Lung Glutathione Levels Research Articles

LRP1 loss in airway epithelium exacerbates smoke-induced oxidative damage and airway remodeling

The LDL receptor-related protein 1 (LRP1) partakes in metabolic and signaling events regulated in a tissue-specific manner. The function of LRP1 in airways has not been studied. We aimed to study the function of LRP1 in smoke-induced disease. We found that bronchial epithelium of patients with chronic obstructive pulmonary disease and airway epithelium of mice exposed to smoke had increased LRP1 expression. We then knocked out LRP1 in human bronchial epithelial cells in vitro and in airway epithelial club cells in mice. In vitro, LRP1 knockdown decreased cell migration and increased transforming growth factor β activation. Tamoxifen-inducible airway-specific LRP1 knockout mice (club Lrp1−/−) induced after complete lung development had increased inflammation in the bronchoalveolar space and lung parenchyma at baseline. After 6 months of smoke exposure, club Lrp1−/− mice showed a combined restrictive and obstructive phenotype, with lower compliance, inspiratory capacity, and forced expiratory volume0.05/forced vital capacity than WT smoke-exposed mice. This was associated with increased values of Ashcroft fibrotic index. Proteomic analysis of room air exposed-club Lrp1−/− mice showed significantly decreased levels of proteins involved in cytoskeleton signaling and xenobiotic detoxification as well as decreased levels of glutathione. The proteome fingerprint created by smoke eclipsed many of the original differences, but club Lrp1−/− mice continued to have decreased lung glutathione levels and increased protein oxidative damage and airway cell proliferation. Therefore, LRP1 deficiency leads to greater lung inflammation and damage and exacerbates smoke-induced lung disease.

The protective effects of prostaglandin E1 on lung injury following renal ischemia–reperfusion in rats

For the purposes of the present study, the protective effect of prostaglandin E1 (PGE1) on lung injury following renal ischemia-reperfusion (RIR) was investigated. Adult male rats were divided into four groups, namely, (I) control rats given physiological saline; (II) rats given PGE1 (20 μg/kg, intravenously); (III) rats subjected to RIR; and (IV) rats subjected to RIR given PGE1 30 min prior to ischemia and just before reperfusion. The right nephrectomy was performed in the RIR model. The left renal pedicle was occluded for 60 min to induce ischemia and then the left kidney was subjected to reperfusion for 60 min. The lungs of rats were used for microscopic and biochemical analyses. Although rats subjected to RIR did not exhibit heavy degenerative alterations in the lung structure, they possessed pulmonary interstitial edema. Lung glutathione levels and catalase, superoxide dismutase, glutathione peroxidase, and tissue factor (TF) activities were decreased in rats subjected to RIR, while lung lipid peroxidation, myeloperoxidase (MPO), xanthine oxidase and serum lactate dehydrogenase (LDH) activities, and blood urea and serum creatinine levels were increased in these rats when compared with the control group. PGE1 treatments resulted in the regression of oxidative stress via induction of antioxidant system, the decreased MPO and LDH activities, the reduced urea and creatinine levels, and the induced TF activity in rats subjected to RIR, while edema still remained permanent. We conclude that PGE1 may be useful in preventing lung injury with the exception of edema that occurred as a result of RIR in rats.

Vapors produced by electronic cigarettes and e-juices with flavorings induce toxicity, oxidative stress, and inflammatory response in lung epithelial cells and in mouse lung.

Oxidative stress and inflammatory response are the key events in the pathogenesis of chronic airway diseases. The consumption of electronic cigarettes (e-cigs) with a variety of e-liquids/e-juices is alarmingly increasing without the unrealized potential harmful health effects. We hypothesized that electronic nicotine delivery systems (ENDS)/e-cigs pose health concerns due to oxidative toxicity and inflammatory response in lung cells exposed to their aerosols. The aerosols produced by vaporizing ENDS e-liquids exhibit oxidant reactivity suggesting oxidants or reactive oxygen species (OX/ROS) may be inhaled directly into the lung during a “vaping” session. These OX/ROS are generated through activation of the heating element which is affected by heating element status (new versus used), and occurs during the process of e-liquid vaporization. Unvaporized e-liquids were oxidative in a manner dependent on flavor additives, while flavors containing sweet or fruit flavors were stronger oxidizers than tobacco flavors. In light of OX/ROS generated in ENDS e-liquids and aerosols, the effects of ENDS aerosols on tissues and cells of the lung were measured. Exposure of human airway epithelial cells (H292) in an air-liquid interface to ENDS aerosols from a popular device resulted in increased secretion of inflammatory cytokines, such as IL-6 and IL-8. Furthermore, human lung fibroblasts exhibited stress and morphological change in response to treatment with ENDS/e-liquids. These cells also secrete increased IL-8 in response to a cinnamon flavored e-liquid and are susceptible to loss of cell viability by ENDS e-liquids. Finally, exposure of wild type C57BL/6J mice to aerosols produced from a popular e-cig increase pro-inflammatory cytokines and diminished lung glutathione levels which are critical in maintaining cellular redox balance. Thus, exposure to e-cig aerosols/juices incurs measurable oxidative and inflammatory responses in lung cells and tissues that could lead to unrealized health consequences.

0986. The effect of eritoran on the severity of lung injury in two different rat lung injury models

Toll like receptors (TLR) play an important role in noninfectious problems in critically ill patients. The central role of TLR4 in sepsis has been clearly demonstrated. However, the role of TLR as a therapeutic target in acute respiratory distress syndrome (ARDS) has not been studied. The goal of this study is to compare the effects of eritoran, a TLR4 antagonist, on severity of ARDS in two different (pulmonary versus extrapulmonary) ARDS rat models. Forty rats were randomized to sham (n=8), extrapulmonary control (n=8), extrapulmonary eritoran (n=8), pulmonary control (n=8), and pulmonary eritoran (n=8) groups. Intestinal ischemia-reperfusion (I/R) via ligation of superior mesenteric artery was used to induce the extrapulmonary ARDS model. Intratracheal instillation of hydrochloric acid was used for the pulmonary ARDS model. Rats received either eritoran 100 µg/kg or an equal volume of placebo solution. Serum tumor necrosis factor- α (TNF-α), interleukin-1β (IL-1β), and IL-6; lung tissue malondialdehyde (MDA), glutathione (GSH), and myeloperoxidase (MPO) levels; lung histopathologic examination; arterial partial oxygen pressure (pO2); and lung wet-to-dry weight ratio (w/d) measurements were used to compare and evaluate the severity of lung injury between the groups. TLR-4 and nuclear factor-κB (NF-κB) gene expressions were determined from lung tissue using polymerase chain reaction technique. Compared to its control group, extrapulmonary eritoran group exhibited significantly less severe lung injury, as indicated by lower mean values for MDA (p 0.05 for all). However, mean values for MPO (p 0.05). However, compared to pulmonary control group the expression of TLR-4 gene was significantly less pronounced in the pulmonary eritoran group (p< 0.05). In conclusion eritoran reduced the severity of lung injury both in pulmonary and extrapulmonary ARDS models. This effect of eritoran was more pronounced in the I/R lung injury model.

Pulmonary Oxidative Stress, Inflammation, and Dysregulated Iron Homeostasis in Rat Models of Cardiovascular Disease

Underlying cardiovascular disease (CVD) is a risk factor for the exacerbation of air pollution health effects. Pulmonary oxidative stress, inflammation, and altered iron (Fe) homeostasis secondary to CVD may influence mammalian susceptibility to air pollutants. Rodent models of CVD are increasingly used to examine mechanisms of variation in susceptibility. Baseline cardiac and pulmonary disease was characterized in healthy normotensive Wistar Kyoto (WKY) rats, cardiovascular compromised spontaneously hypertensive rats (SHR), and spontaneously hypertensive heart failure (SHHF) rats. Blood pressure, heart rate, and breathing frequencies were measured in rats 11 to 12 wk of age, followed by necropsy at 14 to 15 wk of age. Blood pressure and heart rate were increased in SHR and SHHF relative to WKY rats (SHR > SHHF > WKY). Increased breathing frequency in SHHF and SHR (SHR > SHHF > WKY) resulted in greater minute volume relative to WKY. Bronchoalveolar lavage fluid (BALF) protein and neutrophils were higher in SHHF and SHR relative to WKY (SHHF >> SHR > WKY). Lung ascorbate and glutathione levels were low in SHHF rats. BALF Fe-binding capacity was decreased in SHHF relative to WKY rats and was associated with increased transferrin (Trf) and ferritin. However, lung ferritin was lower and Trf was higher in SHHF relative to WKY or SHR rats. mRNA for markers of inflammation and oxidative stress (macrophage inflammatory protein [MIP]-2, interleukin [IL]-1α, and heme oxygenase [HO]-1) were greater in SHHF and SHR relative to WKY rats. Trf mRNA rose in SHR but not SHHF relative to WKY rats, whereas transferrin receptors 1 and 2 mRNA was lower in SHHF rats. Four of 12 WKY rats exhibited cardiac hypertrophy despite normal blood pressure, while demonstrating some of the pulmonary complications noted earlier. This study demonstrates that SHHF rats display greater underlying pulmonary complications such as oxidative stress, inflammation, and impaired Fe homeostasis than WKY or SHR rats, which may play a role in SHHF rats' increased susceptibility to air pollution.

Ghrelin improves burn-induced multiple organ injury by depressing neutrophil infiltration and the release of pro-inflammatory cytokines

Mechanisms of burn-induced skin and remote organ injury involve oxidant generation and the release of pro-inflammatory cytokines. In this study the possible antioxidant and anti-inflammatory effects of ghrelin were evaluated in a rat model of thermal trauma. Wistar albino rats were exposed to 90 degrees C bath for 10 s to induce thermal trauma. Ghrelin, was administered subcutaneously (10 ng/kg/day) after the burn injury and repeated twice daily. Rats were decapitated at 6 h and 48 h after burn injury and blood was collected for the analysis of pro-inflammatory cytokines (TNF-alpha and IL-1beta), lactate dehydrogenase (LDH) activity and antioxidant capacity (AOC). In skin, lung and stomach tissue samples malondialdehyde (MDA) and glutathione (GSH) levels, myeloperoxidase (MPO) and Na(+)-K(+)-ATPase activity were measured in addition to the histological analysis. DNA fragmentation ratio in the gastric mucosa was also evaluated. Burn injury caused significant increase in both cytokine levels, and LDH activity, while plasma AOC was found to be depleted after thermal trauma. On the other hand, in tissue samples the raised MDA levels, MPO activity and reduced GSH levels, Na(+)-K(+)-ATPase activity due to burn injury were found at control levels in ghrelin-treated groups, while DNA fragmentation in the gastric tissue was also reduced. According to the findings of the present study, ghrelin possesses a neutrophil-dependent anti-inflammatory effect that prevents burn-induced damage in skin and remote organs and protects against oxidative organ damage.

Protective Effects of Erdosteine and Vitamins C and E Combination on Ischemia–Reperfusion-Induced Lung Oxidative Stress and Plasma Copper and Zinc Levels in a Rat Hind Limb Model

The aim of this study was to investigate the protective effects of erdosteine and vitamins C and E (VCE) on the lungs after performing hind limb ischemia-reperfusion (I/R) by assessing oxidative stress, plasma copper (Cu), and zinc (Zn) analysis. The animals were divided randomly into four groups as nine rats each as follows: control, I/R, I/R plus erdosteine, and I/R plus VCE combination. I/R period for 60 min was performed on the both hind limbs of all the rats in the groups of I/R, erdosteine with I/R, VCE with I/R allowing 120 min of reperfusion. The animals received orally erdosteine one time in a day and 3 days before I/R in the erdosteine group. In the VCE group, the animals VCE combination received one time in a day and 3 days before I/R, although placebo was given to control and I/R group animals. Lung lipid peroxidation (malondialdehyde [MDA]) level, superoxide dismutase (SOD), and catalase activities were increased, although lung glutathione (GSH) and plasma Zn levels decreased in I/R group in lung tissue compared with the control group. Serum MDA level, creatine kinase, and lactate dehydrogenase activities were increased in I/R group compared with the control. Lung MDA and plasma Zn levels and lung SOD activity were decreased by erdosteine administration, whereas lung GSH levels after I/R increased. The plasma Zn levels and lung SOD activity were decreased by VCE administration, although the plasma Cu and lung GSH levels increased after I/R. In conclusion, erdosteine has an antioxidant role on the values in the rat model, and it has more protective affect than in VCE in attenuating I/R-induced lung injury in rats.

The effects of thinner inhalation on superoxide dismutase activities, malondialdehyde and glutathione levels in rat lungs

Background: Recent years' usage of thinner by the young generation as a drug constitutes a serious problem in the society. Due to common usage in the industrial sector, most people are affected from the manufacturing process to the consuming phase. Aim: Because of these reasons, this project has been preferred to research the effects of thinner on oxidant and antioxidant status. Methods: Totally 46 rats were included in the study. Thirty six rats were separated into six groups with 10 rats in a control group. The first group inhaled thinner for 2 weeks, and the other groups were exposed to thinner for 4, 6, 8, 10 and 12 weeks for 1 h twice a day. On the mentioned duration, rats were autopsied. Lung tissues malondialdehyde (MDA), glutathione (GSH) levels and superoxide dismutase (SOD) activities were determined to designate the oxidant–antioxidant balance. Results: We observed an increase in MDA values both in the acute and the subacute periods. In the chronic period by the consuming of lipid peroxidation products, MDA values decreased and as the oxidative stress continued MDA values again increased. We observed that especially GSH values that has antioxidant feature, decreased until 6 weeks in order to compensate lipid peroxidation products. In the consuming period of lipid peroxidation, the values became fixed and later, these values again increased. There was no relationship between the changing values of MDA and SOD. Conclusions: Thinner is an agent that causes oxidative stress and inhalation of high doses of thinner causes harm to the respiratory system. As there are few reports in the literature on long-term effects of thinner inhalation, more studies might be necessary.

Pulmonary protective effects of curcumin against paraquat toxicity

An early feature of paraquat (PQ) toxicity is the influx of inflammatory cells, releasing proteolytic enzymes and oxygen free radicals, which can destroy the lung epithelium and result in pulmonary fibrosis. Therefore, the ability to suppress early lung injury seems to be an appropriate therapy of pulmonary damage before the development of irreversible fibrosis. Here I show curcumin confers remarkable protection against PQ lung injury. A single intraperitoneal injection of PQ (50 mg kg ) resulted in a significant rise in the levels of protein, angiotensin converting enzyme (ACE), alkaline phosphatase (AKP), N-acetyl-β-D-glucosaminidase (NAG) and thiobarbituric acid reactive substances (TEARS), and neutrophils in the bronchoalveolar lavage fluid (BALF), while a decrease in glutathione levels. In paraquat rats bronchoalveolar lavage (BAL) cell TBARS concentration was increased with a simultaneous decrease in glutathione content. In addition, the data also demonstrated that PQ caused a decrease in ACE and glutathione levels and an increase in levels of TBARS and myeloperoxidase (MPO) activity in the lung. Interestingly, curcumin prevented the general toxicity and mortality induced by PQ and blocked the rise in BALF protein, ACE, AKP, NAG TBARS and neutrophils. Similarly, curcumin prevented the rise in TBARS content in both BAL cell and lung tissue and MPO activity of the lung. In addition, PQ induced reduction in lung ACE and BAL cell and lung glutathione levels was abolished by curcumin treatment. These findings indicate that curcumin has important therapeutic implications in facilitating the early suppression of PQ lung injury.

Ethanol ingestion increases activation of matrix metalloproteinases in rat lungs during acute endotoxemia.

Previously we reported that alcohol abuse increases the incidence of the acute respiratory distress syndrome (ARDS) in septic patients, and that chronic ethanol ingestion in rats depletes alveolar epithelial glutathione and increases endotoxin-mediated lung edema. In this study we examined a potential mechanism by which ethanol-induced glutathione depletion could predispose to acute lung injury. We hypothesized that glutathione depletion activates matrix metalloproteinases (MMPs), thereby increasing degradation of the alveolar extracellular matrix (ECM) during sepsis. Ethanol-fed rats (20% vol/vol in water for 6 wk) were given endotoxin (2 mg/kg, intraperitoneally) followed 2 h later by lung isolation and ex vivo perfusion with n-formyl-methionyl-leucyl-phenylalanine (fMLP) (10(-)(7) M). Ethanol ingestion increased (p < 0.05) MMP-9 and MMP-2 activity, as determined by zymography, in the lung tissue and lavage fluid compared with control-fed rats, and increased (p < 0.05) levels of the 7S fragment of type IV collagen in the lung lavage fluid. Ethanol ingestion increased activation, but not production, of the MMP-9 and MMP-2 zymogens. Finally, although concomitant ingestion of N-acetylcysteine had no effect (p > 0.05) on MMP production, it increased (p > 0.05) lung glutathione levels, blocked (p < 0.05) MMP-9 and MMP-2 activation, and decreased (p < 0.05) levels of the 7S fragment of type IV collagen. We conclude that chronic ethanol ingestion, via glutathione depletion, activates MMPs during sepsis, thereby increasing degradation of the alveolar epithelial ECM. Lois M, Brown LAS, Moss IM, Roman J, Guidot DM. Ethanol ingestion increases activation of matrix metalloproteinases in rat lungs during acute endotoxemia.

Effects of N-acetylcysteine on lung glutathione levels in rats after burn injury

This study was designed to determine the effect of N-acetylcysteine (NAC, a natural hydroxyl radical scavenger) treatment on levels of pulmonary malondialdehyde (MDA, the end product of lipid peroxidation) and glutathione (GSH, a natural antioxidant) in thermally injured rats. Severe skin scald injury (30 percent TBSA) caused a significant decrease in GSH levels, and a significant increase in MDA levels in lung tissue both at 1 h and 1 day postburn injury.Treatment of rats with NAC (15 mg/kg intraperitoneally, 15 min and 12 h following the burn) significantly improved GSH levels, and decreased ongoing lipid peroxidation at 1 day.This study showed that thermal injury resulted in increased pulmonary lipid peroxidation, and this remote organ injury was decreased by treatment with NAC. In addition NAC, a scavenger of hydroxyl radicals, improved GSH levels in the lungs. The higher level of GSH in the lungs of the burned rats treated with NAC could be due to either a decrease in the rate of degradation of GSH or to an increase in its synthesis. No data about these possibilities are provided.

Diethylmaleate attenuates endotoxin-induced lung injury

Alterations in the cellular redox state play a critical role in cell signaling and cell activation, suggesting that administration of sulfhydryl-reactive agents may have important modulatory effects on the inflammatory response. We postulated that intracellular thiol depletion may attenuate the pulmonary inflammatory response after intratracheal administration of endotoxin (LPS) and that this attenuation would supersede the reduction in antioxidant defenses associated with depletion of the endogenous antioxidant, glutathione. Sprague Dawley rats were administered diethylmaleate (6 mmol/kg intraperitoneally), a rapidly acting glutathione-depleting agent, followed by intratracheal administration of LPS. Lung injury was assessed by measuring the transpulmonary flux of 125-I albumin and expressed as a permeability index. Administration of diethylmaleate reduced lung glutathione levels from 1310 +/- 114 to 185 +/- 48 nmol/gm. This was associated with a reduction in the permeability index after LPS treatment (LPS, 0.22 +/- 0.03 versus LPS + diethylmaleate, 0.03 +/- 0.01). Bronchoalveolar lavage fluid polymorphonuclear neutrophil counts were markedly reduced in animals pretreated with diethylmaleate (LPS, 90.5 +/- 24 x 10(6) versus LPS + diethylmaleate, 1.9 +/- 0.4 x 10(6)). Peripheral blood polymorphonuclear neutrophils isolated from animals treated with diethylmaleate had equivalent chemotactic responses to n-formyl-methionyl-leucyl-phenylalanine and normal up-regulation of CD11b as determined by flow cytometry. Levels of bronchoalveolar lavage fluid tumor necrosis factor-alpha were unaffected. Diethylmaleate attenuates LPS-induced lung injury through a reduction in lung polymorphonuclear neutrophil sequestration. Normal peripheral blood neutrophil chemotactic responses and CD11b expression suggest that thiol depletion might mediate this effect through inhibition of endothelial cell adhesion molecule activity.

Oxidants/antioxidants in idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is characterized by an increased oxidant burden and by a deficiency of glutathione, a major antioxidant, in the lung epithelial lining fluid (ELF). Therefore, a rational therapeutic approach is to reverse the imbalance between oxidants and antioxidants in the lung by enhancing the antioxidant screen. With this background, the aim of our study was to evaluate oral N-acetylcysteine (NAC) as a strategy to augment lung glutathione levels in patients with IPF Concentrations of total glutathione in bronchoalveolar lavage fluid (BALF) were quantified spectrophotometrically, before and following oral therapy with 3 x 600 mg NAC per day for 5 days, in 17 nonsmoking patients with biopsy-proven IPF. The volume of ELF recovered by BAL was determined using the urea method. Pretherapy, total glutathione levels in ELF in IPF patients were significantly less than normal (187 ± 36 vs 368 ± 60 μM), in contrast to levels in BALF (0.99 ± 0.12 vs 1.18 ± 19 μM). Following therapy with oral NAC, glutathione levels in BALF were 1.54 ± 0.24 μM (a significant increase compared to pretherapy), whereas the increase in ELF levels (319 ± 92 μM) did not reach significance. The therapy was well-tolerated, and all routine clinical and bronchoscopic parameters remained unchanged. It is thus feasible and safe to augment deficient lung glutathione levels in patients with IPF ; thereby, potentially augmenting pulmonary antioxidant protection. (Eur Respir J 1994 ;7 :431-6)

The effect of oral N-acetylcysteine on lung glutathione levels in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is characterized by an increased oxidant burden and by a deficiency of glutathione, a major antioxidant, in the lung epithelial lining fluid (ELF). Therefore, a rational therapeutic approach is to reverse the imbalance between oxidants and antioxidants in the lung by enhancing the antioxidant screen. With this background, the aim of our study was to evaluate oral N-acetylcysteine (NAC) as a strategy to augment lung glutathione levels in patients with IPF. Concentrations of total glutathione in bronchoalveolar lavage fluid (BALF) were quantified spectrophotometrically, before and following oral therapy with 3 x 600 mg NAC per day for 5 days, in 17 nonsmoking patients with biopsy-proven IPF. The volume of ELF recovered by BAL was determined using the urea method. Pretherapy, total glutathione levels in ELF in IPF patients were significantly less than normal (187 +/- 36 vs 368 +/- 60 microM), in contrast to levels in BALF (0.99 +/- 0.12 vs 1.18 +/- 0.19 microM). Following therapy with oral NAC, glutathione levels in BALF were 1.54 +/- 0.24 microM (a significant increase compared to pretherapy), whereas the increase in ELF levels (319 +/- 92 microM) did not reach significance. The therapy was well-tolerated, and all routine clinical and bronchoscopic parameters remained unchanged. It is thus feasible and safe to augment deficient lung glutathione levels in patients with IPF; thereby, potentially augmenting pulmonary antioxidant protection.

Differing Response of the Glutathione System to Fasting in Neonatal and Adult Guinea Pigs

Abstract Adult, term neonatal and 3 day preterm neonatal guinea pigs were fasted for 48 hr, and the glutathione concentrations of the liver and lung assessed. In adult animals, glutathione concentration decreased by 43% in the liver and 29% in the lung with respect to fed controls. The decrease in liver glutathione was associated with a 75% reduction in the hepatic activity of τ-glutamyltranspeptidase (τGGT). Conversely, both liver and lung glutathione levels in preterm pups remained unchanged following 48 hr food restriction. Likewise, hepatic τGGT, glutathione reductase (GRed) and glutathione peroxidase (GPx) activities were unchanged by fasting in preterm pups. Fasting increased pulmonary GPx activity by 27% in these pups. In fasted, term animals, substantial increases in both lung (65%) and liver (80%) glutathione concentrations were observed, with concomitant increases in GPx and GRed activities. Hepatic τGGT activity was significantly reduced (57%) in term pups. These results may suggest that the neonatal guinea pig can maintain tissue glutathione status during periods of nutrient stress, through an increased capacity for recycling oxidized glutathione and a decrease in turnover of the tripeptide. Guinea pig neonates are therefore able to resist starvation-induced decreases in tissue glutathione levels seen in adult rodents. If this is a general neonatal response it may have important clinical implications in the treatment of preterm babies.

Oxygen-induced lung damage. Relationship to lung mitochondrial glutathione levels.

Several reports suggest there is a relationship between lung glutathione (GSH) levels and susceptibility to oxygen-induced lung damage. However, studies of other organs and cells indicate that a better relationship may exist between mitochondrial GSH levels and oxidant damage. We determined whether there is a similar relationship in the lung using a well-characterized mouse model and a series of interventions that alter lung GSH levels and susceptibility to oxygen-induced lung damage. Mice were fasted or given buthionine sulfoximine (BSO, 20 mM), which reduce total lung GSH levels and increase susceptibility to oxygen-induced lung damage. Mice were also given glutathione monoethyl ester (GSH-ME) intraperitoneally (5 or 10 mM/kg/day for 2 days) or intratracheally (0.2 mM once) in an attempt to increase lung GSH levels. Fasting for up to 3 days and the administration of BSO for 7 to 10 days decreased total lung GSH levels (p < 0.001 for both) but not lung mitochondrial GSH levels. Intraperitoneal administration of GSH-ME increased mitochondrial GSH levels (p < 0.001 in both fed and fasted mice), but it had little effect on total lung GSH levels and no effect on susceptibility to oxygen-induced lung damage. Exposure to 100% oxygen increased mitochondrial GSH levels in both the fed and fasted mice to nearly the same extent (p < 0.001 for both). However, the fasted mice had lower total lung GSH levels compared with the fed mice (p < 0.05) and increased susceptibility to 100% oxygen.(ABSTRACT TRUNCATED AT 250 WORDS)

Differing response of the glutathione system to fasting in neonatal and adult guinea pigs

Adult, term neonatal and 3 day preterm neonatal guinea pigs were fasted for 48 hr, and the glutathione concentrations of the liver and lung assessed. In adult animals, glutathione concentration decreased by 43% in the liver and 29% in the lung with respect to fed controls. The decrease in liver glutathione was associated with a 75% reduction in the hepatic activity of τ-glutamyltranspeptidase (τGGT). Conversely, both liver and lung glutathione levels in preterm pups remained unchanged following 48 hr food restriction. Likewise, hepatic τGGT, glutathione reductase (GRed) and glutathione peroxidase (GPx) activities were unchanged by fasting in preterm pups. Fasting increased pulmonary GPx activity by 27% in these pups. In fasted, term animals, substantial increases in both lung (65%) and liver (80%) glutathione concentrations were observed, with concomitant increases in GPx and GRed activities. Hepatic τGGT activity was significantly reduced (57%) in term pups. These results may suggest that the neonatal guinea pig can maintain tissue glutathione status during periods of nutrient stress, through an increased capacity for recycling oxidized glutathione and a decrease in turnover of the tripeptide. Guinea pig neonates are therefore able to resist starvation-induced decreases in tissue glutathione levels seen in adult rodents. If this is a general neonatal response it may have important clinical implications in the treatment of preterm babies.

Possible Role of Glutathione in Chromium(VI) Metabolism and Toxicity in Rats

The effect of Cr(VI) on liver, kidney, and lung glutathione (GSH) levels and the effect of GSH depletion on Cr(VI)-induced nephrotoxicity were studied in male Sprague-Dawley rats (150-200 g). GSH levels, measured as nonprotein sulfhydryls, were determined between 0.5 and 26 hr after intraperitoneal injection of the maximum non-toxic dose of sodium dichromate (10 mg/kg). While Cr(VI) at this dose did not significantly change hepatic, renal, or pulmonary GSH levels, there appeared to be an initial decrease of hepatic GSH followed by an increase to approximately 120% of control between 5 and 12.5 hr after Cr(VI) treatment. The increase in hepatic GSH levels was significant 5 hr after treatment with 20 mg/kg sodium dichromate, was manifested as an increase in both non-protein sulfhydryls and total glutathione, and was prevented by L-buthionine sulfoximine (BSO) pretreatment. In rats pretreated with 4.0 mmol/kg BSO to deplete GSH, subsequent treatment with Cr(VI) further reduced hepatic GSH levels 2 hr after Cr(VI) treatment and inhibited weight gain in the first 24 hr after treatment. Intraperitoneal injection of Cr(VI) did not inhibit hepatic glutathione reductase activity, even at toxic doses. Depletion of renal GSH to approximately 25% of control with BSO potentiated the acute nephrotoxicity of 30 mg/kg sodium dichromate as measured by serum urea nitrogen levels and relative kidney weight. However, GSH depletion with BSO did not appear to affect the incidence of glucosuria, haematuria, or lysozymuria over a range of Cr(VI) doses, nor did it affect renal uptake of Cr. Taken together, these data show that GSH protects against the acute nephrotoxicity of Cr(VI), although it is not clear whether GSH is directly involved in the intracellular metabolism of Cr(VI) at non-toxic doses.

Pulmonary Toxicity of Thioureas in the Rat

Administration of alpha-naphthylthiourea (ANTU) to rats causes damage to pulmonary endothelial cells and possibly mesothelial lining cells that together may account for the massive pleural effusion characteristic of thiourea toxicity. Using 35S-thiourea as a model compound, the extent of binding of 35S to lung proteins correlated well with the extent of edema, suggesting that the extent of binding of thiourea metabolites is a measure of lung toxicity. ANTU and phenylthiourea (PTU) compete for 35S binding to lung slices, suggesting that these toxins may act in a similar way. Binding of 35S in lung slices from resistant rats is much less than in controls, and resistance cannot be explained by differences in either whole body metabolism or redistribution of thiourea in vivo. Lung glutathione levels (in vitro and in vivo) in normal and resistant rats following thiourea administration were essentially the same. However, at doses of thiourea that cause pleural effusion, there was an increase in total lung glutathione.

Pulmonary toxicity of thioureas in the rat.

Administration of alpha-naphthylthiourea (ANTU) to rats causes damage to pulmonary endothelial cells and possibly mesothelial lining cells that together may account for the massive pleural effusion characteristic of thiourea toxicity. Using 35S-thiourea as a model compound, the extent of binding of 35S to lung proteins correlated well with the extent of edema, suggesting that the extent of binding of thiourea metabolites is a measure of lung toxicity. ANTU and phenylthiourea (PTU) compete for 35S binding to lung slices, suggesting that these toxins may act in a similar way. Binding of 35S in lung slices from resistant rats is much less than in controls, and resistance cannot be explained by differences in either whole body metabolism or redistribution of thiourea in vivo. Lung glutathione levels (in vitro and in vivo) in normal and resistant rats following thiourea administration were essentially the same. However, at doses of thiourea that cause pleural effusion, there was an increase in total lung glutathione.