Role of lipid peroxidation and antioxidants in gastric mucosal injury induced by the hypoxanthine-xanthine oxidase system in rats

Isolation and characterization of flavonoid compounds from Stachytarpheta jamaicensis (L.) Vahl and its role as anti-gastro ulcerative agent in rats

CONTEXT

Stomach ulcer is one of the most common gastrointestinal problems in the world.

OBJECTIVE

This study aimed to isolate flavonoid compounds from methanol extract of the aerial parts of Stachytarpheta jamaicensis (L.) Vahl. and evaluate its protective and therapeutic effects against gastric ulcer.

MATERIALS AND METHODS

Chromatographic techniques were used for the identification of the isolated compounds. To explore the effects of the plant extract, it was administrated by oral gavage for one week either before or post-ethanol ulcer induction. Ranitidine was also evaluated as a reference drug. Stomach pH, gastric juice volume, lesions number, glutathione, superoxide dismutase, malondialdehyde, succinate dehydrogenase, lactate dehydrogenase, acid phosphatase, Interleukin-10, intracellular adhesion molecule-1, prostaglandin E2, and total protein levels were estimated in gastric tissue. Stomach histopathological features were also monitored.

RESULTS

Six flavonoid compounds were isolated, where five of them were isolated for the first time (vitexin, isovitexin, apigenin 7,4'-dimethyl ether, 5,7,2'-trimethoxyflavone, and scutellarein), while apigenin was previously reported. Treatment with plant extract recorded amelioration in all the biochemical parameters.

CONCLUSION

The methanol extract of plant aerial parts had prophylactic and treatment effects against gastric ulcer in rats, where its treatment effect exceeded its protective role. The extract recorded anti-inflammatory, and antioxidant effects due to the presence of flavonoid compounds.

The investigation of the protective effect of cinnamon water extract and vitamin E on malathion-induced oxidative damage in rats

Pesticides and other agricultural protective chemical products are widely used almost all over the world. It poses a serious threat, especially for public health. Many studies have reported that pesticide poisoning is a major problem in morbidity and mortality. Accordingly, it is aimed to determine the protective properties of the cinnamon extract against oxidative stress caused by malathion used as a pesticide within the scope of this study. In total, 30 Wistar-albino rats have fasted for 24 h. Cinnamon water extract (150 mg/kg), vitamin E, corn oil, and malathion (150 mg/kg) was administered by the oral route. Rats were sacrificed 24 h after administration and stomach and liver tissues were removed. Then, catalase, superoxide dismutase enzyme activities, glutathione, and lipid peroxidation amounts were measured in tissues biochemically. It was determined that the oxidative stress occurring in the malathion-treated group was significantly reduced (P < 0.05) in the applied spice dose and in the positive control vitamin E group. On the other hand, with the application of malathion, it has been determined that catalase and lipid peroxidation levels increase, while superoxide dismutase and glutathione levels decrease. With the measured enzyme activity differences, this spice extract was found to be an oxidative stress reducer. Oxidative stress, which can be determined with oxidative/antioxidant parameters, has been significantly prevented by the applications that do not occur.

Lactobacillus fermentum Suo Attenuates HCl/Ethanol Induced Gastric Injury in Mice through Its Antioxidant Effects

The purpose of the study was to determine the inhibitory effects of Lactobacillus fermentum Suo (LF-Suo) on HCl/ethanol induced gastric injury in ICR (Institute for Cancer Research) mice and explain the mechanism of these effects through the molecular biology activities of LF-Suo. The studied mice were divided into four groups: healthy, injured, LF-Suo-L and LF-Suo-H group. After the LF-Suo intragastric administration, the gastric injury area was reduced compared to the injured group. The serum MOT (motilin), SP (substance P), ET (endothelin) levels of LF-Suo treated mice were lower, and SS (somatostatin), VIP (vasoactive intestinal peptide) levels were higher than the injured group mice. The cytokine IL-6 (interleukin 6), IL-12 (interleukin 12), TNF-α (tumor necrosis factor-α) and IFN-γ (interferon-γ) serum levels were decreased after the LF-Suo treatment. The gastric tissues SOD (superoxide dismutase), GSH-Px (glutathione peroxidase), NO (nitric oxide) and activities of LF-Suo treated mice were increased and MDA (malondialdehyde) activity was decreased compared to the injured group mice. By the RT-PCR assay, LF-Suo raised the occludin, EGF (epidermal growth factor), EGFR (epidermal growth factor receptor), VEGF (vascular endothelial growth factor), Fit-1 (fms-like tyrosine kinase-1), IκB-α (inhibitor kappaB-α), nNOS (neuronal nitric oxide synthase), eNOS (endothelial nitric oxide synthase), Mn-SOD, Cu/Zn-SOD, CAT (catalase) mRNA or protein expressions and reduced the COX-2, NF-κB (nuclear factor kappaB), and iNOS (inducible nitric oxide synthase) expressions in gastric tissues compared to the gastric injured group mice. A high concentration (1.0 × 10⁹ CFU/kg b.w.) of LF-Suo treatment showed stronger anti-gastric injury effects compared to a low concentration of (0.5 × 10⁹ CFU/kg b.w.) of LF-Suo treatment. LF-Suo also showed strong survival in pH 3.0 man-made gastric juice and hydrophobic properties. These results indicate that LF-Suo has potential use as probiotics for its gastric injury treatment effects.

Shuidouchi (Fermented Soybean) Fermented in Different Vessels Attenuates HCl/Ethanol-Induced Gastric Mucosal Injury

Shuidouchi (Natto) is a fermented soy product showing in vivo gastric injury preventive effects. The treatment effects of Shuidouchi fermented in different vessels on HCl/ethanol-induced gastric mucosal injury mice through their antioxidant effect was determined. Shuidouchi contained isoflavones (daidzein and genistein), and GVFS (glass vessel fermented Shuidouchi) had the highest isoflavone levels among Shuidouchi samples fermented in different vessels. After treatment with GVFS, the gastric mucosal injury was reduced as compared to the control mice. The gastric secretion volume (0.47 mL) and pH of gastric juice (3.1) of GVFS treated gastric mucosal injury mice were close to those of ranitidine-treated mice and normal mice. Shuidouchi could decrease serum motilin (MTL), gastrin (Gas) level and increase somatostatin (SS), vasoactive intestinal peptide (VIP) level, and GVFS showed the strongest effects. GVFS showed lower IL-6, IL-12, TNF-α and IFN-γ cytokine levels than other vessel fermented Shuidouchi samples, and these levels were higher than those of ranitidine-treated mice and normal mice. GVFS also had higher superoxide dismutase (SOD), nitric oxide (NO) and malonaldehyde (MDA) contents in gastric tissues than other Shuidouchi samples. Shuidouchi could raise IκB-α, EGF, EGFR, nNOS, eNOS, Mn-SOD, Gu/Zn-SOD, CAT mRNA expressions and reduce NF-κB, COX-2, iNOS expressions as compared to the control mice. GVFS showed the best treatment effects for gastric mucosal injuries, suggesting that glass vessels could be used for Shuidouchi fermentation in functional food manufacturing.

Anti-ulcer activity of essential oil constituents

Essential oils have attracted considerable worldwide attention over the last few decades. These natural products have wide-ranging pharmacological activities and biotechnological applications. Faced with the need to find new anti-ulcer agents and the great effort on the development of drugs for the treatment of ulcers, in this review, the anti-ulcer activities of 21 bioactive compounds found in essential oils are discussed.

Lipid hydroperoxide-derived modification of proteins in gastrointestinal tract

Role of lipid peroxidation in the pathogenesis of gastrointestinal diseases has been evaluated by measuring the tissue levels of lipid peroxides as thiobarbituric acid-reactive substances in the animal models as well as human. Recently, N (ε)-(hexanoyl)lysine (HEL) and 4-hydroxy-2-nonenal (HNE) are recognized as reliable and sensitive biomarkers for the early phase and the late phase of lipid peroxidation, respectively. The presence of HNE- and HEL-modified proteins has been demonstrated in in vivo models of several gastrointestinal diseases. In the present review, we introduced HNE-modification of TRPV1 channel in esophageal epithelial cells, HEL-modification of tropomyosin 1 (TMP1) in gastric cancer cells, and HEL-modification of gastrokine 1 in the healing of gastric ulcer.

Effect of ECQ on Iodoacetamide-Induced Chronic Gastritis in Rats

This study investigated effect of extract containing quercetin-3-O-β-D-glucuronopyranoside from Rumex Aquaticus Herba (ECQ) against chronic gastritis in rats. To produce chronic gastritis, the animals received a daily intra-gastric administration of 0.1 ml of 0.15% iodoacetamide (IA) solution for 7 days. Daily exposure of the gastric mucosa to IA induced both gastric lesions and significant reductions of body weight and food and water intake. These reductions recovered with treatment with ECQ for 7 days. ECQ significantly inhibited the elevation of the malondialdehyde levels and myeloperoxidase activity, which were used as indices of lipid peroxidation and neutrophil infiltration. ECQ recovered the level of glutathione, activity of superoxide dismutase (SOD), and expression of SOD-2. The increased levels of total NO concentration and iNOS expression in the IA-induced chronic gastritis were significantly reduced by treatment with ECQ. These results suggest that the ECQ has a therapeutic effect on chronic gastritis in rats by inhibitory actions on neutrophil infiltration, lipid peroxidation and various steps of reactive oxygen species (ROS) generation.

The effect of thiamine and thiamine pyrophosphate on oxidative liver damage induced in rats with cisplatin

The aim of this study was to investigate the effect of thiamine and thiamine pyrophosphate (TPP) on oxidative stress induced with cisplatin in liver tissue. Rats were divided into four groups; thiamine group (TG), TPP + cisplatin group (TPG), healthy animal group (HG), and cisplatin only group (CG). Oxidant and antioxidant parameters in liver tissue and AST, ALT, and LDH levels in rat sera were measured in all groups. Malondialdehyde levels in the CG, TG, TPG, and HG groups were 11 ± 1.4, 9 ± 0.5, 3 ± 0.5, and 2.2 ± 0.48  μ mol/g protein, respectively. Total glutathione levels were 2 ± 0.7, 2.8 ± 0.4, 7 ± 0.8, and 9 ± 0.6 nmol/g protein, respectively. Levels of 8-OH/Gua, a product of DNA damage, were 2.7 ± 0.4 pmol/L, 2.5 ± 0.5, 1.1 ± 0.3, and 0.9 ± 0.3 pmol/L, respectively. A statistically significant difference was determined in oxidant/antioxidant parameters and AST, ALT, and LDH levels between the TPG and CG groups (P < 0.05). No significant difference was determined between the TG and CG groups (P > 0.05). In conclusion, cisplatin causes oxidative damage in liver tissue. TPP seems to have a preventive effect on oxidative stress in the liver caused by cisplatin.

Protective effect of extract from Rumex aquaticus herba on ethanol-induced gastric damage in rats

BACKGROUND/AIMS

In this study, we investigated the gastroprotective effect of extract including quercetin-3-O-β-D-glucuronopyranoside (EIQ) from Rumex aquaticus herba against the ethanol-induced gastric damage in rats.

METHODS

The rats were divided into eight groups composed of a non-ethanol group, only EIQ (10 mg/kg) group, groups with absolute ethanol after pretreatment with various doses of EIQ (1, 3 and 10 mg/kg), rebamipide (10 mg/kg), stillen (40 mg/kg) and a control receiving only absolute ethanol. Ethanol-induced gastric lesions, lipid peroxidation, neutrophil infiltration and glutathione level were measured. Superoxide dismutase (SOD) and catalase activity were assessed by an assay kit. Protein expression of SOD, catalase or hemoxygenase-1 (HO-1) was assessed by western blotting analysis.

RESULTS AND CONCLUSION

In the absolute ethanol treated group, gastric lesion and malondialdehyde levels were significantly increased with enhanced myeloperoxidase activity. Administration of EIQ 1 h prior to ethanol treatment significantly inhibited the formation of gastric lesions and the elevation of the malondialdehyde levels with myeloperoxidase activity. In addition, pretreatment with EIQ significantly increased the level of glutathione, and elevated the activity and protein expression of radical scavenging enzymes, such as SOD, catalase and HO-1. EIQ may exert anti-inflammatory and anti-oxidative effects against ethanol-induced gastric injury through the reduction of lipid peroxidation, myeloperoxidase activity and free radicals.

Silymarin, an antioxidant bioflavonoid, inhibits experimentally-induced peptic ulcers in rats by dual mechanisms

INTRODUCTION

Antioxidants are reported to have antiulcer activity. We investigated silymarin, a bioflavonoid antioxidant, for antiulcer potential.

MATERIALS AND METHODS

Pylorus-ligated Shay rats (n=5) were used as the experimental gastric ulcer animal model. The rats, separated into three groups, were administrated silymarin (50 mg/kg), omeprazole (3.6 mg/kg), or saline (5 ml/kg) per orally daily for 5 days prior to ulcerogenic challenge. Nineteen hours after the challenge, the rats were sacrificed and their stomachs isolated. Formed gastric juice was collected for measurement of volume, titrimetric estimation of free and total acidity, and total acid output by the conventional methods. The ulcer index was calculated. Total acid output and free and combined acid quantities were calculated using the acidity value and the volume of formed gastric juice.

RESULTS

Silymarin exerted significant (P<.05) antiulcer activity (the ulcer index was reduced to 7.4 ± 1.0 from the control value of 19.8 ± 4.1). Silymarin also significantly reduced free and total acidity, gastric juice volume, total acid output, and combined acid content. The results were analyzed by ANOVA and Newman-Keuls multiple comparison test.

CONCLUSION

This study demonstrates that silymarin has significant antiulcer activity. It perhaps acts by decreasing hydrochloric acid output and increasing buffering power (combined acid).

Effect of acute and chronic administration of progesterone, estrogen, FSH and LH on oxidant and antioxidant parameters in rat gastric tissue

This study was conducted to investigate whether gastro-protective and gastro-toxic effects of acute and chronic administration of progesterone, estrogen, FSH and LH were related to oxidant and antioxidant parameters. Chronic administration of progesterone at a low dose (1mg/kg), which probably could not stimulate progesterone receptors (PRs), inhibited oxidative stress of FSH in gastric tissue by suppressing FSH. Progesterone (5mg/kg) may have been caused oxidative stress as reflected by PR stimulation. FSH may have decreased antioxidant parameters and increased oxidant parameters via PRs. Chronic administration of low dose of estrogen (1mg/kg) inhibited LH and but could not stimulate alpha-2 adrenergic receptors, which resulted in oxidative stress in gastric tissue. The higher dose of estrogen (5mg/kg), however, could stimulate alpha-2 receptors, exhibited antioxidant activity in acute and chronic administration. While antioxidant activity of estrogen and LH was blocked with yohimbine (an alpha-2 adrenergic receptor blocker), mifepristone prevented the oxidative stress of progesterone and FSH in gastric tissue. It is concluded that low doses of progesterone may inhibit FSH, whereas high doses of estrogen may stimulate alpha-2 receptors, suggesting that LH could have protective and antioxidant hormone effects.

Mechanism of action of celecoxib on normal and acid-challenged gastric mucosa

Selective COX-2 inhibitor, celecoxib, delays the healing of gastric ulcers by inhibiting prostaglandins synthesis. Therefore, the effect of celecoxib on normal and acid-challenged gastric mucosa was studied. Wistar rats were distributed into four groups: group-1 (vehicle treated), group-2 (celecoxib treated), group-3 (given 0.6N HCl) and group-4 (HCl+celecoxib treated). The gastric mucosa was assessed histopathologically and by evaluating gastric adherent mucus. To assess the role of oxidative stress, the levels of free radicals and antioxidants were measured. The histopathological examination showed mild inflammation in group-2, moderate inflammation in group-3 and severe inflammation in group-4. The results showed an increase in malondialdehyde and a decrease in gastric adherent mucus, nitrite, reactive thiols and glutathione in groups-2-4 as compared to control group. Activity of superoxide dismutase, catalase and glutathione-s-transferase was increased in all the groups except the group-1. The present study suggested that celecoxib aggravated the gastric damage caused by acid which may be mediated by altering the balance between free radicals and antioxidants.

Artemisia asiatica extracts protect against ethanol-induced injury in gastric mucosa of rats

BACKGROUND AND AIM

Based on our previous studies that Artemisia asiatica extracts exert either antioxidative or cytoprotective actions against non-steroidal anti-inflammatory drugs or Helicobacter pylori-induced gastric mucosal injury, or imposes qualified ulcer healing in an acetic acid-induced gastric ulcer model, we investigated the protective effects of Artemisia asiatica extracts against ethanol-induced gastric mucosal injury.

METHODS

Sprague-Dawley rats received 4 g/kg body weight (BW) of absolute ethanol intragastrically, which produced visible hemorrhagic gastric lesions 60 min later.

RESULTS

In this animal setting, the pretreatment of Artemisia extracts (30 or 100 mg/kg BW), 1 h before ethanol administration, significantly attenuated the source of gastric injury, which was assessed with gross and microscopic analysis (P < 0.01). Protection from alcohol-induced damage with Artemisia pretreatment was associated with significantly decreased lipid peroxidation, protecting gastric mucosa from glutathione depletion, as well as the inhibition of the cytochrome 2E1 ethanol-metabolizing enzyme. It attenuated the expressions of ethanol-induced pro-inflammatory cytokines, including interleukin (IL)-1beta and interferon-gamma, a weak activation of IL-10, the inhibition of the alcohol-induced overexpression of intercellular adhesion molecule-1, and the considerable induction of heat shock protein-72 expression in gastric mucosal homogenates.

CONCLUSION

The data suggest that the ethanol extracts of Artemisia asiatica exerted significant protection from alcohol-induced gastric mucosal injury through bio-regulation, which is essential for cytoprotection and anti-inflammation.

The protective effect of darbepoetin alfa on experimental testicular torsion and detorsion injury

AIM

Testicular torsion is a serious urological emergency, usually involving newborns, children, and adolescents which can lead to subfertility and infertility. Prevention of testicular damage caused by torsion is still a clinical and experimental problem. So far many chemicals and drugs have been investigated for decreasing ischemia/reperfusion (I/R) injury in experimental animals. The possible protective effect of darbepoetin alfa, a novel erythropoietic protein, on testicular tissue after I/R injury was examined in this study.

METHODS

Thirty rats were divided into three groups: sham operation, torsion/detorsion, and torsion/detorsion plus darbepoetin alfa groups. After torsion (2 hours) and detorsion (4 hours), bilateral orchiectomy was performed. Malondialdehyde, nitric oxide and glutathione levels were determined in testicular tissue.

RESULTS

Administration of darbepoetin alfa caused a decrease of malondialdehyde and nitric oxide levels and an increase in glutathione levels compared with the torsion/detorsion group. In addition, histological injury scores were significantly decreased in the treatment group more than the torsion/detorsion group.

CONCLUSION

The results suggest that darbepoetin alfa may be a potential protective agent for preventing testicular injury caused by testis torsion.

Effects of L-carnitine on neutrophil-mediated ischemia-reperfusion injury in rat stomach

Reactive oxygen metabolites play an important role in ischemia-reperfusion related gastric injury. Primary sources of reactive oxygen metabolites seem to be the xanthine/xanthine oxidase system and neutrophils accumulating within the reperfused tissue. Tissue myeloperoxidase activity is an important index of neutrophil accumulation. The purpose of the present study was to clarify the effect of L-carnitine on the accumulation of neutrophils and neutrophil-induced gastric mucosal damage in rats exposed to ischemia-reperfusion. Rats were randomly divided into three groups: sham-operated, ischemia-reperfusion and ischemia-reperfusion plus L-carnitine groups. Ischemia was induced by clamping the celiac artery for 30 min and then reperfusion was established for 60 min. Gastric injury was assessed by measuring myeloperoxidase activity in gastric tissue. The neutrophil accumulation and hemorrhagic lesions due to ischemia-reperfusion in gastric mucosa were ascertained in a histological study. L-Carnitine (100 mg kg(-1)) administrated intravenously 5 min before ischemia significantly reduced both the gastric injury and myeloperoxidase activity compared with the ischemia-reperfusion group. The results suggest that L-carnitine provides marked protection against ischemia-reperfusion-related gastric injury which could be due to its ability to reduce neutrophil accumulation in ischemic tissue.

The inhibition of gastric mucosal lesion, oxidative stress and neutrophil-infiltration in rats by the lichen constituent diffractaic acid

The antiulcerogenic effect of diffractaic acid (DA) isolated from Usnea longissima, a lichen species, on indomethacin (IND)-induced gastric lesions was investigated in rats. Administration of 25, 50, 100 and 200 mg/kg doses of DA and ranitidine (RAN) (50 mg/kg dose) reduced the gastric lesions by 43.5%, 52.9%, 91.4%, 96.7% and 72.7%, respectively. It is known that oxidative stress leads to tissue injury in organisms. Thus, in all treated groups of rats, the in vivo activities of the antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and the levels of reduced glutathione (GSH) and lipid peroxidation (LPO) were evaluated. IND caused oxidative stress, which resulted in LPO in tissues, by decreasing the levels of GPx, SOD and GSH as compared to healthy rats. In contrast to IND, the administration of DA and RAN showed a significant decrease in LPO level and an increase in tissue SOD, GPx and GSH levels. However, while CAT activity was significantly increased by the administration of IND, the administration of DA and RAN decreased CAT activity. The administration of IND also increased the myeloperoxidase (MPx) activity, which shows neutrophil infiltration into the gastric mucosal tissues. In contrast to IND, the administration of DA and RAN decreased MPx activity. The changes in activities of gastric mucosal nitric oxide synthases (NOS) throughout the development of gastric mucosal damage induced by IND were also studied. A decrease in constitutive NOS (cNOS) activity and an increase in inducible NOS (iNOS) activity were determined in gastric damaged tissues induced by IND. The administration of DA (100 mg/kg dose) and RAN reversed the activities of iNOS and cNOS. These results suggest that the gastroprotective effect of DA can be attributed to its enhancing effects on antioxidant defense systems as well as reducing effects of neutrophil infiltration.

Hypoxanthine as a graft ischemia marker stimulates catalase activity in the renal vein during reperfusion in humans

BACKGROUND

The impairment of organ function derived from ischemia-reperfusion injury is still an important problem in solid organ transplantation. Cell alterations induced by ischemia prime the tissue for subsequent damage occurring during the reperfusion phase. Purine nucleotides and oxypurines are products of adenine nucleotide degradation. Reperfusion and reoxygenation are characterized by great production of reactive oxygen species and free radicals. On the contrary, superoxide dismutase, catalase, glutathione, and glutathione peroxidase are involved in protecting against free radicals. The aim of the study was to examine the correlation between concentrations of ischemia markers (hypoxanthine or inosine) and the activity of erythrocyte superoxide dismutase, catalase, or glutathione peroxidase.

PATIENTS AND METHODS

The study included 40 renal transplant recipients. Before anastomosis of the kidney vessels with the recipient's iliac vessels, a "0" blood sample was taken from the iliac vein. Then, after anastomosis, the renal vein of the graft was cannulated and blood samples I, II, and III were obtained. The reperfusion of the transplanted kidney was measured with a thermovision camera ThermaCAM SC500.

RESULTS

The plasma concentrations of hypoxanthine and inosine increased in statistically significant fashion immediately after total tissue reperfusion (P < .0001). Catalase activity at 4 minutes after total tissue reperfusion correlated positively with hypoxanthine concentrations immediately after total tissue reperfusion (Rs = +0.49), 2 minutes after total tissue reperfusion (Rs = +0.47), and 4 minutes after total tissue reperfusion (Rs = +0.46). There were no statistically significant correlations between hypoxanthine or inosine concentrations or superoxide dismutase or glutathione peroxidase activities.

CONCLUSIONS

The results of the present study suggest that catalase activity may correlate with the concentration of hypoxanthine in the graft renal vein and other mediators of oxidative stress.

Gastroprotective and antioxidant effects of usnic acid on indomethacin-induced gastric ulcer in rats

Usnea longissima, a medicinal lichen of Anatolia (Turkey), is used in the treatment of gastric ulcer in local folk medicine. In this paper, the gastroprotective effect of usnic acid (UA) isolated from Usnea longissima was investigated in the indomethacin-induced gastric ulcers in rats at doses of 25, 50, 100 and 200 mg/kg body weight. The gastric lesions were significantly reduced by all doses of UA as compared with the indomethacin (25 mg/kg body weight) treated group. In the stomach tissues of treated animals, the in vivo antioxidant levels were evaluated. The administration of indomethacin caused a significant decrease in the levels of superoxide dismutase (SOD), glutathione peroxidase (GPx) and reduced glutathione (GSH), and an increase in the lipid peroxidation (LPO) level (p < 0.05). The administration of all doses of UA reversed the trend, inducing a significant increase of SOD, GSH and GPx levels and a reduction in LPO level in tissues. However, catalase (CAT), glutathione reductase (GR) and myeloperoxidase (MPx) activities, increased by indomethacin, were found to be lower in the UA- and ranitidine-treated groups. The gastric mucosal constitutive NO synthase (cNOS) and inducible NO synthase (iNOS) activities were also investigated in tissues of UA- (100 mg/kg), ranitidine- (50 mg/kg) and indomethacin-treated rat groups. The administration of UA and ranitidine increased the cNOS activity and lowered the iNOS activity as compared with indomethacin-treated group. These results suggest that the gastroprotective effect of UA can be attributed to its reducing effect on the oxidative damage and neutrophil infiltration in tissues.

Effects of water extract of Usnea longissima on antioxidant enzyme activity and mucosal damage caused by indomethacin in rats

In this study, the antiulcerogenic effect of a water extract obtained from the lichen species Usnea longissima was investigated using indomethacin-induced ulcer models in rats. Experimental groups consisted of six rats. Antiulcerogenic activities of 50, 100 and 200mg/kg body wt. doses of the water extract were determined by comparing the negative (treated only with indomethacin) and positive (ranitidine) control groups. Although all doses of the water extract of U. longissima showed significant antiulcerogenic activity as compared to negative control groups, the highest activity was observed with 100 mg/kg body wt. doses (79.8%). The water extract of U. longissima showed moderate antioxidant activity when compared with trolox and ascorbic acids used as positive antioxidants. In addition, the activities of antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST)] were determined in the stomach tissues of rats and compared with those of the negative and positive control groups to expose the effects of antioxidant enzymes on antiulcerogenic activity. SOD and GST enzymes activities in indomethacin-administrated tissues were reduced significantly by indomethacin in comparison to control groups. These enzymes were activated, however, by the water extracts of U. longissima. In contrast to SOD and GST activities, CAT activity was increased by indomethacin and reduced by all doses of U. longissima and ranitidine. The present results indicate that the water extract of U. longissima has a protective effect in indomethacin-induced ulcers, which can be attributed to its antioxidant potential.

Effects of D-002, a product isolated from beeswax, on gastric symptoms of patients with osteoarthritis treated with piroxicam: a pilot study

Non-steroidal anti-inflammatory drugs (NSAIDs) are indicated for treatment of rheumatoid arthritis and osteoarthritis, but often induce gastric adverse experiences (AE), including gastric ulcers and complications. Inhibitors of proton pump and H(2) antagonists are very effective for duodenal ulcer; meanwhile, cytoprotective drugs are more effective for gastric ulcer. D-002 is a mixture of higher aliphatic alcohols obtained from beeswax, wherein triacontanol is the most abundant. D-002 induces anti-ulcer effects through a cytoprotective mechanism, being more effective in protecting against ethanol- and NSAID-induced ulcers. The present double-blind, placebo-controlled clinical study was undertaken to investigate the effects of D-002 on gastric symptoms associated to piroxicam use on patients suffering osteoarthritis. Fifty-nine patients, all taking piroxicam, 20 mg/day, were randomized to placebo or D-002 (40 or 100 mg/day) for 14 days. The primary efficacy variable was the reduction on the frequency of patients with gastric AE compared with placebo. Pain evolution was investigated to discard any influence on D-002 on the analgesic effect of piroxicam. The frequency of patients treated with D-002, 40 and 100 mg/day, reporting acidity [0 of 18 (0%) and 1 of 21 (4.8%), respectively] was lower (P < .05) than in placebo [6 of 20 (30%)]. Also, the frequency of patients treated with 100 mg/day reporting some gastric AE [5 of 21 (23.8%)] was lower (P < .05) than in placebo [13 of 20 (65.0%)]. The analgesic effect of piroxicam was unaffected with D-002. Treatment was well tolerated. Two patients discontinued from the study because of gastrointestinal AE: one in the placebo group and the other treated with D-002, 40 mg/day. Other three patients discontinued because of other AE: mildly uncontrolled hypertension (one in the placebo group, one treated with D-002, 40 mg/day) and headache (one treated with D-200, 100 mg/day). It is concluded that D-002 could be useful for controlling gastric AE of patients treated with NSAIDs, although further studies with a larger sample size and longer follow-up are needed for definitive conclusions.

A PPAR-gamma ligand, 15-deoxy-Delta12,14-prostaglandin J(2), inhibited gastric mucosal injury induced by ischemia-reperfusion in rats

INTRODUCTION

Recent studies have demonstrated the anti-inflammatory action of 15-deoxy-Delta12,14-prostaglandin J(2) (15d-PGJ(2)), a derivative of the PGD(2) metabolic pathway. Acute inflammation, including neutrophil activation, plays a critical role in the pathogenesis of ischemia-reperfusion (I/R). The aim of the present study was to determine the effect of 15d-PGJ(2) on I/R-induced gastric mucosal injury in rats.

METHODS

Gastric mucosal damage was induced in male Wistar rats by clamping the celiac artery for 30 min followed by reperfusion. 15d-PGJ(2) (0.01-1.0 mg/kg) was given to the rats intraperitoneally 1 h before the vascular clamping. The area of gastric mucosal erosions (erosion index) was measured. Thiobarbituric acid reactive substances (TBARS) and tissue-associated myeloperoxidase (MPO) activity were measured in the gastric mucosa as indices of lipid peroxidation and neutrophil infiltration. The expression of tumor necrosis factor-alpha (TNF-alpha) in gastric mucosa was measured by ELISA. In addition, to elucidate whether the protective effects of 15d-PGJ(2) are related to the activation of the PPAR-gamma receptor, we also investigated the effects of a PPAR-gamma antagonist, GW9662.

RESULTS

After 60 min of reperfusion, the area of gastric erosion index had significantly increased from the mean basal levels. The increase in the erosion index was significantly inhibited by pretreatment with 15d-PGJ(2) in a dose-dependent manner. On the other hand, GW9662 reversed the protective effect of 15d-PGJ(2). The concentration of TBARS and MPO activity in the gastric mucosa were both significantly increased after I/R, and pretreatment with 15d-PGJ(2) significantly reduced these increases. The TNF-alpha content was significantly higher in the I/R group than in the sham-operated group. However, the increase in TNF-alpha was significantly inhibited by pretreatment with 15d-PGJ(2).

CONCLUSIONS

15d-PGJ(2) significantly inhibited the severity of acute gastric mucosal injury induced by I/R in rats through PPAR-gamma-dependent mechanisms. This effect may be due, in part, to a reduction in the infiltration of neutrophils into the gastric mucosa, possibly via the inhibition of inflammatory cytokine.

Inhibitory effects of DA-9601 on ethanol-induced gastrohemorrhagic lesions and gastric xanthine oxidase activity in rats

The exposure of gastric mucosa to ethanol produces pathological changes such as inflammatory process, hemorrhagic erosions, even acute ulcers. The gastric mucosal lesions accompanied by a significant decrease of gastric blood flow and increase of reactive oxygen species (ROS) implicate a role of xanthine oxidase in ethanol-induced gastric hemorrhagic erosions. DA-9601, a novel antipeptic formulation of extracts of Artemisia asiatica Nakai, was studied for its inhibitory effect on gastric xanthine oxidase activity and type conversion of the enzyme that has a profound role in free radical generation. Intubation of absolute ethanol (4 g/kg) significantly induced gastrohemorrhagic lesions and lipid peroxidation in the rat stomach. Oral administration of DA-9601 at 40 mg/kg body weight significantly reduced ethanol-induced gastric mucosal hemorrhagic lesions and lipid peroxidation, which was proportional to the inhibitory effect of DA-9601 on alcohol-induced xanthine oxidase-type conversion and enzyme activity. The results suggest that alcohol-induced gastric mucosal damage may be, in part, due to the increased activity of xanthine oxidase and type conversion rate of the enzyme and that the preventive effect of DA-9601 on gastrohemorrhagic lesions would result from its inhibitory action against xanthine oxidase and oxidative stress in alcohol-treated rats.

Protective effect of coadministered superoxide dismutase and catalase against stress-induced gastric mucosal lesions

1. There are conflicting reports as to the protective effect of coadministered native superoxide dismutase (SOD) and catalase against gastric mucosal lesions in rats with water immersion restraint (WIR) stress. It is unclear how coadministered native SOD and catalase protect against WIR stress-induced gastric mucosal lesions. Therefore, in the present study, we re-examined the protective effect of coadministered native SOD and catalase against gastric mucosal lesions in rats with WIR stress. 2. Gastric mucosal lesions were induced in Wistar rats by 3 h WIR. Rats were injected subcutaneously with a mixture of purified bovine erythrocyte SOD and bovine liver catalase 1 h before the onset of WIR. Ulcer index, serum SOD, catalase and xanthine oxidase (XO), uric acid and gastric mucosal SOD, catalase, XO, myeloperoxidase (MPO; an index of tissue neutrophil infiltration), non-protein sulfhydryl (NP-SH) and thiobarbituric acid-reactive substances (TBARS; an index of lipid peroxidation) were assayed in all rats used. 3. Rats with 3 h WIR showed gastric mucosal lesions. Pre-administration of SOD plus catalase to rats with WIR prevented lesion formation. In the serum of rats with WIR alone, XO activity and uric acid concentration increased, whereas SOD and catalase activities did not change. Pre-administration of SOD plus catalase to rats with WIR did not affect increased serum XO activity and uric acid concentration, but did increase serum SOD and catalase activities. In the gastric mucosa of rats with WIR alone, increases in MPO activity and TBARS concentration and a decrease in NP-SH concentration occurred, whereas XO, SOD and catalase activities did not change. Pre-administration of SOD plus catalase to rats with WIR attenuated the changes in gastric mucosal MPO activity and TBARS and NP-SH concentrations, but did not affect gastric mucosal XO, SOD and catalase activities. Pre-administration of SOD plus catalase (in an inactivated form) to rats with WIR had no effect on gastric mucosal lesion formation and the levels of serum and gastric mucosal parameters studied. 4. These results indicate that coadministered native SOD and catalase protect against gastric mucosal lesions in rats with WIR stress and suggest that this protective effect of coadministered native SOD and catalase could be due to their activity to scavenge XO-derived active oxygen species that are increased in the blood.

Antioxidant Effect of D-002 on Gastric Mucosa of Rats with Experimentally Induced Injury

D-002 is a natural mixture of higher aliphatic primary alcohols isolated from beeswax that has antioxidant and antiulcer properties. Because the role of lipid peroxidation in gastric damage is well recognized, this work was designed to investigate the possible effect of D-002 on lipid peroxidation in gastric mucosa in two experimental models of gastric injury in rats: (1) gastric ulcer induced by indomethacin and (2) mucosal injury induced by ischemia-reperfusion (I-R). The results demonstrated a remarkable protective effect of D-002 on lipid peroxidation in gastric ulcer induced by indomethacin and a moderate protective effect of D-002 on gastric erosions and lipid peroxidation induced by I-R.

Impact of oral L-glutamine on glutathione, glutamine, and glutamate blood levels in volunteers

OBJECTIVE

We investigated the effect of glutamine supplementation on plasma glutamine (Gln), glutamate (Glu), and whole-blood glutathione (GSH) concentrations in human volunteers.

METHODS

Subjects first adapted to a standard diet with known intakes of protein, total GSH, cysteine, methionine, and total Glu (Glu values include Glu and Gln) for 3 d. Plasma Gln, Glu, and whole-blood GSH levels were then measured at 4-h intervals over 24 h. Supplemental oral Gln (0.3 g x kg(-1) x d(-1)) was ingested for 10 d and then 24-h plasma levels of Gln, Glu, and whole-blood GSH were measured.

RESULTS

The plasma concentrations of Glu (116%; P = 0.006) and Gln (20%; P = 0.046) were significantly higher, whereas concentrations of GSH were significantly lower (37%; P = 0.00091) after oral Gln supplementation.

CONCLUSION

Oral Gln increases Glu and Gln levels in plasma of healthy subjects but does not increase GSH red cell (whole-blood) levels. Thus, GSH biosynthesis and preservation of GHS stores in red blood cells may involve rate-limiting substrates other than Gln.

The protective action of melatonin on indomethacin-induced gastric and testicular oxidative stress in rats

Reactive oxygen species and lipid peroxidation play a role in the pathogenesis induced by the non-steroidal anti-inflammatory drug indomethacin. Melatonin (MLT) protection against indomethacin-induced oxidative tissue injury was investigated in gastric mucosa and testis of rats. MLT was administered intragastrically (i.g.) 30 min before the administration to fasted rats of 20 mg indomethacin/kg rat given i.g.. The area of gastric lesion as well as thiobarbituric acid reactive substances (TBARS) and lactate dehydrogenase (LDH) activity were found to be significantly increased 4 h after administration of indomethacin in rat gastric mucosa and testis indicating acute oxidative injury. MLT pretreatment reduced gastric lesion area to 80% of the indomethacin-treated rats and reduced the rise in TBARS concentration. MLT treatment reduced the LDH activity increase in testis but not in gastric mucosa. In indomethacin-treated rats, both the cytosolic Cu,Zn superoxide dismutase (Cu,Zn-SOD) and mitochondrial Mn-SOD activities were significantly diminished in gastric mucosa as well as the total SOD activity in testis. In addition, glutathione (GSH) content in both tissues was markedly decreased following indomethacin treatment. Pretreatment with MLT significantly ameliorated both the inhibition of SOD activity and the decreased GSH content in both tissues. Thus, these results show the effective antiperoxidative and preventive actions of MLT against indomethacin-induced gastric mucosal damage and testicular oxidative injury and we propose that this action might be relevant for its use with other free radical generating drugs.

Reactive oxygen species activity, mucosal lipoperoxidation and glutathione in Helicobacter pylori-infected gastric mucosa

BACKGROUND AND AIM

Helicobacter pylori is considered as the major pathogen in Helicobacter pylori-associated gastroduodenal disease, but the mechanism of its action has not been fully explained. This study was performed to assess the reactive oxygen species activity and the damage in Helicobacter pylori-infected gastric mucosa.

METHODS

Gastric biopsy specimens were obtained from 308 patients undergoing endoscopy. Gastric mucosal damage was assessed by using luminol enhanced chemiluminescence, thiobarbituric acid-reactive substance, and mucosal glutathione.

RESULTS

The chemiluminescence and thiobarbituric acid-reactive substance-equivalent levels in the mucosa of patients with Helicobacter pylori-positive gastric mucosa (43.8 +/- 134.9 c.p.m./microg tissue, 157.0 +/- 96.2 nmol/g tissue, respectively) were significantly higher than in those with Helicobacter pylori-negative mucosa (6.8 +/- 20.3 c.p.m./microg tissue, 110.0 +/- 51.6 nmol/g tissue, respectively; P=0.000, P=0.016, respectively). The glutathione levels in the mucosa of patients with Helicobacter pylori-positive gastric mucosa (159.3 +/- 76.6 nmol/microg tissue) were significantly lower than in those with Helicobacter pylori-negative gastric mucosa (212.3 +/- 134.3 nmol/microg tissue; P=0.008). After the data were divided according to the presence of Helicobacter pylori, there were no significant differences in chemiluminescence, thiobarbituric acid-reactive substance, and glutathione among the different macroscopic findings within Helicobacter pylori-positive and -negative gastric mucosa.

CONCLUSIONS

Helicobacter pylori infection plays a pathological role in many gastrointestinal diseases through excessive mucosal-reactive oxygen species production, pronounced membrane damage, and the depletion of gastric anti-oxidants.

Rethinking cystic fibrosis pathology: the critical role of abnormal reduced glutathione (GSH) transport caused by CFTR mutation

Though the cause of cystic fibrosis (CF) pathology is understood to be the mutation of the CFTR protein, it has been difficult to trace the exact mechanisms by which the pathology arises and progresses from the mutation. Recent research findings have noted that the CFTR channel is not only permeant to chloride anions, but other, larger organic anions, including reduced glutathione (GSH). This explains the longstanding finding of extracellular GSH deficit and dramatically reduced extracellular GSH:GSSG (glutathione disulfide) ratio found to be chronic and progressive in CF patients. Given the vital role of GSH as an antioxidant, a mucolytic, and a regulator of inflammation, immune response, and cell viability via its redox status in the human body, it is reasonable to hypothesize that this condition plays some role in the pathogenesis of CF. This hypothesis is advanced by comparing the literature on pathological phenomena associated with GSH deficiency to the literature documenting CF pathology, with striking similarities noted. Several puzzling hallmarks of CF pathology, including reduced exhaled NO, exaggerated inflammation with decreased immunocompetence, increased mucus viscoelasticity, and lack of appropriate apoptosis by infected epithelial cells, are better understood when abnormal GSH transport from epithelia (those without anion channels redundant to the CFTR at the apical surface) is added as an additional explanatory factor. Such epithelia should have normal levels of total glutathione (though perhaps with diminished GSH:GSSG ratio in the cytosol), but impaired GSH transport due to CFTR mutation should lead to progressive extracellular deficit of both total glutathione and GSH, and, hypothetically, GSH:GSSG ratio alteration or even total glutathione deficit in cells with redundant anion channels, such as leukocytes, lymphocytes, erythrocytes, and hepatocytes. Therapeutic implications, including alternative methods of GSH augmentation, are discussed.

Gastric mucosal cell proliferation in ethanol-induced chronic mucosal injury is related to oxidative stress and lipid peroxidation in rats

The oxygen free radicals-induced lipid peroxidation (LP) has been implicated in the pathogenesis of acute ethanol-induced gastric mucosal lesions. However, the role of LP in the generation of chronic gastric mucosal injury is unknown. We have developed a model of chronic mucosal injury induced by continuous ethanol ingestion for 5 days and characterized by marked alterations in plasma membranes from gastric mucosa. Therefore, LP was evaluated in this experimental model. Indicators of peroxidative activity, mucosal glutathione content, thymidine kinase activity (an index of cell proliferation), and histamine H2-receptor (H2R) binding constants were quantified in animals undergoing gastric mucosal damage. The effect of famotidine, a H2R antagonist that readily ameliorates the chronic mucosal injury, was also tested. Increased free radicals and LP levels were detected during gastritis; however, a second, higher peak of LP was noted in mucosal plasma membranes after ethanol withdrawal (recovery period). This further increase of LP coincided with active cell proliferation, decreased mucosal glutathione levels, and diminished specific cimetidine binding by H2R. Administration of famotidine accelerated the mucosal proliferative process, inducing the second lipoperoxidative episode sooner, and preserved the content of glutathione. In addition, LP correlated directly with cell proliferation and inversely with mucosal membrane cimetidine binding. In conclusion, LP seems to be involved in chronic ethanol-induced gastric mucosal injury. However, a further enhancement of plasma membrane LP occurred, associated with increased DNA synthesis and diminished cimetidine binding by membrane H2R. Therefore, increased LP could also participate in the compensatory mucosal proliferation initiated after ethanol withdrawal.

Reduction of lipid peroxidation in different brain regions by a combination of alpha-tocopherol and ascorbic acid

Lipid peroxidation an outcome of free radicals activity has been hypothesized as one of the possible factor involved in the pathogenesis of neuronal damage. We investigated the effects of free radical scavengers, alpha-tocopherol (T) and ascorbic acid (A) combination (TA-combination) to attenuate tert-butyl hydroperoxide (t-BuOOH)-induced lipid peroxidation in different regions of mice brain. Examinations of effect of three regimens (100, 200, 300 mg/kg body weight) of t-BuOOH on mid brain, cerebellum, striatum, cortex and hippocampus revealed dose and time dependent increase in lipid peroxidation. We observed that prior supplementation of TA-combination reduced lipid peroxidation induced by t-BuOOH in every brain region. These findings suggest that TA-combination may play a vital role in protecting the brain tissue against free radicals.