Exposure to waterborne cadmium induce oxidative stress, autophagy and mitochondrial dysfunction in the liver of Procypris merus

Sulfur dioxide increases testosterone biosynthesis by activating ERK1/2 pathway and disrupting autophagy in Leydig cells

Sulfur dioxide (SO2) is a ubiquitous environmental pollutant that has been shown to be toxic to the male reproductive system, but the underlying mechanism remains unclear. Therefore, the SO2-treated mice and primary Leydig cell models were established to investigate the effects of SO2 on the production of testosterone and its specific mechanism. The results demonstrated that SO2 activated the ERK1/2 signaling pathway, leading to increased key proteins expression of testosterone biosynthesis and elevated testosterone levels. The addition of ERK1/2 inhibitor U0126 attenuated SO2-induced increases in key testosterone biosynthetic gene mRNA levels of Star, Cyp17a1, Hsd3b1, and testosterone. Low doses of SO2 reduced the expression of BECLIN1 and LC3 proteins, increased P-4E-BP1 protein expression, and decreased autophagy in Leydig cells. Moreover, increasing doses of SO2 correlate with enhanced Leydig cell autophagy and testosterone levels initially. However, increasing the dose of SO2 resulted in a significant decrease in cell viability and ultimately decreased testosterone levels. These findings suggest that SO2 promotes testosterone production by activating ERK1/2 and disrupting autophagy. This study enriched the dose-effect relationship of SO2 on the male reproductive system and provided a theoretical reference for us to have a comprehensive and dynamic understanding of the SO2 toxic mechanism.

Product of Traditional Chinese Medicine Longgui Yangxinwan Protects the Human Body from Altitude Sickness Damage by Reducing Oxidative Stress and Preventing Mitochondrial Dysfunction

Yu Liu, Zhengyang Zhang, Yongting Luo, Peng An, Jingyi Qi, Xu Zhang, Shuaishuai Zhou, Yongzhi Li, Chong Xu, Junjie Luo, and Jiaping Wang. Product of traditional Chinese medicine longgui yangxinwan protects the human body from altitude sickness damage by reducing oxidative stress and preventing mitochondrial dysfunction. High Alt Med Biol. 26:20-29, 2025. Background: Plateau reaction, caused by high-altitude exposure, results in symptoms like headaches, dyspnea, palpitations, fatigue, shortness of breath, and insomnia due to reduced oxygen levels. Mitochondria are crucial for high-altitude acclimatization as they regulate oxygen metabolism and cellular energy, reducing oxidative stress and maintaining bodily functions. Methods: The study participants were randomly divided into placebo group, Rhodiola group and longgui yangxinwan (Original name: taikong yangxinwan) group, with 20 people in each group. Three groups of subjects were sampled at three time points (PI: pre-intervention; P-D1: high-altitude day 1; P-D7: high-altitude day 7), and blood pressure, blood oxygen, heart rate, hemoglobin, and red blood cell count were measured. The ATP content, mitochondrial DNA copy number, expression of mitochondria-related genes, reactive oxygen species (ROS), glutathione peroxidase (GSH-PX) and malondialdehyde (MDA) levels, and mitochondrial morphology were measured in blood at each time point. Results: Our study results demonstrate that longgui yangxinwan keeps the selected human physiological indicators stable and prevents mitochondrial dysfunction in the high altitude. Mechanically, longgui yangxinwan decreases the level of ROS in human serum, whereas increases the activity of the antioxidant enzyme GSH-PX. At high-altitude day 1 (P-D1) and high-altitude day 7 (P-D7), ROS in the placebo group were 1.5 and 2.2-fold higher than those of the longgui yangxinwan group, respectively. In addition, longgui yangxinwan enhances ATP production capacity, restores the levels of mitochondrial respiratory chain complexes, and effectively maintains mitochondrial morphology and integrity. At P-D1 and P-D7, the ATP levels in the longgui yangxinwan group were 19-fold and 26-fold higher than those in the placebo group, respectively. Conclusions: Our study highlights longgui yangxinwan as a potential drug for protecting humans from high-altitude damage by reducing oxidative stress and preventing mitochondrial dysfunction.

Toxicology Effects of Cadmium in Pomacea canaliculate: Accumulation, Oxidative Stress, Microbial Community, and Transcriptome Analysis

Cadmium (Cd) pollution poses an important problem, but limited information is available about the toxicology effects of Cd on freshwater invertebrates. We investigated the accumulation, oxidative stress, microbial community changes, and transcriptomic alterations in apple snails (Pomacea canaliculata) under Cd stress. The snails were exposed to the 10 μg/L Cd solution for 16 days, followed by a 16-day elimination period. Our results showed that the liver accumulated the highest Cd concentration (17.41 μg/g), followed by the kidneys (8.00 μg/g) and intestine-stomach (6.68 μg/g), highlighting these tissues as primary targets for Cd accumulation. During the elimination period, Cd concentrations decreased in all tissues, with the head-foot and shell exhibiting over 30% elimination rates. Cd stress also resulted in reduced activities of superoxide dismutase (SOD), catalase (CAT), and glutathione transferase (GST) compared to the control group. Notably, even after 16 days of depuration, the enzyme activities did not return to normal levels, indicating persistent toxicological effects. Cd exposure significantly reduced the diversity of gut microbiota in P. canaliculata. Moreover, transcriptome analysis identified differentially expressed genes (DEGs) primarily associated with lysosome function, motor proteins, protein processing in the endoplasmic reticulum, drug metabolism via cytochrome P450 (CYP450), arachidonic acid metabolism, and ECM-receptor interactions. These findings suggest that Cd stress predominantly disrupts cellular transport and metabolic processes. Overall, our study provides comprehensive insights into the toxicological impact of Cd on P. canaliculata and emphasizes the importance of understanding the mechanisms underlying Cd toxicity in aquatic organisms.

Insufficient FUNDC1-dependent mitophagy due to early environmental cadmium exposure triggers mitochondrial redox imbalance to aggravate diet-induced lipotoxicity

Cadmium (Cd) is a toxic contaminant widely spread in natural and industrial environments. Adolescent exposure to Cd increases risk for obesity-related morbidity in young adults including type 2 diabetes and metabolic dysfunction-associated steatotic liver disease (MASLD). Despite this recognition, the direct impact of adolescent Cd exposure on the progression of MASLD later in life, and the mechanisms underlying these effects, remain unclear. Here, adolescent rats received control diet or diets containing 2 mg Cd2+/kg feed for 4 weeks, and then HFD containing 15% lard or control diet in young adult rats was selected for 6 weeks to clarify this issue. Data firstly showed that HFD-fed rats in young adulthood due to adolescent Cd exposure exhibited more severe MASLD, evidenced by increased liver damage, disordered serum and hepatic lipid levels, and activated NLRP3 inflammasome. Hepatic transcriptome analysis revealed the potential effects of mitochondrial dysfunction in aggravated MASLD due to Cd exposure. Verification data further confirmed that mitochondrial structure and function were targeted and disrupted during this process, shown by broken mitochondrial ridges, decreased mitochondrial membrane potential, imbalanced mitochondrial dynamic, insufficient ATP concentration, and enhanced mitochondrial ROS generation. However, mitophagy is inactively involved in clearance of damaged mitochondria induced by early Cd in HFD condition due to inhibited mitophagy receptor FUNDC1. In contrast, FUNDC1-dependent mitophagy activation prevents lipotoxicity aggravated by early Cd via suppressing mitochondrial ROS generation. Collectively, our data show that insufficient FUNDC1-dependent mitophagy can drive the transition from HFD-induced MASLD to MASH, and accordingly, these findings will provide a better understanding of potential mechanism of diet-induced metabolic diseases in the context of early environmental Cd exposure.

Mechanisms insights into bisphenol S-induced oxidative stress, lipid metabolism disruption, and autophagy dysfunction in freshwater crayfish

Bisphenol S (BPS) is widely used in plastic products, food packaging, electronic products, and other applications. In recent years, BPS emissions have increasingly impacted aquatic ecosystems. The effects of BPS exposure on aquatic animal health have been documented; however, our understanding of its toxicology remains limited. This study aimed to explore the mechanisms of lipid metabolism disorders, oxidative stress, and autophagy dysfunction induced in freshwater crayfish (Procambarus clarkii) by exposure to different concentrations of BPS (0 µg/L, 1 µg/L, 10 µg/L, and 100 µg/L) over 14 d. The results indicated that BPS exposure led to oxidative stress by inducing elevated levels of reactive oxygen species (ROS) and inhibiting the activity of antioxidant-related enzymes. Additionally, BPS exposure led to increased lipid content in the serum and hepatopancreas, which was associated with elevated lipid-related enzyme activity and increased expression of related genes. Furthermore, BPS exposure decreased levels of phosphatidylcholine (PC) and phosphatidylinositol (PI), disrupted glycerophospholipid (GPI) metabolism, and caused lipid deposition in the hepatopancreatic. These phenomena may have occurred because BPS exposure reduced the transport of fatty acids and led to hepatopancreatic lipid deposition by inhibiting the transport and synthesis of PC and PI in the hepatopancreas, thereby inhibiting the PI3K-AMPK pathway. In conclusion, BPS exposure induced oxidative stress, promoted lipid accumulation, and led to autophagy dysfunction in the hepatopancreas of freshwater crayfish. Collectively, our findings provide the first evidence that environmentally relevant levels of BPS exposure can induce hepatopancreatic lipid deposition through multiple pathways, raising concerns about the potential population-level harm of BPS and other bisphenol analogues.

The role of miR-216a-mediated Nrf2 pathway in muscle oxidative stress of Siniperca chuatsi induced by cadmium

Cadmium (Cd) is a toxic heavy metal pollutant in the environment. Excessive Cd in water has toxic effects on fish, endangering their healthy growth and ultimately affecting the quality and safety of aquatic products. To evaluate the toxicity of excessive Cd to fish through potential oxidative damage, Siniperca chuatsi was exposed to Cd in water for 15 days. It was found that Cd exposure significantly decreased the survival rate of S. chuatsi and Cd was detected in their muscle. Meanwhile, Cd disrupts the redox balance by reducing antioxidant enzyme activities, increasing reactive oxygen species (ROS) and malondialdehyde (MDA) levels in muscle, and promoting oxidative damage. Histomorphology showed that enlargement of muscle fiber gaps, cell swelling and vacuolar degeneration after Cd exposure. In addition, Cd toxicity induced up-regulating the expression of miR-216a, while down-regulation of Nrf2 protein and its downstream antioxidant enzyme genes expression. Further analysis revealed that miR-216a was significantly negatively correlated with the expression of Nrf2, and injection of miR-216a antagomir significantly enhanced the expression of Nrf2 and antioxidant enzyme genes, as well as the activity of antioxidant enzymes, thereby reducing the damage of Cd to fish. These results suggested that miR-216a-mediated Nrf2 signaling pathway plays an important role in Cd-induced oxidative stress of S. chuatsi muscle.

Acute waterborne cadmium exposure induces liver ferroptosis in Channa argus

The impact of cadmium (Cd) toxicity on fish liver injury has received much attention in recent years. Currently, autophagy, apoptosis and endoplasmic reticulum stress were reported in Cd exposed fish liver, and if there are other mechanisms (such as ferroptosis) and relevant signaling pathways involved in fish remains unknown. An experiment was conducted to investigate Cd toxicity in Channa argus (Cantor, 1842) exposed to 0, 1.0, and 2.0 mg Cd/L of water for 96 h. Cd disrupted the structure of mitochondria in the liver. Besides, Cd induced ferroptosis by significantly increasing the level of Fe2+, ROS, MDA and significantly decreasing the level of Ferritin, GSH, GSH-Px, GPX4, GST and SOD (p < 0.05 in all cases). In addition, the mRNA expression of ferroptosis related genes, gpx4 and slc7a11, were significantly downregulated by Cd. Moreover, Cd exposure significantly inhibited the Nrf2/Keap1 signaling pathway, one of the pathways involved in ferroptosis, by upregulating the mRNA levels of keap1a and keap1b, and downregulating the mRNA levels of nrf2 and its target genes (ho-1, nqo1 and cat). Cd exposure also caused extensive accumulation of vacuoles and lipid droplets in liver, as well as an increase in triglyceride content. Cd significantly affected lipid metabolism related enzyme activity and gene expression, which were also regulated by Nrf2/Keap1 signaling pathway. In summary, these results indicate that ferroptosis is a mechanism in waterborne Cd exposed fish liver injury via the Nrf2/Keap1 signaling pathway and the Cd induced hepatic steatosis is also modulated by Nrf2/Keap1 pathway at the whole-body level in fish. These findings provide new insights into the fish liver injury and molecular basis of Cd toxicity.

A review on heavy metal-induced toxicity in fishes: Bioaccumulation, antioxidant defense system, histopathological manifestations, and transcriptional profiling of genes

AIM

This review provides information about heavy metal occurrence in the environment, destructive mechanisms, and lethal effects on fish.

SUMMARY

Heavy metals (HMs) are one of the major causes of environmental contamination globally. The advancement of industries has led to the emanation of toxic substances into the environment. HMs are stable, imperishable compounds and can accumulate in different fish organs when they reach the aquatic regimes. The most ubiquitous HMs are chromium, arsenic, mercury, cadmium, lead, copper, and nickel which can pollute the environment and affect the physiology of fishes. Accumulation of metals in the fish organs causes structural lesions and functional disturbances. Contamination of heavy metals induces oxidative stress, histopathological manifestations, and altered transcriptional gene regulation in the exposed fishes.

CONCLUSION

Heavy metal bioaccumulation leads to different anomalies in the non-target species. Metal toxicity may cause aquatic organisms to exhibit cellular dysfunction and disturb ecological equilibrium.

Rat Hepatocytes Protect against Lead-Cadmium-Triggered Apoptosis Based on Autophagy Activation

Lead and cadmium are foodborne contaminants that threaten human and animal health. It is well known that lead and cadmium produce hepatotoxicity; however, defense mechanisms against the co-toxic effects of lead and cadmium remain unknown. We investigated the mechanism of autophagy (defense mechanism) against the co-induced toxicity of lead and cadmium in rat hepatocytes (BRL-3A cells). Cultured rat liver BRL-3A cell lines were co-cultured with 10, 20, 40 μM lead and 2.5, 5, 10 μM cadmium alone and in co-culture for 12 h and exposed to 5 mM 3-Methyladenine (3-MA), 10 μM rapamycin (Rapa), and 50 nM Beclin1 siRNA to induce cellular autophagy. Our results show that treatment of BRL-3A cells with lead and cadmium significantly decreased the cell viability, increased intracellular reactive oxygen species levels, decreased mitochondrial membrane potential levels, and induced apoptosis, which are factors leading to liver injury, and cell damage was exacerbated by co-exposure to lead-cadmium. In addition, the results showed that lead and cadmium co-treatment induced autophagy. We further observed that the suppression of autophagy with 3-MA or Beclin1 siRNA promoted lead-cadmium-induced apoptosis, whereas enhancement of autophagy with Rapa suppressed lead-cadmium-induced apoptosis. These results demonstrated that co-treatment with lead and cadmium induces apoptosis in BRL-3A cells. Interestingly, the activation of autophagy provides cells with a self-protective mechanism against induced apoptosis. This study provides insights into the role of autophagy in lead-cadmium-induced apoptosis, which may be beneficial for the treatment of lead-cadmium-induced liver injury.

Impaired intestinal immunity and microbial diversity in common carp exposed to cadmium

Waterborne cadmium (Cd) accumulates in the fish intestine and causes irreversible toxicity by disrupting intestinal immunity and microbial diversity. To explore the toxicity of environmentally available high Cd concentration on intestinal immunity and microbial diversity of fish, we selected the widely used bioindicator model species, Common carp (Cyprinus carpio). Literature review and Cd pollution data supported sequential doses of 0.2, 0.4, 0.8, 1.6, 3.2, and 6.4 mg/L Cd for 30 days. Based on intestinal tissue Cd accumulation, previous studies, and environmentally available Cd data, 0.4 and 1.6 mg/L Cd were selected for further studies. Intestinal Cd bioaccumulation increased significantly to ~100 times in fish exposed to 1.6 mg/L Cd. We observed villous atrophy, increased goblet cells with mucus production, muscularis erosion, and thickened lamina propria due to intense inflammatory cell infiltration in the intestine at this Cd concentration. Cd-induced immunosuppression occurred with increased lysozyme, alkaline phosphate (AKP), and acid phosphate (ACP). High levels of catalase (CAT), total antioxidant capacity (T-AOC), malondialdehyde (MDA), and hydrogen peroxide (H2O2) suggested induced oxidative stress and poor metabolism by α-amylase and lipase suppression for Cd toxicity. Proteobacteria (41.2 %), Firmicutes (21.8 %), and Bacteroidetes (17.5 %) were the dominant bacterial phyla in the common carp intestine. Additionally, potential pathogenic Cyanobacteria increased in Cd-treated fish. The decrease of beneficiary bacteria like Aeromonas, and Cetobacterium indicated Cd toxicity. Overall, these findings indicate harmful consequences of high Cd concentration in the intestinal homeostasis and health status of fish.

Quercetin alleviates cadmium-induced BRL-3A cell apoptosis by inhibiting oxidative stress and the PERK/IRE1α/ATF6 signaling pathway

Cadmium (Cd) is a highly toxic environmental pollutant. The liver is an important metabolic organ in the body and is susceptible to Cd toxicity attacks. Quercetin (Que) is a flavonoid compound with pharmacological activities of scavenging free radicals and antioxidant activity. Previous studies have shown that Que can alleviate Cd caused hepatocyte apoptosis in rats, but the specific mechanism remains unclear. To explore the specific mechanism, we established a model of Cd toxicity and Que rescue in BRL-3A cells and used 4-phenylbutyrate (4-PBA), an endoplasmic reticulum stress (ERS) inhibitor, as positive control. Set up a control group, Cd treatment group, Cd and Que co treatment group, Que treatment group, Cd and 4-PBA co treatment group, and 4-PBA treatment group. Cell Counting Kit-8 (CCK-8) method was employed to measure cell viability. Fluorescence staining was applied to observe cell apoptosis. Flow cytometry was performed to detect reactive oxygen species levels. Real-time quantitative polymerase chain reaction (qRT-PCR) and Western blot method was adopted to detect the mRNA and protein expression levels of ERS and apoptosis-related genes. The results showed that compared with the control group, the Cd treated group showed a significant decrease in cell viability (P < 0.01), an increase in intracellular ROS levels, and apoptosis. The mRNA and protein expression levels of ERS and apoptosis related factors such as GRP78, IRE1α, XBP1, ATF6, Caspase-12, Caspase-3 and Bax in the cells were significantly increased (P < 0.01), while the mRNA and protein expression levels of Bcl-2 were significantly reduced (P < 0.01). Compared with the Cd treatment group, the Cd and Que co treatment group and the Cd and 4-PBA co treatment group showed a significant increase in cell viability (P < 0.01), a decrease in intracellular ROS levels, a decrease in cell apoptosis, and a significant decrease in the expression levels of ERS and apoptosis related factors mRNA and protein (P < 0.01), as well as a significant increase in Bcl-2 mRNA and protein expression (P < 0.01). We confirmed that Que could alleviate the apoptosis caused by Cd in BRL-3A cells, and the effects of Que were similar to those of ERS inhibitor.

Co-exposure to cadmium and microplastics promotes liver fibrosis through the hemichannels -ATP-P2X7 pathway

Microplastics (MPs) and cadmium (Cd) are important environmental pollutants, that damage the liver. However, the effect and mechanism of combined Cd and MPs exposure on liver fibrosis are still largely unknown. In this study investigated, Cd + MPs exposure increased superoxide anion production and promoted extracellular ATP release compared with exposure to Cd or MPs individually. Cd + MPs increased inflammatory cell infiltration, activated the P2X7-NLRP3 signaling pathway, and promoted inflammatory factor release. Cd + MPs aggravated Cd- or MPs-induced liver fibrosis and induced liver inflammation. In AML12/HSC-T6 cell in vitro poisoning model, exposure of AML12 cells to Cd + MPs increased the opening of connexin hemichannels and promoted extracellular ATP release. Treatment of HSC-T6 cells with the supernatant of AML12 cells exposed to Cd + MPs significantly promoted HSC-T6 cell activation. Treatment of HSC-T6 cells with different concentrations of ATP produced similar results. TAT-Gap19TFA, an inhibitor of connexin hemichannels, significantly inhibited the ATP release and activation of Cd + MPs-treated HSC-T6 cells. Finally, the expression of the ATP receptor P2X7 was silenced in HSC-T6 cells, which significantly inhibited their activation. In conclusion, exposure to Cd + MPs promoted liver fibrosis through the ATP-P2X7 pathway and synergistically affected liver inflammation and fibrosis.

Application of Se-Met to CdTe QDs significantly reduces toxicity by modulating redox balance and inhibiting apoptosis

Cadmium tellurium quantum dots (CdTe QDs) as one of the most widely used QDs have been reported the toxicity and biosafety in recent years, little work has been done to reduce their toxicity however. Based on the mechanisms of toxicity of CdTe QDs on liver target organs such as oxidative stress and apoptosis previously reported by other researchers, we investigated the mechanism of action of trace element selenium (Se) to mitigate the hepatotoxicity of CdTe QDs. The experimental results showed that Se-Met at 40-140 μg L-1 could enhance the function of intracellular antioxidant defense system and the molecular structure of related antioxidant enzymes by reduce the production of ROS by 45%, protecting the activity of antioxidants and up-regulating the expression of selenoproteins with antioxidant functions, Gpx1 increase 225% and Gpx4 upregulated 47%. In addition, Se-Met could alleviate CdTe QDs-induced apoptosis by regulating two apoptosis-inducing factors, as intracellular caspase 3/9 expression levels were reduced by 70% and 87%, decreased Ca2+ concentration, and increased mitochondrial membrane potential measurements. Overall, this study indicates that Se-Met has a significant protective effect on the hepatotoxicity of CdTe QDs. Se-Met can be applied to the preparation of CdTe QDs to inhibit its toxicity and break the application limitation.

Review of cadmium toxicity effects on fish: Oxidative stress and immune responses

Cadmium (Cd) in aquatic environments can cause environmental toxicity to fish and induce oxidative stress owing to an excessive production of reactive oxygen species in fish bodies. Fish have developed various antioxidant systems to protect themselves from reactive oxygen species; thus, a change in antioxidant responses in fish can be a criterion for evaluating oxidative stress resulting from Cd exposure. Because Cd exposure may be recognized as an exogenous substance by a fish body, it may lead to the stimulation or suppression of its immune system. Various immune responses can be assessed to evaluate Cd toxicity in fish. This review aimed to identify the impacts of Cd exposure on oxidative stress and immunotoxicity in fish as well as identify accurate indicators of Cd toxicity in aquatic ecosystems.

Spirulina (Arthrospira maxima) mitigates the toxicity induced by a mixture of metal and NSAID in Xenopus laevis

Cadmium (Cd) is often detected in the environment due to its wide use in industry; also, NSAIDs are one of the most consumed pharmaceuticals, particularly diclofenac (DCF). Several studies have reported the presence of both contaminants in water bodies at concentrations ranging from ng L-1 to μg L-1; in addition, they have shown that they can induce oxidative stress in aquatic species and disturb signal transduction, cell proliferation, and intercellular communication, which could lead to teratogenesis. Spirulina has been consumed as a dietary supplement; its antioxidant, anti-inflammatory, neuroprotective, and nutritional properties are well documented. This work aimed to evaluate if Spirulina reduces the damage induced by Cd and DCF mixture in Xenopus laevis at early life stages. FETAX assay was carried out: 20 fertilized oocytes were exposed to seven different treatments on triplicate, control, Cd (24.5 μg L-1), DCF (149 μg L-1), Cd + DCF, Cd+DCF+Spirulina (2 mg L-1), Cd+DCF+Spirulina (4 mg L-1), Cd+DCF+Spirulina (10 mg L-1), malformations, mortality, and growth were evaluated after 96 h, also lipid peroxidation, superoxide dismutase and catalase activity were determined after 192 h. Cd increased DCF mortality, Cd and DCF mixture increased the incidence of malformations as well as oxidative damage; on the other hand, the results obtained show that Spirulina can be used to reduce the damage caused by the mixture of Cd and DCF since it promotes growth, reduce mortality, malformations, and oxidative stress in X. laevis.

Lycopene abolishes typical polyhalogenated carbazoles (PHCZs)-induced hepatic injury in yellow catfish (Pelteobagrus fulvidraco): Involvement of ROS/PI3K-AKT/NF-κB signaling

Aquatic ecosystems are being more contaminated with polyhalogenated carbazoles (PHCZs), which raising concerns about their impact on aquatic organisms. Lycopene (LYC) exhibits several beneficial properties for fish via enhance antioxidant defenses and improve immunity. In this study, we attempted to investigate the hepatotoxic effects of typical PHCZs 3, 6-dichlorocarbazole (3,6-DCCZ) and the protective mechanisms of LYC. In this study, we found that yellow catfish (Pelteobagrus fulvidraco) exposure to 3,6-DCCZ (1.2 mg/L) resulted in hepatic inflammatory infiltration and disordered hepatocyte arrangement. Besides, we observed that 3,6-DCCZ exposure resulted in hepatic reactive oxygen species (ROS) overproduction and excessive autophagosome accumulation, accompanied with inhibition of phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT) pathway. Subsequently, we confirmed that 3,6-DCCZ exposure triggered hepatic uncontrolled inflammatory response via activation of nuclear factor-κB (NF-κB) pathway, along with decreased plasma complement C3 (C3) and complement C4 (C4) levels. Meanwhile, yellow catfish exposed to 3,6-DCCZ exhibit an increased hepatic apoptosis phenomenon, as evidenced by the elevated number of positive TUNEL cells and upregulated expression of caspase3 and cytochrome C (CytC). In contrast, LYC treatment could alleviate the 3,6-DCCZ-induced pathological changes, hepatic ROS accumulation, autophagy, inflammatory response and apoptosis. To sum up, this study provided the demonstration that LYC exerts hepatoprotective effects to alleviate 3,6-DCCZ-induced liver damage by inihibiting ROS/PI3K-AKT/NF-κB signaling in yellow catfish.

Protective effects of calcium against cadmium-induced toxicity in juvenile grass carp (Ctenopharyngodon idellus)

Cadmium (Cd) is one of the dominant metal pollutants present in the aquatic environment that affects ion homeostasis, oxidative stress (OS) and immune responses of aquatic organisms. Given the physicochemical similarities between Cd²⁺ and calcium (Ca²⁺) ions, their antagonism may facilitate the mitigation of Cd-induced toxicity. To better understand the role of Ca in protecting against Cd-induced toxicity in teleosts, juvenile grass carp were exposed to Cd (measured concentration 3 μg/L) and a gradient of Ca concentrations (measured concentration 1.5 mg/L, 2.5 mg/L, 3.0 mg/L, and 3.5 mg/L in the control (CTL) group, low calcium (LCA) group, medium calcium (MCA) group, and high calcium (HCA) group, respectively) for 30 days. Inductively coupled plasma mass spectrometry (ICP-MS) data analyses showed that simultaneous exposure to Ca impaired the accumulation of Cd in all tested tissues. Besides, Ca addition maintained the plasma ion (Na⁺, K⁺, Cl^-) homeostasis, alleviated Cd-induced oxidative stress (OS), and regulated the activities and transcriptional levels of ATPase. Furthermore, transcriptional heatmap analysis demonstrated that several indicator genes for OS and calcium signaling pathway were found to be significantly modulated by Ca addition. This work delineates a protective effect of Ca against Cd-induced toxicity in grass carp, providing new insight into the possible solutions to Cd pollution issues in aquaculture industry.

Hepatoprotective Effects of Taurine Against Cadmium-Induced Liver Injury in Female Mice

Cadmium (Cd), a heavy metal contaminant, seriously threatens human and animal health. Taurine (Tau) has been used against hepatotoxicity caused by different environmental toxins. However, it has not been elucidated whether Tau exerts its protective function against Cd-induced hepatotoxicity. The aim of this study was thus to evaluate the ameliorative function of Tau (500 mg/kg body weight intraperitoneally) on Cd-induced (2 mg/kg body weight intraperitoneally) liver toxicity in mice for 14 days. The histopathologic and ultrastructure changes as well as alterations in indexes related to liver function, antioxidant biomarkers, inflammatory, and apoptosis were evaluated. The results showed that Tau alleviated the vacuolar degeneration, nuclear condensation, mitochondria swelling, and cristae lysis of hepatocytes induced by Cd. In addition, Tau treatment significantly reduced the ALT, AST levels in serum, and inflammatory factor TNF-α and IL-1β in liver tissue. Furthermore, Tau treatment decreased the Bax/Bcl-2 ratio and cleaved caspase-3 protein expression levels. Taken together, these observations demonstrate that Tau has an important hepatic protective function against the inflammation and apoptosis induced by Cd.

Molybdenum and Cadmium Co-induce Pyroptosis via Inhibiting Nrf2-Mediated Antioxidant Defense Response in the Brain of Ducks

Excess molybdenum (Mo) and cadmium (Cd) are harmful to animals, but the neurotoxic mechanism co-induced by Mo and Cd is unclear. To estimate the effects of Mo and Cd co-exposure on pyroptosis by nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated antioxidant defense response in duck brains, 40 healthy 7-day-old ducks were randomly assigned to 4 groups and fed diet supplemented with Mo or/and Cd for 16 weeks, respectively. Results showed that Mo or/and Cd markedly increased Mo and Cd contents; decreased iron (Fe), copper (Cu), zinc (Zn), and selenium (Se) contents, elevated malondialdehyde (MDA) content; and decreased total-antioxidant capacity (T-AOC), total-superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) activities accompanied by pathological damage in brain. Additionally, Mo or/and Cd inhibited Nrf2 pathway via decreasing Nrf2, CAT, SOD1, glutathione S-transferase (GST), hemeoxygenase-1 (HO-1), NAD (P) H:quinone oxidoreductase 1 (NQO1), glutamate-cysteine ligase catalytic subunit (GCLC), and modifier subunit (GCLM) mRNA levels and Nrf2 protein level, which induced pyroptosis through upregulating nucleotide oligomerization domain-like receptor protein-3 (NLRP3), apoptosis-associated speck-like protein (ASC), gasdermin A (GSDMA), gasdermin E (GSDME), interleukin-1β (IL-1β), interleukin-18 (IL-18), Caspase-1, NIMA-related kinase 7 (NEK7) mRNA levels and NLRP3, Caspase-1 p20, gasdermin D (GSDMD), ASC protein levels and IL-1β, and IL-18 contents. Besides, the changes of these indicators were most apparent in the Mo and Cd co-treated group. Collectively, the results certificated that Mo and Cd might synergistically induce pyroptosis via inhibiting Nrf2-mediated antioxidant defense response in duck brains, whose mechanism is closely related to Mo and Cd accumulation.

MafG-like contribute to copper and cadmium induced antioxidant response by regulating antioxidant enzyme in Procambarus clarkii

Avian musculoaponeurotic fibrosarcoma (Maf) proteins play an important role in Nrf2/Keap1 signaling pathway, which mainly resist the oxidant stress. The members of sMaf have a high homology basic leucine zipper (bZIP) and lack trans activation domain, and could interact with other transcriptional regulatory factors as a molecular chaperone. In this study, a full-length MafG-like gene was cloned from Procambarus Clarkii, designated as PcMafG-like, which consisted of an ORF length of 246 bp encoding 82 amino acids, a 5' untranslated region (UTR) of 483 bp, and a 3' UTR of 111 bp. The domain of PcMafG-like had a bZIP-Maf domain that binds to DNA. The cDNA sequence of PcMafG-like was 99 % similar to that of Penaeus vannamei. The mRNA of PcMafG-like was expressed in all tested tissues, and the highest expression was in muscle tissue. Under stimulation of Cu²⁺ and Cd²⁺, PcMafG-like was significantly up-regulated in hepatopancreas and gill, and the same result was testified by situ hybridization. The representative antioxidant genes, CAT, GPx and CZ-SOD, were significantly induced by Cu²⁺; CAT and GPx was induced by Cd²⁺. PcMafG-dsRNA significantly inhibited the expression of these up-regulated genes, but also inhibited the expression of other detected genes CZ-SOD, GST-θ and GST-1like. The antioxidant effect of PcMafG-like was further verified by oxidative stress markers (T-SOD, CuZnSOD, GPx, CAT, GSH and MDA) kits. Cu²⁺ and Cd²⁺ could induce the contents of these oxidative stress markers (MDA, GSH, CZ-SOD, CAT in Cu²⁺/Cd²⁺ treated group, and GSH-Px in Cd²⁺ group), while interference of PcMafG-like significantly inhibited the up-regulation. Furthermore, hematoxylin-eosin staining experiments showed that the degree of pathological damage was dose-dependent and time-dependent, and the pathological damage was more serious after dsRNA interfered with PcMafG-like. In addition, subcellular localization showed that PcMafG-like gene existed in nucleus. The recombinant protein PcMafG-like was expressed and purified in prokaryotic expression. The affinity analysis of promoter by agarose gel electrophoresis suggested that PcMafG-like could bind with CAT promoter in vitro. This indicated that PcMafG-like could activate antioxidant genes.

Antioxidant and genoprotective effects of osthole against cadmium-induced DNA damage: an in vitro study using comet assay

Background and purpose

Osthole, a plant-derived coumarin, has shown numerous pharmacological effects. However, its genoprotective effects against cadmium-induced DNA damage have not been determined yet. Therefore, this project aimed to assess the effectiveness of osthole against genotoxicity caused by cadmium.

Experimental approach

For this purpose, human umbilical vein endothelial cells (HUVECs) were incubated with various concentrations of osthole (40, 60, 80, and 120 µM) 24 h before cadmium chloride (CdCl₂) treatment (40 µM), and then DNA damage was evaluated by comet assay. Furthermore, DPPH and free thiol group assays were applied to evaluate reactive oxygen species scavenger and antioxidant capacities of osthole.

Findings / Results

In the present study, all concentrations of osthole significantly decreased CdCl₂-induced DNA damage. Furthermore, the antioxidant properties of the osthole were confirmed by DPPH and free thiol assays.

Conclusion and implications

Overall, the findings of this project revealed that osthole could ameliorate cadmium-induced genotoxicity probably by its antioxidant activity.

Toxic Effects of Cadmium on Fish

Large amounts of enriched cadmium (Cd) in the environment seriously threatens the healthy and sustainable development of the aquaculture industry and greatly restricts the development of the food processing industry. Studying the distribution and toxic effects of Cd in fish, as well as the possible toxic effects of Cd on the human body, is very significant. A large number of studies have shown that the accumulation and distribution of Cd in fish are biologically specific, cause tissue differences, and seriously damage the integrity of tissue structure and function, the antioxidant defense system, the reproductive regulation system, and the immune system. The physiological, biochemical, enzyme, molecular, and gene expression levels change with different concentrations and times of Cd exposure, and these changes are closely related to the target sites of Cd action and tissues in fish. Therefore, the toxic effects of Cd on fish occur with multiple tissues, systems, and levels.

Investigation on Immune-Related Protein (Heat Shock Proteins and Metallothionein) Gene Expression Changes and Liver Histopathology in Cadmium-Stressed Fish

Heat shock proteins (HSP) are highly conserved in their structure and released in case of stress. Increased metallothionein (MT) synthesis is associated with increased capacity for binding heavy metals. Healthy juveniles of grass carp were exposed to sublethal dose (1.495 mg L⁻¹) of cadmium for 28 days. Simultaneously, a control group was also run to compare difference of total RNA expression levels in cadmium-treated and control groups. The cadmium levels in the tissues of treated fish recorded were 1.78 ± 0.10 mg L⁻¹, 1.60 ± 0.04 mg L⁻¹, and 2.00 ± 0.05 mg L⁻¹, respectively. Several histological alterations including edema, hemorrhage, dilated sinusoids, hypertrophy, hyperplasia, congestion of central vein, and nuclear alterations were observed in cadmium-exposed fish. Stress gene (metallothionein and heat shock proteins) mRNA transcription levels were studied by mRNA extraction and cDNA preparation by using PCR. The expression level of heat shock protein gene was higher as compared to metallothionein and beta-2-microglobulin gene after cadmium exposure. This study reports various stress-related immune-responsive changes of immune proteins, heat shock proteins, metallothionein, and histopathological changes in fish due to cadmium toxicity that make the fish immunocompromised which may be considered as the biomarkers of cadmium toxicity in other experimental species.

Role of endoplasmic reticulum stress in cadmium-induced hepatocyte apoptosis and the protective effect of quercetin

Cadmium (Cd) is one of the most toxic environmental pollutants. Quercetin (Que) is a kind of natural flavonoid with neuroprotective, antioxidant, and free-radical scavenging pharmacological activities. However, whether Que has the protective effect of on Cd-induced rat hepatocyte injury is unclear. This study aimed to determine the protective effect of Que on Cd-induced hepatotoxicity in vivo and in vitro. For in vivo, 36 4-week-old male SD rats were randomly divided into six groups and were treated with CdCl₂ (2 mg/kg b.w.) and/or Que (50 or 100 mg/kg b.w.). Four weeks later, the rats were sacrificed and livers were collected. The levels of alanine aminotransferase, aspartate aminotransferase, glutathione, malondialdehyde, catalase, and superoxide dismutase were measured. Liver histopathological sections were made, and TUNEL method was performed to detect cell apoptosis. The mRNA and protein expression levels of endoplasmic reticulum stress (ERS) signaling pathway-related factors and apoptosis-related factors were detected. For in vitro, BRL-3A rat cells were treated with CdCl₂ (12.5 μM) and/or Que (5 μM Que). The mRNA and protein expression levels of ERS signaling pathway-related factors and apoptosis-related factors were detected. Results showed that Cd led to liver injury, disorder of hepatocyte morphology and structure, decreased BRL-3A cells viabilities, increased oxidative damage. The mRNA and protein expression levels of ERS related factors GRP78, PERK, eIF2α, ATF4, CHOP, IRE1α, XBP1, and ATF6 increased. The mRNA and protein levels of apoptosis related factors Caspase12, Caspase3, and Bax increased, whereas Bcl2 decreased. It indicated that cadmium could activate PERK-eIF2α-ATF4-CHOP, IRE1α-XBP1, and ATF6-CHOP ERS-related signal pathways and lead to apoptosis. Moreover, Que can improve the vitality of hepatocytes, and effectively reduce hepatocytes damage, and reduce oxidative damage by Cd. As a result, the mRNA and protein expression levels of ERS related factors were reduced and hepatocyte apoptosis related factors decreased. Therefore, Que can be used as an effective component in daily diet to prevent Cd toxicity.

Distinct responses from triglyceride and cholesterol metabolism in common carp (Cyprinus carpio) upon environmental cadmium exposure

Due to high persistence and bioavailability, Cadmium (Cd) is one of the most prevalent environmental contaminants, posing an elevating threat to the ecosystems. It has been evidenced that high-dose Cd elicits deleterious effects on aquatic organisms, but the potential toxicities of Cd at environmentally relevant concentrations remains underappreciated. In this study, we used common carp to investigate how environmental Cd exposure affects triglyceride (TG) and cholesterol metabolism and underlying mechanisms. The data indicated that Cd resulted in the shift of TG from the liver to blood and the movement of cholesterol in the opposite direction, ultimately giving rise to the storage of crude lipid in liver and muscle, especially hepatic cholesterol retention. Cholesterol, instead of TG, became the principal cause during the progression of hepatic lipid accumulation. Mechanistic investigations at transcriptional and translational levels further substantiated that Cd blocked hepatic biosynthesis of TG and enhanced TG efflux out of the liver and fatty acid β-oxidation, which collectively led to the compromised TG metabolism in the liver and accelerated TG export to the serum. Additionally, strengthened synthesis, retarded export and oxidation of cholesterol detailed the hepatic prominent cholesterol retention. Taken together, our results demonstrated that environmental exposure to Cd perturbed lipid metabolism through triggering distinct responses from hepatic TG and cholesterol homeostasis. These indicated that environmental factors (such as waterborne Cd) could be a potential contributor to the prevalence of non-alcoholic fatty-liver disease in aquaculture and more efforts should be devoted to the ecological risk assessment of pollutants under environmental scenarios.

Apigenin ameliorates di(2-ethylhexyl) phthalate-induced ferroptosis: The activation of glutathione peroxidase 4 and suppression of iron intake

Di(2-ethylhexyl) phthalate (DEHP) is a widely artificial persistent organic pollutant, the contamination of which infiltrates daily human life from many aspects, imperceptibly causing damage to multiple organs in the body, including the liver. Apigenin (APG) is widely distributed in vegetables and fruits and can relieve or prevent the injuries caused by exogenous chemicals through various pharmacological effects, such as antioxidant effects. To investigate the mechanism of DEHP-induced liver injury and the antagonistic effects of APG, we treated AML12 cells with 1 mM DEHP and/or APG. Ultrastructural morphology analysis indicated that DEHP induced typical ferroptosis-like damage. In addition, we found that DEHP exposure induced ferroptosis by enhancing reactive oxygen species (ROS) levels, disrupting iron homeostasis and lipid peroxidation, and regulating the expression of ferroptosis-related genes. Notably, supplementation with APG significantly inhibited these abnormal changes, and molecular docking further showed evidence of the activating effects of APG ligand on glutathione peroxidase 4 (GPX4). These results demonstrated that the protective effects of APG on DEHP-induced ferroptosis were achieved by activating GPX4 and suppressing intracellular iron accumulation. This information not only adds to DEHP toxicological data but also provides a basis for the practical application of APG.

Characterization, expression, and function analysis of AKR1A1 gene from yellow catfish (Tachysurus fulvidraco)

Aldehyde reductase (AKR1A1) is a carbonyl detoxification protein in toxic aldehyde removal. In the present study, the full-length cDNA of yellow catfish AKR1A1 (TfAKR1A1) was cloned. As expected, yellow catfish AKR1A1 showed similarities with that of other species. Subsequently, prokaryotic expression vector was constructed and recombinant TfAKR1A1 (rTfAKR1A1) was successfully induced and purified. rTfAKR1A1 exhibited reductive activity to many aldehydes and ketones. To determine whether TfAKR1A1 could confer stress tolerance in vitro, the viability of control and TfAKR1A1 expression E. coli under abiotic stress was compared by spot assay. Results showed that the recombinant strain had better stress resistance under cadmium, hydrogen peroxide, and DL-glyceraldehyde stress. Then, effects of an intraperitoneal injection of rTfAKR1A1 protein on cadmium-induced oxidative stress were evaluated. Results displayed that TfAKR1A1 and Nrf2 expression levels were significantly decreased, CAT and SOD expression levels were significantly increased, BCL-2 and IL-10 expression levels were significantly increased, and caspase3a, NF-κB, and IL-1β expression levels were significantly decreased in protein-injection group. Furthermore, oxidative stress indexes in livers under different protein injection doses were examined by ELISA. Results showed that CAT, SOD, and GSH-Px activities were upregulated, ROS and T-AOC contents were also improved, while MDA content was significantly decreased both in lower and middle dose injection groups. Finally, liver pathological section analysis was performed. Results displayed that liver injury degree in protein-injected groups was lower than that of PBS group under cadmium stress. These results suggested that TfAKR1A1 played important roles in response to cadmium stress in yellow catfish.

Effects of short-term exposure to tralopyril on physiological indexes and endocrine function in turbot (Scophthalmus maximus)

Tralopyril is an emerging marine antifouling agent with potential toxic effects on non-target aquatic organisms. To evaluate the toxicity of tralopyril, to turbot (Scophthalmus maximus), we assessed biomarkers, including oxidative stress, neurotoxicity, and osmotic homeostasis regulation enzymes, after a 7-day exposure to tralopyril (5 μg/L, 15 μg/L, 30 μg/L). Superoxide dismutase activity was significantly decreased at 30 μg/L, and Ca²⁺-Mg²⁺-ATPase activity in the gills was significantly increased at 15 μg/L and 30 μg/L. No statistically significant differences in the responses of acetylcholinesterase and nitric oxide were detected. In addition, 15 μg/L and 30 μg/L tralopyril induced hyperthyroidism, reflected by significantly increased of T3 levels. The expression levels of hypothalamus-pituitary-thyroid axis-related genes were also upregulated. The molecular docking results showed that the thyroid system disruption was not caused by competitive binding to the receptor. In addition, the integrated biomarker response index showed that 15 μg/L tralopyril had the greatest effect on turbot. In general, tralopyril caused oxidative damage, affected energy metabolism, and interfered with the endocrine system. These findings could provide reference data for assessing the ecological risk of tralopyril in marine environments.

Rutin Ameliorates Cadmium-Induced Necroptosis in the Chicken Liver via Inhibiting Oxidative Stress and MAPK/NF-κB Pathway

Cadmium (Cd) is a recognized toxic metal and exerts serious hepatotoxicity in animals and humans. Rutin (RUT) is a dietary bioflavonoid with strong antioxidant and anti-inflammatory potential. However, little is known about the alleviating effect of RUT against Cd-induced liver necroptosis. The aim of this study was to ascertain the ameliorative mechanism of RUT on necroptosis triggered by Cd in chicken liver. One hundred twenty-eight 100-day-old Isa hens were randomly divided into four groups: the control group, RUT group, Cd + RUT cotreated group, and Cd group. Cd exposure prominently elevated Cd accumulation and the activities of liver function indicators (ALT and AST). Furthermore, the histopathological results, the overexpression of genes (RIPK1, RIPK3, and MLKL) related to the necroptosis pathway, and low Caspase 8 levels in Cd-exposed chicken liver indicated that Cd intoxication induced necroptosis in chicken liver. Meanwhile, Cd administration drastically increased the levels of oxidizing stress biomarkers (ROS production, MDA content, iNOS activity, and NO generation), and obviously reduced the activities of antioxidant enzymes (SOD, GPx, and CAT) and total antioxidant capacity (T-AOC) in chicken liver. Cd treatment promoted the expression of the main members of the MAPK and NF-κB pathways (JNK, ERK, P38, NF-κB, and TNF-α) and activated heat shock proteins (HSP27, HSP40, HSP60, HSP70, and HSP90). However, RUT application remarkably alleviated these Cd-induced variations and necroptosis injury. Overall, our study demonstrated that RUT might prevent Cd-induced necroptosis in the chicken liver by inhibiting oxidative stress and MAPK/NF-κB pathway.

Toxic effects of waterborne cadmium exposure on hematological parameters, oxidative stress, neurotoxicity, and heat shock protein 70 in juvenile olive flounder, Paralichthysolivaceus

Cadmium-induced toxicity can affect fish embryo development, ion homeostasis regulation, energy metabolism, maturation and growth, stress response, and immunity. However, studies on the toxic effects of cadmium exposure to aquatic animals, particularly olive flounder (Paralichthys olivaceus), are limited. In this study, juvenile P. olivaceus (mean length, 12.9 ± 1.3 cm; mean weight, 23.1 ± 3.2 g) was exposed to waterborne cadmium (0, 50, 100, 200, and 400 μg/L) for 10 d. Hematological parameters, including hematocrit value and hemoglobin level, in P. olivaceus were significantly decreased after waterborne cadmium exposure. Plasma components such as calcium, glucose, cholesterol, glutamic-oxaloacetic transaminase, and glutamic-pyruvic transaminase were significantly altered via cadmium exposure. The activities of antioxidant enzymes, such as superoxide dismutase, catalase, and glutathione S-transferase, were significantly altered in P. olivaceus after cadmium exposure. Acetylcholinesterase activity was significantly inhibited upon waterborne cadmium exposure. Hepatic heat shock protein 70 was significantly upregulated in P. olivaceus after waterborne cadmium exposure. Therefore, waterborne cadmium at concentrations of >100 or 200 μg/L can induce physiological toxicity in P. olivaceus via changes in hematological parameters, antioxidant enzymes, neurotransmitters, and stress indicators.

Dual role of cadmium in rat liver: Inducing liver injury and inhibiting the progression of early liver cancer

The heavy metal cadmium (Cd) can induce damage in liver and liver cancer cells; however, the mechanism underlying its toxicity needs to be further verified in vivo. We daily administered CdCl2 to adult male rats at different dosages via gavage for 12 weeks and established rat liver injury model and liver cancer model to study the dual role of Cd in rat liver. Increased exposure to Cd resulted in abnormal liver function indicators, pathological degeneration, rat liver cell necrosis, and proliferation of collagen fibres. Using immunohistochemistry, we found that the area of GST-P-positive precancerous liver lesions decreased in a dose-dependent manner. Real-time quantitative polymerase chain reaction, western blot, immunohistochemistry, and transmission electron microscopy revealed that Cd induced mitophagy, as well as mitophagy blockade, as evidenced by the downregulation of TOMM20 and upregulation of LC3II and P62 with increasing Cd dose. Next, the expression of PINK1/Parkin, a classic signalling pathway protein that regulates mitophagy, was examined. Cd was found to promote PINK1/Parkin expression, which was proportional to the Cd dose. In conclusion, Cd activates PINK1/Parkin-mediated mitophagy in a dose-dependent manner. Mitophagy blockade likely aggravates Cd toxicity, leading to the dual role of inducing liver injury and inhibiting the progression of early liver cancer.

Exposure to imidacloprid induce oxidative stress, mitochondrial dysfunction, inflammation, apoptosis and mitophagy via NF-kappaB/JNK pathway in grass carp hepatocytes

Imidacloprid (IMI) is a neonicotinoid compound widely used in agriculture production, causing surface water pollution and threatening non-target organisms. The aim of this study was to analyze the effects of IMI on grass carp (Ctenopharyngodon idellus) liver cell (L8824) injury. The L8824 cells were exposed to different doses of IMI (65 mg/L, 130 mg/L and 260 mg/L) for 24 h. Our results demonstrated that exposure IMI significantly suppressed the activity of anti-oxidant enzymes (SOD, CAT and T-AOC) and accumulated oxidase (MDA) levels, and promoting reactive oxygen species (ROS) generation in L8824 cells. Additionally, mitochondrial membrane potential (ΔΨ m), mitochondria-derived ROS and ATP content and the MitoTracker Green indicated that IMI aggravated mitochondrial dysfunction, thereby inducing inflammation and enhancing pro-inflammatory genes (NF-kappaB, TNFα, IL-1β and IL-6) expressions. However, the addition of 2 mM N-acetyl-l-cysteine (NAC) can reverse these adverse effects of high-dose IMI- induced. Hence, ROS is the main factor of IMI-induced mitochondrial dysfunction and inflammation. We further found that exposure to IMI induced apoptosis, which is characterized by promoting release of cytochrome c (Cyt-C), and increasing the expression of Bcl-2-Associated X (BAX), cysteinyl aspartate specific proteinases (Caspase 9 and 3), decreasing Bcl-2 level. Immunofluorescent staining, qRT-PCR and Western Blot results indicated that IMI exposure also activated mitophagy, which was demonstrated by the expression of mitophagy-related genes (BNIP3, LC3B and P62). Conversely, scavenging JNK by SP600125(10 μM) alleviated the expression of mitochondrial apoptosis and mitophagy-related gene induced by high-dose IMI. Therefore, these results of study demonstrated that IMI-induced oxidative stress to regulate mitochondrial dysfunction, thus causing inflammation, mitochondrial apoptosis and mitophagy in grass carp hepatocytes through NF-kappaB/JNK pathway.

The role of DRP1- PINK1-Parkin-mediated mitophagy in early cadmium-induced liver damage

Cadmium (Cd) is an important environmental pollutant that causes varying degrees of damage to multiple systems of the body. However, the specific mechanism of Cd-induced liver mitophagy remains unclear. In the present study, 5-week-old BALB/c mice and a mouse liver parenchyma cell line (AML12) were studied using a combination of in vivo and in vitro studies. We found that Cd damaged liver cells, destroy the structure and function of mitochondria, and increased the production of superoxide anions. This study further examined the effect of Cd on mitochondrial dynamics and mitophagy and showed that Cd increased mitochondrial division and induced mitophagy. The PINK1-Parkin pathway is a classical mitophagy pathway. Cd-induced mitophagy was inhibited after significantly knocking down Pink1. Mdivi-1 can effectively inhibit mitochondrial division. In this study, Mdivi-1 inhibited the expression of DRP1 and significantly inhibited the occurrence of mitophagy induced by Cd. We further examined the effect of Cd on mitophagy flux. Cd did not increase lysosomal colocalization with mitochondria. In summary, Cd increase the level of oxidative stress, destroy the structure and function of mitochondria, destroy the homeostasis of mitochondrial division and fusion, induce mitophagy through the PINK1-Parkin pathway. Mitophagy plays a protective role in early cadmium-induced liver damage.

Effects of long-term cadmium exposure on growth, antioxidant defense and DNA methylation in juvenile Nile tilapia (Oreochromis niloticus)

Cadmium (Cd) is a ubiquitous environmental contaminant, posing serious threats to aquatic organisms. The aims of the present study were to investigate the effects of long-term Cd exposure on the growth, GH/IGF axis, antioxidant defense and DNA methylation in juvenile Nile tilapia (Oreochromis niloticus). To this end, juvenile Nile tilapia were exposed to 0, 10 and 50 µg∙L-1 Cd for 45 and 90 days. The obtained results revealed that exposure to high concentrations of Cd significantly decreased body mass and body length, and down-regulated mRNA levels of GHRs, IGF-I and IGF-II in the liver of Nile tilapia. Cd exposure induced oxidative stress including the reduction of antioxidant activities and increases of malondialdehyde (MDA) and 8-hydroxydeoxyguanosine (8-OHdG) contents. Beside, the global DNA methylation levels significantly decreased with increasing Cd concentration and exposure time, which might result from increased oxidative DNA damage, the down-regulated expression of DNMT3a and DNMT3b and up-regulated expression of TET1 and TET2. In conclusion, long-term Cd exposure could inhibit growth, reduce antioxidant capacity and lead to oxidative damages to lipid and DNA, and decrease global DNA methylation level in juvenile Nile tilapia.

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

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

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

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