Cholinergic-mediated gastric mast cell degranulation with subsequent histamine H1-and H2-receptor activation in stress ulceration in rats

Dose of selective serotonin reuptake inhibitors and risk of upper gastrointestinal bleeding in older adults

BACKGROUND

Selective serotonin reuptake inhibitors (SSRIs) have been associated with an increased risk of upper gastrointestinal bleeding (UGIB) in older patients but little is known about the risk associated with individual SSRI drugs and doses.

AIMS

To quantify the risk of UGIB in relation to individual SSRI use in older adults.

METHODS

We conducted a nested case-control study within a cohort of 9565 patients aged ⩾65 years prescribed SSRIs from 2000 to 2013 using claims data of universal health insurance in Taiwan. Incident cases of UGIB during the follow-up period were identified and matched with three control subjects. Conditional logistic regression was used to estimate the odds ratio (OR) of UGIB associated with individual SSRI use and cumulative dose.

RESULTS

UGIB risk increased with the increasing cumulative doses of SSRIs (adjusted OR: 1.28, 95% confidence interval (CI): 1.02-1.62 for the highest vs. the lowest tertile). Compared with users of other SSRIs, fluoxetine users were at an increased risk of UGIB (adjusted OR: 1.25, 95% CI: 1.03-1.50) with a dose-response manner, whereas paroxetine users had 29% decreased odds (95% CI: 0.56-0.91). The increased risk was only observed among current fluoxetine users.

CONCLUSIONS

Fluoxetine therapy was associated with an increased risk of UGIB in a dose-response manner among older adults.

Design and construction of novel pyridine-pyrimidine hybrids as selective COX-2 suppressors: anti-inflammatory potential, ulcerogenic profile, molecular modeling and ADME/Tox studies

NSAIDs represent a mainstay in pain and inflammation suppression, and their actions are mainly based on inhibiting COX-1 and COX-2 enzymes.Due to the adverse effects of these drugs, especially on the stomach and heart, scientists efforts have been directed to manufacture selective COX-2 without cardiovascular side effects and with minimal effects on the stomach. The cardiovascular side effects are thought to be related to the chemical composition rather than mechanism of action of these drugs.Novel pyridopyrimidines, 9a-j, were prepared and their chemical structures were confirmed by NMR, mass and IR Spectra, and elemental analysis. The effect of the 9a-j compounds on COX-1 and COX-2 was assessed and it was found that 2-hydrazino-5-(4-methoxyphenyl)-7-phenyl-3H-pyrido[2,3-d)pyrimidin-4-one (9d) was the most potent COX-2 inhibitor (IC50 = 0.54 uM) compared to celecoxib (IC50 = 1.11 uM) with selectivity indices of 6.56 and 5.12, respectively.The in vivo inhibition of paw edema of novel compounds 9a-j was measured using carrageenan-induced paw edema method, and that 2-hydrazino-5-(4-methoxyphenyl)-7-phenyl-3H-pyrido[2,3-d)pyrimidin-4-one (9d) showed the best inhibitory activity in comparison with the other compounds and celecoxib.The gastroprotective effect of the potent derivatives 9d, 9e, 9f, 9 g and 9h was investigated. 2-Hydrazino-5-(4-methoxyphenyl)-7-phenyl-3H-pyrido[2,3-d)pyrimidin-4-one (9d) and 7-(chlorophenyl)-hydrazino-5-(4-methoxyphenyl)-3H-pyrido[2,3-d)pyrimidin-4-one (9e) showed ulcer indices comparable to celecoxib (1 and 0.5 vs 0.5, respectively). Docking studies were carried out and they confirmed the mechanistic action of the designed compoundsCommunicated by Ramaswamy H. Sarma.

Role of ADMA/DDAH-1 and iNOS/eNOS signaling in the gastroprotective effect of tadalafil against indomethacin-induced gastric injury

Non-steroidal anti-inflammatory drugs (NSAIDs)-induced gastric ulcers represent a significant clinical concern and adversely affect the quality of life. Inducible nitric oxide synthase/endothelial nitric oxide synthase (iNOS/eNOS) and asymmetric dimethylarginine/ dimethylarginine dimethylaminohydrolase-1 (ADMA/DDAH-1) signaling are key players in gastric ulcer pathogenesis. This work was planned to explore the role of iNOS/eNOS and ADMA/DDAH-1 signaling in rats with indomethacin-induced gastric ulcer, as potential pathways for the gastro-protective effect of tadalafil. Split into 5 separate groups, rats were assigned to control, tadalafil (10 mg/kg, p.o), indomethacin (single oral dose of 60 mg/kg), indomethacin + pantoprazole (40 mg/kg, p.o), and indomethacin + tadalafil (10 mg/kg, p.o). The results indicated that pretreatment with tadalafil significantly reduced ulcer index (UI), increased preventive index (PI), and counteracted indomethacin-induced histopathological aberrations. Tadalafil significantly reduced the gastric content of NO while it significantly elevated that of GSH and enhanced SOD activity. It significantly reduced the gastric expression of TNF-α and ADMA while it significantly elevated that of COX-2, PGE-2, and DDAH-1. Western blot analysis revealed that pretreatment with tadalafil significantly reduced iNOS protein expression while it significantly elevated that of eNOS. Collectively, these data suggest that tadalafil exerts potential protective effect against indomethacin-induced ulcer through suppression of inflammation, attenuation of oxidative stress, and boosting of antioxidants. Moreover, tadalafil protective effects are mediated via upregulation of PGE-2 with modulating the signaling pathways of ADMA/DDAH-1, and iNOS/eNOS. As a result, the current evidence corroborates the use of tadalafil in controlling gastric ulcers and preventing NSAID gastric side effects.

Docking Study, Synthesis, and Anti-Inflammatory Potential of Some New Pyridopyrimidine-Derived Compounds

Background and Purpose

Because of gastrointestinal irritation and kidney toxicity associated with non-steroidal anti-inflammatory drugs and the cardiovascular problems of Coxibs use, developing novel anti-inflammatory agents with reduced toxicity and improved selectivity remains a major challenge. Depending on our previous work, a novel series of pyridopyrimidinones IIIa-i has been synthesized via reaction of 6-amino-2-thioxo-2,3-dihydro-1H-pyrimidin-4-one (I) and phenyldiazenyl aromatic aldehydes (IIa-i). All the new constructed compounds were fully characterized by elemental and spectral analysis.

Methods

The target compounds IIIa–i were investigated for their potential towards COX inhibition, anti-inflammatory properties using carrageenan induced edema model in rat paw, and the ulcer indices of the most active members.

Results

The ethyl pyridopyrmidinone-benzoates IIIf, IIIg and IIIh showed superior inhibitory activity of carrageenan induced edema to celecoxib. Furthermore, the pyridopyrimidinones IIId, IIIf, IIIg, and IIIi exerted improved COX-2 inhibitory activity (IC₅₀ = 0.67–1.02 µM) comparing to celecoxib (IC₅₀ = 1.11 µM). Moreover, the gastric ulcerogenic potential assay of compounds IIIf–h revealed their lower ulcerogenic liability than indomethacin with comparable effect to celecoxib.

Conclusion

Virtual docking investigation of the most active candidates IIId, IIIf, IIIg and IIIi in the active site of COX-2 enzyme showed that these compounds implied interaction and binding motif similar to the cocrystallized ligand bromocelecoxib.

Protective effects of perindopril against indomethacin-induced gastric mucosal damage through modulation of DDAH-1/ADMA and ACE-2/ANG-(1-7) signaling pathways

Indomethacin is a widely used nonsteroidal anti-inflammatory drug; however, its clinical utility is accompanied by serious adverse reactions including peptic ulcers. The current study aims to investigate the protective potential of perindopril against indomethacin-induced gastric injury in rats. Perindopril (4 mg/kg) was administered orally for 7 days and indomethacin (60 mg/kg, single oral dose) was administered on the 7^th day, 1 h after perindopril administration. Pantoprazole was used as a standard agent. Ulcer index (UI), preventive index ratio (PI), histopathological examination, oxidative stress, and inflammatory biomarkers were investigated. Perindopril significantly decreased UI while increased PI and counteracted histopathological aberrations induced by indomethacin. It alleviated indomethacin-induced oxidative stress by lowering NO while increasing GSH content and superoxide dismutase activity. Perindopril significantly downregulated TNF-α and asymmetric dimethylarginine (ADMA), while significantly upregulated COX-2, PGE-2, dimethylarginine dimethylaminohydrolase-1 (DDAH-1), ANG-(1-7), and ACE-2 expression. Together, these findings suggest the gastroprotective effects of perindopril through modulation of DDAH-1/ADMA and ACE-2/ANG-(1-7) signaling.HIGHLIGHTSPerindopril attenuated gastric histopathological damage.It increased GSH content and SOD activity while decreased NO content.It modulated gastric ADMA and DDAH-1 activity.It reduced TNF-α, while increased COX-2 and PGE-2 expression.It upregulated ACE-2 activity and ANG-(1-7) protein expression.

Design and Synthesis of Novel Ibuprofen Derivatives as Selective COX-2 inhibitors and potential anti-inflammatory agents: Evaluation of PGE2, TNF-α, IL-6 and histopathological study

BACKGROUND

The reported binding mode of ibuprofen in the COX-2 binding site indicated that the carboxylic group binds with Arg-120 and Tyr-355 at the entrance of the cyclooxygenase channel and does not extend into the pocket. This accounted for the non-selectivity of ibuprofen. Based on this fact, we assumed that extending the length of the carboxylic acid moiety in ibuprofen and adding more bulky rigid groups as well as bulky groups carrying H-bonding functions might increase the selectivity and reduce the side effects of ibuprofen while maintaining its analgesic and anti-inflammatory activities.

OBJECTIVE

In this work, four series of ibuprofen derivatives were designed and prepared. The compounds were designed by increasing the length of the carboxylate group along with the incorporation of large hydrophobic groups.

METHOD

Four series of ibuprofen derivatives were synthesized starting from ibuprofen. Their chemical structure was confirmed by spectral data. All the compounds were tested for their COX inhibitory activity.

RESULTS

The best COX-2 activity and selectivity were obtained with compounds 5c and 5d, which were subjected to further in vivo testing (carrageenan-induced paw edema, rat serum PGE2, TNF- α and IL-6, hot plate latency test) to investigate their anti-inflammatory and analgesic activities as well as their effects on the gastric mucosa. The anti-inflammatory activity of both compounds was comparable to that of ibuprofen, diclofenac, and indomethacin. Both compounds suppressed the production of PGE2 as well as the rat serum concentrations of both TNF-α and IL-6. This potent anti-inflammatory and analgesic behavior was not accompanied by any effect on the gastric mucosa. Docking simulation studies of the two compounds explained the higher selectivity for the COX-2 enzyme.

CONCLUSION

Potent and selective ibuprofen derivatives can be successively obtained by extending the length of the carboxylic acid moiety in ibuprofen and adding more bulky rigid groups as well as bulky groups with H-bonding functions.

Optimization of pyrazole-based compounds with 1,2,4-triazole-3-thiol moiety as selective COX-2 inhibitors cardioprotective drug candidates: Design, synthesis, cyclooxygenase inhibition, anti-inflammatory, ulcerogenicity, cardiovascular evaluation, and molecular modeling studies

The cardiovascular side effects associated with COX-2 selective drugs were the worst for coxibs leading to their withdrawal from the market a few years after their discovery. Therefore, the design of new series of pyrazole (4a,b 5a,b, 7a,b, 9a,b, 10a-h, and 11a-f) substituted with a triazole moiety as selective COX-2 inhibitors with cardioprotective effect was aimed in this paper. The target compounds were prepared and evaluated in-vitro against COX-1 and COX-2 enzymes. Compound 5-(5-Methyl-1-phenyl-1H-pyrazol-4-yl)-4H-1,2,4-triazole-3-thiol (7a) showed the highest selectivity towards COX-2 enzyme (S.I. = 27.56) and was the most active anti-inflammatory agent. Interestingly, its cardiovascular profile showed the cardiac biomarkers (ALP, AST, CK-MB, and LDH), as well as inflammatory cytokines named (TNF-α and IL-6) nearly similar to the control. Besides, a histopathological study of the heart muscle and the stomach was also included. The results confirmed that compound 7a has a more favorable cardio profile than celecoxib. Moreover, docking simulation for the most selective compounds 4b, 7a, 10e, 11c, and 11e inside COX-2 active site was performed to explain their binding mode. Finally, an ADME study was applied and proved the promising activity of the new compounds as a new oral anti-inflammatory agent. In conclusion, the newly developed compound 7a represents a potential selective COX-2 NSAID candidate with minimum cardiovascular risks.

Novel tetrazole-based selective COX-2 inhibitors: Design, synthesis, anti-inflammatory activity, evaluation of PGE2, TNF-α, IL-6 and histopathological study

To search for effective and selective COX-2 inhibitors, four novel series of tetrazole derivatives were designed based on bioisosteric replacement of SO₂NH₂ in celecoxib with tetrazole ring incorporating different central moieties as chalcone (2a-f), isoxazole (3a-c) or pyrazole (4a-c & 5a-c). Target tetrazoles were synthesized and their structures were confirmed by spectroscopic techniques and elemental analyses. All target compounds were more selective for COX-2 isozyme than COX-1 when compared to standard drugs indomethacin and celecoxib. Compounds 3b, 3c, 4b, 4c, 5b and 5c exhibited potent in vitro COX-2 inhibitory activity (IC₅₀ = 0.039-0.065 μM). Trimethoxy derivatives 3c, 4c and 5c acquired superior COX-2 selectivity index values (SI = 297.67-317.95) and were 1.1 fold higher than celecoxib (SI = 282.22). The most active six compounds were evaluated for their in vivo anti-inflammatory activity and serum levels of PGE₂, TNF-α and IL-6 in addition to their ulcerogenic liability and histopathological profile. At a dose of 50 mg/Kg, compounds 3c and 5c showed better anti-inflammatory activity (% edema inhibition = 29.209-42.643) than celecoxib (% edema inhibition = 28.694-40.114) at different time intervals and were less ulcerogenic (UI = 0.123 and 0.11 in sequent) than celecoxib (UI = 0.167). Also, they displayed potent inhibitory effect on the production of PGE₂ (% inhibition = 81.042 and 82.724 in sequent) greater than celecoxib (% inhibition = 79.666). Compound 5c decreased rat serum concentrations of both TNF-α (% inhibition = 55.349) and IL-6 (% inhibition = 61.561) in a comparable or better activity to celecoxib as reference drug. Finally, docking poses of the most active compounds showed strong binding interactions and effective overall docking energy scores explaining their remarkable COX-2 inhibitory activity.

New pyrazole derivatives possessing amino/methanesulphonyl pharmacophore with good gastric safety profile: Design, synthesis, cyclooxygenase inhibition, anti-inflammatory activity and histopathological studies

New series of pyrazole derivatives Va-c, VIa-c, VIIa-f, and VIII possessing amino/methanesulphonyl moiety as COX-2 pharmacophore were designed and synthesized. All compounds were evaluated for both in vitro COX inhibition and in vivo anti-inflammatory activities and all of them were more potent against COX-2 than COX-1 isozyme and showed good in vivo anti-inflammatory activity. Compounds Va, VIa, VIc and VIIa-c showed good COX-2 SI (246.8-353.8) in comparison with the COX-2 selective drug; celecoxib (326.7). Also, they showed good anti-inflammatory activity with edema inhibition (51-86 and 83-96%) relative to celecoxib (60.6 and 82.8%) after 3 and 5 h respectively. Additionally, these potent derivatives Va, VIa, VIc and VIIa-c were significantly less ulcerogenic (ulcer indexes = 0.7-2.0) than indomethacin (ulcer index = 21.3) and were of acceptable ulcerogenicity when compared with the non-ulcerogenic reference drug celecoxib (ulcer index = 1.3). The obtained ulcerogenic liability data revealed the gastric safety of these derivatives which was confirmed by the histopathological studies. Docking study was performed for all synthesized derivatives to explain their interaction with COX-2 receptor active site.

Gastro-Protective and Anti-Oxidant Potential of Althaea officinalis and Solanum nigrum on Pyloric Ligation/Indomethacin-Induced Ulceration in Rats

Recently, an alternative disease treatment approach is the research of medicaments from traditional medicine. Plants with anti-oxidant capabilities are used as herbal treatments for ulcer diseases. Medicinal/herbal extracts containing phytoconstituents have significant anti-ulcer activities in in vivo experiments on animal models, compared to reference drugs. The current study aims to inspect gastro-protective as well as in vitro and in vivo anti-oxidant potential of Althaea officinalis and Solanum nigrum extracts on pyloric-ligation/indomethacin-induced gastric-ulceration in rats. Rats were divided into six groups: normal control, gastric ulcer control, two standard pretreatment groups receiving omeprazole and misoprostol, and two test pretreatment groups receiving Althaea officinalis and Solanum nigrum. Pretreatments were administrated orally for 14 days. On the 15th day, animals, excluding the normal control group, were exposed to pyloric-ligation followed by indomethacin injection. After four hours, the rat’s stomachs were removed and gastric juice and blood samples were collected. Pyloric-ligation/indomethacin administration caused considerable elevation in ulcer number, ulcer index, acid and pepsin productivity, aggressive factors, and gastric mucosal lipid-peroxide contents. Moreover, reduction in titratable acidity, gastric mucosal nitric-oxide, anti-oxidant contents, and protective factors accompanied gastric-ulceration. Additionally, elevation in pro-inflammatory cytokines content and reduction in cystathionine-β-synthase and heme-oxygenase-1 expression was witnessed. Omeprazole, misoprostol, Althaea officinalis, and Solanum nigrum pretreatments fixed blood and tissue biomarkers, thereby protecting them from pyloric-ligation/indomethacin-induced gastric-ulceration in rats, which is hopeful for clinical examinations.

Gastroprotective and antioxidant effects of fluvoxamine on stress-induced peptic ulcer in rats

Objectives

Stress-induced peptic ulcer disease (SPUD) refers to erosions in the mucosa of the upper gastrointestinal tract that are caused by stress. Some antidepressants are reported to have antioxidant and antiulcer effects. However, histopathological and biochemical evaluation of the anti-ulcer activity of a comparable antidepressant, fluvoxamine, has not been adequately investigated. This study aims to determine the anti-ulcer efficacy of fluvoxamine in reducing stress-induced histopathological and biochemical changes in the gastric mucosa.

Methods

Thirty adult male albino rats were divided into three groups of 10 rats each: the control groups, the SPUD group, and the fluvoxamine-pre-treated group, which received fluvoxamine for eight days before stress exposure. The cold-restraint stress method was used to induce stomach ulcers in the SPUD and fluvoxamine groups. Afterward, the stomachs of rats were removed, opened, and ulcer indices were calculated. Light microscopy was performed following haematoxylin and eosin staining, periodic acid Schiff's, Masson's trichrome staining, and proliferating cell nuclear antigen immunostaining. Gastric tissue levels of oxidative stress markers were measured and compared among groups.

Results

The stomachs of the fluvoxamine-treated rats showed a significantly lower number of ulcers with minimal mucosal injury compared with those of rats from the SPUD group. The oxidative stress marker levels and SPUD ulcer indices were significantly different among groups.

Conclusion

Fluvoxamine pre-treatment exerted a gastroprotective effect against ulcer development and promoted healing of the developed lesions.

Novel tetrazole and cyanamide derivatives as inhibitors of cyclooxygenase-2 enzyme: design, synthesis, anti-inflammatory evaluation, ulcerogenic liability and docking study

Nineteen new compounds containing tetrazole and/or cyanamide moiety have been designed and synthesised. Their structures were confirmed using spectroscopic methods and elemental analyses. Anti-inflammatory activity for all the synthesised compounds was evaluated in vivo. The most active compounds 4c, 5a, 5d-f, 8a and b and 9a and b were further investigated for their ulcerogenic liability and analgesic activity. Pyrazoline derivatives 9b and 8b bearing trimethoxyphenyl part and SO₂NH₂ or SO₂Me pharmacophore showed equal or nearly the same ulcerogenic liability (UI: 0.5, 0.75, respectively), to celecoxib (UI: 0.50). Most of tested compounds showed potent central and/or peripheral analgesic activities. Histopathological investigations were done to evaluate test compounds effect on rat's gastric tissue. The obtained results were in consistent with the in vitro data on COX evaluation. Docking study was also done for all the target compounds inside COX-2-active site.

Prophylactic and curative anti-ulcerogenic activity and the possible mechanisms of action of some desert plants

The present study aimed to evaluate the anti-ulcerogenic activities and the possible mechanisms of action of seven desert plants from different families. Conyza dioscoridis (L.) Desf. (Asteraceae), Euphorbia hirta L. (Euphorpiaceae), Origanum syriacum L., Salvia lanigera L. (Lamiaceae), Sisymbrium irio L., Solanum nigrum Linn. (Solanaceae) and Solenostemma arghel (Del.) Hayne. (Asclepiadaceae), were tested using prophylactic and curative models of absolute ethanol-induced ulcer, at three doses (125, 250 & 500 mg/kg) of each extract.

The investigated extracts possessed dose dependent anti-ulcerogenic activities in both models, with LD₅₀ higher than 5 g/kg. The most effective extracts were C. dioscoridis and S. irio with percent protection of control ulcer; 91.1% and 85.4% respectively. The antisecretory activity of both C. dioscoridis and S. irio appears to be mainly related to the suppression of gastrin release. The in vitro potential radical (DPPH) scavenging activities of the investigated extracts were well supported with the reduction in gastric MDA (50.6% and 43.3%) and enhancing the level of reduced GSH (2.84, 2.59 mg/g tissue) for C. dioscoridis and S. irio respectively. In addition, suppression of the inflammatory mediator TNF-α may be one of the possible mechanisms of action. The alcohol extracts of C. dioscoridis and S. irio showed no alteration on liver and kidney functions. Phytochemical screening of the investigated extracts revealed the presence of flavonoids, tannins and sterols which could be related to the activities.

Protective effects of ginger and marshmallow extracts on indomethacin-induced peptic ulcer in rats

Background:

Gastric ulcer is one of the most serious diseases. Most classic treatment lines produce adverse drug reactions. Therefore, this study aimed to investigate the protective effects of two natural extracts, namely ginger and marshmallow extracts, on indomethacin-induced gastric ulcer in rats.

Materials and Methods:

Animals were divided into five groups; a normal control group, an ulcer control group, and three treatment groups receiving famotidine (20 mg/kg), ginger (100 mg/kg), and marshmallow (100 mg/kg). Treatments were given orally on a daily basis for 14 days prior to a single intra-peritoneal administration of indomethacin (20 mg/kg).

Results:

Indomethacin administration resulted in significant ulcerogenic effect evidenced by significant elevations in ulcer number, ulcer index, and blood superoxide dismutase activity accompanied by significant decreases in gastric mucosal nitric oxide and glutathione levels. In addition, elevations in gastric mucosal lipid peroxides and histamine content were observed. Alternatively, pretreatment with famotidine, ginger or marshmallow significantly corrected macroscopic and biochemical findings, supported microscopically by results of histopathological study.

Conclusion:

These results demonstrate that administration of either ginger or marshmallow extract could protect against indomethacin-induced peptic ulcer in rats presumably via their antioxidant properties and inhibition of histamine release.

Gastric mucosal protection by aegle marmelos against gastric mucosal damage: role of enterochromaffin cell and serotonin

BACKGROUND/AIMS

Serotonin (5-hydroxytryptamine; 5-HT) released from enterochromaffin (EC) cells in gastric mucosa inhibits gastric acidity by increasing the gastric mucus secretion. In the present study, we evaluated the effect of aqueous extract of Aegle marmelos (AM) ripe fruit pulp (250 mg/kg body weight) on mean ulcer index (MUI), EC cells, 5-HT content, and adherent mucosal thickness of ulcerated gastric tissue in adult albino rats.

MATERIAL AND METHODS

Ulceration was induced by using aspirin (500 mg/kg, p.o.), cerebellar nodular lesion and applying cold-restraint stress.

RESULTS

In all cases increased MUI in gastric tissue along with decreased EC cell count was observed with concomitant decrease of 5-HT content and adherent mucosal thickness (P < 0.05). Pretreatment with AM for 14 days decreased MUI, increased EC cell count, and 5-HT content as well as adherent mucosal thickness in all ulcerated group (P < 0.05).

CONCLUSION

AM produces gastric mucosal protection mediated by increased EC cell count and 5-HT levels.

Gastroprotective effect of the iridoid fraction from Barleria prionitis leaves on experimentally-induced gastric ulceration

AIM

To study the gastroprotective effect and in vivo antioxidant potential of a standardized iridoid fraction from B. prionitis leaves (BPE) against different gastric ulcer models in rats.

METHOD

The standardized iridoid fraction from BPE at 50, 100, and 200 mg/kg body weight was administered orally, twice daily for 5 days for prevention from aspirin, ethanol, cold-restraint stress (CRS), and pylorus ligation (PL)-induced ulcers. Estimation of the antioxidant enzyme activity was carried out in a CRS-induced ulcer model, and various gastric secretion parameters including volume of gastric juice, acid output, and pH value were estimated in the PL-induced ulcer model.

RESULTS

BPE showed a dose-dependent ulcer protective effect in PL (18.67%-66.26% protection), aspirin (24.65%-63.25% protection), CRS (20.77%-59.42% protection), and EtOH (16.93%-77.04% protection)-induced ulcers. BPE treatment in PL-rats showed a decrease in acid-pepsin secretion, and enhanced mucin and mucosal glycoproteins. However, BPE reduced the ulcer index with significant decrease in LPO (P < 0.01-0.001), SOD (P < 0.01-0.001), and an increase in CAT (P < 0.01-0.001), activity in the CRS-induced model.

CONCLUSION

The data shows that the iridoid fraction from BPE possesses anti-ulcerogenic and antioxidant potential.

Antiulcer activity of the chloroform extract of Bauhinia purpurea leaf

CONTEXT

Bauhinia purpurea L. (Fabaceae) is a native plant species of many Asian countries, including Malaysia and India. In India, the root, stem, bark, and leaf of B. purpurea are used to treat various ailments, including ulcers and stomach cancer.

OBJECTIVE

In an attempt to establish its pharmacological potential, we studied the antiulcer activity of lipid-soluble extract of B. purpurea obtained via extraction of air-dried leaves using chloroform.

MATERIALS AND METHODS

The rats were administered the chloroform extract (dose range of 100-1000 mg/kg) orally after 24 h fasting. They were subjected to the absolute ethanol- and indomethacin-induced gastric ulcer, and pyloric ligation assays after 30 min. The acute toxicity study was conducted using a single oral dose of 5000 mg/kg extract and the rats were observed for the period of 14 days. omeprazole (30 mg/kg) was used as the standard control.

RESULTS

At 5000 mg/kg, the extract produced no sign of toxicity in rats. The extract exhibited significant (p < 0.05) dose-dependent antiulcer activity for the ethanol-induced model. The extract also significantly (p < 0.05) increased the gastric wall mucus production and pH of gastric content, while significantly (p < 0.05) reducing the total volume and total acidity of the gastric content in the pylorus ligation assay.

DISCUSSION AND CONCLUSION

The extract possesses antiulcer, antisecretory and cytoprotective activities, which could be attributed to its flavonoid and tannin content. These findings provide new information regarding the potential of lipid-soluble compounds of B. purpurea for the prevention and treatment of gastric ulcers.

Antiulcerogenic activities of the extracts and isolated flavonoids of Euphorbia cuneata Vahl

The total alcohol extracts of Euphorbia cuneata Vahl.(Euphorbiaceae) were screened for antiulcerogenic activity using an ethanol-induced ulcer model at doses of 125, 250 and 500 mg/kg. The extracts possessed antiulcerogenic activity in a dose-dependent manner. Four flavonoidal compounds were isolated and identified as naringenin, aromadendrin, apigenin and 4'-O-methoxy-luteolin-7-O-rhamnoglucoside, each demonstrating antiulcerogenic activity with curative ratios ranging from 75.78% to 88.23%. In addition, the alcohol extracts and isolated compounds were shown to scavenge the 1,1-diphenyl,2-picrylhydrazyl radical by different ratio, with the most effective being 4'-O-methoxy-luteolin-7-O-rhamnoglucoside (91.14%). The antioxidant activity of the alcohol extracts and the isolated compounds may explain the antiulcerogenic properties. No side effects were observed on either liver or kidney functions.

The protective role of Aegle marmelos on aspirin-induced gastro-duodenal ulceration in albino rat model: a possible involvement of antioxidants

BACKGROUND/AIM

Gastro duodenal ulcer is a common disorder of the gastrointestinal tract. Several Indian medicinal plants have been traditionally and extensively used to prevent different diseases. In the present research studies, Bael fruit (Aegle marmelos (AM), family: Rutaceae) which are also called as Bilva in ancient Sanskrit was used as a herbal drug and its antioxidative role in aspirin- induced gastroduodenal ulceration in albino rat was evaluated using essential biochemical parameters.

PATIENTS AND METHODS

Mucosal thickness (MT), ulcer index (UI), different biochemical parameters, such as aspartate aminotransferase (AST), alanine aminotransferase (ALT), catalase (CAT), superoxide dismutase (SOD), reduced glutathione (GSH), and lipid peroxidation (LPO) were measured in all the groups, to study the possible involvement of antioxidants with gastroduodenal protection.

RESULTS

A significant decrease in MT, SOD and CAT activities and GSH level and a significant increase in UI, AST, ALT, and ALP activities and LPO level were observed in aspirin treated stomach and duodenum of albino rats.

CONCLUSIONS

Pretreatment with AM fruit pulp extract for 14 consecutive days showed the reverse effects of aspirin suggesting gastro-duodenal protective and anti- ulcerogenic properties of AM through its antioxidant mechanism.

In vivo antiulcer activity of the aqueous extract of Bauhinia purpurea leaf

ETHNOPHARMACOLOGICAL RELEVANCE

Bauhinia purpurea (Fabaceae) is a medicinal plant traditionally used to treat various ailments, including ulcers. In order to establish pharmacological properties of the leaf of Bauhinia purpurea, studies were performed on antiulcer activity of the plant's aqueous extract.

MATERIALS AND METHODS

The Bauhinia purpurea aqueous extract (BPAE) was prepared in the doses of 100, 500 and 1,000 mg/kg. Antiulcer activity of BPAE was evaluated by absolute ethanol- and indomethacin-induced gastric ulcer, and pyloric ligation models. Acute toxicity was also carried out.

RESULTS

BPAE, at the dose of 5,000 mg/kg, did not cause any signs of toxicity to rats when given orally. Oral administration of BPAE exhibited antiulcer activity (p<0.05) in all models used. However, the dose-dependent activity was observed only in the absolute ethanol-induced gastric ulcer model. Histological studies supported the observed antiulcer activity of BPAE. In pyloric ligation assay, BPAE increased the gastric wall mucus secretion.

CONCLUSIONS

The BPAE exhibits antiulcer activity, which could be due to the presence of saponins or sugar-free polyphenols, and, thus, confirmed the traditional uses of Bauhinia purpurea in the treatment of ulcers.

Gastroprotective effect of standardized leaf extract from Argyreia speciosa on experimental gastric ulcers in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Argyreia speciosa (L.f), Sweet (Family Convolvulaceae) is used traditionally in Indian System of Medicine as aphrodisiac, rejuvenating agent, intellect promoting agent, brain tonic and in the therapy of hepatomegaly, diabetes and chronic ulcer.

AIM OF THE STUDY

To study the gastroprotective effect of standardized butanol fraction of Argyreia speciosa leaf (ASE).

MATERIALS AND METHODS

The butanol fraction of Argyreia speciosa leaf (ASE; 50, 100 and 200mg/kg body weight) was administered orally, twice daily for 5 days for prevention from Aspirin (ASP)-, ethanol (EtOH)-, cold-restraint stress (CRS) - and pylorus ligation (PL)-induced ulcers. Estimation of antioxidant enzymes activity was carried out in CRS-induced ulcer model, and various gastric secretion parameters like volume of gastric juice, acid output, and pH value were estimated in PL-induced ulcer model.

RESULT

ASE showed dose-dependent ulcer protective effect in ASP 23.64-58.76% (p<0.01 to p<0.001), EtOH 15.45-58.45% (p<0.001), CRS 19.39-78.36% (p<0.001) and PL 19.67-69.04% (p<0.05 to p<0.01), respectively. The percentage of protection by standard drug ranitidine was 77.77-84.32% (p<0.01 to p<0.001) in various gastric ulcer models. The gastric wall mucus was significantly (p<0.001) enhanced by ASE and is regarded as the first line of defence against EtOH-induced gastric ulcers showing cytoprotective property. ASE showed a marginal decrease in volume, acid pepsin concentration and acid pepsin output. However, ASE reduced the ulcer index with significant decrease in LPO level (p<0.001), and SOD level (p<0.01 to p<0.001) as compared with CRS-induced group. A gradual and significant increase in CAT values were observed at 100 and 200mg/kg dose levels (p<0.01 to p<0.001).

CONCLUSIONS

The results of our study revealed that Argyreia speciosa possess significant dose dependent gastroprotective activity, probably due to its free radical scavenging activity.

Natural Products as Gastroprotective and Antiulcer Agents: Recent Developments

Peptic ulcer, one of the most common gastrointestinal diseases, is a chronic inflammatory disease characterized by ulceration in the regions of the upper gastrointestinal tract where parietal cells are found and where they secrete hydrochloric acid and pepsin. The anatomical sites where ulcer occurs commonly are stomach and duodenum, causing gastric and duodenal ulcer, respectively. Physiopathology of ulcer is due to an imbalance between aggressive factors, such as acid, pepsin, Helicobacter pylori and non-steroidal anti-inflammatory agents, and local mucosal defensive factors, such as mucus bicarbonate, blood flow and prostaglandins. Several drugs are widely used to prevent or treat gastro-duodenal ulcers. These include H2-receptor antagonists, proton pump inhibitors and cytoprotectives. Due to problems associated with recurrence after treatment, there is therefore the need to seek alternative drug sources against ulcers. In recent years, a widespread search has been launched to identify new gastroprotective drugs from natural sources. The aim of the present review is to highlight the recent advances in current knowledge on natural products as gastroprotective and antiulcer agents and consider the future perspectives for the use of these compounds.

Antiulcer and antimicrobial activity of Anogeissus latifolia

Ethnobotanically, the bark of Anogeissus latifolia (Roxb. ex DC.) Wall. ex Guill. and Perr.(Combretaceae) has been reported to be used in the treatment of various disorders including stomach and skin diseases. We studied the antiulcer potential and antimicrobial activity of the 50% aqueous alcoholic extract in order to validate ethnobotanical claims regarding the plant use in the above-mentioned disorders. Gastroprotective potential of the Anogeissus latifolia extract (ALE) (100 and 200mg/kg/body weight) was studied on aspirin, cold-resistant stress (CRS), pylorus ligated (PL) and ethanol-induced ulcers. Status of the antioxidant enzymes superoxide dismutase (SOD) and catalase along with lipid peroxidation (LPO) was also studied in CRS-induced ulcers. The results of the present study showed for the first time that the ALE possessed gastroprotective activity as evidenced by its significant inhibition in the formation of ulcers induced by physical and chemical agents with a maximum of 84.16% curation (200mg/kg body weight) in CRS-induced ulcers. ALE decreased LPO and SOD with concomitant increase in catalase activity in CRS-induced ulcers. Moderate antibacterial activity and antifungal activity was also observed. High performance thin layer chromatography (HPTLC) showed the presence of gallic acid and ellagic acid (0.95%, w/w, 0.25%, w/w, respectively) in the plant. These findings could justify, at least partially, the inclusion of this plant in the management of gastric disorders in traditional medicine.

Antiulcerogenic and ulcer healing effects of Solanum nigrum (L.) on experimental ulcer models: possible mechanism for the inhibition of acid formation

Solanum nigrum, an herbal plant which is recommended in ayurveda for the management of gastric ulcers. Therefore, the purpose of the study was to investigate the antiulcer effect of Solanum nigrum fruits extract (SNE) on cold restraint stress (CRU), indomethacin (IND), pyloric ligation (PL) and ethanol (EtOH) induced gastric ulcer models and ulcer healing activity on acetic acid induced ulcer model in rats. The treatment with SNE at higher dose significantly inhibited the gastric lesions induced by CRU (76.6%), IND (73.8%), PL (80.1%) and EtOH (70.6%), respectively, with equal or higher potency than omeprazole. SNE showed concomitant attenuation of gastric secretory volume, acidity and pepsin secretion in ulcerated rats. In addition, SNE (200 and 400mg/kgb.w.) accelerated the healing of acetic acid induced ulcers after the treatment for 7 days. Further, to ascertain the antisecretory action, the effects of SNE on H(+)K(+)ATPase activity and plasma concentration of gastrin hormone in ulcerated rats were determined. SNE significantly inhibits H(+)K(+)ATPase activity and decreases the gastrin secretion in EtOH-induced ulcer model. The severity of the reaction of ulcerogen and the reduction of ulcer size by SNE was evident by histological findings. Toxicity studies of SNE have also been carried out for its safety evaluation. SNE, thus, offers antiulcer activity by blocking acid secretion through inhibition of H(+)K(+)ATPase and decrease of gastrin secretion. These results further suggest that SNE was found to possess antiulcerogenic as well as ulcer healing properties, which might also be due to its antisecretory activity.

Allophylus serratus: a plant with potential anti-ulcerogenic activity

Allophylus serratus is known to possess various therapeutic properties. We evaluated the anti-ulcerogenic property of crude ethanolic extract of Allophylus serratus (AS) in different ulcer models in Sprague-Dawley rats. The extract at 400 mg/kg body weight, once daily, orally has a significant effect in cold restraint (CRU, 2 h cold restraint stress), aspirin (ASA, 150 mg/kg body weight, orally), alcohol (AL, 1 ml/200 gm of absolute alcohol) and pyloric ligation (PL, 4h ligation) induced gastric ulcer models as it showed protection index of 71.28, 62.50, 90.84 and 64.29% protection, respectively whereas, standard drug omeprazole (OMZ, 10mg/kg body weight) has shown protection index of 85.70, 74.99 and 74.99 in CRU, ASA and PL model respectively. Sucralfate (SUC, 500 mg/kg body weight) as a standard drug in AL model has 93.20% protection. Furthermore, AS has significantly decreased the free acidity (72.41%), total acidity (47.97%) and peptic activity (24.59%), respectively as well as has significantly increased the mucus secretion (29.41%). Conclusively the ulcer protective effect of AS may be due to its anti-secretory along with cytoprotective mechanism.

Antiulcer effects of amylin: a review

Amylin belongs to the calcitonin peptide family. Amylin is a peptide synthesized not only in the beta cells of pancreatic islets, but in small quantities also in other organs like in the intestinal and gastric mucosa, lungs and central nervous system. It is located in the same secretory granules as insulin. Amylin participates in the maintenance of glucose and calcium homeostasis. It also inhibits food intake and decreases body weight. Furthermore, amylin inhibits gastric acid secretion. It protects the gastric mucosa in ulcer models like stress, vagal stimulation, ethanol, acetic acid, reserpine and serotonine administration and pylorus ligation. This protective antiulcer is seen not only at pharmacological but also at near-physiological doses-0.5mkg/kg. Moreover amylin also exerts curative properties in the acetic acid and indomethacin ulcer models. Amylin decreases the aggressive factors like acid-pepsin secretion, increases mast cell stability and increases protective mechanisms like bicarbonate gastric secretion, dilates blood vessels, and it increases lymphatic mesenteric activity. Amylin seems to be a powerful protector of gastric mucosa in animals by increasing the stability of gastric mucosa. Further research remains, however, to be done.

Antiulcer activity of Utleria salicifolia rhizome extract

The effect of 50% ethanolic extract of Utleria salicifolia (USE) was assessed in different acute and chronic gastric ulcer models in rats. USE, 50-200 mg/kg administered orally, twice daily for 5 days showed dose-dependent ulcer protective effect in pylorus ligation (14.48-51.03% protection, P < 0.5 to P < 0.01), aspirin (28.80-56.52% protection, P < 0.5 to P < 0.001), ethanol (13.22-60.74% protection, P < 0.5 to P < 0.001), cold-restraint stress (21.22-77.14% protection, P < 0.05 to P < 0.001), and acetic acid (20.0-84.37% protection, P < 0.5 to P < 0.001)-induced acute and chronic ulcers. USE also significantly (P < 0.001) reduced the ulcer incidence (50 and 10%) and severity (67.83 and 91.34% protection) of duodenal ulcer, induced by cysteamine. Besides USE offered protection (53.52 and 60.58%) against ethanol-induced depletion of gastric wall mucus. However, USE reduced the ulcer index with significant decrease in plasma corticosterone (25.53 and 39.52% protection, P < 0.1 and P < 0.05), lipid peroxidation (18.75 and 47.92% protection, P < 0.01 and P < 0.001), superoxide dismutase (15.80 and 26.61% protection, P < 0.05 and P < 0.001) and increased in catalase (28.42 and 71.0% protection, P < 0.05 and P < 0.001) activity, respectively. Preliminary phytochemical screening of the USE gave the positive test for steroids, alkaloids, terpenoids, saponins and tannins. The HPTLC studies in the toluene: ethyl acetate: formic acid and the densitometric scanning at 254 nm gave three major spots with area corresponding to 28.16, 17.17, and 13.79% at 0.69, 0.78, and 0.88 R(f) values, respectively. The results indicate that USE possesses antiulcer activity.

Gastric Antiulcer Activity of Syngonanthus arthrotrichus SILVEIRA

Syngonanthus arthrotrichus SILVEIRA, popularly known as "sempre-vivas mini-saia," is found in mountains of the Espinhaço range in the Brazilian states of Bahia and Minas Gerais. Extracts of this species contain several constituents, including flavonoids which may have antiulcerogenic activity. An ethanolic extract (EEOH), and flavonoid-rich (FRF) and flavonoid-deficient (FDF) fractions obtained from the scapes of S. arthrotrichus were investigated for their ability to prevent ulceration of the gastric mucosa in mice and rats. In the ethanol/HCl-induced ulcer model, lansoprazole (30 mg/kg), EEOH (50, 100, 250 mg/kg) given orally protected the gastric mucosal against injury in mice by 79%, 78%, 73%, and 64% respectively. In the ethanol-induced gastric ulcer model in rats, the lansoprazole (30 mg/kg), FRF and FDF (100 mg/kg) significantly protected the gastric mucosal of rats by 65%, 38% and 25% respectively when compared with the negative control group. In indomethacin/bethanechol-induced gastric ulcers, cimetidine (100 mg/kg) and the EEOH (100, 250 mg/kg) inhibited gastric ulcer formation by 73%, 55% and 32% respectively. In this exactly model other treatments as cimetidine, FRF and FDF (100 mg/kg) each caused 54%, 36% and 45% inhibition, respectively. In the stress-induced gastric ulcer model, cimetidine (100 mg/kg) and the EEOH (50, 100, 250 mg/kg), inhibited gastric ulcer formation by 63%, 73%, 68% and 69% respectively. In the same model, cimetidine, FRF and FDF (100 mg/kg) significantly protected the gastric mucosal of the mice by 60%, 51% and 47% when compared to the control group. In pylorus-ligated mice, cimetidine (positive control) and FRF significantly decreased gastric acid secretion, increased gastric pH and reduced the acid output when compared to the negative control. FDF had no significant effect on these parameters. The protection provided by FRF probably involved an antisecretory mechanism mediated by flavonoids which were absent in FDF. The amount of adherent mucous in the stomach contents was also evaluated with the treatments carbenoxolone (200 mg/kg), FRF and FDF (100 mg/kg) treatment. Each treatments significantly increased the amount of adherent mucous in the gastric juice (8.67+/-1.73, 3.35+/-1.59, 2.1+/-0.41 mg/g of wet tissue, respectively) compared to the control group, indicating a cytoprotective action on the gastric mucosa. Treatment with FRF plus indomethacin and FDF plus indomethacin reduced the prostaglandin biosyntesis (13.6+/-6.5, 27+/-5.5 pg/well) by the mucosa, indicating that the cytoprotective action on the gastric mucosa was not related to the level of prostaglandins. Only FDF (38+/-17 pg/well) maintained the level of prostaglandins and guaranteed the integrity of the mucosa. The results indicate that the EEOH, FRF and FDF have antisecretory and cytoprotective actions, that may be related to the presence of luteoline in the extract and active fractions.

Effects of the vasoactive intestinal peptide on stress-induced mucosal ulcers and modulation of methylation of histamine in gastric tissue of the rats

Vasoactive intestinal peptide (VIP) prevents stress-induced gastric ulcers, inhibits mast cell degranulation and protects gastric tissue from lipid peroxidation. Histamine has an important role in the development of gastric ulcers and mast cell derived histamine might be essential in this process.

A novel antioxidant and antiapoptotic role of omeprazole to block gastric ulcer through scavenging of hydroxyl radical

The mechanism of the antiulcer effect of omeprazole was studied placing emphasis on its role to block oxidative damage and apoptosis during ulceration. Dose-response studies on gastroprotection in stress and indomethacin-induced ulcer and inhibition of pylorus ligation-induced acid secretion indicate that omeprazole significantly blocks gastric lesions at lower dose (2.5 mg/kg) without inhibiting acid secretion, suggesting an independent mechanism for its antiulcer effect. Time course studies on gastroprotection and acid reduction also indicate that omeprazole almost completely blocks lesions at 1 h when acid inhibition is partial. The severity of lesions correlates well with the increased level of endogenous hydroxyl radical (*OH), which when scavenged by dimethyl sulfoxide causes around 90% reduction of the lesions, indicating that *OH plays a major role in gastric damage. Omeprazole blocks stress-induced increased generation of *OH and associated lipid peroxidation and protein oxidation, indicating that its antioxidant role plays a major part in preventing oxidative damage. Omeprazole also prevents stress-induced DNA fragmentation, suggesting its antiapoptotic role to block cell death during ulceration. The oxidative damage of DNA by *OH generated in vitro is also protected by omeprazole or its analogue, lansoprazole. Lansoprazole when incubated in a *OH-generating system scavenges *OH to produce four oxidation products of which the major one in mass spectroscopy shows a molecular ion peak at m/z 385, which is 16 mass units higher than that of lansoprazole (m/z 369). The product shows no additional aromatic proton signal for aromatic hydroxylation in (1)H NMR. The product absorbing at 278 nm shows no alkaline shift for phenols, thereby excluding the formation of hydroxylansoprazole. The product is assigned to lansoprazole sulfone formed by the addition of one oxygen atom at the sulfur center following attack by the *OH. Thus, omeprazole plays a significant role in gastroprotection by acting as a potent antioxidant and antiapoptotic molecule.

Glyproline peptide family: review on bioactivity and possible origins

Glyproline peptide family includes the simplest proline-containing linear peptides PG, GP, PGP, respective peptides with hydroxylated proline residues and (with some restriction) cyclic PG. Having close structural resemblance they display many similar bioactivities. The suppression of some reactions of blood coagulation and platelet aggregation and protection of gastric mucosa against various ulcerogenic factors are the most important glyproline effects. Glyprolines have two common putative sources: (1) collagen and elastin synthesis and catabolism, and (2) penetration of proline-containing di- and tripeptides from food protein hydrolysate from the intestine into bloodstream. Possible physiological and biochemical mechanisms of glyproline bioactivities are under discussion.

Extracts of Benincasa hispida prevent development of experimental ulcers

Benincasa hispida (B. hispida) is recommended in Ayurveda for the management of peptic ulcers. Therefore, anti-ulcerogenic activity of different extracts of B. hispida (fresh juice, supernatant and residue fraction of centrifuged juice, alcoholic and petroleum ether extract) were studied in aspirin plus restraint, swimming stress, indomethacin plus histamine and serotonin-induced ulcers in rats and mice. The oral feeding of different doses of the extract significantly reduced the ulcer index produced by various ulcerogens. The anti-ulcerogenic effect was dose-dependent in stress induced model of ulcer and not in other models. B. hispida probably has a CNS component in prevention of stress induced ulceration. However, antihistaminic, anti-cholinergic effects and prevention of disturbance in gastric micro-circulation as possible modes of action cannot be ruled out. Chronic toxicity studies carried out for 3 months revealed no deleterious effect of fresh juice of B. hispida on various hematological and biochemical parameters studied. Thus, extracts of B. hispida may be considered to be a drug of natural origin possessing anti-ulcer activity.

Effect of psychogenic stress on gastrointestinal function

This review summarizes the studies published over the last twenty years on the effects of psychogenic stress on gastrointestinal function, using animal models. The effects of stress on gastric ulceration have received wide attention and the central and local mechanisms of mucosal damage have been, for the most part, clearly delineated. In comparison, relatively few studies have focused on the impact of stress on intestinal and colonic physiology, even though its influence on intestinal motility, mucosal permeability and inflammation has been established. More work is necessary in this field, especially considering the importance of irritable bowel syndrome in modern society.

Vagus-mediated activation of mucosal mast cells in the stomach: effect of ketotifen on gastric mucosal lesion formation and acid secretion induced by a high dose of intracisternal TRH analogue

TRH analogue, RX 77368, injected intracisternally (i.c.) at high dose (3 microg/rat) produces gastric mucosal lesion formation through vagal-dependent pathway. The gastric mucosal hyperemia induced by i.c. RX 77368 was shown to be mediated by muscarinic vagal efferent fibres and mast cells. Furthermore, electrical vagal stimulation was observed to induce gastric mucosal mast cell degranulation. The aim of the study was to assess the influence of ketotifen, a mast cell stabilizer, on RX 77368-induced gastric lesion formation and gastric acid secretion. RX 77368 (3 microg, i.c.) or vehicle (10 microL, i.c.) was delivered 240 min prior to the sacrifice of the animals. Ketotifen or vehicle (0.9% NaCl, 0.5 mL) was injected intraperitoneally (i.p.) at a dose of 10 mg x kg(-1) 30 min before RX 77368 injection. The extent of mucosal damage was planimetrically measured by a video image analyzer (ASK Ltd., Budapest) device. In the gastric acid secretion studies, the rats were pretreated with ketotifen (10 mg x kg(-1), i.p.) or vehicle (0.9% NaCl, 0.5 mL, i.p.), 30 min later pylorus-ligation was performed and RX 77368 (3 microg, i.c.) or vehicle (0.9% NaCl, 10 microL, i.c.) was injected. The rats were killed 240 min after i.c. injection, and the gastric acid secretion was measured through the titration of gastric contents with 0.1 N NaOH to pH 7.0. RX 77368 (3 microg, i.c.) resulted in a gastric mucosal lesion formation involving 8.2% of the corpus mucosa (n = 7). Ketotifen elicited an 85% inhibition on the development of mucosal lesions (n = 7, P < 0.001) whereas ketotifen alone had no effect on the lesion formation in the mucosa (n = 7). The RX 77368 induced increase of gastric acid secretion was not influenced by ketotifen pretreatment in 4-h pylorus-ligated animals. Central vagal activation induced mucosal lesion formation is mediated by the activation of mucosal mast cells in the stomach. Mast cell inhibition by ketotifen does not influence gastric acid secretion induced by i.c. TRH analogue in 4-h pylorus-ligated rats.

Mast cell stabilization prevents ethanol-induced rat gastric mucosal injury: mechanisms of protection

INTRODUCTION

We previously demonstrated that 60% ethanol increased macromolecular leakage and induced lesion formation in areas of permanent flow stasis within gastric mucosal vessels. Mast cells and their mediators have been implicated in acute mucosal injury. Fluorescent in vivo microscopy was used to assess the effects of ketotifen, a mast cell stabilizer, and pyrilamine, a histamine (H1)-receptor antagonist, on ethanol-induced rat gastric mucosal injury.

METHODS

Experiments were carried out on anaesthetized rats pretreated orally with ketotifen (1 mg/kg) or pyrilamine (30 mg/kg). Fluorescein isothiocyanate-bovine serum albumin (FITC-BSA; 0.2 mL/100 g), a marker for quantitating macromolecular leakage was administered intra-arterially. Ethanol (60%) or distilled water was applied topically to the gastric mucosa. Macromolecular leakage of FITC-BSA, vessel diameters and leucocyte activity were quantified using image analysis.

RESULTS

Pretreatment with ketotifen or pyrilamine, followed by ethanol, caused no change in macromolecular leakage compared with controls. Both compounds prevented blood flow stasis in all areas and no lesion formation was observed. However, increased leucocyte activity and increases in vessel diameter were observed following pretreatment with ketotifen and pyrilamine, respectively.

CONCLUSIONS

The data suggest that vasoactive substances released from mast cells may be involved in the aetiology of ethanol-induced gastric mucosal damage. The prevention of these normal physiological responses to injury may lead to the employment of other microcirculatory mechanisms of defence.