Effects of acetaminophen on reactive oxygen species and nitric oxide redox signaling in kidney of arsenic-exposed rats

We examined whether acetaminophen could alter renal oxidative stress induced by arsenic; also whether withdrawal of acetaminophen treatment can increase susceptibility of kidney to arsenic toxicity. Acetaminophen (400 and 1600 mg/kg) was co-administered orally to rats for 3 days after preexposure to arsenic (25 ppm) for 28 days (Phase-I) and thereafter, acetaminophen was withdrawn, but arsenic exposure was continued for another 28 days (Phase-II). Acetaminophen enhanced arsenic-induced lipid peroxidation, GSH depletion and ROS production and further decreased superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase activities. Increased peroxidation did not alter kidney weight, but increased serum urea nitrogen and creatinine. Arsenic did not alter basal, iNOS-mediated NO production or iNOS expression. Arsenic decreased cNOS-mediated NO release and eNOS expression in Phase-II. Acetaminophen increased their expressions and NO production in Phase-I. In Phase-II, arsenic-mediated effects on NO remained mostly unaffected with acetaminophen. Results reveal that acetaminophen enhanced the risk of arsenic-mediated oxidative stress in kidney. Discontinuation of acetaminophen administration also increased the susceptibility of kidney to nephrotoxic effect of arsenic. It appeared ROS were primarily responsible for oxidative stress in both the phases. NO may have a minor role in Phase-I, but does not contribute to redox signaling mechanism in Phase-II.     

Influence of repeated preexposure to arsenic on acetaminophen-induced oxidative stress in liver of male rats

We evaluated whether repeated arsenic preexposure can increase acetaminophen-induced hepatic oxidative stress. Rats were exposed to arsenic (25 ppm; rat equivalent concentration of maximum groundwater contamination level) via drinking water for 28 days. Next day, they were given single oral administration of acetaminophen (420 or 1000 mg/kg b.w.). Hepatotoxicity was evaluated by assessing serum biomarkers, cytochrome-P450 (CYP) content, CYP3A4- and CYP2E1-dependent enzymes, lipid peroxidation and antioxidants. Arsenic or acetaminophen increased serum ALT and AST activities and depleted CYP. Arsenic decreased, but acetaminophen increased CYP-dependent enzyme activities. These agents independently increased lipid peroxidation and decreased antioxidants. Arsenic did not alter the effects of acetaminophen on serum biomarkers, caused further CYP depletion and decreased acetaminophen-mediated induction of drug-metabolizing enzymes. Arsenic enhanced the lower dose of acetaminophen-mediated lipid peroxidation and glutathione depletion with no further alterations in enzymatic antioxidants. However, arsenic attenuated the higher dose-mediated lipid peroxidation and glutathione depletion with improvement in glutathione peroxidase and glutathione reductase activities, further decrease in catalase and no alterations in superoxide dismutase and glutathione-S-transferase activities. Results show that arsenic preexposure increased the susceptibility of rats to hepatic oxidative stress induced by the lower dose of acetaminophen, but reduced the oxidative stress induced by the higher dose.     

Repeated preexposure or coexposure to arsenic differentially alters acetaminophen‐induced oxidative stress in rat kidney

Acetaminophen (AP) is a widely used, cheap, and over‐the‐counter nonsteroidal anti‐inflammatory drug. Its toxicity depends on the cytochrome P‐450 (CYP)‐mediated oxidation to the toxic metabolite N‐acetyl‐p‐benzoquinoneimine. On the other hand, arsenic, a global groundwater and environmental contaminant of major public health concern, decreases hepatic CYP content and its dependent monoxygenase activities. We hypothesized that arsenic exposure would reduce the AP toxicity. Our aim was to evaluate the effects of repeated preexposure or coexposure to arsenic on the oxidative stress induced by a single or repeated oral administration of AP in rat kidney and its possible relationship with the effects of arsenic on certain antioxidants. Rats were exposed to arsenic through drinking water at 25 ppm for 28 days. The dosages of AP used for a single administration after arsenic preexposure for 28 days were 420 and 1000 mg kg^?1, while for daily concurrent administration with arsenic for 28 days were 105 and 420 mg kg^?1 body weight. AP increased lipid peroxidation (LPO) in rat kidney where its acute administration caused more LPO than its subacute dosing. Repeated arsenic exposure differentially altered the AP‐induced LPO. Arsenic preexposure antagonized LPO induced by the acute AP administration; in contrast, arsenic coexposure aggravated the repeated dose (AP)‐mediated LPO. Arsenic‐mediated alterations in renal sensitivity to LPO did not appear to be linked to the antioxidants such as reduced glutathione, superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase; nor could it be related to glutathione‐S‐transferase activity. The results indicated that repeated arsenic preexposure decreased susceptibility of rat kidney to acute AP‐mediated oxidative stress; on the contrary, its coexposure rendered the rat kidney more vulnerable to oxidative stress induced by the repeated dosing of AP. © 2009 Wiley Periodicals, Inc. Environ Toxicol, 2011.     

Effects on levels of glutathione and some related enzymes in tissues after an acute arsenic exposure in rats and their relationship to dietary protein deficiency

Arsenic is a potent toxin, carcinogen and modulator of antioxidant defense system. In this study, male rats of Wistar strain, maintained on either 18% or 6% protein (casein) diet, received an acute i.p. exposure to sodium arsenite (As3+) at its LD50 dose (15.86 mg/kg body weight). One hour after the arsenic exposure, glutathione (GSH) concentration was significantly depleted and lipid peroxidation was increased. A relationship between any two of tissue arsenic concentrations, GSH levels and lipid peroxidation values was observed only for liver when the proportional changes of respective parameters in either of the dietary groups of animals were compared. This suggests that, in liver, arsenic metabolism appears dependant upon the GSH concentration. Acute arsenic exposure significantly increased the glutathione peroxidase (GPx) activity in liver of both dietary groups and in kidney of only the 18% protein-fed group of animals. The glutathione-S-transferase (GST) activity significantly decreased in liver of the 18% protein-fed animals while GST increased in kidney of both the 18% and the 6% protein-fed groups. No significant change in glutathione reductase (GR) or glucose-6-phosphate dehydrogenase (G6PDH) activity was observed. In the present investigation, liver as a whole seems to be more affected in terms of GSH level and GST activity. The mode of responses of GPx and GR activities as well as the unaltered G6PDH activity might result in arsenic-induced GSH depletion and increase in lipid peroxidation. The animals of the 6% protein-fed group, appeared to be affected less in terms of tissue arsenic concentration, GSH level and GST activity. lipid peroxidation,     

Alterations in apoptotic caspases and antioxidant enzymes in arsenic exposed rat brain regions: Reversal effect of essential metals and a chelating agent

Arsenic (As) widely studied for its effects as a neurotoxicant. The present study was designed to evaluate the protective effect of calcium, zinc or monoisoamyl dimercaptosuccinic acid (MiADMSA), either individually or in combination on As induced oxidative stress and apoptosis in brain regions (cerebral cortex, hippocampus and cerebellum) of postnatal day (PND) 21, 28 and 3 months old rats. Arsenic exposure significantly decreased the activities of superoxide dismutase (SOD) isoforms, catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) with increase in glutathione s transferase (GST) while lipid peroxidation (LPx), arsenic levels, mRNA expression of caspase 3 and 9 were significantly increased in different brain regions. Arsenic induced alterations in these parameters were greater in PND 28 and more pronounced in cerebral cortex. From the results it is evident that combined supplementation of calcium and zinc along with MiADMSA would be most effective compared to individual administration in reducing arsenic induced neurotoxicity.     

Selenium modulates β‐cyfluthrin‐induced liver oxidative toxicity in rats

This study was designed to investigate the possibility of β‐cyfluthrin to induce oxidative stress and biochemical perturbations in rat liver and the role of selenium in alleviating its toxic effects. Male Wister rats were randomly divided into four groups of seven each, group I served as control, group II treated with selenium (200 µg/kg BW), group III received β‐cyfluthrin (15 mg/kg BW, 1/25 LD₅₀), and group IV treated with β‐cyfluthrin plus selenium. Rats were orally administered their respective doses daily for 30 days. The administration of β‐cyfluthrin caused elevation in lipid peroxidation (LPO) and reduction in the activities of antioxidant enzymes including catalase (CAT), superoxide dismutase (SOD), glutathione S‐transferase (GST), glutathione peroxidase (GPx), and glutathione reductase (GR). A decrease in reduced glutathione (GSH) content was also observed. Liver aminotransferases (AST and ALT) and alkaline phosphatase (ALP) were decreased, whereas lactate dehydrogenase (LDH) was increased. Selenium in β‐cyfluthrin‐induced liver oxidative injury of the rats modulated LPO, CAT, SOD, GSH, GST, GPx, and GR. Also, liver AST, ALT, ALP, and LDH were maintained near normal level due to selenium treatment. It is concluded that selenium scavenges reactive oxygen species and render a protective effect against β‐cyfluthrin toxicity. © 2013 Wiley Periodicals, Inc. Environ Toxicol 29: 1323–1329, 2014.     

Taurine, a conditionally essential amino acid, ameliorates arsenic-induced cytotoxicity in murine hepatocytes

Arsenic is a potent environmental toxin. Present study has been designed to evaluate the protective role of taurine (2-aminoethanesulfonic acid) against arsenic induced cytotoxicity in murine hepatocytes. Sodium arsenite (NaAsO₂) was chosen as the source of arsenic. Incubation of hepatocytes with the toxin (1 mM) for 2 h reduced the cell viability as well as intra-cellular antioxidant power. Increased activities of alanine transaminase (ALT) and alkaline phosphatase (ALP) due to toxin exposure confirmed membrane damage. Toxin treatment caused reduction in the activities of the antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST), glutathione reductase (GR) and glutathione peroxidase (GPx). In addition, the same treatment reduced the level of glutathione (GSH), elevated the level of oxidized glutathione (GSSG) and increased the extent of lipid peroxidation. Incubation of hepatocytes with taurine, both prior to and in combination with NaAsO₂, attenuated the extent of lipid peroxidation and enhanced the activities of enzymatic as well as non enzymatic antioxidants. Besides, taurine administration normalized the arsenic-induced enhanced levels of the marker enzymes ALT and ALP in hepatocytes. The cytoprotective activity of taurine against arsenic poisoning was found to be comparable to that of a known antioxidant, vitamin C. Combining all, the results suggest that taurine protects mouse hepatocytes against arsenic induced cytotoxicity.     

Effects of nanoparticle‐encapsulated curcumin on arsenic‐induced liver toxicity in rats

We investigated the therapeutic effectiveness of the nanoparticle‐encapsulated curcumin (CUR‐NP) against sodium arsenite‐induced hepatic oxidative damage in rats. The CUR‐NP prepared by emulsion technique was spherical in shape with an encapsulation efficiency of 86.5%. The particle size ranged between 120 and 140 nm with the mean particle size being 130.8 nm. Rats were divided into five groups of six each. Group 1 served as control. Group 2 rats were exposed to sodium arsenite (25 ppm) daily through drinking water for 42 days. Groups 3, 4, and 5 were treated with arsenic as in group 2, however, they were administered, empty nanoparticles, curcumin (100 mg/kg bw) and CUR‐NP (100 mg/kg bw), respectively, by oral gavage during the last 14 days of arsenic exposure. Arsenic increased the activities of serum alanine aminotransferase and aspartate aminotransferase and caused histological alterations in liver indicating hepatotoxicity. Arsenic increased lipid peroxidation, depleted reduced glutathione and decreased the activities of superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase in liver. All these effects of arsenic were attenuated with both curcumin and CUR‐NP. However, the magnitude of amelioration was more pronounced with CUR‐NP. The results indicate that curcumin given in nano‐encapsulated form caused better amelioration than free curcumin. © 2013 Wiley Periodicals, Inc. Environ Toxicol 30: 628–637, 2015.     

Oxidative stress modulation by Rosmarinus officinalis in creosote‐induced hepatotoxicity

Coal tar is a significant product generated from coal pyrolysis. Coal tar can be utilized as raw materials for various industries. It is also a type of raw material from which phenols, naphthalenes, and anthracene can be extracted. The present study was designed to investigate the possibility of coal tar creosote to induce oxidative stress and biochemical perturbations in rat liver and the role of rosemary (Rosmarinus officinalis) in ameliorating its toxic effects. Male Wister Albino rats were randomly divided into four groups of seven each, group I served as control; group II treated with rosemary (10 mL of water extract/kg BW for 21 days), group III received coal tar creosote (200 mg/4 mL olive oil/kg BW for 3 days), and group IV treated with both rosemary and coal tar creosote. The administration of coal tar creosote significantly caused elevation in lipid peroxidation (LPO) and reduction in the activities of glutathione peroxidase (GPx), glutathione reductase (GR), superoxide dismutase (SOD), catalase (CAT), and glutathione S‐transferase (GST). A significant decrease in reduced glutathione (GSH) content was also observed. Liver aminotransferases aspartate transaminase (AST) and alanine transaminase (ALT)] and alkaline phosphatase (AlP) were significantly decreased while lactate dehydrogenase (LDH) was increased. Rosemary pretreatment to coal tar creosote‐treated rats decreased LPO level and normalized GPx, GR, SOD, CAT, and GST activities, while GSH content was increased. Also, liver AST, ALT, AlP, and LDH were maintained near normal level due to rosemary treatment. In conclusion, rosemary has beneficial effects and could be able to antagonize coal tar creosote toxicity. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 85–92, 2016.     

Acetaminophen-induced hepatotoxicity.

The analgesic acetaminophen causes a potentially fatal, hepatic centrilobular necrosis when taken in overdose. The initial phases of toxicity were described in Dr. Gillette's laboratory in the 1970s. These findings indicated that acetaminophen was metabolically activated by cytochrome P450 enzymes to a reactive metabolite that depleted glutathione (GSH) and covalently bound to protein. It was shown that repletion of GSH prevented the toxicity. This finding led to the development of the currently used antidote N-acetylcysteine. The reactive metabolite was subsequently identified to be N-acetyl-p-benzoquinone imine (NAPQI). Although covalent binding has been shown to be an excellent correlate of toxicity, a number of other events have been shown to occur and are likely important in the initiation and repair of toxicity. Recent data have shown that nitrated tyrosine residues as well as acetaminophen adducts occur in the necrotic cells following toxic doses of acetaminophen. Nitrotyrosine was postulated to be mediated by peroxynitrite, a reactive nitrogen species formed by the very rapid reaction of superoxide and nitric oxide (NO). Peroxynitrite is normally detoxified by GSH, which is depleted in acetaminophen toxicity. NO synthesis (serum nitrate plus nitrite) was dramatically increased following acetaminophen. In inducible nitric oxide synthase (iNOS) knockout mice, acetaminophen did not increase NO synthesis or tyrosine nitration; however, histological evidence indicated no difference in toxicity. Acetaminophen did not cause hepatic lipid peroxidation in wild-type mice but did cause lipid peroxidation in iNOS knockout mice. These data suggest that NO may play a role in controlling lipid peroxidation and that reactive nitrogen/oxygen species may be important in toxicity. The source of the superoxide has not been identified, but our recent finding that NADPH oxidase knockout mice were equally sensitive to acetaminophen and had equal nitration of tyrosine suggests that the superoxide is not from the activation of Kupffer cells. It was postulated that NAPQI-mediated mitochondrial injury may be the source of the superoxide. In addition, the significance of cytokines and chemokines in the development of toxicity and repair processes has been demonstrated by several recent studies. IL-1beta is increased early in acetaminophen toxicity and may be important in iNOS induction. Other cytokines, such as IL-10, macrophage inhibitory protein-2 (MIP-2), and monocyte chemoattractant protein-1 (MCP-1), appear to be involved in hepatocyte repair and the regulation of proinflammatory cytokines.     

Genetic overexpressing of GPx‐1 attenuates cocaine‐induced renal toxicity via induction of anti‐apoptotic factors

The present study investigates the role of the glutathione peroxidase (GPx)‐1 gene in cocaine‐induced renal damage in mice. Multiple doses of cocaine increased lipid peroxidation, protein oxidation, and glutathione oxidation in the kidney of the non‐transgenic mice (non‐TG mice). The enzymatic activities of GPx and glutathione reductase were significantly decreased in non‐TG mice, whereas superoxide dismutase was increased in the early phase of cocaine exposure. Treatment with cocaine resulted in significant decreases in expression of Bcl‐2 and Bcl‐xl in the kidney of non‐TG mice, which resulted in significant increases in Bax and cleaved‐caspase 3. Consistently, cocaine‐induced tubular epithelial vacuolization and focal tubular necrosis were mainly observed in the proximal tubules in the kidneys of non‐TG mice. These renal pathologic changes were much less pronounced in GPx‐1 TG than in non‐TG mice. These results suggest that the GPx‐1 gene is a protective factor against nephrotoxicity induced by cocaine via interactive modulations between antioxidant and cell survival signaling processes.     

Se-methylselenocysteine modulates antioxidant response of rat spleen to ionizing radiation

Whole body irradiation with a single 10-Gy dose caused increase in lipid peroxidation and a transient decrease in cellular glutathione content in rat spleen, demonstrating elevated oxidative stress. The irradiation also caused increases in activities of glutathione peroxidase (GPx), glutathione reductase (GR), and glucose 6-phosphate dehydrogenase (G6PD), the enzymes carrying out glutathione redox cycling; but not glutamate cysteine ligase (GCL), the enzyme in glutathione synthesis process. Increases in catalase (CAT) activity and heme oxygenase-1 (HO-1) and glutathione S-transferase pi (GSTpi) protein levels were also exhibited after irradiation. Administration of Se-methylselenocysteine (MSC) (0.75 mg/rat/day, for 1 week) resulted in increases in GPx, G6PD, and CAT activities and GSTpi protein level in non-irradiated spleen, without affecting glutathione and lipid peroxidation levels. The MSC pretreatment prior to irradiation abrogated the irradiation-induced increase in lipid peroxidation, and it induced increases in glutathione content, GCL, GPx and CAT activities, and HO-1, GSTpi, and peroxiredoxin 2 protein levels upon irradiation. Our results suggest a role for MSC pretreatment in prevention of irradiation-induced oxidative damage in spleen by reinforcing antioxidant capacity, particularly the glutathione system.     

Comparison of inhibitory effects between acetaminophen–glutathione conjugate and reduced glutathione in human glutathione reductase

Acetaminophen overdose is the most frequent cause of acute liver injury. The main mechanism of acetaminophen toxicity has been attributed to oxidation of acetaminophen. The oxidation product is very reactive and reacts with glutathione generating acetaminophen–glutathione conjugate (APAP‐SG). Although this conjugate has been recognized to be generally nontoxic, we have found recently that APAP‐SG could produce a toxic effect. Therefore, the aim of our study was to estimate the toxicity of purified APAP‐SG by characterizing the inhibitory effect in human glutathione reductase (GR) and comparing that to the inhibitory effect of the natural inhibitor reduced glutathione. We used two types of human GR: recombinant and freshly purified from red blood cells. Our results show that GR was significantly inhibited in the presence of both APAP‐SG and reduced glutathione. For example, the enzyme activity of recombinant and purified GR was reduced in the presence of 4 mm APAP‐SG (with 0.5 mm glutathione disulfide) by 28% and 22%, respectively. The type of enzyme inhibition was observed to be competitive in the cases of both APAP‐SG and glutathione. As glutathione inhibits GR activity in cells under physiological conditions, the rate of enzyme inhibition ought to be weaker in the case of glutathione depletion that is typical of acetaminophen overdose. Notably, however, enzyme activity likely remains inhibited due to the presence of APAP‐SG, which might enhance the pro‐oxidative status in the cell. We conclude that our finding could reflect some other pathological mechanism that may contribute to the toxicity of acetaminophen. Copyright © 2013 John Wiley & Sons, Ltd.     

Hydrogen sulfide inhibits oxidative stress in lungs from allergic mice in vivo

Recent studies show that endogenous hydrogen sulfide (H₂S) plays an anti-inflammatory role in the pathogenesis of airway inflammation. This study investigated whether exogenous H₂S may counteract oxidative stress-mediated lung damage in allergic mice. Female BALB/c mice previously sensitized with ovalbumin (OVA) were treated with sodium hydrosulfide (NaHS) 30 min before OVA challenge. Forty eight hours after antigen-challenge, the mice were killed and leukocyte counting as well as nitrite plus nitrate concentrations were determined in the bronchoalveolar lavage fluid, and lung tissue was analysed for nitric oxide synthase (NOS) activity, iNOS expression, superoxide dismutase (SOD), catalase, glutathione reductase (GR) and glutathione peroxidase (GPx) activities, thiobarbituric acid reactive species and 3-nitrotyrosine containing proteins (3-NT). Pre-treatment of OVA-sensitized mice with NaHS resulted in significant reduction of both eosinophil and neutrophil migration to the lungs, and prevented the elevation of iNOS expression and activity observed in the lungs from the untreated allergic mice, although it did not affect 3-NT. NaHS treatment also abolished the increased lipid peroxidation present in the allergic mouse lungs and increased SOD, GPx and GR enzyme activities. These results show, for the first time, that the beneficial in vivo effects of the H₂S-donor NaHS on allergic airway inflammation involve its inhibitory action on leukocyte recruitment and the prevention of lung damage by increasing endogenous antioxidant defenses. Thus, exogenous administration of H₂S donors may be beneficial in reducing the deleterius impact of allergic pulmonary disease, and might represent an additional class of pharmacological agents for treatment of chronic pulmonary diseases.     

Silybin dihemisuccinate protects against glutathione depletion and lipid peroxidation induced by acetaminophen on rat liver

Acetaminophen hepatotoxicity is characterized by glutathione depletion, cellular necrosis, and, in some instances, by the induction of lipid peroxidation. Silybin dihemisuccinate, a soluble form of the flavonoid silymarin, protects rats against liver glutathione depletion and lipid peroxidation induced by acute acetaminophen intoxication. Other biochemical parameters such as serum transaminases did not show the drastic increase observed under acetaminophen intoxication when animals were treated with the flavonoid. Preliminary results suggest that silybin dihemisuccinate may be another antidote against acetaminophen hepatotoxicity.     

Repeated acetaminophen dosing in rats: adaptation of hepatic antioxidant system

Repeated dosing of acetaminophen (paracetamol) to rats is reported to decrease their sensitivity to its hepatotoxic effects, which are associated with oxidative stress and glutathione depletion. We determined if repeated acetaminophen dosing produced adaptive response of key antioxidant system enzymes. Male rats (Sprague-Dawley, 10 weeks) were given 800, 1200, or 1600 mg/kg/day acetaminophen by oral gavage for 4 days. Liver was assayed for oxidative stress and antioxidant markers: malondialdehyde (MDA), thiobarbituric acid reactive substance (TBARS), total antioxidant status (TAS), glutathione (GSH), glutathione reductase (GR), glutathione peroxidase (GPx), glucose-6-phosphate dehydrogenase (G6PD), catalase (CAT), and superoxide dismutase (SOD), and alanine transaminase (ALT) as a marker of hepatocellular injury. Acetaminophen at 1200/1600 mg/kg decreased GSH 26/47%, GPx 21/26%, CAT 35/28%, SOD 21/12%; and TAS 28/18% (correlated with CAT, r=0.91; SOD, r=0.66; GPx, r=0.45). Despite antioxidant deficiencies, and no TBARS change, MDA decreased 26%/33%/37% at 800/1200/1600 mg/kg, which correlated with increased GR (61%/62%/76%, r=0.77) and G6PD (130%/110%/190%, r=0.78). Both MDA (r=0.68) and G6PD (r=0.71) correlated with hepatic ALT, which decreased 27%/43%/48%, respectively. Resistance to acetaminophen hepatotoxicity produced by repeated exposure is partially attributable to upregulation of hepatic G6PD and GR activity as an adaptive and protective response to oxidative stress and glutathione depletion.     

Differential oxidative stress responses to pure Microcystin-LR and Microcystin-containing and non-containing cyanobacterial crude extracts on Caco-2 cells

Cyanobacterial blooms are a worldwide problem due to the production of cyanotoxins such as microcystins (MCs), causing serious water pollution and public health hazard to humans and livestock. Oxidative stress plays a significant role in MCs toxicity. In the present work the differential oxidative stress responses to pure MCs, and Microcystin-containing and non-containing cyanobacterial crude extracts on the human colon carcinoma cell line Caco-2 has been studied for the first time. After exposure, cells were collected and the antioxidant enzymes activities superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione-S-transferase (GST) were measured. Moreover, lipid peroxidation (LPO) induction, reactive oxygen species (ROS) and reduced glutathione (GSH) content were also analyzed. The oxidative stress biomarkers that experienced higher alterations were ROS, CAT, SOD and GR activities. The MC containing cyanobacterial extract showed the higher toxic effects, followed by pure MC-LR. The non-MC containing cyanobacterial extract showed limited effects mainly in SOD activity, GSH content, and GP and GR activities only at the highest concentration used. These results suggest that MC-LR is the responsible of the oxidative stress responses observed in Caco-2 cells, but other compounds contained in the cyanobacterial extracts can contribute to the toxic effects.     

Markers of oxidative stress in follicular fluid of women with endometriosis and tubal infertility undergoing IVF

Oxidative stress and trace elements in the oocytes environment is explored in endometriosis and impact on in vitro fertilization (IVF) outcome assessed. Follicular fluid was aspirated at the time of oocyte retrieval from endometriosis (n = 200) and tubal infertility (n = 140) and the analytes measured using spectroscopy and HPLC. Increased concentration of reactive oxygen species (ROS), nitric oxide (NO), lipid peroxidation (LPO), iron, lead, cadmium and reduced levels of total antioxidant capacity (TAC), superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), glutathione reductase (GR), vitamins A, C, E, copper, zinc and selenium was observed compared to tubal infertility. Increased ROS and NO in endometriosis and tubal infertility associated with poor oocytes and embryo quality. Increased levels of ROS, NO, LPO, cadmium and lead were observed in women who did not become pregnant compared to women who did. Intrafollicular zinc levels were higher in women with endometriosis who subsequently became pregnant following IVF.     

Nanotoxicity of pure silica mediated through oxidant generation rather than glutathione depletion in human lung epithelial cells

Though, oxidative stress has been implicated in silica nanoparticles induced toxicity both in vitro and in vivo, but no similarities exist regarding dose–response relationship. This discrepancy may, partly, be due to associated impurities of trace metals that may present in varying amounts. Here, cytotoxicity and oxidative stress parameters of two sizes (10 nm and 80 nm) of pure silica nanoparticles was determined in human lung epithelial cells (A549 cells). Both sizes of silica nanoparticles induced dose-dependent cytotoxicity as measured by MTT [3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide] and lactate dehydrogenase (LDH) assays. Silica nanoparticles were also found to induce oxidative stress in dose-dependent manner indicated by induction of reactive oxygen species (ROS) generation, and membrane lipid peroxidation (LPO). However, both sizes of silica nanoparticles had little effect on intracellular glutathione (GSH) level and the activities of glutathione metabolizing enzymes; glutathione reductase (GR) and glutathione peroxidase (GPx). Buthionine-[S,R]-sulfoximine (BSO) plus silica nanoparticles did not result in significant GSH depletion than that caused by BSO alone nor N-acetyl cysteine (NAC) afforded significant protection from ROS and LPO induced by silica nanoparticles. The rather unaltered level of GSH is also supported by finding no appreciable alteration in the level of GR and GPx. Our data suggest that the silica nanoparticles exert toxicity in A549 cells through the oxidant generation (ROS and LPO) rather than the depletion of GSH.