Relationship of antioxidant and oxidative stress markers in different organs following copper toxicity in a rat model

Alleviation of Copper-Induced Hepatotoxicity by Bergenin: Diminution of Oxidative Stress, Inflammation, and Apoptosis via Targeting SIRT1/FOXO3a/NF-κB Axes and p38 MAPK Signaling

Despite its biological importance, excess copper induces organ damage, especially to the liver. Disruption of critical signaling cascades that control redox status, inflammatory responses, and cellular apoptosis significantly contributes to the copper-induced hepatotoxicity. The present work explored the hepatoprotective ability of bergenin against the copper-induced hepatotoxicity using male Wistar rats as a mammalian model. The results revealed that bergenin suppressed the copper-evoked histopathological changes and hepatocellular necrosis as indicated by decreased activity of the liver enzymes ALT and AST in the sera of the copper-intoxicated rats. It decreased hepatic copper content and the copper-induced oxidative stress as revealed by reduced lipid peroxidation and improved activity of the antioxidant enzymes thioredoxin reductase, glutathione peroxidase, catalase, and superoxide dismutase. Bergenin downregulated the inflammatory cytokines TNF-α and IL-6, and the inflammatory cell infiltration to the liver tissues. Additionally, it inhibited the copper-induced apoptosis as indicated by significant reduction in caspase-3 activity. At the molecular level, bergenin activated the antioxidant transcription factor FOXO3a, inhibited the nuclear translocation of the inflammatory transcription factor NF-κB, and suppressed the inflammatory signaling molecules p38 MAPK and c-Fos. Interestingly, bergenin improved the expression of the anti-apoptotic protein Bcl2 and reduced the pro-apoptotic protein BAX. Bergenin markedly enhanced the expression of the histone deacetylase protein SIRT1 that regulates activity of NF-κB and FOXO3a. Collectively, these findings highlight the alleviating activity of bergenin against the copper-induced hepatotoxicity via controlling oxidative stress, inflammation, and apoptosis potentially through upregulation of SIRT1, activation of FOXO3a along with suppression of NF-κB and p38 MAPK signaling.

Association of prenatal multiple metal exposures with child neurodevelopment at 3 years of age: A prospective birth cohort study

Prenatal exposures to toxic metals and trace elements have been linked to childhood neurodevelopment. However, existing evidence remains inconclusive, and further research is needed to investigate the mixture effects of multiple metal exposures on childhood neurodevelopment. We aimed to examine the associations between prenatal exposure to specific metals and metal mixtures and neurodevelopment in children. In this prospective cohort study, we used the multivariable linear regressions and the robust modified Poisson regressions to explore the associations of prenatal exposure to 25 specific metals with neurodevelopment among children at 3 years of age in 854 mother-child pairs from the Jiangsu Birth Cohort (JBC) Study. The Bayesian kernel machine regression (BKMR) was employed to assess the joint effects of multiple metals on neurodevelopment. Prenatal manganese (Mn) exposure was negatively associated with the risk of non-optimal cognition development of children, while vanadium (V), copper (Cu), zinc (Zn), antimony (Sb), cerium (Ce) and uranium (U) exposures were positively associated with the risk of non-optimal gross motor development. BKMR identified an interaction effect between Sb and Ce on non-optimal gross motor development. Additionally, an element risk score (ERS), representing the mixture effect of multiple metal exposures including V, Cu, Zn, Sb, Ce and U was constructed based on weights from a Poisson regression model. Children with ERS in the highest tertile had higher probability of non-optimal gross motor development (RR = 2.37, 95 % CI: 1.15, 4.86) versus those at the lowest tertile. Notably, Sb [conditional-posterior inclusion probabilities (cPIP) = 0.511] and U (cPIP = 0.386) mainly contributed to the increased risk of non-optimal gross motor development. The findings highlight the importance of paying attention to the joint effects of multiple metals on children's neurodevelopment. The ERS score may serve as an indicator of comprehensive metal exposure risk for children's neurodevelopment.

Melatonin alleviates brain injury in copper-laden rats: Underlying benefits for Wilson's disease

Copper serves as an indispensable cofactor for all living organisms, and its excessive accumulation has been associated with a variety of diseases. Wilson's disease (WD) serves as an illustrative example of copper toxicity in humans, frequently presenting with liver and/or neuropsychiatric symptoms. The current therapeutic drugs, penicillamine (PA) and zinc gluconate (ZnG), have constraints, and research on their combination efficacy remains insufficient. It has been reported that melatonin (MLT) plays a vital role in binding to transition metals and exhibits strong antioxidant capacity. To investigate the therapeutic efficacy of MLT and combined treatment, rats were randomly divided into the following seven groups: the control (Con) group, copper-laden model rat (Mod) group, PA-treated group, ZnG-treated group, MLT- treated group, PA-ZnG-treated group, and PA-MLT-treated group. Then potential mechanisms and targets were investigated using a combination of metabolomics and network pharmacology and verified by molecular docking and qPCR. The findings revealed that MLT and the combination significantly improved behavior, pathology and copper levels in copper-laden rats. The results of the metabolomics study showed that profoundly altered metabolites were identified, and alanine, aspartate and glutamate metabolism, pyruvate metabolism, citrate cycle (TCA cycle), and glycolysis/gluconeogenesis were explored. In addition, molecular docking showed that MLT had high binding affinity with key targets, and qPCR results revealed that MLT could reverse the mRNA expression of targets GOT2 and PKM2. It was concluded that MLT effectively improves brain injury in copper-laden rats, and this effect was linked with the altered features of the metabolite profiles.

Associations among environmental exposure to trace elements and biomarkers of early kidney damage in the pediatric population

BACKGROUND

In kidney damage, molecular changes can be used as early damage kidney biomarkers, such as Kidney Injury Molecule-1 and Neutrophil gelatinase-associated lipocalin. These biomarkers are associated with toxic metal exposure or disturbed homeostasis of trace elements, which might lead to serious health hazards. This study aimed to evaluate the relationship between exposure to trace elements and early damage kidney biomarkers in a pediatric population.

METHODS

In Tlaxcala, a cross-sectional study was conducted on 914 healthy individuals. The participants underwent a medical review and a socio-environmental questionnaire. Five early damage kidney biomarkers were determined in the urine with Luminex, and molybdenum, copper, selenium, nickel, and iodine were measured with ICP-Mass.

RESULTS

The eGFR showed a median of 103.75 mL/min/1.73 m2. The median levels for molybdenum, copper, selenium, nickel, and iodine were 24.73 ng/mL, 73.35 ng/mL, 4.78 ng/mL, 83.68 ng/mL, and 361.83 ng/mL, respectively. Except for molybdenum and nickel, the other trace elements had significant associations with the eGFR and the early kidney damage biomarkers. Additionally, we report the association of different exposure scenarios with renal parameters.

DISCUSSION

and Conclusions. Among the explored metals, exposure to Cu and iodine impairs renal function. In contrast, Se may manifest as a beneficial metal. Interactions of Mo-Se and Mo-Iodine seem to alter the expression of NGAL; Mo-Cu for CLU; Mo-Cu, Mo-Se, and Mo-iodine for Cys-C and a-1MG; and Mo-Cu and Mo-iodine for KIM-1; were noticed. Our study could suggest that trace element interactions were associated with early kidney damage biomarkers.

Elucidating cuproptosis in metabolic dysfunction-associated steatotic liver disease

Emerging research into metabolic dysfunction-associated steatotic liver disease (MASLD) up until January 2024 has highlighted the critical role of cuproptosis, a unique cell death mechanism triggered by copper overload, in the disease's development. This connection offers new insights into MASLD's complex pathogenesis, pointing to copper accumulation as a key factor that disrupts lipid metabolism and insulin sensitivity. The identification of cuproptosis as a significant contributor to MASLD underscores the potential for targeting copper-mediated pathways for novel therapeutic approaches. This promising avenue suggests that managing copper levels could mitigate MASLD progression, offering a fresh perspective on treatment strategies. Further investigations into how cuproptosis influences MASLD are essential for unraveling the detailed mechanisms at play and for identifying effective interventions. The focus on copper's role in liver health opens up the possibility of developing targeted therapies that address the underlying causes of MASLD, moving beyond symptomatic treatment to tackle the root of the problem. The exploration of cuproptosis in the context of MASLD exemplifies the importance of understanding metal homeostasis in metabolic diseases and represents a significant step forward in the quest for more effective treatments. This research direction lights path for innovative MASLD management and reversal.

Kidney involvement in Wilson's disease: a review of the literature

Wilson's disease (WD) is a rare inherited disease due to the mutation of the ATP7B gene, resulting in impaired hepatic copper excretion and its pathological accumulation in various organs such as the liver, the nervous system, or the kidneys. Whereas liver failure and neuropsychiatric disorders are the most common features, less is known about the renal complications. We conducted a review of the literature to define the characteristics and pathophysiology of kidney involvement during WD. This review shed light on strong evidence for direct copper toxicity to renal tubular cells. Excessive tubular copper accumulation might present with various degrees of tubular dysfunction, ranging from mild hydroelectrolytic and acid-base disorders to complete Fanconi syndrome. Proximal and distal renal tubular acidosis also favors development of nephrolithiasis, nephrocalcinosis, and bone metabolism abnormalities. Indirect complications might involve renal hypoperfusion as occurs in hepatorenal or cardiorenal syndrome, but also tubular casts' formation during acute hemolysis, rhabdomyolysis, or bile cast nephropathy. Acute kidney failure is not uncommon in severe WD patients, and independently increases mortality. Finally, specific and long-term therapy by D-penicillamin, one of the most efficient drugs in WD, can cause glomerular injuries, such as membranous nephropathy, minimal-change disease, and, rarely, severe glomerulonephritis. Altogether, our study supports the need for interdisciplinary evaluation of WD patients involving nephrologists, with regular monitoring of tubular and glomerular functions, to provide adequate prevention of renal and bone involvement.

Ideal serum non-ceruloplasmin bound copper prediction for long-term treated patients with Wilson disease: a nomogram model

Purpose

This study aimed to explore the factors associated with the optimal serum non-ceruloplasmin bound copper (NCBC) level and develop a flexible predictive model to guide lifelong therapy in Wilson disease (WD) and delay disease progression.

Methods

We retrospectively collected clinical data from 144 patients hospitalized in the Encephalopathy Center of the first affiliated hospital of Anhui University of Chinese Medicine between May 2012 and April 2023. Independent variables were selected using variate COX and LASSO regressions, followed by multivariate COX regression analysis. A predictive nomogram was constructed and validated using the concordance index (C-index), calibration curves, and clinical decision curve analysis, of which nomogram pictures were utilized for model visualization.

Results

A total of 61 (42.36%) patients were included, with an average treatment duration of 55.0 (range, 28.0, 97.0) months. Multivariate regression analysis identified several independent risk factors for serum NCBC level, including age of diagnosis, clinical classification, laminin liver stiffness measurement, and copper to zinc ratio in 24-h urinary excretion. The C-index indicated moderate discriminative ability (48 months: 0.829, 60 months: 0.811, and 72 months: 0.819). The calibration curves showed good consistency and calibration; clinical decision curve analysis demonstrated clinically beneficial threshold probabilities at different time intervals.

Conclusion

The predictive nomogram model can predict serum NCBC level; consequently, we recommend its use in clinical practice to delay disease progression and improve the clinical prognosis of WD.

Chrysin Encapsulated Copper Nanoparticles with Low Dose of Gamma Radiation Elicit Tumor Cell Death Through p38 MAPK/NF-κB Pathways

Improving radiation effect on tumor cells using radiosensitizers is gaining traction for improving chemoradiotherapy. This study aimed to evaluate copper nanoparticles (CuNPs) synthesized using chrysin as radiosensitizer with γ-radiation on biochemical and histopathological approaches in mice bearing Ehrlich solid tumor. CuNPs were characterized with irregular round sharp shape with size range of 21.19-70.79 nm and plasmon absorption at 273 nm. In vitro study on MCF-7 cells detected cytotoxic effect of CuNPs with IC50 of 57.2 ± 3.1 μg. In vivo study was performed on mice transplanted with Ehrlich solid tumor (EC). Mice were injected with CuNPs (0.67 mg/kg body weight) and/or exposed to low dose of gamma radiation (0.5 Gy). EC mice exposed to combined treatment of CuNPs and radiation showed a marked reduction in tumor volume, ALT and CAT, creatinine, calcium, and GSH, along with elevation in MDA, caspase-3 in parallel with inhibition of NF-κB, p38 MAPK, and cyclin D1 gene expression. Comparing histopathological findings of treatment groups ends that combined treatment was of higher efficacy, showing tumor tissue regression and increase in apoptotic cells. In conclusion, CuNPs with a low dose of gamma radiation showed more powerful ability for tumor suppression via promoting oxidative state, stimulating apoptosis, and inhibiting proliferation pathway through p38MAPK/NF-κB and cyclinD1.

Vitamin D alleviates cognitive dysfunction and brain damage induced by copper sulfate intake in experimental rats: focus on its combination with donepezil

This study aimed to demonstrate the potential benefits of donepezil (DPZ) and vitamin D (Vit D) in combination to counteract the neurodegenerative disorders induced by CuSO4 intake in experimental rats. Neurodegeneration (Alzheimer-like) was induced in twenty-four male Wistar albino rats by CuSO4 supplement to drinking water (10 mg/L) for 14 weeks. AD rats were divided into four groups: untreated AD group (Cu-AD) and three treated AD groups; orally treated for 4 weeks with either DPZ (10 mg/kg/day), Vit D (500 IU/kg/day), or DPZ + Vit D starting from the 10th week of CuSO4 intake. Another six rats were used as normal control (NC) group. The hippocampal tissue content of β-amyloid precursor protein cleaving enzyme 1 (BACE1), phosphorylated Tau (p-tau), clusterin (CLU), tumor necrosis factor-α (TNF-α), caspase-9 (CAS-9), Bax, and Bcl-2 and the cortical content of acetylcholine (Ach), acetylcholinesterase (AChE), total antioxidant capacity (TAC), and malondialdehyde (MDA) were measured. Cognitive function tests (Y-maze) and histopathology studies (hematoxylin and eosin and Congo red stains) and immunohistochemistry for neurofilament. Vit D supplementation alleviated CuSO4-induced memory deficits including significant reduction hippocampal BACE1, p-tau, CLU, CAS-9, Bax, and TNF-α and cortical AChE and MDA. Vit D remarkably increased cortical Ach, TAC, and hippocampal Bcl-2. It also improved neurobehavioral and histological abnormalities. The effects attained by Vit D treatment were better than those attained by DPZ. Furthermore, Vit D boosted the therapeutic potential of DPZ in almost all AD associated behavioral and pathological changes. Vit D is suggested as a potential therapy to retard neurodegeneration.

Neuroprotective Effects of P-Coumaric Acid on Haloperidol-Induced Catalepsy Through Ameliorating Oxidative Stress and Brain Dopamine Level

Objective

To evaluate the effect of p-coumaric acid (p-CA) on haloperidol-induced catalepsy in Swiss albino male mice.

Methods

To induce catalepsy, haloperidol (1 mg/kg i.p.) was administered for 21 consecutive days. p-CA (50, 75, and 100 mg/kg, PO) was administered 30 min before haloperidol injection for 21 consecutive days. For catalepsy, locomotor activity and motor coordination scores were recorded on the 17, 14, and 21 days of drug treatment, while the gait analysis score was recorded on day 21. After behavioral testing, animals were sacrificed, and various biochemical and histopathology tests of the brain were conducted. Dopamine, malondialdehyde, reduced glutathione (GSH), superoxide dismutase (SOD), and catalase activity were examined in the brain.

Results

Chronic administration of haloperidol significantly increased catalepsy in mice. It also produced hypolocomotion, motor coordination, and gait disturbance in mice. p-CA significantly inhibited haloperidol-induced catalepsy. Haloperidol significantly increased malondialdehyde levels in the brain. While dopamine levels in the brain dropped along with GSH, SOD, and catalase activity levels, which also had an impact on the histology of the brain. p-CA significantly reduced haloperidol-induced increases in brain oxidative stress, dopamine levels in the brain, and brain histology in mice.

Discussion

p-CA significantly reduced haloperidol-induced catalepsy, possibly through reducing oxidative stress and increasing brain dopamine levels. It can be a good candidate drug for extrapyramidal symptoms in Parkinson’s disease and adjuvant therapy with antipsychotic drugs.

Glutathione improves testicular spermatogenesis through inhibiting oxidative stress, mitochondrial damage, and apoptosis induced by copper deposition in mice with Wilson disease

BACKGROUND AND OBJECTIVE

There are considerable evidence of reproductive impairment in male organisms with Wilson disease (WD). The purpose of this study was to observe spermatogenesis, mitochondrial damage, apoptosis, and the level of oxidative stress in the testes of Wilson disease model TX mice, and to observe the effect and mechanism of glutathione on testicular spermatogenesis.

METHODS

Mice were divided into a normal control group (control group), Wilson disease model TX mice group (WD group), penicillamine-treated TX mice group (penicillamine group) and glutathione-treated TX mice group (glutathione group). Testicular coefficient, histomorphology of testis and epididymis, number of spermatozoa, apoptosis of spermatogenic cells and expression of apoptosis-related proteins were observed. Ultrastructural analysis of mitochondria and mitochondrial membrane potential (MMP) monitored using JC-1 dye were used to detect mitochondrial damage. The levels of malondialdehyde (MDA), glutathione (GSH), catalase (CAT), and reactive oxygen species (ROS) in testicular cells were measured to assess oxidative stress.

RESULTS

Testicular coefficient did not change in mice with Wilson disease. However, the tissue structure of the testicular seminiferous tubules was damaged, and the number of spermatozoa in the epididymal lumen was significantly reduced in WD group. The apoptosis rate in the testes was significantly increased. The protein expression of the pro-apoptotic proteins Bax and Caspase-3 significantly increased, and the expressions of the anti-apoptotic protein Bcl-2 significantly decreased. The levels of ROS and MDA significantly increased, and the levels of CAT and GSH significantly decreased. Mitochondria with abnormal ultrastructure and the rate of JC-1 positive cells were significantly increased in the WD group. After copper chelation by penicillamine, the structure of the testicular seminiferous tubules and the number of spermatozoa in the epididymal lumen were significantly improved. The number of apoptotic cells was significantly reduced. The levels of Bax and Caspase-3 decreased, and the expression of Bcl-2 increased. The contents of CAT and GSH increased, and the levels of ROS and MDA decreased significantly. The abnormal mitochondria and JC-1 positive cells was significantly decreased. The histomorphology of seminiferous tubules, spermatogenic function, apoptosis rate, apoptosis-related proteins, mitochondrial damage, and oxidative stress in Wilson disease TX mice significantly improved after glutathione treatment.

CONCLUSION

Copper deposition in Wilson disease can lead to oxidative stress injury, mitochondrial damage, and apoptosis in the testis, leading to the impairment of spermatogenesis. Glutathione may improve testicular spermatogenesis in male Wilson disease TX mice by inhibiting copper deposition-induced oxidative stress, mitochondrial damage, and apoptosis.

Associations between co-exposure to multiple metals and renal function: a cross-sectional study in Guangxi, China

The association between co-exposure to multiple metals and renal function is poorly understood. We aimed to evaluate the individual and joint effects of metal exposure on renal function in this study. We performed a cross-sectional study including 5828 participants in Guangxi, China, in 2019. Urine concentrations of 17 metals were detected by inductively coupled plasma mass spectrometry (ICP-MS). Logistic regression model and restricted cubic spline (RCS) were applied to investigate the association of individual metal exposure with renal dysfunction. Weighted quantile sum (WQS) regression and Bayesian kernel machine regression (BKMR) were used to assess the co-exposure effects of the metals. Participants with the highest quartile of urinary Cu were at 1.84-fold (95% confidence interval (CI): 1.20-2.87) increased risk of renal dysfunction compared with the lowest quartile. The highest quartiles of urinary Sr, Cs, V, Ba, and Se were associated with 0.27-fold (95% CI: 0.17-0.43), 0.33 (95% CI: 0.19-0.53), 0.41 (95% CI: 0.25-0.65), 0.58 (95% CI: 0.36-0.90), and 0.33 (95% CI: 0.19-0.56) decreased risk of renal dysfunction compared with their lowest quartile, respectively. Furthermore, urinary Ba and Cu were non-linearly correlated with renal dysfunction. The WQS analysis showed that mixed metal exposure was inversely associated with renal dysfunction (OR = 0.47, 95% CI: 0.35-0.62), and Sr accounted for the largest weight (52.2%), followed by Cs (32.3%) in the association. Moreover, we observed a potential interaction between Cu, Cs, and Ba for renal dysfunction in BKMR model. Exposure to Se, Sr, Cs, V, and Ba is associated with decreased risk of renal dysfunction, whereas an increased risk is associated with Cu exposure. Co-exposure to these metals is negatively associated with renal dysfunction, and Sr and Cs are the main contributors to the associations.

Re-evaluation of the existing health-based guidance values for copper and exposure assessment from all sources

Copper is an essential micronutrient and also a regulated product used in organic and in conventional farming pest management. Both deficiency and excessive exposure to copper can have adverse health effects. In this Scientific Opinion, the EFSA 2021 harmonised approach for establishing health-based guidance values (HBGVs) for substances that are regulated products and also nutrients was used to resolve the divergent existing HBGVs for copper. The tightly regulated homeostasis prevents toxicity manifestation in the short term, but the development of chronic copper toxicity is dependent on copper homeostasis and its tissue retention. Evidence from Wilson disease suggests that hepatic retention is indicative of potential future and possibly sudden onset of copper toxicity under conditions of continuous intake. Hence, emphasis was placed on copper retention as an early marker of potential adverse effects. The relationships between (a) chronic copper exposure and its retention in the body, particularly the liver, and (b) hepatic copper concentrations and evidence of toxicity were examined. The Scientific Committee (SC) concludes that no retention of copper is expected to occur with intake of 5 mg/day and established an Acceptable Daily Intake (ADI) of 0.07 mg/kg bw. A refined dietary exposure assessment was performed, assessing contribution from dietary and non-dietary sources. Background copper levels are a significant source of copper. The contribution of copper from its use as plant protection product (PPP), food and feed additives or fertilisers is negligible. The use of copper in fertilisers or PPPs contributes to copper accumulation in soil. Infant formula and follow-on formula are important contributors to dietary exposure of copper in infants and toddlers. Contribution from non-oral sources is negligible. Dietary exposure to total copper does not exceed the HBGV in adolescents, adults, elderly and the very elderly. Neither hepatic copper retention nor adverse effects are expected to occur from the estimated copper exposure in children due to higher nutrient requirements related to growth.

Association of copper exposure with prevalence of chronic kidney disease in older adults

BACKGROUND & AIMS

Metal exposure is suspected to be associated with the risk of chronic kidney disease (CKD). Copper (Cu) is an essential yet toxic trace element in humans. Epidemiological evidence on the association of Cu exposure with CKD remains inconsistent. This study aims to investigate the association of blood Cu and its co-exposure to other metals with CKD.

METHODS

A cross-sectional study was conducted among 3285 older participants in Zhejiang, China. The whole blood levels of Cu as well as other 10 metals were measured using the inductively coupled plasma mass spectrometry (ICP-MS). CKD events were defined as the presence of albuminuria or estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m². Multivariable logistic regression and linear regression models were applied to assess the association of Cu with kidney function. The Bayesian kernel machine regression (BKMR) was used to examine the association of metal interactions with CKD.

RESULTS

In logistic models, we found a dose-dependent positive association between blood Cu and the prevalence of CKD. Compared to the lowest quartile of blood Cu, the odds ratio (OR) of CKD in the highest quartile was 1.65 (95% confidence interval, CI: 1.25, 2.17), and the β of eGFR was -1.74 (95% CI: -3.15, -0.34) after adjusting for multiple covariates. The positive linear dose-response association was found between blood Cu and the OR of CKD, and negative linear association was found between Cu and the β of eGFR. The positive association between blood Cu and CKD risk was stronger at lower level of manganese (Mn) in the BKMR model.

CONCLUSION

The whole blood level of Cu was remarkably associated with the risk of CKD and showed positive dose-response relationships in the older Chinese population. The toxicity of Cu on kidney function could be antagonized by the exposure of Mn. These findings shed new light on the potential role of Cu in kidney health.

Oral Administration of Copper Chloride Damages DNA, Lowers Antioxidant Defense, Alters Metabolic Status, and Inhibits Membrane Bound Enzymes in Rat Kidney

Copper (Cu) is a heavy metal that is widely used in industries and is also an essential micronutrient for living beings. However, excess Cu is toxic and human exposure to high levels of this metal results in numerous adverse health effects. We have investigated the effect of oral administration of copper chloride (CuCl₂), a Cu(II) compound, on various parameters of oxidative stress, cellular metabolism, and DNA integrity in the rat kidney. This was done to delineate the molecular mechanism of Cu(II) toxicity. Adult male rats were randomly divided into five groups. Animals in four CuCl₂-treated groups were separately administered single acute oral dose of CuCl₂ at 5, 15, 30, and 40 mg/kg body weight. Animals in the fifth group were not given CuCl₂ and served as the control. All rats were sacrificed 24 h after the dose of CuCl₂ and their kidneys removed. CuCl₂ administration led to significant alterations in enzymatic and non-enzymatic parameters of oxidative stress. It changed the activities of metabolic and membrane bound enzymes and also decreased the activities of brush border membrane enzymes. CuCl₂ treatment dose-dependently enhanced DNA damage and DNA-protein crosslinking in renal cells, when compared to the control group. The administration of CuCl₂ also resulted in marked morphological changes in the kidney, with more prominent alterations at higher doses of CuCl₂. These results clearly show that CuCl₂ impairs the antioxidant defense system resulting in oxidative damage to the kidney.

D-ribose-L-cysteine reduces oxidative stress and inflammatory cytokines to mitigate liver damage, and memory decline induced by copper sulfate in mice

BACKGROUND

Current evidences have implicated copper in amyloid aggregation that trigger the downstream oxidative stress-mediated neuroinflammation that characterized memory deterioration in patients with Alzheimer's disease (AD). Thus, this study was designed to evaluate the effect of D-Ribose-L-Cysteine (DRLC), a potent antioxidant agent, on copper sulfate (CuSO₄)-induced memory deterioration and the biochemical mechanisms underpinning its action in mice.

METHODS

Male Swiss mice were randomly distributed into 5 groups (n = 10/group). Mice in group 1 were given distilled water (control), group 2 CuSO₄ (100 mg/kg) while groups 3-5 were pretreated with CuSO₄ (100 mg/kg) 30 min before administration of DRLC (10, 25 and 50 mg/kg). Treatments were given through oral gavage, daily for 28 days. Memory function was evaluated on day 28 using Y-maze test. The isolated liver and brain tissues were then processed for oxidative stress biomarkers, and proinflammatory cytokines [tumor necrosis factor- α (TNF-α) and interleukin-6)] assays. Brian acetylcholinesterase (AChE) and liver enzymes [aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities were also determined.

RESULTS

DRLC reversed memory impairment and dysregulated levels of malondialdehyde, glutathione, nitrite and glutathione S-transferase in the liver and brain tissues of mice pretreated with CuSO₄. The increased proinflammatory cytokines concentrations in the liver and brain tissues of mice pretreated with CuSO₄ were reduced by DRLC. The elevated brain AChE and liver enzymes activities induced by CuSO₄ were also reduced by DRLC.

CONCLUSION

Taken together, these findings suggest that DRLC attenuates CuSO₄-induced memory dysfunctions in mice through enhancement of antioxidative pathway, inhibition of pro-inflammatory cytokines and augmentation of liver function.

Recent Advances of Optical Sensors for Copper Ion Detection

A trace element copper (Cu2+) ion is the third most plentiful metal ion that necessary for all living organisms and playing a critical role in several processes. Nonetheless, according to cellular needs, deficient or excess Cu2+ ion cause various diseases. For all these reasons, optical sensors have been focused rapid Cu2+ ion detection in real-time with high selectivity and sensitivity. Optical sensors can measure fluorescence in the refractive index-adsorption from the relationships between light and matter. They have gained great attention in recent years due to the excellent advantages of simple and naked eye recognition, real-time detection, low cost, high specificity against analytes, a quick response, and the need for less complex equipment in analysis. This review aims to show the significance of Cu2+ ion detection and electively current trends in optical sensors. The integration of optical sensors with different systems, such as microfluidic systems, is mentioned, and their latest studies in medical and environmental applications also are depicted. Conclusions and future perspectives on these advances is added at the end of the review.

Investigation of Thiol/Disulfide Homeostasis and Ischemia-Modified Albumin Levels in Children with Wilson Disease

BackgroundThe aim of the present study was to assess thiol/disulfide homeostasis (TDH) parameters and ischemia-modified albumin (IMA) levels in children with Wilson Disease (WD) and to compare them to healthy controls. Methods: Based on the inclusion and exclusion criteria, fifteen children with WD and twenty-nine healthy children were enrolled, and serum thiol/disulfide and IMA levels were compared between groups. Results: The mean values of native and total thiols were significantly lower in the WD group than in the control group. The mean value of disulfide was significantly higher in the WD group than in the control group. The mean percentages of disulfide/total thiol and native thiol/total thiol were higher in the WD group than in the control group. The IMA value was also higher in the WD group than in the control group. Conclusion: The present study demonstrating altered thiol/disulfide parameters indicates increased oxidative stress in children with WD.

Histopathological and Biochemical Comparative Study of Copper Oxide Nanoparticles and Copper Sulphate Toxicity in Male Albino Mice Reproductive System

Copper (Cu) is an essential trace element for the efficient functioning of living organisms. Cu can enter the body in different ways, and when it surpasses the range of biological tolerance, it can have negative consequences. The use of different nanoparticles, especially metal oxide nanoparticles, is increasingly being expanded in the fields of industry and biomedical materials. However, the impact of these nanoparticles on human health is still not completely elucidated. This comparative study was conducted to evaluate the impacts of copper oxide nanoparticles (CuO NPs) and copper sulphate (CuSO₄ 0.5 (H₂O)) on infertility and reproductive function in male albino mice BALB/c. Body weight, the weight of male reproductive organs, malondialdehyde (MDA) level, caspase-3 level, and the presence of Ki67 and CD68, as detected using the amino-histochemistry technique, were investigated. Animals were treated with 25 and 35 mg/kg of CuO NPs and CuSO₄ 0.5 (H₂O) by oral gavage for 14 days. The control group was given distilled water by oral gavage. Body weight significantly decreased at the end of experiments in both treated groups in a concentration- and time-dependent manner compared with the control group. Weights of testes and epididymis (head and tail), as well as the weight of the seminal vesicle, showed a significant decrease compared with the control. However, the average weights of the seminal vesicle and prostate significantly increased. Caspase-3 and MDA levels increased in the CuO NP and CuSO₄ 0.5 (H₂O) groups compared with the control group, and there was a significant difference between the two concentrations used. Immunohistochemical results detected a significant decrease in Ki67 protein in the treatment groups compared with the control. However, increase in CD68 protein was found in groups treated with CuO NPs and CuSO₄ 0.5 (H₂O) compared with the control group. Overall, this in vivo comparative study of CuO NPs and CuSO₄ 0.5 (H₂O) showed that oral intake of copper NPs at 25 and 23 mg/kg was safer to the mice reproductive system than CuSO₄ 0.5 (H₂O) at the same dose. CuSO₄ 0.5 (H₂O) significantly influenced the histopathological and toxicological alteration responses.

Protective Mechanism of Gandou Decoction in a Copper-Laden Hepatolenticular Degeneration Model: In Vitro Pharmacology and Cell Metabolomics

Gandou decoction (GDD) is a classic prescription for the treatment of hepatolenticular degeneration (HLD) in China; however, the liver-protecting mechanism of this prescription needs further evaluation. In the present study, we explored the protective mechanisms of GDD in a copper-laden HLD model using integrated pharmacology and cellular metabolomics in vitro. The results revealed that GDD could significantly promote copper excretion in copper-laden HLD model cells and improve the ultrastructural changes in hepatocytes. In addition, GDD could decrease the extent of lipid peroxidation, levels of reactive oxygen species, and the release rate of lactate dehydrogenase while increasing the activity of superoxide dismutase and the ratio of glutathione to oxidized glutathione in the copper-laden HLD model cells. On conducting statistical analysis of significant metabolic changes, 47 biomarkers and 30 related metabolic pathways were screened as pharmacological reactions induced by GDD in HLD model cells. d-glutamate and d-glutamine metabolic pathways showed the highest importance and significance among the 30 metabolic pathways, and the differential expression levels of the glutamine synthetase (GS) and the renal type and liver type GLS (GLS1 and GLS2) proteins were verified by Western blotting. Collectively, our data established the underlying mechanism of GDD therapy, such as the promotion of copper excretion and improvement in oxidative stress by regulating the expressions of GS, GLS1, and GLS2 protein to protect hepatocytes from injury.

Therapeutic role of nitroglycerin against copper-nitrilotriacetate induced hepatic and renal damage

Earlier we have shown that exposure to copper-nitrilotriacetate (Cu-NTA) manifests toxicity by generating oxidative stress and potent induction of proliferative reaction in the liver and kidney. In the study, we look at the impact of nitroglycerin (GTN) administration on Cu-NTA-induced oxidative stress and hyperproliferative response in the liver and kidney. GTN administration intraperitoneally to male Wistar rats after Cu-NTA administration intraperitoneally caused substantial protection against Cu-NTA-induced tissue injury, oxidative stress and hyperproliferative response. Cu-NTA administration at a dose of 4.5 mg/kg body weight produces significant ( p < .001) elevation in biochemical parameters including aspartate aminotransferase (AST), alanine aminotransferase (ALT), blood urea nitrogen (BUN) and creatinine (CREA) with a concomitant increase in microsomal lipid peroxidation. Along with these alterations, we discovered a substantial increment in [3H]thymidine incorporation into hepatic and renal DNA synthesis ( p < .001). Cu-NTA-induced tissue damage and lipid peroxidation in hepatic and renal tissues were inhibited by GTN treatment in a dose-dependent manner ( p < .05–0.001). Furthermore, GTN can suppress the hyperproliferative response elicited by Cu-NTA by down-regulating the rate of [3H]thymidine incorporation into hepatic and renal DNA ( p < .01–0.001). Protective effect of GTN against Cu-NTA was also confirmed by histopathological changes in liver and kidney. This result suggests that GTN may serve as a scavenger for reactive oxygen species (ROS) and reduces toxic metabolites of Cu-NTA, thereby avoiding tissue injury and oxidative stress. Further, administration of NO inhibitor, NG-Nitroarginine methyl ester (L-NAME), exacerbated Cu-NTA induced oxidative tissue damage and cell proliferation. Overall, GTN reduces Cu-NTA-induced tissue damage, oxidative stress, and proliferative response in the rat liver and kidney, according to these findings. On the basis of the above results, present study suggests that GTN may be a potential therapeutic agent for restoration of oxidative damage and proliferation to liver and kidney.

Dietary Copper Supplementation Increases Growth Performance by Increasing Feed Intake, Digestibility, and Antioxidant Activity in Rex Rabbits

Copper is often used as a growth promoter, at the same time copper is one of the most important essential trace elements for fur animals, especially Rex rabbits. However, too much copper added to the diet may harm animal health, and copper excreted in feces can pollute the environment. In this study, 3-month-old Rex rabbits were randomly divided into four groups and fed a basal diet containing 0, 30, 60, or 120 mg/kg Cu for 5 weeks. The diet supplemented with 30 mg/kg Cu significantly increased (P < 0.05) the average daily feed intake (ADFI) and the average daily gain (ADG) and also the activity of serum Cu-Zn (zinc) superoxide dismutase and the digestibility of ether extract. Supplemental Cu up to 120 mg/kg did not significantly adversely affect the Zn metabolism of growing Rex rabbits. Overall, the data in this study indicate that 30 mg/kg is the optimal level of Cu supplementation in the diet of growing Rex rabbits. The results will provide a reference to improve the breeding of Rex rabbits and possibly other animals. In follow-up studies, the amount of copper in the diet should be reduced as much as possible from the baseline of 30 mg/kg copper.

Effects of Long-Term Exposure to Copper on the Keap1/Nrf2 Signaling Pathway and Msr-Related Redox Status in the Kidneys of Rats

The objective of the present study was to examine the effects of long-term exposure on oxidative damage, Keap1/Nrf2 signaling pathway, and Msr-related redox status in the kidneys of rats. Therefore, in this experimental study, a total of 32 CD-1 rats were randomized into 4 groups and treated with 30-, 60-, and 120-mg/kg Cu for 24 weeks. Different serum biomarkers suggestive of renal functions, pathological changes, and oxidative stress were analyzed in kidney tissues. Moreover, the levels of the Keap1/Nrf2 signaling pathway and redox status-related gene mRNA and proteins were also detected. The results indicated that Cu exposure dramatically increased the contents of creatinine and carbamide. Furthermore, histopathological alterations and mitochondrial damage in kidneys of rats of different Cu-treated groups were obviously observed. In addition, Cu exposure markedly changed the levels of glutathione, catalase, and total antioxidant capacity, and upregulated the contents of protein carbonyl, nitric oxide, and malondialdehyde. Moreover, higher levels of Cu treatments significantly increased the expression of Keap1/Nrf2 signaling pathway and redox status-related genes (NQO1, SOD-1, TRX, MsrA, MsrB1, MsrB2, MsrB3). Simultaneously, the mRNA expression levels of Nrf2, HO-1, and CAT were upregulated in rats exposed to 30- and 60-mg/kg Cu, but downregulated in the 120-mg/kg Cu group compared with the control group. Moreover, the Keap1/Nrf2 signaling pathway and redox status-related protein expression levels (HO-1, SOD-1, TRX, MsrA, MsrB1, MsrB2) were significantly increased in treated rats. In summary, it is suggested that the Keap1/Nrf2 signaling pathway and activation of Msr prevent Cu-induced nephrotoxicity and attenuate oxidative damage.

Copper chloride inhibits brush border membrane enzymes, alters antioxidant and metabolic status and damages DNA in rat intestine: a dose-dependent study

Copper (Cu) is an extensively used heavy metal and an indispensible micronutrient for living beings. However, Cu is also toxic and exerts multiple adverse health effects when humans are exposed to high levels of this metal. We have examined the effect of single acute oral dose of copper chloride (CuCl₂) on parameters of oxidative stress, cellular metabolism, membrane and DNA damage in rat intestine. Adult male Wistar rats were divided into four groups and separately administered a single oral dose of 5, 15, 30 and 40 mg CuCl₂/kg body weight. Rats not administered CuCl₂ served as the control. Oral administration of CuCl₂ led to significant alterations in the activities of metabolic and membrane-bound enzymes; brush border enzymes were inhibited by 45-75% relative to the control set. Inhibition of antioxidant enzymes diminished the metal-reducing and free radical quenching ability of the cells. Oxidative damage caused cellular oxidation of thiols, proteins and lipids. Diphenylamine and comet assays showed that CuCl₂ treatment enhanced DNA damage while DNA-protein crosslinking was also increased in the intestinal cells. Examination of stained sections showed that CuCl₂ treatment led to marked histological changes in the intestine. All the changes seen were in a CuCl₂ dose-dependent manner with more prominent alterations at higher doses of CuCl₂. These results clearly show that oral administration of CuCl₂ results in oxidative damage to the intestine which can impair its digestive and absorptive functions.

Metabolomics and transcriptomics indicated the molecular targets of copper to the pig kidney

Copper poses huge environmental and public health concerns due to its widespread and persistent use in the past several decades. Although it is well established that at higher levels copper causes nephrotoxicity, the exact mechanisms of its toxicity is not fully understood. Therefore, this experimental study for the first time investigates the potential molecular mechanisms including transcriptomics, metabolomics, serum biochemical, histopathological, cell apoptosis and autophagy in copper-induced renal toxicity in pigs. A total of 14 piglets were randomly assigned to two group (7 piglets per group) and treated with a standard diet (11 mg CuSO4 per kg of feed) and a high copper diet (250 mg CuSO4 per kg of feed). The results of serum biochemical tests and renal histopathology suggested that 250 mg/kg CuSO4 in the diet significantly increased serum creatinine (CREA) and induced renal tubular epithelial cell swelling. Results on transcriptomics and metabolomics showed alteration in 804 genes and 53 metabolites in kidneys of treated pigs, respectively. Combined analysis of transcriptomics and metabolomics indicated that different genes and metabolism pathways in kidneys of treated pigs were involved in glycerophospholipids metabolism and glycosphingolipid metabolism. Furthermore, copper induced mitochondrial apoptosis characterized by increased bax, bak, caspase 3, caspase 8 and caspase 9 expressions while decreased bcl-xl and bcl2/bax expression. Exposure to copper decreased the autophagic flux in terms of increased number of autophagosomes, beclin1 and LC3b/LC3a expression and p62 accumulation. These results indicated that the imbalance of glycosphingolipid metabolism, the impairment of autophagy and increase mitochondrial apoptosis play an important role in copper induced renal damage and are useful mechanisms to understand the mechanisms of copper nephrotoxicity.

Does Hyperglycemia Cause Oxidative Stress in the Diabetic Rat Retina?

Diabetes, being a metabolic disease dysregulates a large number of metabolites and factors. However, among those altered metabolites, hyperglycemia is considered as the major factor to cause an increase in oxidative stress that initiates the pathophysiology of retinal damage leading to diabetic retinopathy. Diabetes-induced oxidative stress in the diabetic retina and its damaging effects are well known, but still, the exact source and the mechanism of hyperglycemia-induced reactive oxygen species (ROS) generation especially through mitochondria remains uncertain. In this study, we analyzed precisely the generation of ROS and the antioxidant capacity of enzymes in a real-time situation under ex vivo and in vivo conditions in the control and streptozotocin-induced diabetic rat retinas. We also measured the rate of flux through the citric acid cycle by determining the oxidation of glucose to CO2 and glutamate, under ex vivo conditions in the control and diabetic retinas. Measurements of H2O2 clearance from the ex vivo control and diabetic retinas indicated that activities of mitochondrial antioxidant enzymes are intact in the diabetic retina. Short-term hyperglycemia seems to influence a decrease in ROS generation in the diabetic retina compared to controls, which is also correlated with a decreased oxidation rate of glucose in the diabetic retina. However, an increase in the formation of ROS was observed in the diabetic retinas compared to controls under in vivo conditions. Thus, our results suggest of diabetes/hyperglycemia-induced non-mitochondrial sources may serve as major sources of ROS generation in the diabetic retina as opposed to widely believed hyperglycemia-induced mitochondrial sources of excess ROS. Therefore, hyperglycemia per se may not cause an increase in oxidative stress, especially through mitochondria to damage the retina as in the case of diabetic retinopathy.

Activation of the ROS/HO-1/NQO1 signaling pathway contributes to the copper-induced oxidative stress and autophagy in duck renal tubular epithelial cells

The aim of this study was to investigate the crosstalk between oxidative stress and autophagy through the ROS/HO-1/NQO1 pathway caused by copper (Cu). Duck renal tubular epithelial cells were treated in Cu sulfate (CuSO₄) (0, 100 and 200 μM) for 12 h, and in the combination of CuSO₄ (200 μM) and reactive oxygen species (ROS) scavenger (butyl hydroxyanisole, BHA, 100 μM), or HO-1 inhibitor (zinc protoporphyrin, ZnPP, 10 μM) for 12 h. Results revealed that Cu could significantly elevate the levels of intracellular ROS, superoxide dismutase, hydrogen peroxide, malondialdehyde, glutathione, simultaneously reduce catalase and glutathione peroxidase levels, and upregulate HO-1, SOD-1, CAT, NQO1, GCLM mRNA levels and HO-1, SOD-1 protein levels. Additionally, Cu could observably increase the number of autophagosomes, acidic vesicle organelles (AVOs) and LC3 puncta; upregulate mRNA levels of mTOR, Beclin-1, ATG7, ATG5, ATG3, LC3II and protein levels of Beclin-1, LC3II/LC3I, downregulate LC3I mRNA level. Both treatments with BHA and ZnPP could significantly alleviate the changes of antioxidant indexes levels and ROS accumulation, reduce the increase of the number of autophagosomes, AVOs and LC3 puncta, and mitigate the above changed oxidative stress and autophagy related mRNA and protein levels induced by Cu. In summary, our findings indicated that excessive Cu could induce oxidative stress and autophagy by activating the ROS/HO-1/NQO1 pathway, and inhibition of HO-1 might attenuate Cu-induced oxidative stress and autophagy in duck renal tubular epithelial cells.

Associations among Heavy Metals and Proteinuria and Chronic Kidney Disease

Background: The prevalence of chronic kidney disease (CKD) is increasing annually in Taiwan. In addition to traditional risk factors, heavy metals contribute to the development of CKD. The aim of this study was to investigate associations among heavy metals and proteinuria and CKD in the general population in Southern Taiwan. We also explored the interaction and synergetic effects among heavy metals on proteinuria. Methods: We conducted a health survey in the general population living in Southern Taiwan between June 2016 and September 2018. Seven heavy metals were measured: blood lead (Pb) and urine nickel (Ni), chromium (Cr), manganese (Mn), arsenic (As), copper (Cu), and cadmium (Cd). Proteinuria was measured using reagent strips. CKD was defined as an estimated glomerular filtration rate (eGFR) of <60 mL/min/1.73 m². Results: The mean age of the 2447 participants was 55.1 ± 13.2 years and included 977 males and 1470 females. Participants with high blood Pb and high urine Ni, Mn, Cu, and Cd were significantly associated with proteinuria. Interactions between blood Pb and urine Cr, and between urine Cd and Cu, had significant effects on proteinuria. The participants with high blood Pb and high urine Cu were significantly associated with an eGFR of <60 mL/min/1.73 m². Conclusion: High blood Pb and high urine Cu may be associated with proteinuria and an eGFR of <60 mL/min/1.73 m². High urine Ni, Mn, and Cd were significantly associated with proteinuria. Co-exposure to Cd and Cu, and Pb and Cr, may have synergistic effects on proteinuria.

Molecular Mechanisms Underlying Protective Role of Quercetin on Copper Sulfate-Induced Nephrotoxicity in Mice

Copper overload is an established cause of nephrotoxicity, but the precise molecular mechanism remains unknown. Our study aimed to investigate the molecular mechanism of copper sulfate (CuSO₄)-induced nephrotoxicity and the protective effect of the natural compound quercetin using a mouse model. Mice were orally administered CuSO₄ only (200 mg/kg per day), or co-administered CuSO₄ (200 mg/kg per day) plus quercetin (25, 50, or 100 mg/kg per day), or quercetin only (100 mg/kg per day), or vehicle for 28 days. The blood and kidneys were collected for the examination of serum biomarkers, oxidative stress biomarkers, changes in histopathology and gene and protein expression. Our results show that quercetin supplementation attenuates CuSO₄-induced renal dysfunction and tubular necrosis in a dose-dependent manner. Quercetin supplementation at 50 and 100 mg/kg significantly attenuated CuSO₄-induced oxidative damage. Quercetin supplementation also inhibited the activities of caspases-9 and-3, and the expression of p53 and Bax mRNAs. Furthermore, quercetin supplementation markedly activated the expression of Nrf2 and HO-1 mRNAs, but inhibited the expression of NF-κB, IL-1β, IL-6, and TNF-α mRNAs. In conclusion, our results revealed that quercetin supplementation could inhibit CuSO₄-induced nephrotoxicity in mice via the inhibition of mitochondrial apoptotic and NF-κB pathways and the activation of Nrf2/HO-1 pathway. Our study highlights quercetin as a potential candidate in treating copper overload-induced nephrotoxicity.

Gandou Decoction Decreases Copper Levels and Alleviates Hepatic Injury in Copper-Laden Hepatolenticular Degeneration Model Rats

Objective: This study was designed to investigate the therapeutic efficacy and underlying mechanisms of Gandou Decoction (GDD) in copper-laden hepatolenticular degeneration (HLD) model rats. Methods: In this study, high-performance liquid chromatography (HPLC) fingerprint analysis and eight representative active components were simultaneously measured for quality control of GDD. The therapeutic effect of GDD in HLD was studied by constructing a rat model of copper-laden HLD. The copper levels in the liver, serum, urine, and feces were quantified by atomic absorption spectrophotometry (AAS). Subsequently, UV-Vis spectrophotometry was used to study the coordination ability of copper ion (Cu2+) with six representative active components in GDD to explore its potential copper expulsion mechanism. Serological indexes including alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (AKP) were evaluated. Hepatic indicators including superoxide dismutase (SOD), glutathione (GSH), and the total antioxidant capacity (T-AOC) were determined. Moreover, the liver tissue was stained with hematoxylin-eosin to observe the histological changes. Results: Thirty characteristic fingerprint peaks were used to assess the similarities among 10 samples and showed the similarity was >0.98, indicating a good correlation among the common peaks. Simultaneous quantification of eight markers in GDD was then performed to determine the consistency of quality. GDD could decrease the serum and hepatic copper levels by increasing the urinary and fecal copper content in copper-laden rats. Meanwhile, the results of UV-Vis absorption studies show that six representative active ingredients in GDD can coordinate with Cu2+, indicating that complexing copper removal may be a potential mechanism for GDD to play a role in copper removal. Serum hepatic enzyme markers AST, ALT, and AKP activities and antioxidant enzyme SOD, T-AOC activities, and GSH level in hepatic tissue showed the protection of GDD against liver injury induced by excessive copper. Additionally, the hepatoprotective effect of GDD was also evidenced by the results of the liver histological evaluation. Conclusions: This study suggested that GDD could reduce the serum and hepatic copper levels through promoting urinary and fecal copper excretion in copper-laden rats. At the same time, GDD could alleviate hepatic injury by inhibition of oxidative stress.

Molecular Insights of Copper Sulfate Exposure-Induced Nephrotoxicity: Involvement of Oxidative and Endoplasmic Reticulum Stress Pathways

The precise pathogenic mechanism in Cu exposure-cause nephrotoxicity remains unclear. This study investigated the underlying molecular mechanism of copper sulfate (CuSO₄)-induced nephrotoxicity. Mice were treated with CuSO₄ at 50, 100, 200 mg/kg/day or co-treated with CuSO₄ (200 mg/kg/day) and 4-phenylbutyric acid (4-PBA, 100 mg/kg/day) for 28 consecutive days. HEK293 cells were treated with CuSO₄ (400 μM) with or without superoxide dismutase, catalase or 4-PBA for 24 h. Results showed that CuSO₄ exposure can cause renal dysfunction and tubular necrosis in the kidney tissues of mice. CuSO₄ exposure up-regulated the activities and mRNA expression of caspases-9 and -3 as well as the expression of glucose-regulated protein 78 (GRP78), GRP94, DNA damage-inducible gene 153 (GADD153/CHOP), caspase-12 mRNAs in the kidney tissues. Furthermore, superoxide dismutase and catalase pre-treatments partly inhibited CuSO₄-induced cytotoxicity by decreasing reactive oxygen species (ROS) production, activities of caspases-9 and -3 and DNA fragmentations in HEK293 cells. 4-PBA co-treatment significantly improved CuSO₄-induced cytotoxicity in HEK293 cells and inhibited CuSO₄ exposure-induced renal dysfunction and pathology damage in the kidney tissues. In conclusion, our results reveal that oxidative stress and endoplasmic reticulum stress contribute to CuSO₄-induced nephrotoxicity. Our study highlights that targeting endoplasmic reticulum and oxidative stress may offer an approach for Cu overload-caused nephrotoxicity.

Oxidative damage under As3+ and/or Cu2+ stress leads to apoptosis and autophagy and may be cross-talking with mitochondrial disorders in bursa of Fabricius

Arsenic (As) exists in many forms in the whole natural environment, with As³⁺ the highest toxicity. Herein our study demonstrated that arsenic trioxide (As₂O₃) at a dose of 30 mg/kg caused serious oxidative damage to chickens' bursa of Fabricius (BF) in a time-dependent manner. Copper (Cu) is a necessary micronutrient and a key catalytic cofactor of many enzymes. We found excessive Cu (in the form of 300 mg/kg copper sulfate (CuSO₄)) also induced severe oxidative stress (OxS), and its co-exposure with As³⁺ had a greater destructive power against oxidative system. Under electron microscope, swollen mitochondria, disappeared cristae and agglutinated chromatin were observed, accompanied by myeloid structure and autophagosome. The results showed apoptosis and autophagy occurred under the action of As³⁺ and Cu²⁺, and the situation was more serious in combined exposure group, which was further explained by terminal deoxynucleotidyl transferase (TdT)-mediated 2'-Deoxyuridine 5'-Triphosphate (dUTP) Nick-End Labeling (TUNEL). By quantitative real time polymerase chain reaction (RT-qPCR) and western blot, we found that mitochondrial dynamics were disordered under OxS, and the abnormal changes of B-cell lymphoma (Bcl)-2, p53, Bcl-2-interacting protein (Beclin)-1 and autophagy-related gene (ATG) 4B indicated the crosstalk between apoptosis and autophagy. In conclusion, apoptosis and autophagy of BF induced by As³⁺ and Cu²⁺ and mitochondrial disorder are closely related to the collapse of antioxidant system, and their connections are inseparable. Our results provide a reference for environmental risk prevention and selection of poultry feed additives and pesticides to avoid the health risks caused by As³⁺ and Cu²⁺ exposure.

Advances in the mechanism of high copper diets in restraining pigs growth

High copper feed has been widely used as an inexpensive and highly effective feed additive to promote growth performance of pigs. However, long-term feeding of high copper feed may reduce the growth-promoting effects of copper, time-dependent accumulation of copper in animal tissues and organs, and copper toxicity thereby reducing the growth performance of pigs. Due to the widespread effects of high copper supplementation in animals' diets, the benefits and drawbacks of high copper feeding in pigs have been reported in several studies. Meanwhile, few of these studies have systematically described the mechanism by which high copper diets restrain pig growth. Therefore, to address the concerns and give a better understanding of the mechanism of high copper diet in restraining pig growth in different systems, this paper reviews the research progress of long-term supplementation of high copper on the growth of pigs and provides some suggestions and further research directions.

Movement Disorder in Copper Toxicity Rat Model: Role of Inflammation and Apoptosis in the Corpus Striatum

The pattern of copper (Cu) toxicity in humans is similar to Wilson disease, and they have movement disorders and frequent involvement of corpus striatum. The extent of cell deaths in corpus striatum may be the basis of movement disorder and may be confirmed in the experimental study. To evaluate the extent of apoptosis and glial activation in corpus striatum following Cu toxicity in a rat model, and correlate these with spontaneous locomotor activity (SLA), six male Wistar rats were fed normal saline (group I) and another six were fed copper sulfate 100 mg/kgBWt/daily orally (group II). At 1 month, neurobehavioral studies including SLA, rotarod, and grip strength were done. Corpus striatum was removed and was subjected to glial fibrillary acidic protein (GFAP) and caspase-3 immunohistochemistry. The concentration of tissue Cu, total antioxidant capacity (TAC), glutathione (GSH), malondialdehyde (MDA), and glutamate were measured. Group II rats had higher expression of caspase-3 (Mean ± SEM 32.67 ± 1.46 vs 4.47 ± 1.08; p < 0.01) and GFAP (41.81 ± 1.68 vs 31.82 ± 1.27; p < 0.01) compared with group I. Neurobehavioral studies revealed reduced total distance traveled, time moving, the number of rearing, latency to fall on the rotarod, grip strength, and increased resting time compared with group I. The expression of GFAP and caspase-3 correlated with SLA parameters, tissue Cu, GSH, MDA, TAC, and glutamate levels. The impaired locomotor activity in Cu toxicity rats is due to apoptotic and inflammatory-mediated cell death in the corpus striatum because of Cu-mediated oxidative stress and excitotoxicity.

Destruction of redox and mitochondrial dynamics co-contributes to programmed cell death in chicken kidney under arsenite or/and copper (II) exposure

BACKGROUND

Sub-chronic arsenic (arsenite) exposure-induced oxidative toxicity leads to adverse effects in various organ systems, especially the kidney. Copper sulphate (Cu²⁺), known for its extensive uses in agriculture, has also been reported to have pro-oxidation properties. Both of these two potential toxic elements can bio-accumulate through food chain, thus endangering human health. However, their interaction study in the kidney is scanty.

AIM

To investigate the synergism effects of Cu²⁺ in arseniasis-elicited oxidative stress and cascaded renal injury in chickens.

RESULTS

Arsenite intoxication decreased renal antioxidant system along with ATPases. Arsenite exposure also significantly elicited disequilibrium of mitochondrial homeostasis, accompanying by elevated apoptotic and autophagic cell death. The disturbed morphological and ultrastructural changes further corroborated arsenite nephrotoxicity. These anomalies aligned with the findings in Cu²⁺ groups, which co-administrated with arsenic further deteriorated these pathological changes. This synergism was achieved partially via the inactivation of phosphoinositide-3-kinase/protein kinase b/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway through the activation of P53.

CONCLUSIONS

Copper excess and arsenic exposure can function independently or cooperatively to affect oxidative stress, mitochondrial dynamics and programmed cell death. These results highlighted the need to take precautions against copper and arsenic co-exposure when considering their impact in susceptible animals/populations.

Protective effects of tribulus terrestris extract and angiotensin blockers on testis steroidogenesis in copper overloaded rats

The rational of the current study was to assess whether Tribulus terrestris extract (TTE) could alleviate long-term copper (Cu) overload-induced testicular dysfunction compared to enalapril and losartan. Rats were administered either vehicle (control group, n = 10) or copper sulfate pentahydrate (CuSO₄·5H₂O, 200 mg/kg, p.o) for 90 days (n = 40). Cu-treated rats were randomized into four equal groups. One group was left untreated (Cu group) while the remaining three groups were daily co-treated with one of the following treatments along with CuSO4: TTE (10 mg/kg, p.o); enalapril (30 mg/kg, p.o); losartan (10 mg/kg, p.o). Excess Cu intake resulted in Cu overload coupled with a significant elevation in systolic blood pressure and serum angiotensin II levels along with a reduction in serum nitric oxide level. All concomitant treatments led to an alleviation of such deleterious effects. However, only losartan failed to ameliorate angiotensin II elevation. Additionally, all treatments protected the testes against Cu-overload-elicited zinc depletion and oxidative stress. Regarding reproductive function, the relative weights of testes, serum levels of testosterone and luteinizing hormone; the expression of steroidogenic genes; the protein levels of angiotensin II type 1 receptor and angiotensin converting enzyme 1, in addition to its activity, they were significantly reduced. Amongst all treatments, only TTE and E were able to revert these reproductive changes. In conclusion TTE and E were able to protect against Cu overload-induced impairment of testicular steroidogenesis. Thus, they might be considered as prophylactic drugs of choice against hypertension and testicular dysfunction to ameliorate Cu overload risk.

Effects of Super Nutritional Hepatic Copper Accumulation on Hepatocyte Health and Oxidative Stress in Dairy Cows

Concerns regarding excessive hepatic copper concentrations in dairy cows have increased. The objective of this study was to determine the association of hepatic copper concentrations with evidence of liver disease. Blood and liver samples were collected at the time of slaughter in cull dairy cows (n=100). Liver samples were analyzed for copper using inductively coupled plasma mass spectrometry and crude fat using liquid-liquid extraction and gravimetry. Serum samples were analyzed for glutamate dehydrogenase, γ-glutamyltransferase, sorbitol dehydrogenase, aspartate aminotransferase activities, and bile acid concentrations. Liver samples were examined histologically for inflammation, fibrosis, and rhodanine staining. Animals were stratified by hepatic copper concentration and samples in the highest and lowest quintiles (Q5 and Q1) were evaluated for oxidative stress. Systemic indices of oxidative stress included serum reactive oxygen and nitrogen species (RONS) and total antioxidant potential (AOP). Tissue-level oxidative stress was assessed by immunohistochemistry using 4-hydroxynonenal (4HNE) and 3-nitrotyrosine (3NIT) stains to score the relative abundance and distribution of oxidized lipid and protein products, respectively. Mean hepatic copper concentration was 496.83 μg/g and median 469.72 μg/g and ranged from 70.56 to 1264.27 μg/g dry tissue. No association was found between hepatic copper concentrations and clinicopathological or histological evidence of hepatic damage or dysfunction. There was a significant increase in the amount of IHC staining of 4HNE and 3NIT in Q5 compared with Q1. Moreover, the IHC staining mirrored the distribution of the copper-specific stain rhodanine. These results demonstrate that cows with elevated hepatic copper concentrations had no evidence of active liver disease but had increased hepatic oxidative stress.

Copper in the suprachiasmatic circadian clock: A possible link between multiple circadian oscillators

The mammalian circadian clock in the suprachiasmatic nucleus (SCN) is very robust, able to coordinate our daily physiological and behavioral rhythms with exquisite accuracy. Simultaneously, the SCN clock is highly sensitive to environmental timing cues such as the solar cycle. This duality of resiliency and sensitivity may be sustained in part by a complex intertwining of three cellular oscillators: transcription/translation, metabolic/redox, and membrane excitability. We suggest here that one of the links connecting these oscillators may be forged from copper (Cu). Cellular Cu levels are highly regulated in the brain and peripherally, and Cu affects cellular metabolism, redox state, cell signaling, and transcription. We have shown that both Cu chelation and application induce nighttime phase shifts of the SCN clock in vitro and that these treatments affect glutamate, N-methyl-D-aspartate receptor, and associated signaling processes differently. More recently we found that Cu induces mitogen-activated protein kinase-dependent phase shifts, while the mechanisms by which Cu removal induces phase shifts remain unclear. Lastly, we have found that two Cu transporters are expressed in the SCN, and that one of these transporters (ATP7A) exhibits a day/night rhythm. Our results suggest that Cu homeostasis is tightly regulated in the SCN, and that changes in Cu levels may serve as a time cue for the circadian clock. We discuss these findings in light of the existing literature and current models of multiple coupled circadian oscillators in the SCN.

Deciphering the ionic homeostasis, oxidative stress, apoptosis, and autophagy in chicken intestine under copper(II) stress

As cofactors of several enzymatic, copper (Cu) participates in many essential metabolic processes. Also, as a heavy metal, it exhibits highly toxic to the organism if excessive. This study endeavored to detect the pathophysiological changes in the jejunum of chickens, which were insulted by CuSO₄ (300 mg/kg diet) for 90 days. Results showed metabolic disorders of trace elements evidenced by their significant downregulations (Na, Al, Li, B, Cr, Ni, Sn, Sb, Ba) and upregulations (Cu, Si, As, Cd, Se, and Tl) in 90 days. Simultaneously, increased TdT-mediated dUTP nick end labeling (TUNEL)-positive nuclei and distinct ultrastructural apoptotic features were observed. Meanwhile, in 30, 60, and 90 days, indicators of oxidative stress, apoptosis, autophagy, and mitochondrial dynamic were detected to uncover the molecular mechanism behind these pathological changes. The results showed that suppressed antioxidant ability was companied by increased mRNA and protein levels of proapoptosis and mitochondrial fission activating genes in the Cu group compared with chickens in the control group (P < 0.05). Moreover, the markers of autophagy long-chain 3 (LC3-II/LC3-I), Bcl-2-interacting protein (beclin-1), and autophagy-related gene (ATG4B and ATG5) displayed a time-dependent increase during 30, 60, and 90 days. We conjectured that subchronic copper poisoning, under the background of redistribution of trace elements, induced oxidative stress and cascaded apoptosis, autophagy, and mitochondrial disorder, which contributed to jejunotoxicity in chicken. Collectively, our study provides a basic assessment of subchronic Cu exposure on poultry, voicing concerns about copper pollution by anthropogenic activities.

Metabolic profiling of copper-laden hepatolenticular degeneration model rats and the interventional effects of Gandou decoction using UPLC-Q-TOF/MS

The direct cause of hepatolenticular degeneration (HLD) is copper metabolic disorder caused by autosomal recessive inheritance. Gandou decoction (GDD), a classical traditional Chinese medicine formula, exhibits unambiguous therapeutic effect on HLD in China for decades. However, the mechanism of effect on HLD is not clear. With this purpose, the effects of copper content and histopathology inspection on the HLD rat model were investigated. Then, metabolomics study based on ultra-performance liquid chromatography quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF/MS^E) analysis and multivariate statistical analysis was adopted to further reveal the mechanism of action of GDD against HLD. The results showed that the characteristics of liver tissues after GDD treatment were significantly reversed, close to the control group, suggesting that GDD has a therapeutic effect on HLD. Furthermore, HLD interferes with 2 metabolites of the metabolic pathway in rats. Among them, up-regulation of Lactic acid, Tryptophan, Phenylalanine, Triacylglycerol and down-regulation of Linoleic acid, Alpha Linolenic acid, Phosphatidylcholine, Taurine is particularly significant. Analysis of metabolic pathways by a unique pathway analysis revealed significant changes in several pathways including lipid metabolism, amino metabolism and glucose metabolism in HLD. This study showed that GDD could provide satisfactory therapeutic effects on HLD and metabolomics study can be utilized to further understand the molecular mechanisms.

Mitochondria and Reactive Oxygen Species in Aging and Age-Related Diseases

Aging has been linked to several degenerative processes that, through the accumulation of molecular and cellular damage, can progressively lead to cell dysfunction and organ failure. Human aging is linked with a higher risk for individuals to develop cancer, neurodegenerative, cardiovascular, and metabolic disorders. The understanding of the molecular basis of aging and associated diseases has been one major challenge of scientific research over the last decades. Mitochondria, the center of oxidative metabolism and principal site of reactive oxygen species (ROS) production, are crucial both in health and in pathogenesis of many diseases. Redox signaling is important for the modulation of cell functions and several studies indicate a dual role for ROS in cell physiology. In fact, high concentrations of ROS are pathogenic and can cause severe damage to cell and organelle membranes, DNA, and proteins. On the other hand, moderate amounts of ROS are essential for the maintenance of several biological processes, including gene expression. In this review, we provide an update regarding the key roles of ROS-mitochondria cross talk in different fundamental physiological or pathological situations accompanying aging and highlighting that mitochondrial ROS may be a decisive target in clinical practice.

The effects of Mucuna pruriens on the renal oxidative stress and transcription factors in high-fructose-fed rats

In the present study, we evaluated the effects of M. pruriens administration on metabolic parameters, oxidative stress and kidney nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and nuclear factor (erythroid-derived 2)-like 2 (Nrf2) signaling pathways in high-fructose fed rats. Male rats (n = 28) were divided into 4 groups as control, M. pruriens, fructose, and M. pruriens plus fructose. All rats were fed a standard diet supplemented or no supplemented with M. pruriens (200 mg/kg/d by gavage). Fructose was given in drinking water for 8 weeks. High fructose consumption led to an increase in the serum level of glucose, triglyceride, urea and renal malondialdehyde (MDA) levels. Although M. pruriens treatment reduced triglyceride and MDA levels, it did not affect other parameters. M. pruriens supplementation significantly decreased the expression of NF-ҡB and decreased expression of Nrf2 and HO-1 proteins in the kidney. This study showed that the adverse effects of high fructose were alleviated by M. pruriens supplementation via modulation of the expression of kidney nuclear transcription factors in rats fed high fructose diet.

Developing on-site paper colorimetric monitoring technique for quick evaluating copper ion concentration in mineral wastewater

With the reinforce of the copper mining, the on-site monitoring of the accompanied effluent discharge is highly demanded for the emergency response to minimize the negative effect of the effluent on the surrounding ecosystem. On the basis of the specific interaction between Cu²⁺ and l-Cysteine (l-Cys), which was modified on gold nanoparticles (Au NPs), and the aggregation dependent surface plasmon resonance (SPR) of Au NPs, we developed an easy-on-going paper colorimetric method for the quick evaluating the copper ion concentration in the waste water excreted from the copper mine. The color change of l-Cys modified Au NPs (l-Cys-Au NPs)immobilized on a filter paper was very sensitive to the Cu²⁺ concentration and free of interference from other metal ions typically in waste water. The proposed paper colorimetry has the LOD of 0.09mg/L and the linear range of 0.1-10mg/L, respectively, with the RSD (n=5) was 6.6% for 1mg/L Cu²⁺ and 3.5% for 5mg/L Cu²⁺. The quantitative analysis results for the mineral wastewater is in good agreement the China National Environmental Protection Standards HJ485-2009, which indicates the current method could be developed to the on-site detection technique for the emergency response in monitoring Cu²⁺ in industrial wastewater or polluted water.

Environmental pollution and kidney diseases

The burden of disease and death attributable to environmental pollution is becoming a public health challenge worldwide, especially in developing countries. The kidney is vulnerable to environmental pollutants because most environmental toxins are concentrated by the kidney during filtration. Given the high mortality and morbidity of kidney disease, environmental risk factors and their effect on kidney disease need to be identified. In this Review, we highlight epidemiological evidence for the association between kidney disease and environmental pollutants, including air pollution, heavy metal pollution and other environmental risk factors. We discuss the potential biological mechanisms that link exposure to environmental pollutants to kidney damage and emphasize the contribution of environmental pollution to kidney disease. Regulatory efforts should be made to control environmental pollution and limit individual exposure to preventable or avoidable environmental risk. Population studies with accurate quantification of environmental exposure in polluted regions, particularly in developing countries, might aid our understanding of the dose-response relationship between pollutants and kidney diseases.

Fluorescence “off” and “on” signalling of esculetin in the presence of copper and thiol: a possible implication in cellular thiol sensing

The fluorescence intensity of esculetin was drastically reduced in the presence of a copper ion, which was regenerated in the presence of GSH. The copper–esculetin system was able to detect GSH in a cellular model.

Copper or/and arsenic induce oxidative stress-cascaded, nuclear factor kappa B-dependent inflammation and immune imbalance, trigging heat shock response in the kidney of chicken

Excessive amount of copper (Cu) and inorganic arsenic (iAs) coexists in drinking water in many regions, this is associated with high risk of nephropathy, defined as chronic structural and functional disorders of the kidney. However, the underlying mechanisms are not well understood. In this study, a total of 72 day-old Hy-line chickens were exposed to 300 mg/kg copper sulphate or/and 30 mg/kg arsenic trioxide for 12 weeks. Indicators of oxidative stress, inflammation and heat shock proteins (HSPs) production were analyzed in kidney. The results showed that, when the toxicant was administrated alone, there is an antagonism between redox homeostasis during the first 4 weeks, which follows a collapse of antioxidant system manifested by damaged biomembrane structure. What's worse, oxidative damage-cascaded histopathological lesions were accompanied by increases of proinflammatory mediators and an imbalance of "Th1/Th2 drift" (Th, helper T cell) regulated by nuclear factor kappa B (NF-κB). Simultaneously, intense heat shock response went with the organism. The above-mentioned renal lesions and indicators changes were time-dependent, more complex and deteriorated effects were observed in Cu/iAs combined groups compared with the others. This study supports Cu and iAs have a synergistic type on the nephro-toxicological process additively. In conclusion, oxidative stress and inflammatory induced by Cu or/and iAs are potential mechanisms in their nephrotoxicity, increased heat shock response may play a renoprotection function in tissues damage.