The role of HO-1 in protection against lead-induced neurotoxicity

Role of Nrf2/HO-1, PPAR-γ, and cytoglobin signals in the pathogenesis of methotrexate-induced testicular intoxication in rats and the protective effect of diacerein

Methotrexate (MTX) is an inhibitor of folic acid reductase used in managing a variety of malignancies. Testicular injury by MTX is one of its serious adverse effects. The current investigation aims to assess the protective effects of diacerein (DIA) on testicular injury by MTX and clarify the possible underlying mechanisms. Testicular injury in rats was induced by a single injection of 20 mg/kg body weight of MTX. DIA was given in 25 mg/kg body weight/day and 50 mg/kg body weight/day doses for 10 days. Compared to the MTX group, DIA attenuated testicular intoxication as evidenced by improvement of testicular histopathological abnormalities and increased serum testosterone and luteinizing hormone. DIA attenuated testicular oxidative stress changes by lowering testicular MDA and boosting GSH content and SOD activity. Moreover, administration of DIA attenuated MTX-induced testicular inflammation, as proved by decreased TNF-α and IL-6. At the molecular level, DIA induced significant upregulation in Nrf2, HO-1, PPAR-γ, and cytoglobin protein expression. The present results proved that DIA, in a dose-dependent manner, exhibited notable amelioration of testicular toxicity induced by MTX through augmentation of anti-inflammatory and antioxidant effects combined by upregulating Nrf2/HO-1, PPAR-γ, and cytoglobin signaling.

The application of human-derived cell lines in neurotoxicity studies of environmental pollutants

As industrial and societal advancements progress, an increasing number of environmental pollutants linked to human existence have been substantiated to elicit neurotoxicity and developmental neural toxicity. For research in this field, human-derived neural cell lines have become excellent in vitro models. This study examines the utilization of immortalized cell lines, specifically the SH-SY5Y human neuroblastoma cell line, and neural cells derived from human pluripotent stem cells, in the investigation of neurotoxicity and developmental neural toxicity caused by environmental pollutants. The study also explores the culturing techniques employed for these cell lines and provides an overview of the standardized assays used to assess various biological endpoints. The environmental pollutants involved include a variety of organic compounds, heavy metals, and microplastics. The utilization of cell lines derived from human sources holds significant significance in elucidating the neurotoxic effects of environmental pollutants and the underlying mechanisms. Finally, we propose the possibility of improving the in vitro model of the human nervous system and the toxicity detection methods.

Effects of food-borne cholesterol supplementation on lead-induced neurodevelopmental impairments of rats based on BDNF signaling pathway and cholesterol metabolism

Despite the ubiquity and prevalence of lead (Pb) in the environment and industry, the mechanism of lead-induced neurotoxicity in the brain remains unclear, let alone its prevention and treatment. In this study, we hypothesized that exogenous cholesterol supplementation acts as an effective remedy for lead-induced neurodevelopmental impairments caused by lead. Forty 21-day-old male rats were randomly divided into four groups and administered 0.1 % lead water and/or 2 % cholesterol-containing feed for 30 d. Ultimately, rats in the lead group lost weight, accompanied by spatial learning and memory impairments as verified by the Morris water maze test, in which the escape latency of rats was prolonged, and the number of crossings in the target platform and the residence time in the target quadrant were significantly diminished compared to the control group. Hematoxylin-Eosin (H&E) staining and Nissl staining illustrated that typical pathological morphology occurred in the brain tissue of the lead group, where the tissue structure was loose, the number of hippocampal neurons and granulosa cells decreased significantly and were arranged loosely, along with enlarged intercellular space, light matrix staining, and decline in Nissl bodies. In addition, inflammatory response and oxidative stress were significantly induced by lead. Immunofluorescence experiments showed apparent activation of astrocytes and microglia, followed by the enhancement of TNF-α and IL-β levels. Moreover, the MDA content in the lead group was elevated dramatically, whereas the activities of SOD and GSH were significantly inhibited. As for the mechanism, western blot and qRT-PCR experiments were performed, where lead could significantly inhibit the BDNF-TrkB signaling pathway, lowering the protein expression of BDNF and TrkB. Cholesterol metabolism was also affected by lead exposure, in which cholesterol metabolism-related protein expression and gene transcription, including SREBP2, HMGCR, and LDLR, were downregulated. However, cholesterol supplementation efficiently detoxified the negative effects of lead-induced neurotoxicity, reversing the inflammatory response, oxidative stress, inactivation of the BDNF signaling pathway, and imbalance of cholesterol metabolism, thus improving the learning and memory ability of rats. In brief, our study demonstrated that cholesterol supplementation could ameliorate the deficiency of learning and memory induced by lead, which is closely associated with the initiation of the BDNF/TrkB signaling pathway and regulation of cholesterol metabolism.

Lead exposure represses mitochondrial metabolism by activation of heme-binding protein BACH1 in differentiated SH-SY5Y cell

Exposure to lead (Pb), a known toxin causing developmental neurotoxicity, can impair neurogenesis and oxidative phosphorylation (OXPHOS), but the mechanism is not clarified. In the current study, we aim to explore the effects of Pb on the differentiation of SH-SY5Y cells and investigate the role of heme and heme-binding protein BACH1 during differentiation. We found that Pb exposure caused a shift from OXPHOS to glycolysis, resulting in neurogenesis impairment by decreasing neurite growth and downregulation of PSD95 and Synapsin-1 in differentiated SH-SY5Y cells. Heme reduction mediated this mitochondria metabolism repression caused by Pb depending on BACH1 activation. Hemin supplement alleviated Pb-induced OXPHOS damage and adenosine triphosphate (ATP) reduction in differentiated SH-SY5Y cells, and further protected for Pb-induced damage of synapse. Heme binding factor BACH1 was negatively regulated by heme content and BACH1 knockout rescued the Pb-induced transcription and expression decline of genes related to OXPHOS and abrogated Pb-induced growth inhibition of axon promotion and synapse formation. Collectively, the present study demonstrates that heme deficiency mediates OXPHOS damage caused by Pb through BACH1 activation, resulting in neurogenesis impairment.

Lead-induced neurodevelopmental lesion and epigenetic landscape: Implication in neurological disorders

Lead (Pb) was implicated in multiple genotoxic, neuroepigenotoxic, and chromosomal-toxic mechanisms and interacted with varying synaptic plasticity pathways, likely underpinning previous reports of links between Pb and cognitive impairment. Epigenetic changes have emerged as a promising biomarker for neurological disorders, including cognitive disorders, Alzheimer's disease (AD), and Parkinson's disease (PD). In the present review, special attention is paid to neural epigenetic features and mechanisms that can alter gene expression patterns upon environmental Pb exposure in rodents, primates, and zebrafish. Epigenetic modifications have also been discussed in population studies and cell experiment. Further, we explore growing evidence of potential linkage between Pb-induced disruption of regulatory pathway and neurodevelopmental and neurological disorders both in vivo and in vitro. These findings uncover how epigenome in neurons facilitates the development and function of the brain in response to Pb insult.

Xin-Ji-Er-Kang Alleviates Isoproterenol-Induced Myocardial Hypertrophy in Mice through the Nrf2/HO-1 Signaling Pathway

Xin-Ji-Er-Kang (XJEK) inhibited cardiovascular remodeling in hypertensive mice in our previous studies. We hypothesized that XJEK may prevent isoproterenol (ISO)-induced myocardial hypertrophy (MH) in mice by ameliorating oxidative stress (OS) through a mechanism that may be related to the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1(HO-1) pathways. Forty SPF male Kunming mice were randomized into 5 groups (n = 8 mice per group): control group, MH group, MH + different doses of XJEK (7.5 g/kg/day and 10 g/kg/day), and MH + metoprolol (60 mg/kg/day). On the eighth day after drug treatment, electrocardiogram (ECG) and echocardiography were performed, the mice were sacrificed, and blood and heart tissues were collected for further analysis. XJEK administration markedly ameliorated cardiovascular remodeling (CR), as manifested by a decreased HW/BW ratio and CSA and less collagen deposition after MH. XJEK administration also improved MH, as evidenced by decreased atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and β-myosin heavy chain (β-MHC) levels. XJEK also suppressed the decreased superoxide dismutase (SOD) and catalase (CAT) activities and increased malondialdehyde (MDA) levels in serum of mice with MH. XJEK-induced oxidative stress may be related to potentiating Nrf2 nuclear translocation and HO-1 expression compared with the MH groups. XJEK ameliorates MH by activating the Nrf2/HO-1 signaling pathway, suggesting that XJEK is a potential treatment for MH.

Folic acid alleviates lead acetate-mediated cardiotoxicity by down-regulating the expression levels of Nrf2, HO-1, GRP78, and CHOP proteins

The purpose of this study was to explore the interventional effects of folic acid on the heart damage caused by lead acetate exposure. Twenty-four 60-day-old male Sprague-Dawley (SD) rats were randomly divided into 4 groups with 6 rats in each group. The control group (C group) was normal rats; the lead exposure group (L group) rats drank 0.2% lead acetate solution freely for 14 days. The rats in the intervention group (T group) were given 0.2% lead acetate solution for 14 days, respectively, and 0.4 mg/kg BW folic acid solution was given to the rats by gavage on the 7th day of lead administration. The rats in the folic acid group (group E) were given 0.4 mg/kg BW folic acid solution by gavage. To weigh rat body weight and heart weight, calculate heart index, and observe the expression level of nuclear factor erythroid 2-related factor 2(Nrf2), heme oxygenase 1(HO-1), glucose-regulated protein 78/binding immunoglobulin protein (GRP78), and C/EBP-homologous protein (CHOP) by immunofluorescence method. The results showed that compared with group C, serum lead levels in group L and T were significantly increased (P < 0.05); superoxide dismutase (SOD), glutathione (GSH), and glutathione peroxidase (GSH-PX) levels in group L were significantly decreased (P < 0.05), and malondialdehyde (MDA) content was significantly higher increased (P < 0.05), and the GSH-PX content in group T were significantly increased in group L (P < 0.05), and the MDA content in group T was significantly lower than that in group L (P < 0.05). Compared with group C, the expression of Nrf2, HO-1, GRP78, and CHOP in group L increased significantly, and the difference was statistically significant (P < 0.05). Compared with the L group, the expression of Nrf2, HO-1, GRP78, and CHOP in the T group was reduced. Therefore, folic acid has a certain protective effect on the oxidative damage of lead-exposed rat heart tissue. Lead exposure will increase ROS, NO, MDA, and other oxidizing substances and reduce the level of GSH, SOD, CAT, GPx, and other antioxidant factors, which will lead to cardiac hypertrophy, cardiac index increase, oxidative stress, Nrf2, and HO-1. The expression of stress-related proteins such as GRP78 and CHOP also increased, leading to cardiomyocyte apoptosis. After a folic acid intervention, these changes can be significantly reversed.

Maternal Dietary Forsythia suspensa Extract Supplementation Induces Changes in Offspring Antioxidant Status, Inflammatory Responses, Intestinal Development, and Microbial Community of Sows

This experiment aims to investigate the effect of maternal diet supplemented with Forsythia suspensa extract (FSE) on the performance, antioxidant status, inflammatory responses, intestinal development, and microbial community of sows. A total of 24 gestating sows (Landrace × Yorkshire) were assigned to 2 treatments with 12 sows per treatment. From d 107 of gestation to d 21 of lactation, sows were supplemented with a basal diet as control (CON) or an FSE diet (basal diet + 100 mg/kg FSE). Compared with CON, sows fed FSE showed lower (P &lt; 0.05) wean-to-estrus interval, body weight loss, and higher (P &lt; 0.05) average daily gain of suckling piglet. Sows fed FSE had reduced (P &lt; 0.05) serum malondialdehyde (MDA) content and enhanced (P &lt; 0.05) catalase and glutathione peroxidase (GSH-Px) contents at farrowing and weaning compared with CON. The suckling piglets of FSE-fed sows had increased (P &lt; 0.05) mRNA expressions of nuclear factor erythroid-2 related factor 2, heme oxygenase-1 in the liver, and lower (P &lt; 0.05) serum MDA content on d 0, 7, and 14 of lactation. Sows fed FSE had lower (P &lt; 0.05) serum tumor necrosis factor-α (TNF-α) and interleukin-8 (IL-8) contents at farrowing and reduced (P &lt; 0.05) serum IL-6 and IL-8 contents at weaning compared with CON. Piglets from FSE-fed sows had enhanced (P ≤ 0.05) villus height and villus height to crypt depth ratio in the jejunum, and higher (P &lt; 0.05) protein expression of Occludin in jejunal mucosa compared with CON. Sows fed FSE tended to have higher (P = 0.09) relative abundance of Lactobacillus at genus level in feces at weaning compared with CON. Our results showed maternal diet supplemented with FSE in lactating sows could effectively induce improvement of performance, antioxidant status, anti-inflammatory function, intestinal morphology, barrier function, and microbial community.

Lead acetate induces hippocampal pyramidal neuron degeneration in mice via up-regulation of executioner caspase-3, oxido-inflammatory stress expression and decreased BDNF and cholinergic activity: Reversal effects of Gingko biloba supplement

PURPOSE

It has been hypothesized that compounds with strong anti-oxidant activity might mitigate lead-induced neurotoxicity that resulted to neuronal degeneration.Ginkgo biloba supplement (GB-S) is a neuroactive supplement which has been reported to demonstrate neuroprotective effects. In this study, we investigated the reversal effect and the underlying mechanism of GB-S following lead-induced neurotoxicity in mice.

METHODS

Male Swiss mice (n = 8) were pre-treated with lead acetate (100 mg/kg) for 30 min before GB-S (10 mg/kg and 20 mg/kg) or Ethylenediaminetetraacetic acid (EDTA) (50 mg/kg) intraperitoneally for 14 consecutive days. Memory impairment symptoms were evaluated on day 13 and 14 using Y-maze and Novel object recognition test (NORT) respectively. Thereafter, spectrophotometry, ELISA, immunohistochemistry and histomorphormetry were used to estimate the degree and expression of biomarkers of neuronal inflammation: oxido-inflammatory stress, apoptosis and degeneration in the hippocampus (HC).

RESULTS

Lead acetate treatment significantly (p < 0.05) induced neurobehavioral impairment which was reversed by GB-S as evident in increased percentage alternation and discrimination index. GB-S significantly (p < 0.05) reduced lipid peroxidation and nitrite level, inhibited TNF-α and acetylcholinesterase activity and improved glutathione, catalase and superoxide dismutase activity in the HC. Moreover, GB-S inhibited hippocampal apoptosis via elevated expression of caspase-3 with marked increase level of brain derived neurotrophic factor (BDNF). Also, the histomorphormetric study showed that GB-S rescued death of pyramidal neurons (CA3) in the HC.

CONCLUSION

Our findings however suggest that GB-S decreased memory impairment progression induced by lead acetate via mechanisms connected to inhibition of oxido-inflammatory stress mediators, restrained acetylcholinesterase activity, up-regulated BDNF/Caspase-3 expression and suppression of hippocampal pyramidal neuron degeneration in mice.

Melatonin salvages lead-induced neuro-cognitive shutdown, anxiety, and depressive-like symptoms via oxido-inflammatory and cholinergic mechanisms

INTRODUCTION

Lead is the most used nonphysiological neurotoxic heavy metal in the world that has been indicated to interfere with the cognitive and noncognitive processes via numerous mechanisms. The neuroprotective effect of melatonin is well known, but the effect of its interaction with lead in the brain remains inconclusive.

OBJECTIVE

To assess the therapeutic role of melatonin on cognitive deficit, anxiety and depressive-like symptoms in matured male Wistar rats exposed to a subchronic lead chloride (PbCl₂ ).

METHODS

Twenty male Wistar rats were blindly randomized into four groups (n = 5/group): group 1 to 4 underwent intragastric administration of physiological saline (10 ml/kg; vehicle), PbCl₂ (50 mg/kg), melatonin (10 mg/kg) and PbCl₂ + melatonin respectively for a period of 4 weeks during which neurobehavioral data were extracted, followed by neurochemical and histopathological evaluations.

RESULTS

Exposure to PbCl₂ reduced cognitive performance by increasing the escape latency and average proximity to the platform zone border, decreasing average path length in the platform zone, cognitive score, and time spent in probing. It raised the thigmotaxis percentage, time spent in rearing, number of pellet-like feces, and time spent in the dark compartment of a bright/dark box which are predictors of anxiety. It also induced depressive-like behavior as immobility time was enhanced. PbCl₂ deranged neurochemicals; malondialdehyde, interlukin-1β, and tumor necrotic factor-α were increased while superoxide dismutase and acetylcholinesterase were decreased without remarkable alteration in reduced glutathione and nitric oxide. Administration of PbCl₂ further disrupted neuronal settings of hippocampal proper and dentate gyrus. In contrast, the supplementation of melatonin reversed all the neurological consequences of PbCl₂ neurotoxicity by eliciting its properties against oxidative and nonoxidative action of PbCl₂ .

CONCLUSION

These findings suggest that melatonin down-regulates neurotoxicant interplays in the brain systems. Therefore, this study suggests the use of melatonin as an adjuvant therapy in neuropathological disorders/dysfunctions.

Emodin resists to Cyprinid herpesvirus 3 replication via the pathways of Nrf2/Keap1-ARE and NF-κB in the ornamental koi carp (Cyprinus carpio haematopterus)

Cyprinid herpesvirus 3 (CyHV-3) causes high mortality in carp. Emodin has been shown of the effects of antioxidant, anti-inflammatory and antiviral. In present study, we investigated the preventive effects and mechanism of emodin on CyHV-3 infection. The ornamental koi carp (Cyprinus carpio haematopterus) were intraperitoneally injected with emodin (10 mg/kg, 20 mg/kg, or 40 mg/kg). 72 h later, an intraperitoneal injection of CyHV-3 was administered, and collected the samples one week later to detect the antioxidant parameters, antioxidant genes, inflammatory genes and to perform histopathology assays. The results showed that emodin significantly suppressed CyHV-3 replication (P < 0.05), improved the koi survival rate and slowed the damage caused by CyHV-3. Emodin treatment increased the antioxidant activity and decreased the lipid peroxidation level of the koi. Compared to the CyHV-3 group, emodin treatment resulted in the same antioxidant parameters after CyHV-3 infection. Emodin treatment activated the Nuclear factorery throid 2-related factor 2/Kelch-like ECH-associated protein 1-antioxidatant response element (Nrf2/Keap1-ARE) pathway and upregulated the expression of heme oxygenase 1 (HO-1), superoxide dismutase (SOD), and catalase (CAT) in the hepatopancreas after CyHV-3 infection. Emodin activated the nuclear factor kappa-B (NF-κB) pathway and decreased the expression of interleukin-6 (IL-6), interleukin-8 (IL-8), and tumour necrosis factor-α (TNF-α) in the koi induced by CyHV-3. In conclusion, emodin treatment can suppress CyHV-3 replication and reduce the mortality of koi caused by CyHV-3. Emodin improves antioxidant function, relieves oxidative stress and inflammation cytokines via Nrf2/Keap1-ARE and NF-κB pathways, and protects against the adverse effects induced by CyHV-3.

Synthesis and biological evaluation of 1,2,4-oxadiazole core derivatives as potential neuroprotectants against acute ischemic stroke

Here, we report the synthesis and neuroprotective capacity of 27 compounds with a bisphenol hydroxyl-substituted 1,2,4-triazole core or 1,2,4-oxadiazole core for stroke therapy. In vitro studies of the neuroprotective effects of compounds 1-27 on sodium nitroprusside (SNP)-induced apoptosis in PC12 cells indicate that compound 24 is the most effective compound conferring potent protection against oxidative injury. Compound 24 inhibits reactive oxygen species (ROS） accumulation and restores the mitochondrial membrane potential (MMP). Moreover, further analysis of the mechanism showed that compound 24 activates the antioxidant defence system by promoting the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and increasing the expression of haem oxygenase 1 (HO-1). An in vivo study was performed in a rat model of transient focal cerebral ischaemia generated by the intraluminal occlusion of the middle cerebral artery (MCAO). Compound 24 significantly reduced brain infarction and improved neurological function. Overall, compound 24 potentially represents a promising compound for the treatment of stroke.

Papaverine, a Phosphodiesterase 10A Inhibitor, Ameliorates Quinolinic Acid-Induced Synaptotoxicity in Human Cortical Neurons

Phosphodiesterase-10A (PDE10A) hydrolyse the secondary messengers cGMP and cAMP, two molecules playing important roles in neurodevelopment and brain functions. PDE10A is associated to progression of neurodegenerative diseases like Alzheimer's, Parkinson's, Huntington's diseases, and a critical role in cognitive functions. The present study was undertaken to determine the possible neuroprotective effects and the associated mechanism of papaverine (PAP), a PDE10A isoenzyme inhibitor, against quinolinic acid (QUIN)-induced excitotoxicity using human primary cortical neurons. Cytotoxicity potential of PAP was analysed using MTS assay. Reactive oxygen species (ROS) and mitochondrial membrane potential were measured by DCF-DA and JC10 staining, respectively. Caspase 3/7 and cAMP levels were measured using ELISA kits. Effect of PAP on the CREB, BNDF and synaptic proteins such as SAP-97, synaptophysin, synapsin-I, and PSD-95 expression was analysed by Western blot. Pre-treatment with PAP increased intracellular cAMP and nicotinamide adenine dinucleotide (NAD⁺) levels, restored mitochondrial membrane potential (ΔΨm), and decreased ROS and caspase 3/7 content in QUIN exposed neurons. PAP up-regulated CREB and BDNF, and synaptic protein expression. In summary, these data indicate that PDE10A is involved in QUIN-mediated synaptotoxicity and its inhibition elicit neuroprotection by reducing the oxidative stress and protecting synaptic proteins via up-regulation of cAMP signalling cascade.

Protective effects of selenium in tacrolimus-induced lung toxicity: potential role of heme oxygenase 1

The present study aimed to evaluate the protective effects of selenium (Sel) administration against tacrolimus (Tac) - induced lung toxicity and to assess the relation between heme oxygenase 1 (HO-1) and these effects. The study was conducted on 36 Wistar male albino rats equally divided into four groups: (i) normal control; (ii) Sel (0.1 mg/kg per day p.o. for four weeks); (iii) TAC 3 mg/mL as single oral dose on 27th day; and (iv) Tac + Sel. Lung tissues, lung homogenate, and bronchoalveolar lavage of the sacrificed animals were investigated biochemically and histopathologically, by immunohistochemistry or by PCR. The Tac group showed significantly lower expression of HO-1. Administration of Sel was associated with increased HO-1 expression. Oxidative (malondialdehyde, reduced glutathione, superoxide dismutase, myeloperoxidase, and glutathione peroxidase activity) and nitrosative stress (nitric oxide) markers and markers of inflammation (interleukin 1β (IL-1β), IL-6, and IL-10) showed changes corresponding to HO-1 levels in rat groups. Tac group showed the highest expression of caspase-3. Sel exerted a protective role against Tac-induced lung toxicity.

Xinmailong Attenuates Doxorubicin-Induced Lysosomal Dysfunction and Oxidative Stress in H9c2 Cells via HO-1

The clinical use of doxorubicin (DOX) is limited by its cardiotoxicity, which is closely associated with oxidative stress. Xinmailong (XML) is a bioactive peptide extracted from American cockroaches, which has been mainly applied to treat chronic heart failure in China. Our previous study showed that XML attenuates DOX-induced oxidative stress. However, the mechanism of XML in DOX-induced cardiotoxicity remains unclear. Heme oxygenase-1 (HO-1), an enzyme that is ubiquitously expressed in all cell types, has been found to take antioxidant effects in many cardiovascular diseases, and its expression is protectively upregulated under DOX treatment. Lysosome and autophagy are closely involved in oxidative stress as well. It is still unknown whether XML could attenuate doxorubicin-induced lysosomal dysfunction and oxidative stress in H9c2 cells via HO-1. Thus, this study was aimed at investigating the involvement of HO-1-mediated lysosomal function and autophagy flux in DOX-induced oxidative stress and cardiotoxicity in H9c2 cells. Our results showed that XML treatment markedly increased cell proliferation and SOD activity, improved lysosomal function, and ameliorated autophagy flux block in DOX-treated H9c2 cells. Furthermore, XML significantly increased HO-1 expression following DOX treatment. Importantly, HO-1-specific inhibitor (Znpp) or HO-1 siRNA could significantly attenuate the protective effects of XML against DOX-induced cell injury, oxidative stress, lysosomal dysfunction, and autophagy flux block. These results suggest that XML protects against DOX-induced cardiotoxicity through HO-1-mediated recovery of lysosomal function and autophagy flux and decreases oxidative stress, providing a novel mechanism responsible for the protection of XML against DOX-induced cardiomyopathy.

Signal transduction associated with lead-induced neurological disorders: A review

Lead is a heavy metal pollutant that is widely present in the environment. It affects every organ system, yet the nervous system appears to be the most sensitive and primary target. Although many countries have made significant strides in controlling Pb pollution, Pb poisoning continuous to be a major public health concern. Exposure to Pb causes neurotoxicity that ranges from neurodevelopmental disorders to severe neurodegenerative lesions, leading to impairments in learning, memory, and cognitive function. Studies on the mechanisms of Pb-induced nervous system injury have convincingly shown that this metal can affect a plethora of cellular pathways affecting on cell survival, altering calcium dyshomeostasis, and inducing apoptosis, inflammation, energy metabolism disorders, oxidative stress, autophagy and glial stress. This review summarizes recent knowledge on multiple signaling pathways associated with Pb-induced neurological disorders in vivo and in vitro.

Roflumilast, a cAMP-Specific Phosphodiesterase-4 Inhibitor, Reduces Oxidative Stress and Improves Synapse Functions in Human Cortical Neurons Exposed to the Excitotoxin Quinolinic Acid

The overexpression of phosphodiesterase 4 (PDE4) enzymes is reported in several neurodegenerative diseases. PDE4 depletes cyclic 3'-5' adenosine monophosphate (cAMP) and, in turn, cAMP response element-binding protein (CREB) and brain-derived neurotrophic factor (BDNF), the key players in cognitive function. The present study was undertaken to investigate the mechanism behind the protective effects of roflumilast (ROF), a cAMP-specific PDE4 inhibitor, against quinolinic acid (QUIN)-induced neurotoxicity using human primary cortical neurons. Cytotoxicity was analyzed using an MTS assay. Reactive oxygen species (ROS) and mitochondrial membrane potential were measured by DCF-DA and JC-10 staining, respectively. Caspase 3/7 activity was measured using an ApoTox-Glo Triplex assay kit. cAMP was measured using an ELISA kit. The protein expression of CREB, BDNF, SAP-97, synaptophysin, synapsin-I, and PSD-95 was analyzed by the Western blotting technique. QUIN exposure down-regulated CREB, BDNF, and synaptic protein expression in neurons. Pretreatment with ROF increased the intracellular cAMP, mitochondrial membrane potential, and nicotinamide adenine dinucleotide (NAD⁺) content and decreased the ROS and caspase 3/7 levels in QUIN-exposed neurons. ROF up-regulated the expression of synapse proteins SAP-97, synaptophysin, synapsin-I, PSD-95, and CREB and BDNF, which indicates its potential role in memory. This study suggests for the first time that QUIN causes pre- and postsynaptic protein damage. We further demonstrate the restorative effects of ROF on the mitochondrial membrane potential and antiapoptotic properties in human neurons. These data encourage further investigations to reposition ROF in neurodegenerative diseases and their associated cognitive deficits.

Mild traumatic brain injury exacerbates Parkinson's disease induced hemeoxygenase-2 expression and brain pathology: Neuroprotective effects of co-administration of TiO2 nanowired mesenchymal stem cells and cerebrolysin

Mild traumatic brain injury (mTBI) is one of the leading predisposing factors in the development of Parkinson's disease (PD). Mild or moderate TBI induces rapid production of tau protein and alpha synuclein (ASNC) in the cerebrospinal fluid (CSF) and in several brain areas. Enhanced tau-phosphorylation and ASNC alters the molecular machinery of the brain leading to PD pathology. Recent evidences show upregulation of constitutive isoform of hemeoxygenase (HO-2) in PD patients that correlates well with the brain pathology. mTBI alone induces profound upregulation of HO-2 immunoreactivity. Thus, it would be interesting to explore whether mTBI exacerbates PD pathology in relation to tau, ASNC and HO-2 expression. In addition, whether neurotrophic factors and stem cells known to reduce brain pathology in TBI could induce neuroprotection in PD following mTBI. In this review role of mesenchymal stem cells (MSCs) and cerebrolysin (CBL), a well-balanced composition of several neurotrophic factors and active peptide fragments using nanowired delivery in PD following mTBI is discussed based on our own investigation. Our results show that mTBI induces concussion exacerbates PD pathology and nanowired delivery of MSCs and CBL induces superior neuroprotection. This could be due to reduction in tau, ASNC and HO-2 expression in PD following mTBI, not reported earlier. The functional significance of our findings in relation to clinical strategies is discussed.

Coinhibition of activated p38 MAPKα and mTORC1 potentiates stemness maintenance of HSCs from SR1-expanded human cord blood CD34+ cells via inhibition of senescence

The stemness of ex vivo expanded hematopoietic stem cells (HSCs) is usually compromised by current methods. To explore the failure mechanism of stemness maintenance of human HSCs, which were expanded from human umbilical cord blood (hUCB) CD34⁺ cells, by differentiation inhibitor Stem Regenin 1 (SR1), an antagonist of aryl hydrocarbon receptor, we investigated the activity of p38 mitogen‐activated protein kinase α (p38 MAPKα, p38α) and mammalian target of rapamycin complex 1 (mTORC1), and their effect on SR1‐expanded hUCB CD34⁺ cells. Our results showed that cellular senescence occurred in the SR1‐expanded hUCB CD34⁺ cells in which p38α and mTORC1 were successively activated. Furthermore, their coinhibition resulted in a further decrease in hUCB CD34⁺ cell senescence without an effect on apoptosis, promoted the maintenance of expanded phenotypic HSCs without differentiation inhibition, increased the hematopoietic reconstitution ability of multiple lineages, and potentiated the long‐term self‐renewal capability of HSCs from SR1‐expanded hUCB CD34⁺ cells in NOD/Shi‐scid/IL‐2Rγ^null mice. Our mechanistic study revealed that senescence inhibition by our strategy was mainly attributed to downregulation of the splicesome, proteasome formation, and pyrimidine metabolism signaling pathways. These results suggest that coinhibition of activated p38α and mTORC1 potentiates stemness maintenance of HSCs from SR1‐expanded hUCB CD34⁺ cells via senescence inhibition. Thus, we established a new strategy to maintain the stemness of ex vivo differentiation inhibitor‐expanded human HSCs via coinhibition of multiple independent senescence initiating signal pathways. This senescence inhibition‐induced stemness maintenance of ex vivo expanded HSCs could also have an important role in other HSC expansion systems.

Metformin alleviates lead-induced mitochondrial fragmentation via AMPK/Nrf2 activation in SH-SY5Y cells

As a widely acknowledged environmental pollutant, lead (Pb) exhibits neurological toxicity primarily due to the vulnerability of neural system. It is suggested that Pb could perturb mitochondrial function, triggering the following disturbance of cellular homeostasis. Here, we focused on the role of mitochondrial dynamics in Pb-induced cell damage. Pb exposure enhanced mitochondrial fragmentation and elevated p-Drp1 (s616) level in a reactive oxygen species (ROS) dependent manner, leading to cell death and energy shortage. By applying metformin, an AMP-activated protein kinase (AMPK) activator, these impairments could be alleviated via activation of AMPK, validated by experiments of pharmacological inhibition of AMPK. Further investigation confirmed that nuclear factor erythroid 2-related factor 2 (Nrf2), a transcription factor managing antioxidative function, and its downstream antioxidant detoxifying enzyme were activated by metformin, resulting in the inhibition of the Pb-caused oxidative stress. Moreover, Nrf2 mediated the protection of metformin against mitochondrial fragmentation induced by Pb exposure, while knockdown of Nrf2 abrogated the protective effect. Finally, the treatment of Mdivi-1, a mitochondrial fission inhibitor, reversed Pb-triggered cell death, revealing that excessive mitochondrial fission is detrimental. To conclude, metformin could ameliorate Pb-induced mitochondrial fragmentation via antioxidative effects originated from AMPK/Nrf2 pathway activation, promoting energy supply and cell survival.

•

Pb caused mitochondrial fragmentation in a ROS dependent manner.

•

Metformin alleviated Pb-induced mitochondrial fission via Nrf2 activation.

•

AMPK mediated metformin-induced Nrf2 activation.

•

Inhibition of mitochondrial fragmentation rescued Pb-induced cell death.

Curcumin protects against methylmercury-induced cytotoxicity in primary rat astrocytes by activating the Nrf2/ARE pathway independently of PKCδ

Methylmercury (MeHg) is a ubiquitous environmental toxicant that leads to long-lasting neurological deficits in animals and humans. Curcumin, a polyphenol obtained from the rhizome of turmeric, has well-known antioxidant functions. Here, we evaluated curcumin's efficacy in mitigating MeHg-induced cytotoxicity and further investigated the underlying mechanism of this neuroprotection in primary rat astrocytes. Pretreatment with curcumin (2, 5, 10 and 20 μM for 3, 6, 12 or 24 h) protected against MeHg-induced (5 μM for 6 h) cell death in a time and dose-dependent manner. Curcumin (2, 5, 10 or 20 μM) pretreatment for 12 h significantly ameliorated the MeHg-induced astrocyte injury and oxidative stress, as evidenced by morphological alterations, lactate dehydrogenase (LDH) release, reactive oxygen species (ROS) generation, and glutathione (GSH) and catalase (CAT) levels. Moreover, curcumin pretreatment increased Nrf2 nuclear translocation and downstream enzyme expression, heme oxygenase-1 (HO-1) and NADPH quinone reductase-1 (NQO1). Knockdown of Nrf2 with siRNA attenuated the protective effect of curcumin against MeHg-induced cell death. However, both the pan-protein kinase C (PKC) inhibitor, Ro 31-8220, and the selective PKCδ inhibitor, rottlerin, failed to suppress the curcumin-activated Nrf2/Antioxidant Response Element(ARE) pathway and attenuate the protection exerted by curcumin. Taken together, these findings confirm that curcumin protects against MeHg-induced neurotoxicity by activating the Nrf2/ARE pathway and this protection is independent of PKCδ activation. More studies are needed to understand the mechanisms of curcumin cytoprotection.

The Neuroprotective Role of Coenzyme Q10 Against Lead Acetate-Induced Neurotoxicity Is Mediated by Antioxidant, Anti-Inflammatory and Anti-Apoptotic Activities

Heavy metal exposure, in lead (Pb) particularly, is associated with severe neuronal impairment though oxidative stress mediated by reactive oxygen species, and antioxidants may be used to abolish these adverse effects. This study investigated the potential neuroprotective role of coenzyme Q10 (CoQ₁₀) against lead acetate (PbAc)-induced neurotoxicity. Twenty-eight male Wistar albino rats were divided into four equal groups (n = 7) and treated as follows: the control group was injected with physiological saline (0.9% NaCl); the CoQ₁₀ group was injected with CoQ₁₀ (10 mg/kg); PbAc group was injected with PbAc (20 mg/kg); PbAc + CoQ₁₀ group was injected first with PbAc, and after 1 h with CoQ₁₀. All groups were injected intraperitoneally for seven days. PbAc significantly increased cortical lipid peroxidation, nitrate/nitrite levels, and inducible nitric oxide synthase expression, and decreased glutathione content, superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase activity and mRNA expression, as well as nuclear factor erythroid 2–related factor 2 (Nrf2) and homoxygenase-1 (HO-1) expression. PbAc also promoted the secretion of interleukin-1ß and tumor necrosis factor-α, inhibited interleukin-10 production, triggered the activation of pro-apoptotic proteins, and suppressed anti-apoptotic proteins. Additionally, PbAc increased the cortical levels of serotonin, dopamine, norepinephrine, GABA, and glutamate, and decreased the level of ATP. However, treatment with CoQ₁₀ rescued cortical neurons from PbAc-induced neurotoxicity by restoring the balance between oxidants and antioxidants, activating the Nrf2/HO-1 pathway, suppressing inflammation, inhibiting the apoptotic cascade, and modulating cortical neurotransmission and energy metabolism. Altogether, our findings indicate that CoQ₁₀ has beneficial effects against PbAc-induced neuronal damage through its antioxidant, anti-inflammatory, anti-apoptotic, and neuromodulatory activities.

PMA-triggered PKCε activity enhances Nrf2-mediated antiviral response on fish rhabdovirus infection

Viral infection is often accompanied with alteration of intracellular redox state, especially an imbalance between reactive oxygen species (ROS) production and antioxidant cellular defenses. The previous studies showed that an antioxidant cellular defense system, the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2), played an important role against spring viraemia of carp virus (SVCV) infection in fish. To further reveal the mediated mechanism that Nrf2 active state was affected by protein kinase C (PKC), here we evaluated SVCV replication in host cells by treated with a strong activator of PKC phorbol-12-myristate-13-acetate (PMA) and an inhibitor staurosporine. Our results showed that PMA significantly repressed SVCV replication and viral-induced apoptosis in Epithelioma papulosum cyprini (EPC) cell, suggesting that PKC may exhibit an anti-SVCV effect. Likewise, PMA resulted in a higher phosphorylation levels of PKCε rather than PKCα/β to participate in the activation of Nrf2, mainly involved in the activation of Nrf2 phosphorylation of Ser40 to favor Nrf2 translocation to nucleus. Furthermore, the data revealed that PMA up-regulated an antiviral response heme oxygenase-1 (HO1) gene expression that was confirmed as the key player against SVCV infection by HO1 specific siRNA. Overall, this study provided a new therapeutic target for the treatment of SVCV infection, and modulating PKC activity could be used for the prevention and treatment of SVCV.

Hemin provides protection against lead neurotoxicity through heme oxygenase 1/carbon monoxide activation

The neurotoxicity of lead (Pb) is well established, and oxidative stress is strongly associated with Pb-induced neurotoxicity. Heme oxygenase 1 (HO-1) is an important antioxidative enzyme for protection against oxidative stress in many disease models. In this study, we applied hemin, the substrate and a well-known inducer of HO-1, to investigate the possible role of HO-1 in protecting against Pb neurotoxicity. Hemin can significantly attenuate Pb acetate-induced cell death and oxidative stress in the hippocampus and frontal cortex of developmental rats. Consistent with in vivo results, the protective effects of hemin were also observed in SH-SY5Y cells after inducing cell survival and maintaining redox balance. However, knocking down HO-1 could significantly abolish the cytoprotective action of hemin against Pb toxicity, confirming HO-1 contributed to the protection. Finally, the HO-1-derived production of carbon monoxide, but not of bilirubin or Fe²⁺ , mediated the protective effects of HO-1 activation induced by hemin treatment against Pb-induced cell death and oxidative stress in SHSY5Y cells. Overall, this study showed that hemin provided protection against Pb neurotoxicity by HO-1/carbon monoxide activation.

The effects of lead exposure on the expression of HMGB1 and HO-1 in rats and PC12 cells

Lead (Pb) is an environmental neurotoxic metal. Chronic exposure to Pb causes deficits of learning and memory in children and spatial learning deficits in developing rats. In this study we investigated the effects of Pb exposure on the expression of HMGB1 and HO-1 in rats and PC12 cells. The animals were randomly divided to three groups: control group; low lead exposure group; high lead exposure group; PC12 cells were divided into 3 groups: 0 μM (control group), 1 μM and 100 μM Pb acetate. The results showed that Pb levels in blood and brain of Pb exposed groups were significantly higher than that of the control group (p < 0.05). The expression of HMGB1 and HO-1 were increased in Pb exposed groups than that of the control group (p < 0.05). Moreover, we found that the up-regulation of HO-1 in Pb exposure environment inhibited the expression of HMGB1.

The toxic influence of dibromoacetic acid on the hippocampus and pre-frontal cortex of rat: involvement of neuroinflammation response and oxidative stress

Dibromoacetic acid (DBA) exsits in drinking water as a by-product of disinfection as a result of chlorination or ozonation processes. Hippocampus and pre-frontal cortex are the key structures in memory formation and weanling babies are more sensitive to environmental toxicant than adults, so this study was conducted to evaluate the potential neurotoxicity effects of DBA exposure when administered intragastrically for 4 weeks to weanling Sprague-Dawley rats, at concentration of 0, 20, 50, 125 mg/kg via the neurobehavioral and neurochemical effects. Results indicated that animals weight gain and food consumption were not significantly affected by DBA. However, morris water maze test showed varying degrees of changes between control and high-dose group. Additionally, the level of malondialdehyde (MDA) and generation of reactive oxygen species (ROS) in the hippocampus and pre-frontal cortex of rats increased significantly. The activities of total superoxide dismutase (SOD) and the glutathione (GSH) content in the hippocampus and pre-frontal cortex of rats decreased significantly after treatment with DBA. Treatment with DBA increased the protein and mRNA expression of Iba-1, NF-κB, TNF-α, IL-6, IL-1β and HO-1 in the hippocampus and pre-frontal cortex of rats. These data suggested that DBA had a toxic influence on the hippocampus and pre-frontal cortex of rats, and that the mechanism of toxicity might be associated with the neuroinflammation response and oxidative stress.

Attenuation of Lead-Induced Neurotoxicity by Omega-3 Fatty Acid in Rats

Background

Lead is widely distributed in the environment and has been found to be associated with various health problems including neurodegenerative diseases.

Purpose

In view of the increasing health risk caused by lead, this study has been carried out to investigate the neuroprotective effect of omega-3 fatty acid (omega-3FA) in lead-induced neurotoxicity in rats.

Methods

Biochemical parameters including oxidative stress in brain regions, lead levels in blood and brain regions and histopathological examination of brain regions of rats were carried out in the present study.

Results

Rats exposed to lead (lead acetate 7.5 mg/kg body weight p.o. for 14 days) caused a significant increase in the levels of lipid peroxidation, protein carbonyl content, ROS production and decreased the activities of glutathione peroxidase, superoxide dismutase and catalase in the cerebellum and cerebral cortex, respectively, as compared to controls. Abnormal histopathological changes and increase in the levels of lead in blood and brain were also observed as compared to controls. Co-treatment of lead with omega-3FA (750 mg/kg body weight p.o. for 14 days) decreased the levels of lipid peroxidation, protein carbonyl content, ROS production and increased the activities of glutathione peroxidase, superoxide dismutase and catalase and showed protection in the histopathological study as compared to rats treated with lead alone.

Conclusions

The result of the present study shows that lead-induced oxidative stress and histopathological alteration in the brain region were significantly protected with co-treatment of lead and omega-3FA. This could be due to its strong antioxidant potential and metal-binding property.

Omega-3 fatty acid attenuates oxidative stress in cerebral cortex, cerebellum, and hippocampus tissue and improves neurobehavioral activity in chronic lead-induced neurotoxicity

Objectives: In view of the increasing risk of lead on human health, the present study has been carried out to investigate the neuroprotective effect of omega-3 fatty acid on chronic lead-induced neurotoxicity and behavioral impairment in rats. Methods: Different neurobehavioral parameters, biochemical assays, and histopathological analyses in brain regions of rats were conducted. Results: Rats exposed to different doses of lead (lead acetate 2.5, 5.0, 7.5 mg/kg body weight p.o. for 90 days) caused a significant decrease in body weight, brain weight, and behavioral changes as compared to controls. Abnormal histopathological and increased levels of lead in blood and brain regions increased the levels of ROS, LPO, PCC and decreased the levels of GSH with concomitant reduction in SOD, CAT, and GPx activities in the brain region of rats treated with different doses of lead as compared to controls. Co-treatment of lead with omega-3 fatty acid (500 mg/kg body weight p.o. for 90 days) decreased the levels of ROS, LPO, PCC, and increased the level of GSH, also increased SOD, CAT, and GPx activity and showed improvements in behavioral as well as histopathological changes as compared to lead-treated groups. Discussion: Our results proved that omega-3 fatty acid improved behavioral deficits, altered histopathological and oxidative stress in lead-intoxicated rats. Among three different doses, 2.5 mg/kg b.wt. of lead along with omega-3 fatty acid was the most preventive dose for the neurotoxicity. This work reveals the potential of omega-fatty acid as a protective drug for lead neurotoxicity.

HO‑1 alleviates cholesterol‑induced oxidative stress through activation of Nrf2/ERK and inhibition of PI3K/AKT pathways in endothelial cells

Heme oxygenase‑1 (HO‑1), as an inducible and cytoprotective enzyme, has a protective effect against cellular oxidative stress. In the present study, cholesterol was used to induce lipid overload and increase reactive oxygen species (ROS), leading to oxidative stress in EA.hy926 cells. In the present study, western blotting and immunofluorescence analysis were used to detect the expression level of important molecules in the metabolism process of cholesterol. It was confirmed that cholesterol stimulation upregulated the expression of HO‑1 in a time‑dependent manner via the activation and translocation of nuclear factor erythroid 2‑related factor 2 (Nrf2), activation of the mitogen‑activated protein kinase (MAPK)/extracellular signal‑regulated kinase (ERK) signaling pathway and increasing intercellular Ca2+ ([Ca2+]i) concentration. The results showed that increasing the expression of HO‑1 decreased activation of the phosphoinositide 3‑kinase (PI3K)/AKT signaling pathway and inhibited the expression of c‑Myc. It was confirmed that cholesterol‑mediated oxidative damage in vascular endothelial cells induced an increase in the expression of HO‑1 via the activation of Nrf2 and the MAPK/ERK signaling pathway, and increasing the [Ca2+]i concentration. The overexpression of HO‑1 alleviated oxidative damage through inhibition of the PI3K/AKT signaling pathway and downregulation of the expression of c‑Myc.

HO-1/EBP interaction alleviates cholesterol-induced hypoxia through the activation of the AKT and Nrf2/mTOR pathways and inhibition of carbohydrate metabolism in cardiomyocytes

Heme oxygenase-1 (HO-1) is an inducible and cytoprotective enzyme that provides a defense against oxidant damage. The present study screened 137 HO-1/interacting proteins using a profound co-immunoprecipitation (Co-IP) coupled with proteomics, and profiled the global HO-1 interactome network, including oxidative phosphorylation, endoplasmic reticulum and transport vesicle functions. Among these molecules, we observed that a novel interactor, emopamil-binding protein (EBP), is closely related to the cholesterol metabolism process. This study demonstrated that cholesterol promotes excessive oxidative stress and alters the energy metabolism in cardiomyocytes, further triggering numerous cardiovascular diseases. We observed that cholesterol caused the overexpression of EBP and HO-1 by the activation of AKT and Nrf2/mTOR pathways. In addition, HO-1 and EBP performed a myocardial protective function. The overexpression of HO-1 alleviated the cholesterol-induced excessive oxidative stress status by inhibition of the carbohydrate metabolism. Notably, we also confirmed that the loss of partial HO-1 activity aggravated the oxidative damage and cardiac systolic function induced by a high-fat diet in HO-1 heterozygous (HO-1^+/−) mice. These findings indicate that the HO-1/EBP interaction plays a protective role in alleviating the dysfunction of oxidative stress and cardiac systolic function induced by cholesterol stimulation.

Tangluoning, a traditional Chinese medicine, attenuates in vivo and in vitro diabetic peripheral neuropathy through modulation of PERK/Nrf2 pathway

Prolonged hyperglycemia-induced oxidative stress and endoplasmic reticulum stress have been demonstrated to play a key role in progression of diabetic peripheral neuropathy (DPN). PERK/ Nrf2 pathway plays a predominant role in oxidative and endoplasmic reticulum (ER) stress which is associated with cell survival. This study examined the modulation of the PERK/Nrf2 pathway and apoptosis by a traditional Chinese medicine Tangluoning (TLN) in streptozotocin-induced DPN rat models and the effects of serum TLN on the PERK/Nrf2 pathway, apoptosis, intracellular reactive oxygen species and mitochondrial membrane potential in Schwann cells cultured in 150 mM glucose. It is found that TLN attenuated oxidative and ER stress and apoptosis through the PERK/Nrf2 pathway by upregulating p-PERK, Nrf2/ARE pathways and downregulating the CHOP-related apoptosis pathways in the experimental DPN models both in vivo and in vitro.

Mutagenicity and oxidative damage induced by an organic extract of the particulate emissions from a simulation of the deepwater horizon surface oil burns

Emissions from oil fires associated with the "Deepwater Horizon" explosion and oil discharge that began on April 20, 2010 in the Gulf of Mexico were analyzed chemically to only a limited extent at the time but were shown to induce oxidative damage in vitro and in mice. To extend this work, we burned oil floating on sea water and performed extensive chemical analyses of the emissions (Gullett et al., Marine Pollut Bull, in press, ). Here, we examine the ability of a dichloromethane extract of the particulate material with an aerodynamic size ≤ 2.5 µm (PM2.5 ) from those emissions to induce oxidative damage in human lung cells in vitro and mutagenicity in 6 strains of Salmonella. The extract had a percentage of extractable organic material (EOM) of 7.0% and increased expression of the heme oxygenase (HMOX1) gene in BEAS-2B cells after exposure for 4 hr at 20 µg of EOM/ml. However, the extract did not alter mitochondrial respiration rate as measured by extracellular flux analysis. The extract was most mutagenic in TA100 +S9, indicative of a role for polycyclic aromatic hydrocarbons (PAHs), reflective of the high concentrations of PAHs in the emissions (1 g/kg of oil consumed). The extract had a mutagenicity emission factor of 1.8 ± 0.1 × 105 revertants/megajoulethermal in TA98 +S9, which was greater than that of diesel exhaust and within an order of magnitude of open burning of wood and plastic. Thus, organics from PM2.5 of burning oil can induce oxidative responses in human airway epithelial cells and are highly mutagenic. Environ. Mol. Mutagen. 58:162-171, 2017. © 2017 Wiley Periodicals, Inc.

Astragaloside IV attenuates lead acetate-induced inhibition of neurite outgrowth through activation of Akt-dependent Nrf2 pathway in vitro

Recently, oxidative stress is strongly associated with lead (Pb)-induced neurotoxicity. We reported previously that Astragaloside IV (AS-IV) possesses potent antioxidant properties. Here, we evaluate the hypothesis that AS-IV attenuates lead acetate (PbAc)-mediated inhibition of neurite outgrowth might mainly result from its antioxidant property via serine/threonine protein kinase (Akt)-dependent activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. Interestingly, AS-IV attenuates PbAc-induced inhibition of neurite outgrowth and displayed potential antioxidant properties by inhibiting reactive oxygen species (ROS). Concomitantly, AS-IV enhanced phase II detoxifying enzymes such as heme oxygenase 1 (HO-1), thioredoxin reductase (TrxR), and glutamate cysteine ligase catalytic subunit (GCLc). Conversely, AS-IV had no effect on GCL modulatory subunit (GCLm) and superoxide dismutase (SOD) activity/expression. Furthermore, AS-IV evoked Akt phosphorylation, and subsequent induced phosphorylation of glycogen synthase kinase-3β (GSK-3β) at Ser9 (that is, inactivation), which stimulated Nrf2-mediated antioxidant response element (ARE)-containing activation. Importantly, Akt locates upstream of GSK-3β and regulates phase II detoxifying enzymes gene expression through Nrf2 nuclear accumulation in PC12 cells exposed to PbAc. Noteworthy, these results were further confirmed through signalling pathway inhibitors, dominant negative mutant and short hairpin RNA technology. Collectively, these in vitro findings suggest that AS-IV attenuates PbAc-induced inhibition of neurite outgrowth attributed to its antioxidant properties and may be a promising candidate for the treatment of lead developmental neurotoxicity.

Protective Effects of PGC-1α Against Lead-Induced Oxidative Stress and Energy Metabolism Dysfunction in Testis Sertoli Cells

The reproductive system is sensitive to lead (Pb) toxicity, which has long been an area of research interest, but the underlying mechanisms remain to be illustrated. Peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) is pivotal in mitochondrial function. In this study, mouse testis Sertoli cells (TM4 cells), PGC-1α lower-expression (PGC-1α(-)) TM4 cells and PGC-1α overexpression (PGC-1α(+)) TM4 cells were used to explore the protective roles of PGC-1α against lead toxicity on the mouse reproductive system. Lead acetate (PbAc) exposure decreased the expression level of PGC-1α, increased the intracellular level of reactive oxygen species (ROS), and reduced the level of ATP in the three TM4 cell lines. The effects of PbAc on intracellular ATP level and on ROS content were significantly weakened in PGC-1α(+)TM4 cells versus TM4 cells and were significantly amplified in PGC-1α(-)TM4 cells versus TM4 cells. These results suggest that PGC-1α is a protective factor against PbAc-induced oxidative stress and energy metabolism dysfunction in the mouse reproductive system, thereby holding the potential of being developed as a preventive or therapeutic strategy against disorders induced by lead exposure.

Protocatechualdehyde Protects Against Cerebral Ischemia-Reperfusion-Induced Oxidative Injury Via Protein Kinase Cε/Nrf2/HO-1 Pathway

Oxidative stress is closely related to the pathogenesis of ischemic stroke. Protocatechualdehyde (PCA) is a phenolic acid compound that has the putative antioxidant activities. The present study was aimed to investigate the molecular mechanisms involved in the antioxidative effect of PCA against cerebral ischemia/reperfusion (I/R) injury. The experiment stroke model was produced in Sprague-Dawley rats via middle cerebral artery occlusion (MCAO). To model ischemia-like conditions in vitro, differentiated SH-SY5Y cells were exposed to transient oxygen and glucose deprivation (OGD). Treatment with PCA significantly improved neurologic score, reduced infarct volume and necrotic neurons, and also decreased reactive oxygen species (ROS) production, 4-hydroxynonenal (4-HNE), and 8-hydroxy-2'-deoxyguanosine (8-OHdG) contents at 24 h after reperfusion. Meanwhile, PCA significantly increased the transcription nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) expressions in the ischemic cerebral cortex as shown by immunofluorescence staining and Western blot analysis. In vitro experiment showed that PCA protected differentiated SH-SY5Y cells against OGD-induced injury. Likewise, PCA also increased markedly the Nrf2 and HO-1 expressions in a dose-dependent manner. The neuroprotection effect of PCA was abolished by knockdown of Nrf2 and HO-1. Moreover, knockdown of protein kinase Cε (PKCε) also blocked PCA-induced Nfr2 nuclear translocation, HO-1 expression, and neuroprotection. Taken together, these results provide evidences that PCA can protect against cerebral ischemia-reperfusion-induced oxidative injury, and the neuroprotective effect involves the PKCε/Nrf2/HO-1 pathway.