Effect of potassium dichromate on renal brush border membrane enzymes and phosphate transport in rats

Analysis of relationship between mixed heavy metal exposure and early renal damage based on a weighted quantile sum regression and Bayesian kernel machine regression model

BACKGROUND

Occupation, environmental heavy metal exposure, and renal function impairment are closely related. The relationship between mixed metal exposure and chronic renal injury is inadequately described, and the interaction between each metal is poorly explored.

OBJECTIVE

This cross-sectional study assessed mixed heavy metal exposure in the general population and their relationship with early renal impairment, as well as possible interactions between metals.

METHODS

The study was conducted in two communities in Taiyuan City in northern China. Multiple linear regression, weighted quantile sum (WQS) and bayesian kernel machine regression (BKMR) regression were used to explore the relationship of mixed heavy metal exposure with indicators of early kidney injury (N-acetyl-β-D- glucosidase (UNAG), urinary albumin (UALB)). Meanwhile, BKMR was used to explore the possible interactions between mixed heavy metal and indicators of early kidney injury.

RESULTS

Based on the WQS regression results, we observed adjusted WQS coefficient β (β-WQS) of 0.711 (95% CI: 0.543, 0.879). Notably, this change was primarily driven by As (35.6%) and Cd (22.5%). In the UALB model, the adjusted β-WQS was 0.657 (95% CI: 0.567, 0.747), with Ni (30.5%), Mn (22.1%), Cd (21.2%), and As (18.6%) exhibiting higher weights in the overall effect. The BKMR results showed a negative interaction between As and other metals in the UNAG and UALB models, a positive interaction between Mn and Ni and other metals. No significant pairwise interaction was observed in the association of metals with indicators of early kidney injury.

CONCLUSION

Through multiple linear regression, WQS regression, and BKMR analyses, we found that exposure to mixed heavy metals such as Cd, Cr, Pb, Mn, As, Co and Ni was positively correlated with UNAG and UALB. Moreover, there are complex interactions between two or more heavy metals in more than one direction.

Hexavalent chromium induces renal apoptosis and autophagy via disordering the balance of mitochondrial dynamics in rats

The use of hexavalent chromium (Cr(VI)) in many industrial processes has resulted in serious environmental pollution problems. Cr(VI) causes organ toxicity in animals after ingestion or inhalation. However, the exact mechanism by which Cr(VI) produces kidney damage remains elusive. Herein, we investigated whether Cr(VI)-induced kidney damage is related to the disorder of mitochondrial dynamics. In this study, 28 male rats were divided into four groups and intraperitoneally injected with 0, 2, 4, and 6 mg/kg body weight potassium dichromate for 5 weeks. Experiment included analysis of renal histopathology and ultrastructure, determination of biochemical indicators, and measurement of related protein content. The results showed that Cr(VI) induced kidney injury through promotion of oxidative stress, apoptosis, and disorder of mitochondrial dynamics in a dose-dependent manner. The protein levels of the silent information regulator two ortholog 1 (Sirt1), peroxisome proliferation-activated receptor-g coactivator-1a (PGC-1a), and autophagy-related proteins were significantly decreased after Cr(VI) exposure. These findings suggest that Cr(VI) leads to the disorder of mitochondrial dynamics by inhibiting the Sirt1/PGC-1a pathway, which leads to renal apoptosis and autophagy in rats.

Comparative Cr, As and CCA induced Cytostaticity in mice kidney: A contribution to assess CCA toxicity

CCA (Chromium Copper Arsenate) treated wood, widely used in outdoor residential structures and playgrounds, poses considerable dangers of leaching of its components to the environment. In this study, mouse kidney samples were used to evaluate the effects of CCA, chromium trioxide (CrO₃) and arsenic pentoxide (As₂O₅) on cell pathophysiology by flow cytometry. Samples were collected after 14, 24, 48 and 96 h of animal exposure. While Cr had no statistically significant cytostatic effects, As₂O₅ induced a S-phase delay in animals exposed for 24 h, and over time a G0/G1 phase blockage. The effects of CCA in S-phase were similar, but more severe than those of As₂O₅. Since environmental and public health hazards due to the long durability of CCA-treated wood products, these data confirm that CCA has profoundly toxic effects on cell cycle, distinct from the compounds themselves. These cytostatic effects support cell cycle dynamics as a valuable endpoint to assess the toxicity of remaining CCA-treated infrastructures, and the expected increased waste stream over the coming decades.

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.

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.

Hepatoprotective effect of Taraxacum officinale leaf extract on sodium dichromate-induced liver injury in rats

Taraxacum officinale (L.) Weber, commonly known as Dandelion, has been widely used as a folkloric medicine for the treatment of liver and kidney disorders and some women diseases such as breast and uterus cancers. The main objective of the present study was to assess the efficiency of T. officinale leaf extract (TOE) in treating sodium dichromate hazards; it is a major environmental pollutant known for its wide toxic manifestations witch induced liver injury. TOE at a dose of 500 mg/kg b.w was orally administered once per day for 30 days consecutively, followed by 10 mg/kg b.w sodium dichromate was injected (intraperitoneal) for 10 days. Our results using Wistar rats showed that sodium dichromate significantly increased serum biochemical parameters. In the liver, it was found to induce an oxidative stress, evidenced from increase in lipid peroxidation and changes in antioxidative activities. In addition, histopathological observation revealed that sodium dichromate causes acute liver damage, necrosis of hepatocytes, as well as DNA fragmentation. Interestingly, animals that were pretreated with TOE, prior to sodium dichromate administration, showed a significant hepatoprotection, revealed by a significant reduction of sodium dichromate-induced oxidative damage for all tested markers. These finding powerfully supports that TOE was effective in the protection against sodium dichromate-induced hepatotoxicity and genotoxicity and, therefore, suggest a potential therapeutic use of this plant as an alternative medicine for patients with acute liver diseases.

Toxic effects of chromium (VI) by maternal ingestion on liver function of female rats and their suckling pups

Potassium dichromate (K(2)Cr(2)O(7)) is an environmental contaminant widely recognized as a carcinogen, mutagen, and teratogen toward humans and animals. This study investigated the effects of K(2)Cr(2)O(7) on the hepatic function of pregnant and lactating rats and their suckling pups. Experiments were carried out on female Wistar rats given 700 ppm of K(2)Cr(2)O(7) in their drinking water from the 14th day of pregnancy until day 14 after delivery. Hepatotoxicity was objectified by the significant increase in liver malondialdehyde content and a significant accumulation of chromium in this soft tissue. Moreover, exposure to K(2)Cr(2)O(7) induced a decrease of glutathione, nonprotein thiols, and vitamin C in the liver of mothers and their suckling pups. Alteration of the antioxidant system in the treated group was confirmed by the significant decline of antioxidant enzyme activities such as catalase, glutathione peroxidase, while liver superoxide dismutase activity increased in mothers and decreased in their offspring. It was found that K(2)Cr(2)O(7) induced liver damages as evidenced by the elevation of plasma aminotransferases, lactate dehydrogenase activities, and bilirubin levels. Impairment of the hepatic function corresponded histologically. Our investigation revealed hemorrhage, leukocytes infiltration cells, and necrosis, which were more pronounced in the hepatocytes of mothers than in those of their suckling pups.

Protective effect of ω-3 polyunsaturated fatty acids (PUFAs) on sodium nitroprusside-induced nephrotoxicity and oxidative damage in rat kidney

Sodium nitroprusside (SNP) a nitric oxide (NO) donor has proven toxic effects. Dietary ω-3 polyunsaturated fatty acid (PUFA) has been shown to reduce the severity of numerous ailments. Present study examined whether intake of fish oil (FO)/flaxseed oil (FXO, Omega Nutrition, St Vancouver, Canada) would have protective effect against SNP-induced toxicity. Male Wistar rats (150 ± 10 g) were used in this study. Initially animals were divided into two groups: one fed on normal diet and the other on 15% FO/FXO for 15 days. On the 16th day, SNP (1.5 mg/kg body weight) was administered intraperitoneally for 7 days daily. After 7 days animals were killed, kidneys were harvested for further analysis. SNP induced nephrotoxicity by increasing serum creatinine and blood urea nitrogen, SNP significantly decreased malate dehydrogenase, glucose-6-phosphatase, fructose-1,6-bisphosphatase and malic enzyme but increased lactate dehydrogenase and glucose-6-phosphate dehydrogenase. Brush border membrane enzymes such as alkaline phosphatase, γ-glutamyl transpeptidase and leucine amino peptidase were also decreased. The activity of catalase and glutathione peroxidase decreased concomitantly with increased lipid peroxidation, indicating that the significant kidney damage has been inflicted by SNP. Feeding of FO and FXO with SNP ameliorated the changes in various parameters caused by SNP. The results of the present study suggest that ω-3 PUFA-enriched FO and FXO from seafoods and plant sources, respectively, are similarly effective in reducing SNP-induced nephrotoxicity and oxidative damage. Thus, vegetarians who cannot consume FO can have similar health benefits from plant-derived ω-3 PUFA.

Oxidative stress induced by chromium (VI) in bone of suckling rats

Exposure to hexavalent chromium Cr(VI) compounds is of concern in many Cr-related industries and their surrounding environments. K2Cr2O7 is widely recognized as an animal and human carcinogen, mutagen, and teratogen. The present study investigated the bone maturity of suckling rats whose mothers were treated with K2Cr2O7. Experiments were carried out on female Wistar rats given 700 ppm of K2Cr2O7 in their drinking water from the 14th day of pregnancy until day 14 after delivery. Exposing dams to K2Cr2O7 caused disorders in the bone of their progeny. As corollary to this, malondialdehyde levels increased, while glutathione, a non-protein thiol and vitamin C decreased. Alteration of the antioxidant system in the treated group was also confirmed by the significant decline of superoxide dismutase, catalase, and glutathione peroxidase activities. Furthermore, K2Cr2O7 induced changes in bone mineralization, especially calcium and phosphorus levels, which decreased. Whereas, in plasma and urine, they increased and decreased inversely. These results suggest that K2Cr2O7 accelerated bone resorption activity. In fact, in treated pups, total tartrate-resistant acid phosphatase, which reflected bone resorption, was enhanced while total alkaline phosphatase, which reflected bone formation, was reduced. The impairment of bone function was corresponded histologically.

Cardioprotective effects of selenium on chromium (VI)-induced toxicity in female rats

Acute exposure to hexavalent chromium compounds can cause cardiotoxicity. Our study pertains to the protective effect of selenium against K(2)Cr(2)O(7)-induced cardiotoxicity. Female Wistar rats were divided into four groups of six each: group I served as controls which received standard diet; group II received in drinking water K(2)Cr(2)O(7) alone (700 ppm); group III received both K(2)Cr(2)O(7) and Se (0.5 Na(2)SeO(3) mg/kg of diet); group IV received Se (0.5 mg/kg of diet) for 3 weeks. The exposure of rats to chromium promoted oxidative stress with an increase in malondialdehyde levels and a decrease in antioxidant non-enzymatic levels such as glutathione, non-protein thiol and vitamin C, while, an increase in glutathione peroxidase, superoxide dismutase and catalase activities was observed. However, plasma transaminases, lactate dehydrogenase activities, cholesterol, triglycerides and low density lipoprotein-cholesterol levels increased, and high density lipoprotein-cholesterol decreased. Coadministration of Se restored the parameters cited above to near-normal values. The histopathological findings confirmed the biochemical results.

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

Chromium is a toxic metal implicated in human diseases. This study was focused on investigating the possible protective effect of Se against K(2)Cr(2)O(7). Female Wistar rats, used in this study, were divided into four groups of six animals each: group I served as control which received standard diet; group II received orally only K(2)Cr(2)O(7) (700 ppm equivalent to 67 mg/kgbw); group III received both K(2)Cr(2)O(7) and Se (0.5 mg/kg of diet); group IV received Se (0.5mg Na(2)SeO(3)/kg of diet). The exposure of rats to K(2)Cr(2)O(7) for 21 days provoked renal damages with a significant increase in kidney malondialdehyde, superoxide dismutase, plasma creatinine, and uric acid levels, while catalase, glutathione peroxidase, non-protein thiol, Metallothionein and plasma urea levels decreased. Coadministration of Se in the diet of chromium-treated group improved malondialdehyde, renal biomarkers levels and antioxidant enzyme activities. Kidney histological studies confirmed biochemical parameters and the beneficial role of selenium.

Potassium dichromate-induced changes on urinary-specific activities of gamma-glutamyl transpeptidase and alanine aminopeptidase enzymes

It has been reported that potassium dichromate-induced nephrotoxicity is evidenced by diminution in creatinine clearance, increase in urinary protein, and structural damage to the proximal tubules. Damage to tissue often leads to the release of enzymes from the injured cells into the extracellular fluids. The aim of this study was to establish whether potassium dichromate induces changes in the urinary-specific activities of gamma-glutamyl transpeptidase and alanine aminopeptidase enzymes. Our results show that the administration of a single intraperitoneal dose of potassium dichromate decreased the activity of such enzymes in urine.

Acute renal failure enhances the antidotal activity of pralidoxime towards paraoxon-induced respiratory toxicity

We recently showed in a rat model of dichromate-induced acute renal failure (ARF) that the elimination but not the distribution of pralidoxime was altered resulting in sustained plasma pralidoxime concentrations. The aim of this study was to compare the efficiency of pralidoxime in normal and acute renal failure rats against paraoxon-induced respiratory toxicity. Ventilation at rest was assessed using whole-body plethysmography after subcutaneous administration of either saline or paraoxon (50% of the LD(50)), in the control and ARF rats. Thirty minutes after administration of paraoxon, either saline or 50mg/kg of pralidoxime was administered intramuscularly. ARF had no significant effects on the ventilation at rest. The effects of paraoxon on respiration were not significantly different in the control and ARF group. Paraoxon increased the total time (T(TOT)), expiratory time (T(E)) and tidal volume (V(T)), and decreased the respiratory frequency (f). In paraoxon-poisoned rats with normal renal function, pralidoxime had a significant but transient effect regarding the T(TOT) and V(T) (p<0.05). In the ARF group, the same dose of pralidoxime significantly decreased the T(TOT), T(E), and V(T) and increased f during 90 min (p<0.01). In conclusion, pralidoxime had partial and transient effects towards paraoxon-induced respiratory toxicity in control rats; and a complete and sustained correction in ARF rats.

Effect of trichloroethylene (TCE) toxicity on the enzymes of carbohydrate metabolism, brush border membrane and oxidative stress in kidney and other rat tissues

Trichloroethylene (TCE), an industrial solvent, is a major environmental contaminant. Histopathological examinations revealed that TCE caused liver and kidney toxicity and carcinogenicity. However, biochemical mechanism and tissue response to toxic insult are not completely elucidated. We hypothesized that TCE induces oxidative stress to various rat tissues and alters their metabolic functions. Male Wistar rats were given TCE (1000 mg/kg/day) in corn oil orally for 25 d. Blood and tissues were collected and analyzed for various biochemical and enzymatic parameters. TCE administration increased blood urea nitrogen, serum creatinine, cholesterol and alkaline phosphatase but decreased serum glucose, inorganic phosphate and phospholipids indicating kidney and liver toxicity. Activity of hexokinase, lactate dehydrogenase increased in the intestine and liver whereas decreased in renal tissues. Malate dehydrogenase and glucose-6-phosphatase and fructose-1, 6-bisphosphatase decreased in all tissues whereas increased in medulla. Glucose-6-phosphate dehydrogenase increased but NADP-malic enzyme decreased in all tissues except in medulla. The activity of BBM enzymes decreased but renal Na/Pi transport increased. Superoxide dismutase and catalase activities variably declined whereas lipid peroxidation significantly enhanced in all tissues. The present results indicate that TCE caused severe damage to kidney, intestine, liver and brain; altered carbohydrate metabolism and suppressed antioxidant defense system.

Nephrotoxicity of CCA-treated wood: A comparative study with As(2)O(5) and CrO(3) on mice

The purpose of this work was to assess the acute toxicity on male mice to a chromated copper arsenate (CCA) solution, a widespread wood preservative used in building industry until 2002. Animals were subcutaneously injected with CCA (7.2mg/kg arsenic and 10.2mg/kg chromium per body weight), CrO(3) (10.2mg/kg), As(2)O(5) (7.2mg/kg) and NaCl (0.9%) per se, during 48h and 96h, for histopathology, histochemistry, chromium and arsenic analysis. The results showed some histopathological changes within renal tubules lumen of CCA exposed animals (during 48h, and 96h), and CrO(3) (for the period of 96h). Furthermore, the renal levels of arsenic and chromium in treated animals were statistically more evident than controls. Although, the same contents of pentavalent arsenic and hexavalent chromium were injected into treated animals with CCA and with the prepared solutions of As(2)O(5) and CrO(3), a different distribution of the pattern of these compounds was observed in kidneys.

Effect of different doses of hexavalent chromium on mandibular growth and tooth eruption in juvenile Wistar rats

Not only workers employed at industrial plants are exposed to intoxication with the element they manipulate, the population at large is also at risk of suffering health problems caused by contaminating wastes inadequately treated for their safe disposal. As a result certain toxic substances, such as hexavalent chromium,has reached the general population including children. The present study sought to evaluate the effect of intoxication with hexavalent chromium on body and mandibular growth and tooth eruption in suckling Wistar rats. Potassium dichromate was administered by gavage in a dose of 6.25 or 12.5mg/kg body weight (b.w.) to one of the two groups of 4-day-old Wistar rats during 10 days. Our results showed that the effects of chromium are dose-dependent. Morphometric studies of body growth showed lower body weight in both experimental groups and shorter tail length in animals receiving 12.5mg/kg b.w. dose of chromium, compared with controls. All parameters of mandibular growth were lower in the experimental group receiving 12.5mg/kg b.w. of chromium. Differences in tooth eruption were observed at the level of the first molar in animals receiving 12.5mg/kg and of the second molar in those receiving 6.25mg/kg b.w. of chromium. Chromium was found to affect all the studied parameters.

Vitamin C attenuates potassium dichromate-induced nephrotoxicity and alterations in renal brush border membrane enzymes and phosphate transport in rats

BACKGROUND

Exposure to chromium compounds can result in nephrotoxicity. The administration of potassium dichromate (K(2)Cr(2)O(7)), a hexavalent chromium compound, results in impairment in functions of renal brush border membrane (BBM).

METHODS

The effect of vitamin C (ascorbic acid) on K(2)Cr(2)O(7)-induced nephrotoxicity, changes in BBM enzymes, Pi transport and the anti-oxidant status of rat kidney were studied. Animals were divided into 4 groups and were intraperitoneally given saline (control), vitamin C alone, K(2)Cr(2)O(7) alone and vitamin C plus K(2)Cr(2)O(7). Nephrotoxicity was evaluated by urea and creatinine levels in the serum. Anti-oxidant status was evaluated in kidney homogenates.

RESULTS

A single dose of K(2)Cr(2)O(7) (15 mg/kg body weight) resulted in an increase of serum urea nitrogen and creatinine levels, increase in lipid peroxidation and decrease in total sulfhydryl groups. However, prior treatment with a single dose of vitamin C (250 mg/kg body weight) protected the kidney from the damaging effects of K(2)Cr(2)O(7). It greatly ameliorated the K(2)Cr(2)O(7)-induced nephrotoxicity and reduction in Pi transport, activities of catalase, Cu-Zn superoxide dismutase and BBM enzymes. This was accompanied by decrease in lipid peroxidation and recovery of sulfhydryl content of renal cortex.

CONCLUSIONS

Vitamin C is an effective chemoprotectant against K(2)Cr(2)O(7)-induced acute renal failure and dysfunction of the renal BBM in rats.