Lipid peroxidation inhibition reduces NF-kappaB activation and attenuates cerulein-induced pancreatitis

Increased lipid peroxidation, enhanced nuclear factor kappa-B (NF-kappaB) activation and augmented tumor necrosis factor-alpha (TNF-alpha) production have been implicated in cerulein-induced pancreatitis. We investigated whether lipid peroxidation inhibition might reduce NF-kappaB activation and the inflammatory response in cerulein-induced pancreatitis. Male Sprague-Dawley rats of 230-250g body weight received administration of cerulein (80 microg/kg s.c. for each of four injections at hourly intervals). A control group received four s.c. injections of 0.9% saline at hourly intervals. Animals were randomized to receive either raxofelast, an inhibitor of lipid peroxidation (20 mg/kg i.p. administered with the first cerulein injection) or its vehicle (1 ml/kg of a 10% DMSO/NaCl solution). All these rats were sacrificed 2 h after the last injection of either cerulein or its vehicle. Raxofelast administration (20 mg/kg i.p. with the first cerulein) significantly reduced malondialdehyde (MDA) levels, an index of lipid peroxidation (CER + DMSO = 3.075 +/- 0.54 micromol/g; CER + raxofelast = 0.693 +/- 0.18 micromol/g; p < 0.001), decreased myeloperoxidase (MPO) activity (CER + DMSO = 22.2 +/- 3.54 mU/g; CER + raxofelast = 9.07 +/- 2.05 mU/g, p < 0.01), increased glutathione levels (GSH) (CER + DMSO = 5.21 +/- 1.79 micromol/g; CER + raxofelast = 15.71 +/- 2.14 micronol/g; p < 0.001), and reduced acinar cell damage evaluated by means of histology and serum levels of both amylase (CER + DMSO = 4063 +/- 707.9 U/l; CER + raxofelast = 1198 +/- 214.4 U/l; p < 0.001), and lipase (CER + DMSO = 1654 +/- 330 U/l; CER + raxofelast = 386 +/- 118.2 U/l; p < 0.001), Furthermore, raxofelast reduced pancreatic NF-kappaB activation and the TNF-alpha mRNA levels and tissue content of mature protein in the pancreas. Indeed, lipid peroxidation inhibition might be considered a potential therapeutic approach to prevent the severe damage in acute pancreatitis.     

Protective effect of L-carnitine on renal ischaemia-reperfusion injury in the rat

This study was designed to investigate the effect of L-carnitine in ischaemia and reperfusion of the rat kidney. Rats were randomly allocated into three groups. Group I (control group; n = 6) received no treatment. Group II (isotonic saline group; n = 6), received 2 ml of isotonic saline 15 min before the renal ischaemia, and group III (carnitine group; n = 6) received L-carnitine hydrochloride (100 mg kg(-1)) intraperitoneally. At the end of the reperfusion period, rats were sacrificed. Tissue malondialdehyde level (MDA), myeloperoxidase (MPO) activity, and nitrite/nitrate (NO) level of renal tissue were measured to evaluate the lipid peroxidation, neutrophil function, and nitric oxide metabolism, respectively. The tissue levels of MDA, MPO and NO were lower in group III (71.8 +/- 8.4, 172.1 +/- 27.4 U g(-1) tissue, 76.3 +/- 29.7 micromol l(-1) respectively) than levels in groups I (103.4 +/- 13.4 nmol g(-1), 325.9 +/- 20.2 U g(-1) tissue, 144.5 +/- 39.2 micromol l(-1), respectively) and II (103.5 +/- 11.4 nmol g(-1), 317.1 +/- 41.5 U g(-1) tissue, 148.9 +/- 23.9 micromol l(-1), respectively). It is shown that carnitine protects kidney tissue against ischaemia-reperfusion injury.     

Octreotide ameliorates alendronate-induced gastric injury

Alendronate causes serious gastrointestinal adverse effects. The aim of this study was to investigate whether octreotide, a synthetic somatostatin analogue, improves the alendronate-induced gastric injury. Rats were administered 20mg/kg alendronate by gavage for 4 days, either alone or following treatment with octreotide (0.1 ng/kg, i.p.). On the last day, following drug administration, pilor ligation was performed and 2h later, rats were killed and stomachs were removed. Gastric acidity and tissue ulcer index values, lipid peroxidation (as assessed by malondialdehyde, MDA) and glutathione (GSH) levels, myeloperoxidase (MPO) activity as well as the histologic appearance of the stomach tissues were determined. Chronic oral administration of alendronate induced significant gastric damage, increasing lipid peroxidation (37.1+/-3.2 nmol/g) and myeloperoxidase activity (57.6+/-3.7 U/g), while tissue glutathione levels (09.+/-0.1 micromol/g) decreased. Treatment with octreotide prevented this damage as well as the changes in biochemical parameters (MDA: 23.4+/-1.3 nmol/g; MPO: 31.68 U/g; GSH: 15.+/-0.1 micromol/g). Findings of the present study suggest that alendronate induces oxidative gastric damage by a local irritant effect, and that octreotide ameliorates this damage by inhibiting neutrophil infiltration and reducing lipid peroxidation. Therefore, its therapeutic role as a "ulcer healing" agent must be further elucidated in alendronate-induced gastric mucosal injury.     

Levetiracetam protects against kainic acid-induced toxicity

We investigated the Levetiracetam (LVT) ability to protect the brain against kainic acid (KA) induced neurotoxicity. Brain injury was induced by intraperitoneal administration of KA (10 mg/kg). Sham brain injury rats were used as controls. Animals were randomized to receive either LVT (50 mg/kg) or its vehicle (1 ml/kg) 30 min. before KA administration. Animals were sacrificed 6 hours after KA injection to measure brain malonildialdehyde (MDA), glutathione levels (GSH) and the mRNA for interleukin-1beta (IL-1beta) in the cortex and in the diencephalon. Behavioral changes were also monitored. Intraperitoneal administration of LVT decreased significantly MDA in the cortex (KA + vehicle = 0.25 +/- 0.03 nmol/mg protein; KA + LVT = 0.13 +/- 0.01 nmol/mg protein; P < 0.005), and in the diencephalons (KA + vehicle = 1,01 +/- 0.2 nmol/mg protein; KA + LVT = 0,33 +/- 0,08 nmol/mg protein; P < 0.005), prevented the brain loss of GSH in both cortex (KA + vehicle = 5 +/- 1 micromol/g protein; KA + LVT = 15 +/- 2 micromol/g protein; P < 0.005) and diencephalons (KA + vehicle = 9 +/- 0.8 micromol/g protein; KA + LVT = 13 +/- 0.3 micromol/g protein; P < 0.05), reduced brain IL-1beta mRNA and markedly controlled seizures. Histological analysis showed a reduction of cell damage in LVT treated samples. The present data indicate that LVT displays neuro-protective effects against KA induced brain toxicity and suggest that these effects are mediated, at least in part, by inhibition of lipid peroxidation.     

The effects of Maras powder (smokeless tobacco) on oxidative stress in users

Maras Powder (MP) is a special kind of smokeless tobacco widely used in the southeast region of Turkey especially in Kahramanmaras and Gaziantep and other southeastern cities. It is obtained from a tobacco species, Nicotiana rustica L and ash of oak or grapevine wood. Tobacco may increase oxidative stress, which is related to the products of the oxygen metabolism taking place in all cells. Cellular antioxidants, e.g. catalase (CAT), superoxide dismutase (SOD) and glucose 6-phosphate dehydrogenase (G6PD) protect the cell against oxidative damage. An imbalance between the ROS and antioxidants in favour of ROS is described as oxidative stress. In this study, we aimed to investigate the effect of MP on antioxidant enzyme levels and lipid peroxidation. We measured malondialdehyde (MDA), CAT, SOD and G6PD levels in blood of 68 MP users and 30 healthy controls who did not use MP. CAT, SOD and G6PD levels were lower in MP users than in the controls. On the other hand, lipid peroxidation levels (MDA), one of the best indicators of cytological damage, was increased in MP users compared with the controls. The present study showed that MP increases oxidative stress, which may cause many systemic disorders, including arteriosclerosis.     

A comparative study on lipid peroxidation, activities of antioxidant enzymes and viability of cattle and buffalo bull spermatozoa during storage at refrigeration temperature

A comparative study was conducted to monitor the activities of some antioxidant enzymes, lipid peroxidation and viability of cattle and buffalo bull spermatozoa during storage of semen at refrigeration temperature over a period of 72 h. Semen samples, collected from six cross bred cattle bulls (group I) and six Murrah buffalo bulls (group II), were diluted in egg-yolk-citrate and the spermatozoa were separated from seminal plasma by centrifugation at 4 degrees C in a refrigerated centrifuge. The malondialdehyde (MDA) production in group I increased from 1.17+/-0.29 at 0 h to 7.50+/-0.52 nmol/10(8)spermatozoa after 72 h of storage while in group II it increased from 1.99+/-0.26 to 8.70+/-0.10 nmol/10(8)spermatozoa in the same period. However, buffalo bull spermatozoa had a significantly higher (p<0.05) lipid peroxidation at 0 h as well as at 12, 24 and 48 h (p<0.01) periods. The activities of antioxidant enzymes viz. SOD, GPx and G6PD in both the groups showed a similar pattern of change i.e. the activities declined successively in spermatozoa and increased in the seminal plasma. However, the activities of these three enzymes remained significantly higher in the cattle bull spermatozoa than that in buffalo bull spermatozoa. Amount of MDA produced in spermatozoa of both the groups was negatively correlated while SOD, GPx and G6PD activities in spermatozoa were positively correlated to the motility and viability of spermatozoa. Sperm motility as well as viability was significantly less (p<0.05) in group II than that in group I. SOD, GPx and G6PD activities in spermatozoa of both the groups were negatively correlated to lipid peroxidation of spermatozoa cell membrane. The results showed that the less activities of antioxidant enzymes in buffalo bull spermatozoa was due to higher lipid peroxidation that indicated that they were more prone to oxidative stress as compared to cattle bull spermatozoa when stored at refrigeration temperature.     

Effect of thinner inhalation on lipid peroxidation and some antioxidant enzymes of people working with paint thinner

Paint thinner is a commonly used industrial solvent with considerable potential for abuse by inhalation. Paint thinner is taken into the body by inhalation or by contact with the skin. Paint thinner is oxidized gradually by cytochrome P450-dependent monooxygenase and consequently free radicals are produced. In the present study we measured plasma malondialdehyde (MDA, a product of lipid peroxidation) levels as an indicator of oxidative damage and activity levels of antioxidant enzymes gluthatione peroxidase (GSH-Px) and superoxide dismutase (SOD) in erythrocytes of a group of people (n = 18) working with paint thinner. The control group was composed of 18 healthy adults. There was a statistically significant (p < 0.001) increase in MDA (2.0+/-0.7 nmol ml(-1)) and GSH-Px (86.5+/-16.6 U g(-1) Hb) activity levels in people working with paint thinner compared with control subjects (MDA: 1.0+/-0.3 nmol ml(-1); GSH-Px: 53.9+/-14.5 U g(-1) Hb). Similarly, there was also an increase (p < 0.05) in the SOD levels (1079+/-214.6 U g(-1) Hb) of people working with paint thinner compared with controls (953.3+/-46.7 U g(-1) Hb). Based on our results, it can be concluded that paint thinner inhalation may increase lipid peroxidation and consequently induce antioxidant enzymes.     

Absent effect of zinc deficiency on the oxidative stress of erythrocytes in chronic uremic rats

Both anemia and zinc deficiency are commonly observed in patients with chronic uremia. Oxidative stress of red blood cells (RBC) has been suggested to participate in the development of anemia in these patients with chronic uremia due to reduced life span of RBC. Whether zinc deficiency aggravates the effect of oxidative stress on RBC of chronic uremia is still not understood. We thus performed the study to determine the influence of zinc deficiency on the oxidative stress of RBC in uremic rats. Zinc deficiency was induced by long-term dietary zinc deficiency. Five-sixth nephrectomy (5/6 Nx) was used to produce chronic uremia. Experiment was carried out in the following five groups: normal control (NL), chronic uremia (Nx), chronic uremia + dietary zinc deficiency (Nx-D), Nx-D + zinc supplement (Nx-DZ) and Chronic uremia + pair-fed (Nx-PF). Osmotic fragility and lipid peroxidation of RBC were used to evaluate the oxidative stress of RBC. Five weeks after 5/6 nephrectomy (Nx), 5/6 Nx rats present a syndrome of uremia to elevate the levels of plasma creatinine and urea, and reduce the level of plasma zinc (1.12 +/- 0.08 vs 1.35 +/- 0.05 ug/ml). But they does not find to produce anemia and to increase osmotic fragility and lipid peroxidation in RBC. Dietary zinc deficiency in Nx-D group produced severe anorexia and reduced plasma zinc and selenium levels and the activity of RBC-GPX. Yet in Nx-D rats, osmotic fragility and susceptibility of lipid peroxidation in red cells did not increase, because of the increase of plasma copper level (1.85 +/- 0.3 vs 1.41 +/- 0.05 microg/ml) and RBC-SOD activity (1.95 +/- 0.27 vs 0.78 +/- 0.05 unit/g Hb). Zinc supplement in Nx-D rats (Nx-DZ group) recovered the appetite and normalized the levels of plasma zinc, copper and selenium. Food restriction in 5/6 Nx rats (Nx-PF group) decreased plasma copper level and increased osmotic fragility of RBC and elevated the susceptibility of lipid peroxidation after stressing RBC with H2O2 Because Nx-PF rats presented a lower RBC-SOD activity (0.44 +/- 0.11 vs 0.78 +/- 0.05 unit/g Hb) and a lower plasma copper level. We further found a positive relationship (r=0. 802,p<0.01) between plasma copper level and RBC-SOD activity in normal and uremic rats. This study suggests that RBC-SOD activity may play an important role in preventing RBC oxidative stress. Plasma copper level may be a marker of RBC-SOD activity. We conclude, in chronic uremia, zinc deficiency doses not result in RBC oxidative stress as plasma copper level is normal, but may affect the absorption of intestinal nutrition.     

Serum levels of TNF-alpha,sIL-2R,IL-6, and IL-8 are increased and associated with elevated lipid peroxidation in patients with Behçet's disease

AIM: Behçet''s disease (BD) is asystemic immunoinflammatory disorder and the aetiopathogenesis is to be specified. Cytokines play a role in immune response and in many inflammatory diseases. The aim of this case-control study is to investigate serum pro-inflammatory cytokine tumour necrosis factor (TNF)-alpha, interleukin-1beta (IL-1beta), soluble IL-2 receptor (sIL-2R), IL-6, and chemokine IL-8 levels in patients with BD. We also determined the end product of lipid peroxidation (malondialdehyde (MDA)) in BD patients as an index for oxidative stress. METHODS: A total of 37 patients (19 men, 18 women) with BD (active, n = 17; inactive, n = 20) and 20 age-matched and sex-matched healthy control subjects (11 men, nine women) included in this cross-sectional, blinded study. Serum TNF-alpha, IL-1beta, sIL-2R, IL-6 and IL-8 levels were determined by a spectrophotometer technique using the immulite chemiluminescent immunometric assay. Lipid peroxidation was evaluated by Wasowicz et aL The levels of cytokines and lipid peroxidation in the active period were compared with the inactive period of the disease. Results are expressed as mean +/- standard error. RESULTS: IL-1beta levels were below the detection limits of the assay (< 5 pg/ml) in all samples. Mean levels of MDA (8.1+/-0.7 micromol/l), sIL-2R (800+/-38 U/ml), IL-6 (12.6+/-1.1 pg/ml), IL-8 (7.2+/-0.4 pg/ml), and TNF-alpha (7.9+/-0.5 pg/ml) in active BD patients were significantly higher than those in inactive patients (4.3+/-0.5 micromol/l, p < 0.01; 447+/-16 U/ml, p < 0.001; 8.3+/-0.6 pg/ml, p = 0.006; 5.3+/-0.1 pg/ml, p < 0.001; and 5.1 0.2 pg/ml, p < 0.001; respectively) or control subjects (2.1+/-0.2 micromol/l, p < 0.001; 446+/-20 U/ml, p < 0.001; 6.4+/-0.2 pg/ml, p < 0.001; 5.4+/-0.1 pg/ml, p < 0.001; and 4.7+/-0.1 pg/ml, p < 0.001, respectively). On the contrary, only the mean IL-6 level was significantly different between inactive BD and control subjects (p = 0.02). All acute phase reactants were significantly higher in active BD than in inactive period (for each, p < 0.01). Conclusions: High levels of sIL-2R, IL-6, IL-8 and TNF-alpha indicate the activation of immune system in BD. Serum sIL-2R, IL-6, IL-8 and TNF-alpha seem to be related to disease activity. Increased lipid peroxidation suggests oxidative stress in BD and therefore tissue damage in such patients. Amelioration of clinical manifestations would be envisaged by targeting these cytokines, chemokines and lipid peroxidation with pharmacological agents.     

Prophylactic effects of magnesium and vitamin E in rat spinal cord radiation damage: evaluation based on lipid peroxidation levels

This study investigated the neuroprotective effects of magnesium sulfate prophylaxis and vitamin E prophylaxis in a rat model of spinal cord radiation injury. Groups were subjected to different treatment conditions for 5 days prior to irradiation, and outcomes were evaluated on the basis of lipid peroxidation levels in cord tissue. Four groups of rats were investigated: no radiation/treatment (n = 4), intraperitoneal (i.p.) saline 1 ml/day (n = 6), i.p. vitamin E 100 mg/kg/day (n = 6), and i.p. magnesium sulfate 600 mg/kg/day (n = 6). The thoracic cord of each non-control rat was exposed to 20 Gy radiation in a LINAC system using 6 MV x-rays, and malondialdehyde (MDA) levels (reflecting lipid peroxidation level) were determined 24 hours post-irradiation. The MDA levels in thoracic cord segments from the control rats were used to determine baseline lipid peroxidation. The mean levels in the control, saline-only, vitamin E, and magnesium sulfate groups were 12.12 +/- 0.63, 27.0 +/- 2.81, 17.71 +/- 0.44, and 14.40 +/- 0.47 nmol/mg tissue, respectively. The MDA levels in the saline-only group were significantly higher than baseline, and the levels in the vitamin E group were significantly lower than those in the saline group (P < 0.05 for both). The levels in the magnesium sulfate group were dramatically lower than those in the saline group (P < 0.001). The results indicate that i.p. magnesium sulfate has a marked neuroprotective effect against radiation-induced oxidative stress in the rat spinal cord.     

Adenosine deaminase enzyme activity is increased and negatively correlates with catalase,superoxide dismutase and glutathione peroxidase in patients with Behçet's disease: original contributions/clinical and laboratory investigations

AIM: Behçet''s disease (BD) is an inflammatory vasculitis with immunologic, endothelial and neutrophil alterations. Adenosine deaminase (AD) is a marker of T-cell activation and is related to the production of reactive oxygen species by neutrophils with the production of NO(*), O(2)(*-), H(2)O(2) and OH(*). We reported increased tumour necrosis factor-alpha, soluble interleukin-2 receptor, interleukin-6, interleukin-8 and NO(*) in active BD. As there is a relation between cytokines, T cells and oxidative stress in inflammatory diseases, this study further evaluated: (1) plasma AD activity and its correlation with acute phase reactants; (2) thiobarbituric acid-reactive substances (TBARS) as an indicator for lipid peroxidation; and (3) antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GSHPx) and catalase in patients with BD. The effect of disease activity and correlations between the measured parameters were explored. METHODS: A total of 35 active (n=17) or inactive (n=18) patients with BD (16 men, 19 women) satisfying International Study Group criteria, and 20 age-matched and sex-matched controls (nine men, 11 women) were included in this cross-sectional case-control study. AD and TBARS were measured in plasma, catalase in red blood cells (RBC), and SOD and GSHPx in both plasma and RBC in both groups. Acute phase reactants (alpha(1)-antitrypsin, alpha(2)-macroglobulin, neutrophils, erythrocyte sedimentation rate) were used to classify patients as active or inactive. RESULTS: Plasma AD (mean+/-standard error of the mean, 36.1+/-0.7 U/l) and TBARS (4.2+/-0.1 nmol/ml) levels were significantly (for each, p<0.001) higher in BD than in controls (24.1+/-0.8 U/l and 1.6+/-0.1 nmol/ml, respectively). RBC catalase activity was significantly (p<0.001) lower in BD than in controls (120.9+/-3.8 versus 160.3+/-4.1 k/g haemoglobin). SOD and GSHPx activities were significantly lower in both plasma and erythrocytes of patients with BD than in controls (plasma SOD, 442.4+/-8.6 versus 636.4+/-9.2 U/ml, p<0.001; RBC SOD, 3719.2+/-66.0 versus 4849.7+/-49.0 U/g haemoglobin, p<0.001; plasma GSHPx, 73.1+/-1.5 versus 90.6+/-2.9 U/ml, p<0.001; RBC GSHPx, 600.7+/-8.0 versus 670.6+/-10.1 U/g haemoglobin, p<0.001). Active BD patients had significantly lower antioxidant enzymes (except RBC catalase) and higher AD and TBARS levels than inactive subjects (for each, p<0.01). When considering all BD patients, a significant positive correlation was present between AD and TBARS (p<0.001) whereas both AD and TBARS were negatively correlated with antioxidant enzymes (for each, p<0.05). CONCLUSIONS: AD and lipid peroxidation are increased and associated with defective antioxidants in BD, suggesting interactions between activated T cells and neutrophil hyperfunction. Measures of pro-oxidative stress and antioxidative defence with AD activity as an indicator of T-cell activation can be considered as significant supportive diagnostic indicators, especially in active disease. In addition, strengthening the antioxidant defence may contribute to treatment modalities.     

Combined effects of 2,4-D and azinphosmethyl on antioxidant enzymes and lipid peroxidation in liver of Oreochromis niloticus

This study aims to investigate the effects of the herbicide 2,4-D and the insecticide azinphosmethyl on hepatic antioxidant enzyme activities and lipid peroxidation in tilapia. Fish were exposed to 27 ppm 2,4-D, 0.03 ppm azinphosmethyl and to a mixture of both for 24, 48, 72 and 96 h. Activities of catalase (EC 1.11.1.6), glutathione-S-transferase (GST, EC 2.5.1.18) and the level of malondialdehyde (MDA) in the liver of Oreochromis niloticus exposed to 2,4-D and azinphosmethyl, both individually and in combination, were not affected by the pesticide exposures. However, glucose-6-phosphate dehydrogenase (G6PD, EC 1.1.1.49) and glutathione reductase (GR, EC 1.6.4.2) activities in individual and combined treatments, increased significantly compared to controls. Furthermore, glutathione peroxidase (GPx, EC 1.11.1.9) activity increased in individual treatment, while the same enzyme activity decreased in combination. 2,4-D did not affect the activity of superoxide dismutase (SOD, EC 1.15.1.1), but the activity of this enzyme in azinphosmethyl treatment decreased, while its activity increased in combination. Combined treatment of the pesticides exerted synergistic effects in the activity of SOD, while antagonistic effects were found in the activities of G6PD, GPx, GR. The results indicate that O. niloticus resisted oxidative stress by antioxidant mechanisms and prevented increases in lipid peroxidation.     

Effect of acetaminophen on heme metabolism in rat liver

BACKGROUND AND AIMS: Acetaminophen (APAP) or paracetamol is a hepatotoxic drug through mechanisms involving oxidative stress. To know whether mammalian cells possess inducible pathways for antioxidant defense, we have to study the relationship between heme metabolism and oxidative stress. METHODS: fasted female Wistar rats received a single injection of APAP (3.3 mmol kg(-1) body weight) and then were killed at different times. Heme oxygenase-1 (HO), delta-aminolevulinic acid (ALA) synthase, ALA dehydratase, and porphobilinogenase activities, lipid peroxidation, GSH, catalase and glutathione peroxidase, were measured in liver homogenates. The antioxidant properties of bilirubin and S-adenosyl-L-methionine were also evaluated. RESULTS: APAP increased lipid peroxidation (115% +/- 6; S.E.M., n=12 over control values) 1 h after treatment. GSH reached a minimum at 3 h (38% +/- 5) increasing thereafter. At the same time antioxidant enzymes reached minimum values (catalase, 5. 6 +/- 0.4 pmol mg(-1) protein, glutathione peroxidase, 0.101 +/- 0.006 U mg(-1) protein). HO induction was observed 6 h after treatment reaching a maximum value of 2.56 +/- 0.12 U mg(-1) protein 15 after injection. ALA synthase (ALA-S) induction occurred after enhancement of HO, reaching a maximum at 18 h (three-fold the control). ALA dehydratase activity was first inhibited (31 +/- 3%) showing a profile similar to that of GSH, while porphobilinogenase activity was not modified along the whole period of the assay. Administration of bilirubin (5 micromol kg(-1) body weight) or S-adenosyl L-methionine (46 micromol kg(-1) body weight) 2 h before APAP treatment entirely prevented the increase in malondialdehyde (MDA) content, the decrease in GSH levels as well as HO and ALA-S induction. CONCLUSION: This study shows that oxidative stress produced by APAP leads to increase in ALA-S and HO activities, indicating that toxic doses of APAP affect both heme biosynthesis and degradation.     

Lipid peroxidation and antioxidant enzymatic systems in rat retina as a function of age

In the present study, we have assayed the enzymatic activity of Cu,Zn–SOD, Mn–SOD, GSH–Px, GSH-Red, Cat, and G6PD in rat retina as a function of age. Conjugated diene levels and MDA formation were also determined. The conjugated diene levels in rat retina were found to increase significantly with age, accompanied by a marked decrease in GSH–Px and Cat activities. No agerelated change in MDA levels and in GSH-Red and G6PD activity was found, whereas a significant increase in SOD activity was observed between 1 and 4 months. Decreased GSH–Px and Cat activity is related to increased lipid peroxidation with age.     

Evaluation of oxidative stress in patients with cancer

The oxidative stress is considered to be involved in the pathophysiology of cancers. In the current study we explored the oxidative stress in patients with different cancers and corresponding benign diseases by evaluation of the level of lipid peroxidation products (MDA level) in the plasma and the activity of erythrocyte antioxidant defense enzymes superoxide dismutase (SOD) and catalase (CAT). Significantly higher plasma levels of lipid peroxidation products were detected in patients with early and advanced cancers in comparison to the healthy volunteers (mean 3.1 micromol/l and 2.3 micromol/l, p = 0.0003 and p = 0.029, respectively, t-test). In addition, 10-20 days after radical operations of cancer patients with normal postoperative recovery period, the plasma levels of MDA decreased and reached values close to the controls (mean 2.0 micromol/l). SOD in erythrocytes of patients with benign diseases and malignant solid tumors before and after surgery did not differ from that of the controls. In contrast, CAT activity of patients with early cancers was found to be significant higher than that of the controls (mean 22157.2 U/gHb vs. 12832.0 U/gHb, p = 0.032, t-test). A decrease of CAT activity was observed after surgery (mean 15225.0 U/gHb). In conclusion, our results suggest the presence of an increased oxidative stress accompanied by a lack of changes of erythrocyte SOD activity and an adaptive increase of CAT activity.     

Role of hexokinase in the regulation of erythrocyte hexose monophosphate pathway under oxidative stress

Human erythrocytes overloaded with homogeneous human hexokinase (up to 15-times the activity of normal RBC) show almost unmodified rates of glucose metabolized in the HMP, however hexokinase-loaded RBC are able to metabolize 1.5 fold more glucose than controls through the HMP when an oxidizing agent like methylene blue (5 to 100 microM) is present. Similarly, RBC loaded with inactivating anti-hexokinase IgG (12 +/- 3% residual hexokinase activity) show HMP rates unchanged under resting conditions, but only 12% of the HMP rate found in normal controls under oxidative stress. These data provide clear evidence that the HMP rate under conditions of oxidative stress is controlled by hexokinase activity and suggest that RBC from patients with hexokinase deficiency are not able to increase the HMP rate under oxidative stress like erythrocytes from individuals with G6PD deficiency.     

Relationship between the rate of erythrocyte hexose monophosphate pathway and the glucose 6-phosphate concentration

Erythrocytes of individuals with increased (+ 50%) or reduced (-35%) hexokinase activity contain respectively 70 and 17 nmole/ml RBC of glucose-6-phosphate (normal concentration 30 +/- 5nmole/ml RBC) and show comparable rates of the HMP (60 +/- 5nmole/hr/ml RBC). Similarly, in RBC of different ages, obtained by density gradient ultracentrifugation, the glucose-6-phosphate concentration range from 57 (young cells) to 18 (old cells) nmole/ml RBC but the rate at which glucose is utilized in the HMP is unchanged. These data exclude a regulatory role of glucose 6-phosphate in the HMP even if its concentration is under that required for maximal G6PD activity.     

Malathion-induced oxidative stress in a parasitoid wasp: effect on adult emergence, longevity, fecundity, and oxidative and antioxidative response of Pimpla turionellae (Hymenoptera: Ichneumonidae)

Effects of an organophosphorus insecticide, malathion, on survivorship and lipid peroxidation of the greater wax moth, Galleria mellonella (L.), pupae were investigated by rearing the newly hatched larvae on an artificial diet containing 0.01, 0.1, 1, 10, and 100 ppm of the insecticide. As bioindicators of long-term physiological stress responses, the adult emergence rate, longevity, and fecundity associated with lipid peroxidation level and antioxidant enzyme activity in the endoparasitoid Pimpla turionellae (L.) (Hymenoptera: Ichneumonidae) were determined by rearing the parasitoid on a factitious host, G. mellonella pupae treated with malathion. At 100 ppm, malathion significantly decreased pupation rate of G. mellonella larvae and the rate of adult emergence of the parasitoid from these pupae. This concentration resulted in a significant increase in the lipid peroxidation product malondialdehyde (MDA) in both the host and the parasitoid. Malathion at 1 and 10 ppm significantly increased pupation rate and lipid peroxidation level of G. mellonella pupae. The adult emergence rate of P. turionellae was significantly decreased from 63.7 to 20% by these concentrations, whereas MDA content was increased by two- and three-fold, respectively, compared with the control (45.3 +/- 3.2 nmol/ g protein). The longevity of adults was significantly extended from 52.5 +/- 5.7 to 75.7 +/- 6.3 d when the parasitoids emerged from host pupae exposed with 0.1 ppm malathion. At low concentrations (0.01 and 0.1 ppm), malathion significantly increased the number of eggs laid per female per day. However, the lowest concentration (0.01 ppm) had no significant effect on hatchability, whereas 0.1 ppm of the insecticide resulted in significant decrease in egg hatch compared with the control. A significant increase in total superoxide dismutase (SOD) activity for low concentrations of malathion (0.01-1 ppm) was found compared with the control. There was a significant positive correlation of SOD activities with adult longevity and fecundity. This study suggested that malathion-induced oxidative stress was causative factor in the deterioration of biological fitness and that increased SOD activities may have resulted in decreased oxidative damage, which retarded the rate of deteriorative physiological changes in P. turionellae in response to sublethal doses of malathion.     

Effect of Kupffer cell inactivation on ethanol-induced protein adducts in the liver

Tissue deposition of protein adducts derived from ethanol metabolism and lipid peroxidation, has been suggested to play a role in the initiation of alcoholic liver disease. The mechanisms modulating adduct formation have, however, remained unclear. We used immunohistochemical methods to examine acetaldehyde (AA) and malondialdehyde (MDA) adducts and cytochrome P4502E1 and P4503A2 expression in rats after administration of (i) an ethanol-diet (n = 6), (ii) ethanol-diet plus gadolinium chloride (GdCl(3)), a selective Kupffer cell toxicant (n = 7), or (iii) control diet (n = 6). A 4 week ethanol treatment resulted in liver steatosis, necrosis, and inflammation and deposition of protein adducts with both AA and MDA, which colocalized with areas of fatty change. The intensities (mean +/- SD) of the immunohistochemical reactions for both AA (2.50 +/- 1.23) and MDA (3.00 +/- 1.10) adducts were significantly higher in the ethanol-fed animals than in the controls (0.083 +/- 0.20) (0.16 +/- 0.25) (p <.001). GdCl(3) prevented adduct accumulation, the mean immunohistochemistry scores being 0.86 +/- 1.07 for AA and 1.64 +/- 0.63 for MDA, the former showing a more striking reduction (p <.01). The hepatic cytochrome enzymes were not different in the ethanol-fed groups with or without GdCl(3). The data indicates that Kupffer cells are involved in the generation of protein adducts with both acetaldehyde and ethanol-induced lipid peroxidation products in alcoholic liver disease.     

Lipid peroxidation up-regulates BACE1 expression in vivo: a possible early event of amyloidogenesis in Alzheimer's disease

Increased lipid peroxidation is shown to be an early event of Alzheimer's disease (AD). However, it is not clear whether and how increased lipid peroxidation might lead to amyloidogenesis, a hallmark of AD. Glutathione peroxidase 4 (Gpx4) is an essential antioxidant defense enzyme that protects an organism against lipid peroxidation. Gpx4+/- mice show increased lipid peroxidation in brain, as evidenced by their elevated levels of 4-hydroxy-2-nonenal. To understand the role of lipid peroxidation in amyloidogenesis, we studied secretase activities in Gpx4+/- mice as a function of age. Both young (6 months) and middle-aged (17-20 months) Gpx4+/- mice had higher levels of beta-secretase activity than their age-matched wildtype controls, and the increased beta-secretase activity in Gpx4+/- mice was a result of up-regulation of beta-site amyloid precursor protein cleavage enzyme 1 (BACE1) expression at the protein level. The high level of BACE1 protein led to increased endogenous beta-amyloid (Abeta)(1-40) in middle-aged Gpx4+/- mice. We further studied amyloidogenesis in APPGpx4+/- mice. Our data indicate that APPGpx4+/- mice had significantly increased amyloid plaque burdens and increased Abeta(1-40) and Abeta(1-42) levels compared with APPGpx4+/+ mice. Therefore, our results indicate that increased lipid peroxidation leads to increased amyloidogenesis through up-regulation of BACE1 expression in vivo, a mechanism that may be important in pathogenesis of AD at early stages.