Stress-induced Gastric Mucosal Damage Research Articles

Integrating network pharmacology and experimental verification to study the mechanism of Polygonum hydropiper total flavonoids against stress-induced gastric mucosal damage

ContextPolygonum hydropiper L. (P. hydropiper) has outstanding clinical efficacy in treating both acute and chronic gastroenteritis. However, the definite mechanism remains unclear. ObjectiveThis study aimed to explore the potential mechanisms of the total flavonoid of P. hydropiper (FPH) in stress-induced gastric mucosal damage (SGMD) rats through a combination of network pharmacology, molecular docking, and animal experiments. MethodsNetwork pharmacology and molecular docking were utilized to predict the potential mechanisms of FPH against SGMD. In experimental studies, SGMD rat models were established using water-immersion restraint stress (WIRS). FPH was administered at doses of 140, 70, and 35 mg/kg, with ranitidine serving as a positive control, through gavage once daily for 6 consecutive days after model establishment. Stomach and serum specimens were analyzed using HE staining, Western blotting, qPCR, and ELISA to investigate the protective mechanism of FPH in SGMD. ResultsThe network pharmacology analysis identified 16 active ingredients and 183 common targets, with potential pathways including PI3K/Akt, MAPK and Keap1/Nrf2. In vivo experiments demonstrated that FPH intervention alleviated SGMD pathological changes, reduced elevated serum IL-6 and TNF-α levels, and enhanced SOD and GSH activity in rats. Additionally, FPH increased the protein expression of p62, Nrf2, HO-1, PI3K, and p-Akt, along with mRNA levels of Nrf2, p62, and HO-1. ConclusionsFPH exerts a gastric mucosal protective effect by upregulating antioxidant gene expression through the PI3K/Akt and Keap1/Nrf2 pathways. This study provides an experimental basis for the potential clinical treatment of SGMD with the traditional Chinese medicine P. hydropiper.

Comprehensive fecal metabolomics and gut microbiota study of the protective mechanism of herbal pair Polygonum hydropiper-Coptis chinensis in rats with stress-induced gastric mucosal damage.

Introduction: Stress-related gastric mucosal lesions (SGMLs) are the most common complication in critical care patients. Previous studies have demonstrated that herbal pair (HP), Polygonum hydropiper-Coptis chinensis (HP P-C) has the anti-SGML effect. However, the underlying mechanism of HP P-C against SGML remains elusive. This study aimed to elucidate how HP P-C extracts exert their protective effects on SGML by examining the role of gut microbiota and metabolites. Methods: SD rats were pretreated with different doses of HP P-C extracts for 6 days, followed by inducing SGML with water-immersion restraint stress (WIRS). After a comprehensive evaluation of serum and gastric tissue indicators in rats, 16S rRNA sequencing and metabolomics analyses were conducted to assess the impact of HP P-C on the fecal microorganisms and metabolites and their correlation. Results: Animal experiment suggested that pretreatment with HP P-C effectively reduced the gastric mucosal lesions, remarkably increased superoxide dismutase (SOD) activity in SGML model rats induced by WIRS. 16S rRNA sequencing analysis showed that HP P-C altered the composition of gut microbiota by raising the abundance of Lactobacillus and Akkermansia. In addition, metabolomics data identified seventeen main differential metabolites related to WIRS-induced gastric mucosal injury, primarily involving in tyrosine metabolism and betalain biosynthesis. HP P-C was found to regulate tyrosine metabolism and betalain biosynthesis by down-regulating the tyramine, L-tyrosine and L-dopa and up -regulating the gentisic acid and dopaquinone. Conclusion: Taken together, this study indicated that HP P-C could effectively protect against WIRS-induced gastric mucosal lesions by modulating intestinal flora and metabolites.

Protective effect of alpha-ketoglutarate against water-immersion restraint stress-induced gastric mucosal damage in mice

Gastric lesions have several aetiologies, among which stress is the most prominent. Therefore, identification of new therapies to prevent stress is of considerable importance. Alpha-ketoglutarate (α-kg) several beneficial effects and has shown promise in combating oxidative stress, inflammation, and premature aging. Thus, this study aimed to evaluate the protective effect of α-kg in a gastric damage model by water-immersion restraint stress (WIRS). Pretreatment with α-kg decreased stress-related histopathological scores of tissue oedema, cell loss, and inflammatory infiltration. The α-kg restored the percentage of type III collagen fibres. Mucin levels were preserved as well as the structure and area of the myenteric plexus ganglia were preserved after pretreatment with α-kg. Myeloperoxidase (MPO) levels and the expression of pro-inflammatory cytokines (TNF-α and IL-1β) were also reduced following α-kg pretreatment. Decreased levels of glutathione (GSH) in the stress group were restored by α-kg. The omeprazole group was used as standard drug e also demonstrated improve on some parameters after the exposition to WIRS as inflammatory indexes, GSH and mucin. Through this, was possible to observe that α-kg can protect the gastric mucosa exposed to WIRS, preserve tissue architecture, reduce direct damage to the mucosa and inflammatory factors, stimulate the production of type III collagen and mucin, preserve the myenteric plexus ganglia, and maintain antioxidant potential. Due to, we indicate that α-kg has protective activity of the gastric mucosa, demonstrating its ability to prevent damage associated with gastric lesions caused by stress.

Quercetin Improves Mitochondrial Function and Inflammation in H2O2-Induced Oxidative Stress Damage in the Gastric Mucosal Epithelial Cell by Regulating the PI3K/AKT Signaling Pathway.

Functional dyspepsia (FD) is one of the most common functional gastrointestinal disorders, the therapeutic strategy of which it is limited due to its complex pathogenesis. Oxidative stress-induced damage in gastric mucosal epithelial cells is related to the pathogenesis and development of FD. Quercetin (Que) is one of the active ingredients of Zhishi that showed antioxidant, antiapoptotic, and anti-inflammatory effects. The aim of this study is to investigate the effect of Que on oxidative stress-induced gastric mucosal epithelial cells damage and its underlying molecular mechanism. The gastric mucosal epithelial cell line GES-1 was treated with 200 μM of H2O2 to construct an oxidative stress-induced damage model. The H2O2 cells were then administrated with different concentrations of Que. The results indicated that high concentration of Que (100 μM) showed cytotoxicity in H2O2-induced GES-1 cells. However, appropriate concentration of Que (25 and 50 μM) alleviated the oxidative stress damage induced by H2O2, as demonstrated by the increase of proliferation, decrease of ROS generation, apoptosis, inflammation, and alleviation of mitochondrial function and cell barrier. In addition, Que increased the activation of phosphorylation of PI3K and AKT decreased by H2O2. To investigate whether Que alleviated the oxidative stress damage in GES-1 cells by the PI3K/AKT signaling pathway, the GES-1 cells were treated with Que (25 μM) combined with and without LY294002, the PI3K inhibitor. The results showed that LY294002 suppressed the alleviation effect on Que in H2O2-induced GES-1 cells. In conclusion, the current study demonstrates that Que alleviates oxidative stress damage in GES-1 cells by improving mitochondrial function and mucosal barrier and suppressing inflammation through regulating the PI3K/AKT signaling pathway, indicating the potential therapeutic effects of Que on FD.

Neurons and Astrocytes in Ventrolateral Periaqueductal Gray Contribute to Restraint Water Immersion Stress-Induced Gastric Mucosal Damage via the ERK1/2 Signaling Pathway

BackgroundThe restraint water immersion stress (RWIS) model includes both psychological and physical stimulation, which may lead to gastrointestinal disorders and cause gastric mucosal damage. The ventrolateral periaqueductal gray (VLPAG) contributes to gastrointestinal function, but whether it is involved in RWIS-induced gastric mucosal damage has not yet been reported.MethodsThe expression of glial fibrillary acidic protein, neuronal c-Fos, and phosphorylated extracellular signal regulated kinase 1/2 in the VLPAG after RWIS was assessed using western blotting and immunocytochemical staining methods. Lateral ventricle injection of astrocytic toxin L-a-aminoadipate and treatment with extracellular signal-regulated kinase (ERK)1/2 signaling pathway inhibitor PD98059 were further used to study protein expression and distribution in the VLPAG after RWIS.ResultsThe expression of c-Fos, glial fibrillary acidic protein, and phosphorylated extracellular signal regulated kinase 1/2 in the VLPAG significantly increased following RWIS and peaked at 1 hour after RWIS. Lateral ventricle injection of the astrocytic toxin L-a-aminoadipate significantly alleviated gastric mucosal injury and decreased the activation of neurons and astrocytes. Treatment with the ERK1/2 signaling pathway inhibitor PD98059 obviously suppressed gastric mucosal damage as well as the RWIS-induced activation of neurons and astrocytes in the VLPAG.ConclusionsThese results suggested that activation of VLPAG neurons and astrocytes induced by RWIS through the ERK1/2 signaling pathway may play a critical role in RWIS-induced gastric mucosa damage.

Pretreatment with intestinal trefoil factor alleviates stress-induced gastric mucosal damage via Akt signaling.

BACKGROUNDStress-related gastric mucosal damage or ulcer remains an unsolved issue for critically ill patients. Stress ulcer prophylaxis has been part of routine intensive care, but uncertainty and controversy still exist. Co-secreted with mucins, intestinal trefoil factor (ITF) is reported to promote restitution and regeneration of intestinal mucosal epithelium, although the mechanism remains unknown.AIMTo elucidate the protective effects of ITF on gastric mucosa and explore the possible mechanisms.METHODSWe used a rat model of gastric mucosal damage induced by water immersion restraint stress and lipopolysaccharide-treated human gastric epithelial cell line to investigate the potential effects of ITF on damaged gastric mucosa both in vivo and in vitro.RESULTSITF promoted the proliferation and migration and inhibited necrosis of gastric mucosal epithelia in vitro. It also preserved the integrity of gastric mucosa by upregulating expressions of occludin and zonula occludens-1. In the rat model, pretreatment with ITF ameliorated the gastric mucosal epithelial damage and facilitated mucosal repair. The protective effects of ITF were confirmed to be exerted via activation of Akt signaling, and the specific inhibitor of Akt signaling LY249002 reversed the protective effects.CONCLUSIONITF might be a promising candidate for prevention and treatment of stress-induced gastric mucosal damage, and further studies should be undertaken to verify its clinical feasibility.

Effects of Restraint Water-Immersion Stress-Induced Gastric Mucosal Damage on Astrocytes and Neurons in the Nucleus Raphe Magnus of Rats via the ERK1/2 Signaling Pathway

Restraint water-immersion stress (RWIS) consists of psychological and physical stimulation, and it has been utilized in the research of gastric mucosal damage. It has been shown by previous studies that the nucleus raphe magnus (NRM) is closely involved in the gastrointestinal function, but its functions on the stress-induced gastric mucosal injury (SGMI) have not been thoroughly elucidated to date. Consequently, in this research, we aim to measure the expression of astrocytic glial fibrillary acidic protein (GFAP), neuronal c-Fos, and phosphorylation extracellular signal regulated kinase 1/2 (p-ERK1/2) in the process of RWIS with immunohistochemistry and western blot methods. What is more, we detect the relation between astrocytes and neurons throughout the stress procedure and explore the regulation of the ERK1/2 signaling pathway on the activity of astrocytes and neurons after RWIS. The results indicated that all three proteins expression multiplied following peaked 3h substantially. The SMGI, astrocyte and neuron activity were affected after the astrocytotoxin L-A-aminohexanedioic acid (L-AA) and c-fos antisense oligonucleotide (ASO) injections. After the injection of PD98059, the gastric mucosal injury, astrocyte and neuron activity significantly fell off. These results suggested that RWIS-induced activity of astrocytes and neurons in the NRM may play a significant part in gastric mucosa damage via the ERK1/2 signaling pathway.

Astrocytes and neurons in locus coeruleus mediate restraint water immersion stress-induced gastric mucosal damage through the ERK1/2 signaling pathway

Restraint water-immersion stress (RWIS) is considered to be a compound stress model that includes psychological and physical stimulation and may cause gastric mucosal damage. Studies have shown that locus coeruleus (LC) is involved in the gastrointestinal function, but whether it is involved in RWIS-induced gastric mucosal damage has not yet been reported. Here, we investigated the expression of glial fibrillary acidic protein (GFAP), c-Fos, and phosphorylation extracellular signal regulated kinase 1/2 (p-ERK1/2) in the LC after RWIS using immunocytochemical staining and western blotting in order to explore whether the ERK1/2 signaling pathway interacts with the neuron-astrocyte network in the LC during RWIS and whether it is involved in causing RWIS-induced gastric mucosal damage. Expression of c-Fos, GFAP, and p-ERK1/2 increased significantly following RWIS and peaked at 3 h after RWIS. After intracerebroventricular injection of c-Fos antisense oligodeoxynucleotides (ASO) and astrocytic toxin L-a-aminoadipate (L-AA), the gastric mucosal damage and the activation of neurons and astrocytes in the LC significantly decreased. Intracerebroventricular injection of ERK1/2 signaling pathway inhibitor PD98059 suppressed gastric mucosal damage as well as the RWIS-induced activation of neurons and astrocytes in the LC. Activation of LC neurons and astrocytes induced by RWIS through the ERK1/2 signaling pathway may play a critical role in RWIS-induced gastric mucosa damage.

Effects of moxibustion pretreatment on extracellular signal-regulated kinase signaling transduction pathway in the gastric tissues of rats with gastric mucosal damage

Objective To observe the effects of moxibustion pretreatment on the protein expressions of epidermal growth factor receptor (EGFR), phosphorylation extracellular signal-regulated kinase 1/2 (p-ERK1/2) and activated protein-1 (AP-1), the key factors of extracellular signal-regulated kinase signaling transduction pathway in gastric tissue of rats with stress-induced gastric mucosal damage, and to discuss the mechanisms of moxibustion therapy in promoting the restoration of damaged gastric mucosa.

A polysaccharide from Aloe vera L. var. chinensis (Haw.) Berger prevents damage to human gastric epithelial cells in vitro and to rat gastric mucosa in vivo

Reactive oxygen species (ROS) are implicated in the aetiology of gastric disorders and are a key pathogenic feature in gastric mucosal injury. Interventions that eliminate ROS are of high clinical value in treating gastric diseases. Here, we demonstrate that APS-F1, a glucogalactomannan polysaccharide from Aloe vera L. var. chinensis (Haw.) Berger, protects against oxidative stress-induced gastric mucosal damage. Human gastric epithelial GES-1 cells were treated with APS-F1 before H2O2 exposure. APS-F1 markedly attenuated cell apoptosis and injury; prevented H2O2-induced redox disturbance manifested as increases in intracellular ROS and thiobarbituric acid reactive substances (TBARS) level and decreases in superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activity; prevented H2O2-induced an increase in [Ca2+]i and mitochondrial membrane potential disruption, in association with PGC-1α activation, HO-1 induction and suppression of NF-κB expression. In vivo, APS-F1 ameliorated ethanol-induced gastric damage. Our findings provide the first evidence that APS-F1 protects against H2O2-induced gastric injury.

Interactions between astrocytes and neurons in the brainstem involved in restraint water immersion stress-induced gastric mucosal damage.

Restraint water-immersion stress (RWIS) is considered a compound stress model as it includes both psychological and physical stimulation. Studies have shown that neurons are involved in RWIS, but the role of astrocytes in RWIS has not been reported as yet. Here, we tested our hypothesis that astrocytes are involved in RWIS and interact with neurons in the brainstem to regulate gastric mucosal damage induced by RWIS. RWIS of different durations (0.5, 1, 2, 3, and 5 h) induced significant gastric mucosal damage and activated astrocytes by increasing the expression of glial fibrillary acidic protein and neurons, as indicated by the Fos expression in the nucleus of solitary tract and the dorsal motor nucleus of the vagus. Intracerebroventricular administration of both astroglial toxin L-α-aminoadipate and c-fos antisense oligodeoxy nucleotides reduced RWIS-induced gastric mucosal damage. Immunohistochemistry results showed that L-α-aminoadipate decreased the activation of both astrocytes and neurons by RWIS. Similarly, antisense oligodeoxy nucleotides significantly suppressed activation of both neurons and astrocytes induced by RWIS. Our data showed that astrocytic and neuronal activations may be closely related to the gastric mucosal damage induced by RWIS through reciprocal 'crosstalk'. This study suggests that an intervention targeting this interaction may offer some novel therapeutic strategies for gastric ulcers.

Melatonin is more effective than ascorbic acid and β-carotene in improvement of gastric mucosal damage induced by intensive stress.

IntroductionOxidative stress has been considered to play a primary role in the pathogenesis of stress-induced gastric damage. The aim of this study was to investigate the effects of melatonin, ascorbic acid and β-carotene on stress-induced gastric mucosal damage.Material and methodsFifty-six male Wistar albino rats were divided into control, stress, stress + standard diet, stress + saline, stress + melatonin, stress + ascorbic acid and stress + β-carotene groups. The rats from stress groups were exposed to starvation, immobilization and cold by immobilizing for 8 h at +4°C following 72-hour food restriction. Following stress application, melatonin, ascorbic acid and β-carotene were administered for 7 days. Specimens of gastric tissue were prepared for microscopic and biochemical examinations.ResultsMean histopathological damage scores and mean tissue malondialdehyde levels were significantly decreased but mean tissue glutathione levels and glutathione peroxidase and superoxide dismutase activities were increased in treatment groups vs. stress groups in general. Mean histopathological damage scores of the stress + Mel group was lower than those of stress + D, stress + S, stress + β-car (p < 0.05) and stress + Asc groups (p < 0.005). Additionally, mean tissue catalase activity of the stress + Mel group was higher than that of stress + S (p < 0.005), stress + D (p < 0.05) and stress + β-car groups (p < 0.05).ConclusionsMelatonin is more effective than ascorbic acid and β-carotene in improvement of gastric damage induced by intensive stress. We suggest that as well as the direct antioxidant and free radical scavenging potency of melatonin, its indirect effect via the brain-gut axis might account for its greater beneficial action against stress-induced gastric damage.

Protective function of compound Danshen injection on stress-induced gastric mucosal damage of rats

Objective To investigate the effects of compound Danshen injection on stress-induced gastric mucosal damage and its mechanism.Methods Sprague Dawley rats were used to establish immersion restraint cold stress model.50 SD rats were randomly divided into five groups(n=10 per group):① the normal control group; ② the stress model group; ③ the group treated with low dose of compound Danshen injection(50 mg/kg) ; ④ the group treated with medial dose of compound Danshen injection(100 mg/kg) ; ⑤the group treated with high dose of compound Danshen injection (200 mg/kg).The gastric mucosal ulcer index (UI),the level of malondialdehyde (MDA) in gastric mucosa,the activity of superoxide dismutase (SOD),and plasma intedeukin-1beta (IL-1β)content were detected.Results Compared with the normal control group [(0.7± 0.4) mm,(0.25 ± 0.03)nmol/mg,and (246.5 ± 45.4)Nu/mg],the stress model group exhibited a markedly increase in gastric mucosal UI[(28.4±4.5)mm](P＜0.01) and MDA level [(0.60±0.08)nmol/mg](P＜0.01) and a decrease in the activity of gastric mucosal SOD [(122.5 ±14.2) Nu/mg] (P＜0.01).In addition,an elevated level of plasma IL-1β[(31.6±8.4) pg/ml vs (8.5±3.1) pg/ml] (P＜0.01) was observed in the stress model group.Pretreatment with compound Danshen injection dose-dependently attenuated the gastric mucosal damage,characterized by a markedly decrease in gastric mucosal UI [(22.8 ± 3.7)mm、(12.2 ±3.5)mm,(6.2 ± 1.6)mm] and MDA level [(0.52 ± 0.07)nmol/mg,(0.32 ± 0.06)nmol/mg,(0.28 ±0.03)nmol/mg] and an increase in the activity of gastric mucosal SOD[(135.2± 13.6)Nu/mg,(220.7±33.5)Nu/mg,(251.2±23.7)Nu/mg] (P＜0.01).Meanwhile,compound Danshen injection reduced the content of plasma IL-1β[(27.2±7.5)pg/ml,(13.5±5.3)pg/ml,(9.3±4.4)pg/ml] (P＜0.01).Conclusion Compound Danshen injection exhibits preventive protection on the stress-induced gastric mucosal damage by water immersion restraint cold stress in SD rats,the mechanism of which might be linked to its inhibition of gastric mucosal oxidation stress and the reduced release of inflammatory mediator IL-1β. Key words: Ulcer; Rat; Compound Danshen injection; Interleukin-1beta

Muscimol microinjection into cerebellar fastigial nucleus exacerbates stress-induced gastric mucosal damage in rats

To investigate the effects of microinjection of the GABA(A) receptor agonist muscimol into cerebellar fastigial nucleus (FN) on stress-induced gastric mucosal damage and the underlying mechanism in rats. Stress-induced gastric mucosal damage was induced in adult male SD rats by restraining and immersing them in cold water for 3 h. GABA(A) receptor agonist or antagonist was microinjected into the lateral FN. The decussation of superior cerebellar peduncle (DSCP) was electrically destroyed and the lateral hypothalamic area (LHA) was chemically ablated by microinjection of kainic acid. The pathological changes in the gastric mucosa were evaluated using TUNEL staining, immunohistochemistry staining and Western blotting. Microinjection of muscimol (1.25, 2.5, and 5.0 μg) into FN significantly exacerbated the stress-induced gastric mucosal damage in a dose-dependent manner, whereas microinjection of GABA(A) receptor antagonist bicuculline attenuated the damage. The intensifying effect of muscimol on gastric mucosal damage was abolished by electrical lesion of DSCP or chemical ablation of LHA performed 3 d before microinjection of muscimol. Microinjection of muscimol markedly increased the discharge frequency of the greater splanchnic nerve, significantly increased the gastric acid volume and acidity, and further reduced the gastric mucosal blood flow. In the gastric mucosa, further reduced proliferation cells, enhanced apoptosis, and decreased anti-oxidant levels were observed following microinjection of muscimol. Cerebellar FN participates in the regulation of stress-induced gastric mucosal damage, and cerebello-hypothalamic circuits contribute to the process.

Target molecules of molecular chaperone (HSP70 family) in injured gastric mucosa in vivo

Aims Several recent studies, including ours, have indicated the importance of heat shock proteins (HSPs) in cytoprotection against cytotoxic agents and environmental stresses mediated by the chaperone function of HSPs (molecular chaperones). However, the target molecule that is recognized by HSPs in damaged cells currently remains unknown. As HSPs rapidly recognize and bind to degenerated protein in cells, target molecules of HSPs might be key molecules for the initiation and pathogenesis of cellular damage. In the present study, gastric mucosal proteins that specifically bind to the HSP70 family (HSC70) were analyzed using HSC70-affinity chromatography. Main methods The gastric mucosa was removed from Sprague–Dawley rats after exposure to water immersion-stress for 0, 1, 3 or 5 h. Soluble fractions of each gastric mucosa were applied to the HSC70-affinity column separately. After washing off non-specific binding proteins, specific binding proteins were eluted by ATP-containing buffer. Binding proteins were analyzed by SDS-polyacrylamide gel electrophoresis. In addition, the amino acid sequence of purified proteins was also analyzed. Key findings Specific HSC70-binding proteins with a molecular weight of 200-kDa and 45-kDa were eluted from an affinity column when gastric mucosal homogenate of 1-h stress exposure was applied. The amino acid sequencing showed that these binding proteins were cytoskeletal myosin (heavy chain) and actin, respectively. Significance During the pathogenesis of stress-induced gastric mucosal damage, structurally degenerated cytoskeletal myosin (heavy chain) and actin may be key or initiation molecules which structural changes were firstly recognized by molecular chaperone.

Nociceptin/orphanin FQ prevents gastric damage induced by cold-restraint stress in the rat by acting in the periphery

The influence of peripheral nociceptin/orphanin FQ (N/OFQ) on cold restraint-induced gastric mucosal damage in the rat was investigated. Exposure to cold-restraint for 3 and 4 h caused the formation of hemorrhagic lesions in the glandular portion of the stomach. N/OFQ dose-dependently decreased lesion formation, in the range 0.03–1 μg/kg/h i.p. Its effect was reversed by the selective NOP receptor antagonist [Nphe 1Arg 14Lys 15]N/OFQ–NH 2 (UFP-101), 30 μg/kg/h ip. The selective NOP receptor agonist [(pF)Phe 4Aib 7Arg 14Lys 15]N/OFQ–NH 2 (UFP-112), 0.01–0.3 μg/kg/h i.p., similarly reduced lesion formation. Light and scanning electron microscopy confirmed the protective activity of N/OFQ. Cold-restraint stress causes a reduction in mucus content and in adhering mucus layer, partly counteracted by N/OFQ. These results suggest that N/OFQ counteracts acute stress-induced gastric mucosal damage by interacting with NOP receptor and by influencing mucous cell activity.

Cytoprotective effects of eupatilin, a novel antioxidative flavone, in oxidative stress-induced gastric mucosal cell damage

Cytoprotective effects of eupatilin, a novel antioxidative flavone, in oxidative stress-induced gastric mucosal cell damage

Nitric Oxide Releasing Aspirin Protects the Gastric Mucosa against Stress and Promotes Healing of Stress-Induced Gastric Mucosal Damage: Role of Heat Shock Protein 70

Background/Aim: Nitric oxide (NO) releasing nonsteroidal anti-inflammatory drugs do not cause gastric mucosal damage, despite inhibition of the cyclooxygenase activity to a similar extent as conventional nonsteroidal anti-inflammatory drugs that induce such damage. We compared the effects of native aspirin (ASA) with those of NO-releasing ASA (NO-ASA) on the development and healing of acute gastric lesions induced by water immersion and restraint stress (WRS) and the mucosal expression of heat shock protein 70 (HSP70). Methods: Wistar rats received: (1) vehicle; (2) ASA (40 mg/kg i.g), and (3) NO-ASA (2.5–40 mg/kg i.g.), followed 0.5 h later by 3.5 h of WRS with or without glyceryl trinitrate, the donor of NO, and carboxy-PTIO, a NO scavenger. Healing of WRS lesions was assessed 0–24 h after termination of WRS. Number of gastric lesions, gastric mucosal blood flow (GBF), malondialdehyde (MDA) content, and RT-PCR expression of HSP70 mRNA were determined. Results: WRS caused typical bleeding erosions that were aggravated by aspirin and this was accompanied by a fall in the GBF and a significant rise in the mucosal MDA concentrations. In contrast, NO-ASA, which raised significantly the luminal content of NO_x, reduced number of WRS lesions and mucosal MDA levels while increasing significantly the GBF. These protective and hyperemic effects of NO-ASA against WRS lesions were mimicked by addition of glyceryl trinitrate to native ASA and significantly attenuated by carboxy-PTIO added to NO-ASA. HSP70 mRNA was significantly upregulated by WRS, and this was significantly attenuated by ASA, but not by NO-ASA. NO-ASA decreased significantly the MDA content and induced overexpression of HSP70 mRNA during healing of WRS lesions.Conclusion: NO-ASA exhibits mucosal protective and healing effects against WRS-induced gastric lesions due to the release of NO, which induces gastric hyperemia, and the attenuation of lipid peroxidation and counteracts the inhibition of HSP70 expression induced by native ASA.

Ammonia enhances emotional stress-induced mouse gastric mucosal damage in communication box paradigm

Background. The relationship between Hipylori (Hpj-colonization and the formation of stress-induced gastric mucosal injury has remained unknown. In the Hp-infected gastric mucosa, urease-dependent ammonia (NH3) production is reportedly important to induce gastric lesions. The present study was designed to investigate whether NHrpretreatment enhances the formation of gastric lesion in response to emotional stress. Method. Twelve CS7BL/6 mice were treated with 0.01%-NH3 through the gastric tube once a day for a week before applying emotional stress, and other II mice were treated with distilled water. To provide emotional stress, the communication box paradigm, in which each mouse (responder) was placed in transparent plastic compartment adjacent to mice receiving electrical stimulation (3 hours (19:30-22:30) per day for 3 days; sender), was used. After the overnight fasting, the stomach of each animal was examined. Macroscopic and microscopic evaluation were performed in each stomach. Mucosal activity of myeloperoxidase (MPO), an index of neutrophil accumulation, as well as the contents of thiobarbitulate reactive substances (TBARS), an index of mucosal lipid peroxidation were measured (Free Radie. Bioi. Med. 26:679, 1999). Results. The responder mice pretreated with 0.01%-NH3 (NH3-responder) developed more severe gastric lesions than those pretreated with distilled water (control-responder). MPO activity was enhanced in NH3-responder (0.72±0.3S mU/mg protein) more than that in the control-responder (0.3S±0.09 mU/mg protein) (p<O.OS). TBARS contents further increased in NH3-responder (4.84± 1.36 nmol/mg protein) compared with those in the control-responder (2.2S±0.6S nmol/mg protein) (p<O.OS). Luminol-dependent chemiluminescence (compatible to neutrophil-derived OCn was higher in NHrresponder (S.22±0.S4 countsl mg) than that in the control-responder (2.76± 1.S0 counts/mg). Conclusion. Intragastric ammonia overloading such as Hp-colonization could enhance gastric mucosal lesion in response to emotional stress. This injury may be associated with an enhanced production of oxygen free radicals from accumulated neutrophils.

Role of endogenous endothelin-1 in stress-induced gastric mucosal damage and acid secretion in rats

In rats subjected to 8 h water-immersion stress, gastric and duodenal mucosal hemorrhage and erosions were detected by macroscopic and histopathological examination. Moreover, plasma and gastric mucosal endothelin-1 (ET-1) levels rose appreciably in a time-related manner during water immersion, with a higher concentration detected in gastric mucosa. Thus, the percentage increases in plasma (gastric mucosal) ET-1, relative to basal levels, after 1, 4 and 8 h of water immersion were 86(172), 169(322) and 210(391)%, respectively. Likewise, a marked increase of gastric acid output was demonstrated 30 min after water immersion and lasted for 3 h. Pretreatment with the endothelin ET A/ET B receptor blocker, bosentan (30 and 100 mg kg −1), orally, dose-dependently antagonized gastric and duodenal mucosal damage as indicated by reductions in lesion lengths of 67 and 80%, respectively. Similar protective effects on mucosa were observed when bosentan was given by the intramuscular route. On the other hand, bosentan suppressed the rate of acid output by 30.3±2.1% in the stressed rats, but had no such effect in non-stressed animals. Taken together, results from this study implicate the endogenous peptide, ET-1, as a powerful mediator of stress-evoked gastro-duodenal mucosal damage and, moreover, present bosentan as a potential protector against hyperacidity and mucosal erosion that occur as a consequence of stress.