochrome c was released after 24 h of exposure to Cd and followed by mild activation of caspase-9 at the 36-h time point, indicating that mitochondria stress is a late event. Therefore, we concluded that ER is the major killer organelle in Cd-induced mesangial cell apoptosis and that calcium oscillation plays a pivotal role.

Effect of quercetin on metallothionein, nitric oxide synthases and cyclooxygenase-2 expression on experimental chronic cadmium nephrotoxicity in rats

Inflammation can play a key role in Cd-induced dysfunctions. Quercetin is a potent oxygen free radical scavenger and a metal chelator. Our aim was to study the effect of quercetin on Cd-induced kidney damage and metallothionein expression. The study was performed in Wistar rats that were administered during 9 weeks with either cadmium (1.2 mg Cd/kg/day, s.c.), quercetin (50 mg/kg/day, i.p.) or cadmium + quercetin. Renal toxicity was evaluated by measuring blood urea nitrogen concentration and urinary excretion of enzymes marker of tubular damage. Endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) renal expression were assessed by Western blot. Renal expression of metallothionein 1 and 2 (MT-1, MT-2) and eNOS mRNA was assessed by Northern blot. Our data demonstrated that Cd-induced renal toxicity was markedly reduced in rats that also received quercetin. MT-1 and MT-2 mRNA levels in kidney were substantially increased during treatment with Cd, being even higher when the animals received Cd and quercetin. Renal eNOS expression was significantly higher in rats receiving Cd and quercetin than in animals receiving Cd alone or in control rats. In the group that received Cd, COX-2 and iNOS expression was markedly higher than in control rats. In the group Cd+quercetin, no changes in COX-2 and iNOS expression were observed compared with the control group. Our results demonstrate that quercetin treatment prevents Cd-induced overexpression of iNOS and COX-2, and increases MT expression. These effects can explain the protection by quercetin of Cd-induced nephrotoxicity.

No effects of hematuria and proteinuria in school days, and probably current pregnancy and current lactation also, as risk factors of cadmium-induced renal tubular dysfunction among adult women in general populations in Japan.

This study was initiated to examine if hematuria and proteinuria in school days, current pregnancy, or current lactation are risk factors of cadmium-induced tubular dysfunction for adult women among general populations in Japan. For this purpose, a database of 9,967 never-smoking adult women were reviewed for urinary levels of cadmium (Cd) and three other elements, calcium (Ca), magnesium (Mg), and zinc (Zn), and two tubular dysfunction markers of alpha1-microglobulin (alpha1-MG) and beta2-microglobulin (beta2-MG); the analyte concentrations were corrected for creatinine (cr) and expressed as, e.g., Cd-Ucr. From the total, 160 cases were selected as those who were informed of urinary abnormality (i.e., proteinuria, hematuria, or both) in their school days (the abnormality being found to be transient, later), and each case was matched by age and prefecture of residence. Separately, seven women with persistent urinary abnormality, seven pregnant women, and six lactating women were identified, and the case was matched with three cases each of the same age and living in the same prefecture. Statistical analyses showed that Cd-Ucr and other markers were not elevated in the transient urinary abnormality group as compared with the matched controls. This was also observed in the subjects with persistent abnormality. In the pregnant women, alpha1-MG-Ucr and possibly beta2-MG-Ucr were elevated, but Cd-Ucr did not increase, suggesting that the observed elevation in alpha1-MG and beta2-MG was not due to the effects of Cd but a part of the physiology of pregnancy itself. There was no change in marker levels in lactating women except for an increase in alpha1-MG. In overall evaluation, it was considered prudent to conclude that urinary abnormality in school days does not increase the risk of Cd-induced nephrotoxicity in adult women, whereas the negative findings with pregnancy and lactation should be taken as preliminary because the numbers of cases studied were limited.