Pb-induced Toxicity Research Articles

Moringa oleifera Leaf Extract Attenuates Pb Acetate-induced Testicular Damage in Rats.

Lead (Pb) remains a common contaminant in the environment in many parts of the world. Pb exposure adversely affects many human organs, including the gonads, via oxidant and inflammatory marker propagation in affected tissues. Moringa oleifera leaf extract (MOE) is a rich source of antioxidants, reported to have robust anti-inflammatory properties. This investigation assessed whether MOE could mitigate testicular damage caused by Pb acetate treatment in rats. Four experimental groups were used: control animals (saline only), MOE (MOE only), PbAc (Pb acetate injection only), and MOE+PbAc. All treatments were administered for two weeks, after which animals were sacrificed, and tissues and serum were examined. To confirm the potential antioxidant effect of MOE, the total polyphenolic (TP) and flavonoid (TF) concentrations were determined. The obtained results revealed that the TP concentration was 17.4 mg gallic acid equivalents per gram MOE dried weight and the TF concentration was 5.6 mg of quercetin equivalents per gram MOE dried weight. Moreover, MOE partially restored levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) and testosterone and significantly attenuated oxidative stress biomarkers, malondialdehyde (MDA) and nitric oxide (NO), compared to levels observed in the PbAc-only group. MOE significantly increased the enzymatic and non-enzymatic antioxidant molecules superoxide dismutase (SOD) and catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR), and glutathione (GSH). Testicular levels of inflammatory cytokines tumor necrosis factor-alpha (TNFα) and interleukin-1beta (IL-1β) were significantly decreased in MOE+PbAc compared to PbAc. MOE also significantly decreased pro-apoptotic Bax and caspase- 3 mRNA and protein levels and increased anti-apoptotic Bcl-2 mRNA and protein levels. MOE extract was associated with significant antioxidant, anti-inflammatory, and anti- apoptotic activity that ameliorated testicular damage induced by Pb acetate. MOE is proposed as a favorable adjuvant to existing treatments for Pb-induced toxicity.

Effect of dietary vitamins in oral bioaccessibility of lead in contaminated soils based on the physiologically based extraction test

To determine the effect of vitamin supplements on the oral bioaccessibility of Pb in soils, Pb bioaccessibility was measured in the presence of 9 vitamins by a physiologically based extraction test. Gastric Pb bioaccessibility (G-BA, 2.6–83.3%) was found to be mostly reduced (1.1–3.1 fold) in the presence of B vitamins, specifically vitamins B1, B6, and B9. In contrast, a significant increase in Pb G-BA was observed with vitamin C and E involved. In the small intestinal phases, Pb bioaccessibility (I-BA) ranged from 0.1% to 16.0%, being 5–50 fold lower than the corresponding G-BA values. Vitamin C supplementation showed a 7-fold increase in Pb I-BA, with a similar increase presented in approximately 30% of samples treated to vitamin B involvement. Lead liberation in gastrointestinal digests was associated with the dissolution of Fe and Mn regulated by vitamins. In conclusion, the addition of B vitamins resulted in the reduction of gastric Pb bioaccessibility, but the bioaccessibility value increased in participation of vitamin C and E. Elevated intestinal bioaccessibility was found especially for vitamin C. This should contribute to more accurate assessment of health risks from contaminated soils. Nutritional management aimed at preventing Pb-induced toxicity can benefit from knowledge of vitamin influence on soil Pb bioaccessibility.

Chemopreventive effect of riboflavin on the potassium bromate-induced renal toxicity in vivo.

Potassium bromate (PB) is a general food additive, flavor enhancer, a by-product of water disinfection, and a class 2 carcinogen. It exerts various toxic effects in a dose- and time-dependent manner in vivo. This study is to explore the chemopreventive efficacy of vitamin B2 (riboflavin, RF) in PB-administered Swiss albino rats. The rats were distributed into five groups: control (group 1), PB alone (group 2, 150mg/kg), RF alone (group 3, 2mg/kg), PB + RF1 (group 4, 150 and 2mg/kg), and PB + RF2 (group 5, 150 and 4mg/kg). All the rodents were sacrificed after the completion of the treatment cycle. Then, blood and kidney samples were subjected to biochemical analysis. Group 2 demonstrated vivid signs of renal toxicities evidenced by altered renal function markers (urea, creatinine, albumin, glutathione-S-transferase) and redox status parameters (superoxide dismutase, catalase, glutathione reductase, reduced glutathione, lipid, and protein oxidation products). However, group 3 exhibited a slight alteration in many of the parameters while groups 4 and 5 demonstrated dose-dependent chemopreventive efficiency of RF against PB-induced alterations. Besides, RF seemed to facilitate apoptosis as well as inhibition of the necrosis in the PB-pre-challenged groups, as demonstrated by the cleaved PARP and lactate dehydrogenase activity. Also, the histopathological analysis and comet assay validate the biochemical results of the treatment groups significantly. All these results plead that RF has a significant chemopreventive property against PB-induced toxicity in vivo. Therefore, RF is a suitable agent in preventing the PB-induced toxicities at the clinical and industrial levels.

Characterisation of early responses in lead accumulation and localization of Salix babylonica L. roots

BackgroundLead (Pb) is a harmful pollutant that disrupts normal functions from the cell to organ levels. Salix babylonica is characterized by high biomass productivity, high transpiration rates, and species specific Pb. Better understanding the accumulating and transporting Pb capability in shoots and roots of S. babylonica, the toxic effects of Pb and the subcellular distribution of Pb is very important.ResultsPb exerted inhibitory effects on the roots and shoots growth at all Pb concentrations. According to the results utilizing inductively coupled plasma atomic emission spectrometry (ICP-AES), S. babylonica can be considered as a plant with great phytoextraction potentials as translocation factor (TF) value > 1 is observed in all treatment groups throughout the experiment. The Leadmium™ Green AM dye test results indicated that Pb ions initially entered elongation zone cells and accumulated in this area. Then, ions were gradually accumulated in the meristem zone. After 24 h of Pb exposure, Pb accumulated in the meristem zone. The scanning electron microscopy (SEM) and energy-dispersive X-ray analyses (EDXA) results confirmed the fluorescent probe observations and indicated that Pb was localized to the cell wall and cytoplasm. In transverse sections of the mature zone, Pb levels in the cell wall and cytoplasm of epidermal cells was the lowest compared to cortical and vessel cells, and an increasing trend in Pb content was detected in cortical cells from the epidermis to vascular cylinder. Similar results were shown in the Pb content in the cell wall and cytoplasm of the transverse sections of the meristem. Cell damage in the roots exposed to Pb was detected by propidium iodide (PI) staining, which was in agreement with the findings of Pb absorption in different zones of S. babylonica roots under Pb stress.ConclusionS. babylonica L. is observed as a plant with great potential of Pb-accumulation and Pb-tolerance. The information obtained here of Pb accumulation and localization in S. babylonica roots can furthers our understanding of Pb-induced toxicity and its tolerance mechanisms, which will provide valuable and scientific information to phytoremediation investigations of other woody plants under Pb stress.

Alleviating effects of reduced graphene oxide against lead-induced cytotoxicity and oxidative stress in human alveolar epithelial (A549) cells.

Broad application of reduced graphene oxide (rGO) and ubiquitous lead (Pb) pollution may increase the possibility of combined exposure of humans. Information on the combined effects of rGO and Pb in human cells is scarce. This work was designed to explore the potential effects of rGO on Pb-induced toxicity in human alveolar epithelial (A549) cells. Prepared rGO was polycrystalline in nature. The formation of a few layers of visible creases and silky morphology due to high aspect ratio was confirmed. Low level (25 μg/mL) of rGO was not toxic to A549 cells. However, Pb exposure (25 μg/mL) induced cell viability reduction, lactate dehydrogenase enzyme leakage with rounded morphology in A549 cells. Remarkably, Pb-induced cytotoxicity was significantly mitigated by rGO co-exposure. Pb-induced mitochondrial membrane potential loss, cell cycle arrest and higher activity of caspase-3 and -9 enzymes were also alleviated by rGO co-exposure. Moreover, we observed that Pb exposure causes generation of pro-oxidants (e.g., reactive oxygen species, hydrogen peroxide and lipid peroxidation) and antioxidant depletion (e.g., glutathione and antioxidant enzymes). In addition, the effects of Pb on pro-oxidant and antioxidant markers were significantly reverted by GO co-exposure. Inductively coupled plasma-mass spectrometry suggested that due to the adsorption of Pb on rGO sheets, accessibility of Pb ions for A549 cells was limited. Hence, rGO reduced the toxicity of Pb in A549 cells. This research warrants further study to work on detailed underlying mechanisms of the mitigating effects of rGO against Pb-induced toxicity on a molecular level.

Evaluating the role of vitexin on hematologic and oxidative stress markers in lead-induced toxicity in mice

We aimed to evaluate the effect of vitexin on some hematologic parameters and oxidative stress markers in lead-induced toxicity in mice. Forty adult male albino mice were divided into five groups of eight animals comprising: control; Pb; vitexin; Pb + vitexin; and Pb + vitexin (post) groups. Blood samples collected were analyzed using an auto hematology analyzer for sixteen parameters including red cell distribution width (RDW), red blood cell (RBC), and white blood cell (WBC). The levels of oxidative stress markers were also assessed. In Pb-treated group, RDW, RBC, MCV, Hb, Hct, granulocytes, and blood lead level were significantly different from the control group as well as Pb + vitexin (post) group. In Pb + vitexin groups, MCHC, platelets, and lymphocytes counts were significantly different from the control group. There was no difference in MPV, MID, and WBC between the groups. MDA level in Pb-treated group was significantly high while SOD and GPx levels were low. In Pb + vitexin-treated groups, SOD and GPx levels were significantly high while MDA was low. Pb-induced toxicity caused significant changes in the values of hematologic parameters and oxidative markers measured but vitexin was able to mitigate some of the changes. Some of the values were inconsistent with Pb intoxication.

Using Cordyceps militaris extracellular polysaccharides to prevent Pb2+-induced liver and kidney toxicity by activating Nrf2 signals and modulating gut microbiota.

In this study, we investigated the protective efficacy of extracellular polysaccharide from Cordyceps militaris (CEP-I) in liver and kidney and their regulating effect on gut microbiota against Pb-induced toxicity in vivo. The results indicated that CEP-I could reduce the Pb2+ content and organ index of liver and kidney in mice. Besides, biochemical analysis showed that CEP-I could improve the activity of glutathione peroxidase (GSH-Px), malondialdehyde (MDA) and superoxide dismutase (SOD) in serum and organs, restore the physiological indexes of total protein (TP), albumin (ALB), blood urea nitrogen (BUN) and creatinine (CRE) in serum and decrease the enzyme activity of lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) in the liver and kidney of mice poisoned by Pb2+. This indicated that CEP-I has a protective effect on organs against damage in mice. In addition, CEP-I could regulate the expression of key proteins in the Nrf2 signaling pathway, including NF-E2-related factor 2 (Nrf2), Kelch-like ECH-associated protein-1 (Keap1), Heme oxygenase (HO-1) and NAD(P)H: quinone oxidoreductase 1 (NQO1). Furthermore, the intestinal flora analysis results indicated that CEP-I also has the capacity to regulate the intestinal flora imbalance caused by Pb2+ in poisoned mice. In conclusion, we hope that this study can provide theoretical basis for the treatment of tissue damage induced by Pb2+.

Zinc ameliorates lead toxicity by reducing body Pb burden and restoring Pb-induced haematological and biochemical derangements

Background:Studies on nutritional factors, including zinc in ameliorating the deleterious effects of potentially toxic elements have been scarce and the findings have been inconsistent.Aim:The aim of the present study was to evaluate the ameliorative potential of zinc against lead-induced toxicity in rats.Materials and methods:Male albino rats (n = 24) assigned into four groups of six/group: normal control (NC), zinc control (ZnC; 20 mg/kg ZnCl2), lead control (PbC; 50 mg/kg PbCl2) and lead plus zinc (Pb + Zn; 50 mg/kg PbCl2plus 20 mg/kg ZnCl2), respectively were investigated. All administrations were through oral route and lasted for 42 days after which blood samples were collected for haematological and biochemical analyses using standard techniques.Results:Results showed that packed cell volume (PCV), haemoglobin concentration (HBC), red blood cell count (RBC) were significant (p < 0.05) reduced while total white blood cell count (TWBC), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC) and platelets were significantly elevated in PbC group in comparison with NC and ZnC. Also liver and renal function parameters as well as the liver and kidney malondialdehyde (MDA) were elevated while antioxidant enzymes; catalase (CAT) and superoxide dismutase (SOD) were significantly (p < 0.05) reduced in PbC group in comparison with NC and ZnC. Concentrations of lead were in the order: blood > liver > kidney in the PbC group. In addition to restoration of the altered parameters, administration of zinc in Pb + Zn group significantly reduced the raised lead concentrations in the plasma and organs.Conclusion:Reduction in body Pb burden and restoration of Pb-induced derangements in haematological and biochemical parameters by Zn strongly support the ameliorative property of Zn against Pb-induced toxicity.

Comparative study on the effects of salinomycin, monensin and meso-2,3-dimercaptosuccinic acid on the concentrations of lead, calcium, copper, iron and zinc in lungs and heart in lead-exposed mice

Background and aimEnvironmental lead (Pb) exposure damages the lungs and is a risk factor for death from cardiovascular disease. Pb induces toxicity by a mechanism, which involves alteration of the essential elements homeostasis. In this study we compare the effects of salinomycin (Sal), monensin (Mon) and meso-2,3-dimercaptosuccinic acid (DMSA) on the concentrations of lead (Pb), calcium (Ca), copper (Cu), iron (Fe) and zinc (Zn) in the lungs and heart of lead-exposed mice. MethodsSixty days old male ICR mice were divided into five groups: control (Ctrl) – untreated mice obtained distilled water for 28 days; Pb-intoxicated group (Pb) – exposed to 80 mg/kg body weight (BW) Pb(NO3)2 during the first 14 days of the experimental protocol; DMSA-treated (Pb + DMSA) – Pb-exposed mice, subjected to treatment with an average daily dose of 20 mg/kg BW DMSA for two weeks; Monensin-treated (Pb + Mon) – Pb-exposed mice, obtained an average daily dose of 20 mg/kg BW tetraethylammonium salt of monensic acid for 14 days; Pb + Sal - Pb-exposed mice, treated with an average daily dose of 20 mg/kg BW tetraethylammonium salt of salinomycinic acid for two weeks. On the 29th day of the experiment the samples (lungs and heart) were taken for atomic absorption analysis. ResultsThe results revealed that exposure of mice to Pb for 14 days significantly increased the concentration of the toxic metal in both organs and elevated the cardiac concentrations of Ca, Cu and Fe compared to untreated mice. Pb exposure diminished the lung concentrations of Ca and Zn compared to that of untreated controls. DMSA, monensin and salinomycin decreased the concentration of Pb in the lungs and heart. Among the tested chelating agents, only salinomycin restored the cardiac Fe concentration to normal control values. ConclusionThe results demonstrated the potential application of polyether ionophorous antibiotic salinomycin as antidote for treatment of Pb-induced toxicity in the lungs and heart. The possible complexation of the polyether ionophorous antibiotics with Ca(II) and Zn(II), which can diminish the endogenous concentrations of both ions in the lungs should be taken into account.

Nitric Oxide Enhances Cytotoxicity of Lead by Modulating the Generation of Reactive Oxygen Species and Is Involved in the Regulation of Pb2+ and Ca2+ Fluxes in Tobacco BY-2 Cells.

Lead is a heavy metal known to be toxic to both animals and plants. Nitric oxide (NO) was reported to participate in plant responses to different heavy metal stresses. In this study, we analyzed the function of exogenous and endogenous NO in Pb-induced toxicity in tobacco BY-2 cells, focusing on the role of NO in the generation of reactive oxygen species (ROS) as well as Pb2+ and Ca2+ fluxes using non-invasive micro-test technology (NMT). Pb treatment induced BY-2 cell death and rapid NO and ROS generation, while NO burst occurred earlier than ROS accumulation. The elimination of NO by 2-4-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) resulted in a decrease of ROS, and the supplementation of NO by sodium nitroprusside (SNP) caused an increased accumulation of ROS. Furthermore, the addition of exogenous NO stimulated Pb2+ influx, thus promoting Pb uptake in cells and aggravating Pb-induced toxicity in cells, whereas the removal of endogenous NO produced the opposite effect. Moreover, we also found that both exogenous and endogenous NO enhanced Pb-induced Ca2+ effluxes and calcium homeostasis disorder. These results suggest that exogenous and endogenous NO played a critical regulatory role in BY-2 cell death induced by Pb stress by promoting Pb2+ influx and accumulation and disturbing calcium homeostasis.

The remedial effect of Thymus vulgaris extract against lead toxicity-induced oxidative stress, hepatorenal damage, immunosuppression, and hematological disorders in rats.

The Thymus vulgaris (T. vulgaris) has been used in foods for the flavor, aroma, and preservation and in folk medicines. The objective of the present work was to determine the antioxidant and protective effects of T. vulgaris extract against lead (Pb)-intoxicated rats. A thirty-two male Sprague-Dawley were randomly assigned into 4 equal groups and treated for sixweeks as follows: group I (GP-I), served as negative control; GP-II, -III, and -IV received either Pb acetate in drinking water (500mg/L), T. vulgaris extract (500mg/kg/day) by oral gavage or Pb acetate with T. vulgaris extract, respectively. Blood samples were collected at the end of the study week 6 to measure the hepatic and renal biochemical markers, complete blood count alongside the serum levels of interleukin (IL)-1β, IL-6, IL-10, tumor necrosis (TNF)-α, and interferon (IFN)-γ. Additionally, liver and kidney tissue specimens were collected for histopathology as well as to measure the antioxidant-reduced glutathione (GSH), glutathione peroxidase (GPx), catalase (CAT), and superoxide dismutase (SOD) alongside the lipid peroxidation marker, malonaldehyde (MDA). The results indicated that Pb toxicity increased the serum levels of IL-1β, IL-6, and TNF-α, whereas IL-10 and IFN-γ were reduced. The results showed disturbed liver and renal functions; increased serum levels of ALT, AST, ALP, total bilirubin, creatinine, and urea; and decreased total protein, albumin, and calcium. The GSH, Gpx, and CAT levels were significantly decreased in the Pb-administrated group, while MDA was increased. However, regarding the hepatorenal markers, those animals treated with T. vulgaris alone did not induce any significant changes. Moreover, the combined treatment with T. vulgaris extract together with Pb showed significant improvement in Pb-induced toxicity in all the tested parameters compared to the negative control group. We investigated the potential protective effects of the medicinal plant T. vulgaris in vivo, since there are no publications that address the potential protective effect of this leaf extract against Pb-induced hepatorenal toxicity. Our studies concluded that the T. vulgaris extract reduces Pb overload in hepatorenal tissues, and that this has a potential immunomodulatory role, antioxidant activity, and a protective effect against Pb toxicity.

Ameliorative effect of zinc oxide nanoparticles against potassium bromate-mediated toxicity in Swiss albino rats.

Potassium bromate (PB) is a commonly used food additive, a prominent water disinfection by-product, and a class IIB carcinogen. It exerts a various degree of toxicity depending on its dose and exposure duration consumed with food and water in the living organisms. The present investigation aims to demonstrate the protective efficacy of zinc oxide nanoparticles (ZnO NPs) derived from Ochradenus arabicus (OA) leaf extract by green technology in PB-challenged Swiss albino rats. The rodents were randomly distributed, under the lab-standardized treatment strategy, into the following six treatment groups: control (group I), PB alone (group II), ZnO alone (group III), ZnO NP alone (group IV), PB + ZnO (group V), and PB + ZnO NPs (group VI). The rats were sacrificed after completion of the treatment, and their blood and liver samples were collected for further analysis. Group II showed extensive toxic effects with altered liver function markers (alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, lactate dehydrogenase, gamma-glutamyl transferase, glutathione-S-transferase, and thioredoxin reductase) and compromised redox status (SOD, CAT, GR, GPx, GSH, MDA, and total carbonyl content). The histopathological analysis and comet assay further supported the biochemical results of the same group. Besides, group III also showed moderate toxicity evidenced by an alteration in most of the studied parameters while group IV demonstrated mild toxicity after biochemical analysis indicating the excellent biocompatibility of the NPs. However, group VI exhibited attenuation of the PB-induced toxic insults to a significant level as compared to group II, whereas group V failed to show similar improvement in the studied parameters. All these findings entail that the ZnO NPs prepared by green synthesis have significant ameliorative property against PB-induced toxicity in vivo. Moreover, administration of the NPs improved the overall health of the treated animals profoundly. Hence, these NPs have significant therapeutic potential against the toxic effects of PB and similar compounds in vivo, and they are suitable to be used at the clinical and industrial levels.

Preventive effect of TiO2 nanoparticles on heavy metal Pb-induced toxicity in human lung epithelial (A549) cells

Wide application of TiO2 nanoparticles (nTiO2) and ubiquitous lead (Pb) pollution in natural environment enhance the chance of co-exposure of humans to Pb and nTiO2. We investigated the effects of nTiO2 on Pb-induced toxicity in human lung epithelial (A549) cells. Results showed that nTiO2 was not toxic to A549 cells. Conversely, Pb-induced cytotoxicity and oxidative stress in A549 cells were evidenced by cell viability reduction, cell membrane damage, reactive oxygen species generation and depletion of antioxidants. The Pb was also found to alter the regulation of apoptotic genes and cell cycle. Interestingly, in co-exposure group (nTiO2 + Pb), nTiO2 effectively attenuated the cytotoxicity, oxidative stress and apoptotic responses of Pb in A549 cells. Cellular uptake experiments demonstrated that nTiO2 increased the bioaccumulation of Pb in cells. However, due to strong adsorption of Pb on nTiO2, free Pb ions were not available even inside the cells. Hence, nTiO2 significantly prevented the bioavailability and toxicity of Pb in A549 cells. This is the first report providing insight into understanding the mechanism of nTiO2 mediated prevention against Pb-induced toxicity in human cells. This study warranted further research on co-exposure effects of nTiO2 and Pb at in vivo mammalian models.

Differential response to lead toxicity in rat primary microglia and astrocytes

Lead (Pb) is one of the most widely studied occupational and environmental toxins. Chronic exposure to Pb affects neural function in the central nervous system (CNS). Glial cells in the CNS, such as microglia and astrocytes, respond differently to Pb-induced toxicity. However, the underlying mechanism has not yet been identified. We measured the cell viability and intracellular Pb uptake in rat primary microglia and astrocytes using the CCK-8 assay and inductively coupled plasma mass spectrometry, and found that Pb decreased microglial viability at lower dosages than in astrocytes, while Pb uptake was greater in astrocytes. Pb-induced oxidative stress in microglia results in increased production of reactive oxygen species, down-regulation of glutathione, and enhanced Nrf2 protein expression, while there was no obvious change in astrocytes. The role of Nrf2 in Pb-induced oxidative stress has also been confirmed in primary microglia with the use of Nrf2 small interfering RNA and an Nrf2 agonist. These data indicate that primary microglia were more sensitive to Pb exposure than astrocytes, which is associated with an obvious oxidative stress response and up-regulation of Nrf2 might be involved in this process.

Protective effects of a Lachnum polysaccharide against liver and kidney injury induced by lead exposure in mice

This study was designed to investigate the liver and kidney protective efficacy of a Lachnum polysaccharide (LEP) against Pb-induced toxicity in mice. The results showed that LEP decreased the Pb-induced bodyweight loss and organ index. Moreover, biochemical analysis showed that treatment of LEP could improve antioxidant status (CAT, GSH-Px and MDA) and the injury of tissues (liver and kidney). In addition, the histopathological observations indicated that LEP could attenuate liver and kidney cell injury induced by Pb. For further studies, key proteins involved in hepatic and kidney apoptosis, including cleaved caspase-3, Bax, Bcl-2, TGF-β1 and α-SMA, were quantified. The present findings demonstrated that LEP is strongly effective in protecting against the liver and kidney injury induced by Pb. We hope this research can offer a theoretical base for development of polysaccharide based on nutraceutical food in future.

Role of AMPK pathway in lead-induced endoplasmic reticulum stress in kidney and in paeonol-induced protection in mice

Paeonol is a natural flavonoid isolated from Moutan Cortex, which has been found to exhibit antioxidant, anti-apoptotic, anti-aging and anti-inflammatory bioactivities. Herein, we investigated the nephroprotective efficacy of paeonol against Pb-induced toxicity and elucidated the potential mechanisms. The results revealed that paeonol significantly ameliorated renal dysfunction and histology changes of Pb-treated mice. Paeonol inhibited oxidative stress and increased activities of antioxidant enzyme in the kidneys of Pb-treated mice. Paeonol decreased the nuclear factor-κB activation and over-production of inflammatory cytokines tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6). Paeonol suppressed endoplasmic reticulum (ER) stress in kidneys of in the Pb treatment group and primary kidney mesangial cells. Moreover, paeonol increased the denosine 5‘-monophosphate-activated protein kinase (AMPK) phosphorylation and decreased the activations of glycogen synthase kinase-3 (GSK-3), protein kinase RNA-like ER kinase (PERK), inositol-requiring protein-1 (IRE1), c-jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK). These results were further confirmed in primary kidney mesangial cells. Taken together, these findings indicate that paeonol could protect kidney form Pb-induced injury by inhibiting oxidative stress, ER stress and inflammation via the AMPK and GSK-3 pathway. Paeonol might be a potential therapeutic agent to inhibit ER stress-associated inflammation in lead-stimulated kidneys.

Neuroprotective Action of the CB1/2 Receptor Agonist, WIN 55,212-2, against DMSO but Not Phenobarbital-Induced Neurotoxicity in Immature Rats.

The developing brain is uniquely susceptible to drug-induced increases in programmed cell death or apoptosis. Many compounds, including anticonvulsant drugs, anesthetic agents, and ethanol, when administered in a narrow postnatal window in rodents, result in increased pruning of neurons. Here, we report that dimethyl sulfoxide (DMSO) triggers widespread neurodegeneration in the immature (postnatal day, P7) rat brain, an effect consistent with a prior report in neonatal mice. We found that the synthetic cannabinoid receptor agonist WIN 55,212-2 (WIN) exerts a neuroprotective effect against DMSO-induced cell death. We extended these findings to determine if WIN is neuroprotective against another drug class known to increase developmental cell death, namely antiseizure drugs. The antiseizure drug phenobarbital (PB) remains the primary treatment for neonatal seizures, despite significantly increasing cell death in the developing rodent brain. WIN exerts antiseizure effects in immature rodent seizure models, but increases the toxicity associated with neonatal ethanol exposure. We thus sought to determine if WIN would protect against or exacerbate PB-induced cell death. Unlike either the prior report with ethanol or our present findings with DMSO, WIN was largelywithout effect on PB-induced cell death. WIN alone did not increase cell death over levels observed in vehicle-treated rats. These data suggest that WIN has a favorable safety profile in the developing brain and could potentially serve as an adjunct therapy with phenobarbital (albeit one that does not attenuate PB-induced toxicity).

Tissue-specific molecular and cellular toxicity of Pb in the oyster (Crassostrea gigas): mRNA expression and physiological studies

Lead (Pb) is one of the ubiquitous and toxic elements in aquatic environment. In oysters, gills and digestive glands are the main target organs for Pb-induced toxicity, but there is limited information on the molecular mechanisms underlying its toxicity. The present study investigated the Pb-induced toxicity mechanisms in the Pacific oyster (Crassostrea gigas) based on transcriptome, phenotypic anchoring, and validation of targeted gene expression. Gene ontology and pathway enrichment analyses revealed the differential Pb toxicity mechanisms in the tissues. In the gills, Pb disturbed the protein metabolism, with the most significant enrichment of the “protein processing in endoplasmic reticulum” pathway. The main mechanism comprised of a Pb-stimulated calcium (Ca2+) increase by the up-regulation of transporter-Ca-ATPase expression. The disturbed Ca2+ homeostasis then further induced high expressions of endoplasmic reticulum (ER) chaperones, leading to ER stress in the oysters. Unfolded proteins induced ER associated degradation (ERAD), thereby preventing the accumulation of folding-incompetent glycoproteins. However, Pb mainly induced oxidative reduction reactions in the digestive gland with high accumulation of lipid peroxidation products and high expression of antioxidant enzymes. Further, Pb induced fatty acid β-oxidation and CYP450 catalyzed ω-oxidation due to increased metabolic expenditure for detoxification. The increased content of arachidonic acid indicated that Pb exposure might alter unsaturated fatty acid composition and disturb cellular membrane functions. Taken together, our results provided a new insight into the molecular mechanisms underlying Pb toxicity in oysters.

Antioxidant and Antiapoptotic Effects of Fraxetin against Lead Induced Toxicity in Human Neuroblastoma Cells

Exposure to lead (Pb), a toxic heavy metal produces a wide range of adverse health effects. Both adults and children can suffer from the effects of Pb-poisoning, but childhood Pb-poisoning is much more frequent. Low-level Pb-exposure can result in reduced IQ, learning disabilities, attention deficit disorders, behavioural problems, stunted growth, impaired hearing, and kidney damage. Oxidative stress is proposed as an intracellular mechanism in Pb-induced toxicity, suggesting the fact that antioxidants might play a very important role in the treatment of Pb-poisoning. The present study was designed to investigate whether fraxetin (FXT), an important coumarin has a beneficial effect on human SH-SY5Y neuroblastoma cells exposed to Pb. In the present study, the cells were exposed to different concentrations (0.01-10 mM) of Pb for 48 hours to determine the concentration (IC50 = 5 mM) at which 50% inhibition in the viability of cells.

Sensitive biomarkers identification for differentiating Cd and Pb induced toxicity on zebrafish embryos

Cadmium (Cd) and lead (Pb) are naturally existing heavy metals that pose significant health risks. The present study aims to identify sensitive biomarkers for differentiating the toxicities induced by Cd and Pb and for providing clues for the early prediction of toxicity and environmental risk assessment. Indicators related to oxidative stress and inflammatory responses in zebrafish treated with Cd and Pb over time (from 24hpf to 96hpf) were compared. Furthermore, endpoints such as embryo lethality and teratogenicity were detected. Then, several related genes involved in oxidative stress and inflammatory responses characterizing both Cd and Pb exposure, along with key molecules in the MAPKs pathway, were compared at the mRNA level, allowing the selection of the most sensitive and informative biomarkers. Significant increases in reactive oxygen species (ROS) production were observed in zebrafish exposed to Cd and Pb. Cd and Pb exposure induced developmental toxicity, influencing survival rate, hatching rate, larval growth, and heart rate and causing abnormal embryonic development. Similar trends in SOD1 and SOD2 gene expression were induced by Cd and Pb, while nuclear factor erythroid-2 related factor 2 (Nrf2) gene expression responded differently to each metal. In addition, Cd and Pb induced a delayed activation of the CAT and HO-1 genes, with no apparent change in the 24hpf and 48hpf groups. Genes related to immunotoxicity were activated significantly in a time-dependent manner, and these genes exhibited different sensitivities to Cd and Pb. MAPKs pathway genes were also activated in a time-dependent manner, and the expression of these genes showed different effects under Cd and Pb treatment. In summary, the present works have identified some potential sensitive biomarkers. The Nrf2 gene is a potential biomarker to differentiate Pb-induced toxicity from that of Cd, and the IFN-γ gene may be used as a sensitive biomarker for evaluating the risk of Pb contamination. We found that the timeline of MAPKs pathway activation helped to differentiate these two metals toxicities. Furthermore, Pb induced the early activation of ERK2/3 and JNK1, while p38 MAPKs showed delayed activation with no apparent change in the 24hpf group. Cd induced an early activation of ERK2 and a delayed activation of p38a, p38b, ERK3 and JNK1, indicating that the JNK1 pathway is sensitive to Pb exposure, while the p38 pathway may be susceptible to Cd. This work contributes to sensitive biomarker identification and early environmental risk evaluation for chemicals as well as toxicity prediction.