Seriate histomorphometry of whole rat stomach: an accurate and reliable method for quantitative analysis of mucosal damage

Interplay of Biochemical, Genetic, and Immunohistochemical Factors in the Etio-Pathogenesis of Gastric Ulcer in Rats: A Comparative Study of the Effect of Pomegranate Loaded Nanoparticles Versus Pomegranate Peel Extract

Background

Few data are available about the role of herbal extract loaded nanoparticles as an alternative safe medicine for the management of a gastric ulcer.

Aim

This work is targeted at exploring the physiological effects of pomegranate loaded nanoparticles (PLN) against an indomethacin IND-induced gastric ulcer and comparing the results with traditional pomegranate peel extract (PPE).

Methods

Twenty-four rats were equally distributed into four groups: control, IND-treated, PLN-treated, and PPE-treated groups. Gross examination of gastric mucosa, and the calculation of ulcer and inhibition indices were done. Serum malondialdehyde (MDA), total antioxidant capacity (TAC), interleukin 2 (IL-2), IL-6, IL-10, gastric homogenate prostaglandin E₂ (PGE₂), and nitric oxide (NO) were estimated. Mucosal endothelial nitric oxide synthase (eNOS mRNA) expression was identified by qPCR. Histological and immuno-histochemical staining of Tumor necrosis factor-α (TNF-α) and eNOS of stomach mucosa were performed.

Results

In comparison with the control group, IND-treated rats showed visible multiple ulcers with ulcer index, serum MDA, IL-2 and IL-6 were elevated while IL-10, PGE₂, NO, and eNOS mRNA expression were significantly reduced. Damaged surface epithelium with disrupted glandular architecture and heavy leucocyte infiltration of lamina propria was noticed. Immunohistochemical staining of stomach mucosa revealed marked increased TNF-α and reduced eNOS. Oral administration of PLN and PPE succeeded in improving the gross mucosal picture, and all biochemical, histological, and immunohistochemical alterations.

Conclusion

Both PLN and PPE potently alleviated IND-induced gastric ulceration via increasing TAC, PGE₂, NO, eNOS mRNA, and protein expression. However, the healing effect of PLN was obviously greater than PPE-treated rats.

The effect of metformin on indomethacin-induced gastric ulcer: Involvement of nitric oxide/Rho kinase pathway

Gastric ulcer is a very common disease that represent an economic burden. Non-steroidal anti-inflammatory drugs induce ulcer in old patients and in patients with comorbidities. Indomethacin is widely used to induce gastric ulcer in animal models. Diabetic patients are highly susceptible to develop gastric ulcer. Metformin, the first line medication for the treatment of type II diabetes melilites that have many off label uses in non-diabetic patients, has been recently reported to have anti-inflammatory activities. Therefore, this research was conducted to assess the possible healing effects of metformin on gastric ulcers induced by indomethacin in rats. Indomethacin (48 mg/kg) single dose increased stomach acidity, ulcer index and induced histopathological changes. Indomethacin also decreased mucin levels and increased the activity of tumor necrosis factor-α (TNF-α), nuclear factor kappa-B (NF-κB), Rho-associated protein kinas-1 (ROCK-1) and decreased the levels of the protective nitric oxide (NO). After the induction of ulcer, rats were treated by omeprazole (30 mg/kg) or metformin (50, 100 or 200 mg/kg). Omeprazole and metformin were found to decrease stomach acidity and ulcer index, restored the histological features and increased mucin levels. Both also decreased the levels of NF-κB, TNF-α, ROCK-1 and increased NO. Metformin exerted ulcer healing effects comparable to that of omeprazole. This can be attributed, at least partly, to its anti-inflammatory activity and increasing NO levels.

Design, synthesis and molecular modeling of novel aryl carboximidamides and 3-aryl-1,2,4-oxadiazoles derived from indomethacin as potent anti-inflammatory iNOS/PGE2 inhibitors

The development of NSAIDs/iNOS inhibitor hybrids is a new strategy for the treatment of inflammatory diseases by suppression of the overproduction of PGE₂ and NO. A novel series of aryl carboximidamides 4a-g and their cyclized 3-aryl-1,2,4-oxadiazoles 5a-g counterparts derived from indomethacin 1 were synthesized. Most of the target compounds displayed lower LPS-induced NO production IC₅₀ in RAW 264.7 cells and potent in vitro iNOS and PGE2 inhibitory activity than indomethacin. Moreover, in carrageenan-induced rat paw oedema method, most of them exhibited higher in vivo anti-inflammatory activity than the reference drug indomethacin. Notably, 4 hrs after carrageenan injection, compound 4a proved to be the most potent anti-inflammatory agent in this study, with almost two- and eight-fold more active than the reference drugs indomethacin (1) and celecoxib, respectively. Compound 4a proved to be inhibitor to LPS-induced NO production, iNOS activity and PGE2 with IC₅₀ of 10.70 μM, 2.31 μM, and 29 nM; respectively. Compounds 4a and 5b possessed the lowest ulcerogenic liabilities (35% and 38%, respectively) compared to 1. Histopathological analysis revealed that compounds 4a and 5b demonstrated reduced degeneration and healing of ulcers. Molecular docking studies into the catalytic binding pocket of the iNOS protein receptor (PDB ID: 1r35) showed good correlation with the obtained biological results. Parameters of Lipinski's rule of five and ADMET analysis were calculated where compound 4a had reasonable drug-likeness with acceptable physicochemical properties so it could be used as promising orally absorbed anti-inflammatory therapy and entitled to be used as future template for further investigations.

Chemical constituents and gastro-protective potential of Pachira glabra leaves against ethanol-induced gastric ulcer in experimental rat model

Gastric ulcer is a very common illness that adversely affects a significant number of people all over the globe. Phytochemical investigation of P. glabra leaf alcohol extract (PGLE) resulted in the isolation and Characterization of a new nature compound, quercetin-3- O-α -L-rhamnosyl-(1'''-6'')-(4''- O -acetyl)-β -D-galactoside (4), in addition to seven known compounds. They are ferulic acid (1), p- coumaric acid (2), quercetin 3-O-α-L-rhamnoside-3'-O-β-D-glucoside (3), quercetin-3- O-α -L-rhamnosyl-(1'''-6'')-(4''- O -acetyl)- β -Dgalactoside (4), quercetin-3- O-β -D-galactoside (5), 7-hydroxy maltol-3-O-β-D-glucoside (6), maltol-3- O-β -D-glucoside (7), and methyl coumarate (8) that were first to be isolated from the genus Pachira. PGLE demonstrated in vitro anti-Helicobacter pylori activity. Moreover, the in vivo gastroprotective assessment of PGLE at different dosses, 100, 200, and 400 mg/kg against ethanol induced ulceration revealed a dose-dependent gastroprotection comparable to omeprazole. PGLE attenuated gastric lesions and histopathological changes triggered by ethanol. Interestingly, PGLE exhibited an anti-inflammatory effect through down-regulating the expression of nuclear factor-ĸB and pro-inflammatory enzyme cyclooxygenase-2 in the ulcer group. It also hindered apoptosis through decreasing Bax and increasing Bcl-2 expression hence decreasing Bax/Bcl2 ratio with a subsequent reduction in caspase 3 expression. Collectively, P. glabra is a rich reservoir of various phytochemicals reflecting a promising potential for alleviation of gastric ulcer through the mediation of inflammatory and apoptotic cascades.

In vivo cellular and molecular gastroprotective mechanisms of chrysin; Emphasis on oxidative stress, inflammation and angiogenesis

Gastric ulcer is one of the major gastrointestinal disorders affecting people worldwide. Despite medical advances, management of gastric ulcer and its complications remains a challenge facing medicine nowadays. In addition, currently available medicines exhibit limited efficacy and several side effects. In the current study, the potential protective effects of chrysin -naturally occurring flavonoid - were tested against indomethacin-induced gastric ulcer model in rats. It was found that chrysin in both doses; 50 and 100mg/kg were effective in promoting mucus secretion and preventing the rise in ulcer and lesion indices, acid production and histologic changes induced by indomethacin. During investigation of the possible underlying mechanisms, chrysin significantly attenuated indomethacin-induced oxidative injury and inflammatory response. Also, chrysin activated peroxisome proliferator activated receptor-ɣ (PPAR-ɣ) leading to a phenotypic switch from pro-inflammatory M1 macrophages to the anti-inflammatory M2 macrophages that evidenced by the upregulated mRNA expression levels of PPAR-ɣ and M2 marker genes (Arg-1 and CD206) and down regulation of M1 marker genes (IL-6 and CCL3). Furthermore, chrysin promoted angiogenesis via increasing expression of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and cluster of differentiation-31 (CD31). Collectively, these findings indicate that chrysin possesses a potential protective effect against indomethacin-induced gastric ulcer.

Gastric mucosa injury quantification in an ischemia - Reperfusion experimental model

Gastric ischemia - reperfusion (I/R) injury is an important clinical problem, which is developed in more than 80% of critically ill patients. I/R is caused by interruption of blood supply to an organ or tissue followed by blood reflow into the exposed area, leading to multiple organ failure and death. Gastric reactance has been proposed to measure tissue injury caused by ischemia. The present study evaluates a new method to quantify gastric tissue damage due to I/R, and assess its relation to gastric reactance changes. Twenty Wistar rats were randomly assigned to 4 groups: control, ischemia, I/R 30 min, I/R 1 h. Local gastric ischemia was induced by clamping the celiac artery for 30 min and reperfusion was done for 30-60 min. In all groups, gastric impedance was measured, and then gastric mucosa samples were taken for light microscopy. There were statistical significant differences (p <;0.05) among the groups with respect to the index of gastric injury proposed, which was greater in I/R 1 h group. Also, impedance parameters increased in I/R groups with respect to control, and ischemia groups. The proposed index of gastric injury allowed gastric mucosa damage quantification, and it was related with gastric impedance increase, which is an objective method to evaluate tissue injury.

Vanillin abrogates ethanol induced gastric injury in rats via modulation of gastric secretion, oxidative stress and inflammation

Vanillin is commonly used as an additive in food, medicine and cosmetics, but its effect has not yet been studied in gastric injury. Therefore the effect of vanillin was studied in experimental gastric ulcer. Gastric secretion and acidity were studied in pylorus ligated rats. Ulcer index, levels of gastric mucus, malondialdehyde (MDA), myeloperoxidase activity (MPO), expression of nuclear factor kappa B (NF-κB) p65, and histopathological changes were determined in ethanol induced gastric ulcer. Pre treatment with vanillin significantly reduced gastric secretion (P < 0.001) and acidity (P < 0.0001) and gastric ulcer index scores (P < 0.001). and augmented the gastric mucosal defense. Vanillin significantly restored the depleted gastric wall mucus levels (P < 0.0001) induced by ethanol and also significantly attenuated ethanol induced inflammation and oxidative stress by the suppression of gastric MPO activity (P < 0.001), reducing the expression of NF-κB p65 and the increased MDA levels (P < 0.001). Vanillin was also effective in alleviating the damage to the histological architecture and the activation of mast cells induced by ethanol.

Together the results of this study highlight the gastroprotective activity of vanillin in gastric ulcers of rats through multiple actions that include inhibition of gastric secretion and acidity, reduction of inflammation and oxidative stress, suppression of expression of NF-κB, and restoration of the histological architecture.

Morin protects gastric mucosa from nonsteroidal anti-inflammatory drug, indomethacin induced inflammatory damage and apoptosis by modulating NF-κB pathway

BACKGROUND

Deregulation in prostaglandin (PG) biosynthesis, severe oxidative stress, inflammation and apoptosis contribute to the pathogenesis of nonsteroidal anti-inflammatory drug (NSAID)-induced gastropathy. Unfortunately, most of the prescribed anti-ulcer drugs generate various side effects. In this scenario, we could consider morin as a safe herbal potential agent against IND-gastropathy and rationalize its action systematically.

METHODS

Rats were pretreated with morin for 30 min followed by IND (48 mgkg(-1)) administration for 4 h. The anti-ulcerogenic nature of morin was assessed by morphological and histological analysis. Its effects on the inflammatory (MPO, cytokines, adhesion molecules), ulcer-healing (COXs, PGE(2)), and signaling parameters (NF-κB and apoptotic signaling) were assessed by biochemical, RP-HPLC, immunoblots, IHC, RT-PCR, and ELISA at the time points of their maximal changes due to IND administration.

RESULTS

IND induced NF-κB and apoptotic signaling in rat's gastric mucosa. These increased proinflammatory responses, but reduced the antioxidant enzymes and other protective factors. Morin reversed all the adverse effects to prevent IND-induced gastric ulceration in a PGE2 independent manner. Also, it did not affect the absorption and/or primary pharmacological activity of IND.

CONCLUSIONS

The gastroprotective action of morin is primarily attributed to its potent antioxidant nature that also helps in controlling several IND-induced inflammatory responses.

GENERAL SIGNIFICANCE

For the first time, the study reveals a mechanistic basis of morin mediated protective action against IND-induced gastropathy. As morin is a naturally abundant safe antioxidant, future detailed pharmacokinetic and pharmacodynamic studies are expected to establish it as a gastroprotective agent.

Vasopressin Aggravates Cardiopulmonary Bypass-Induced Gastric Mucosal Ischemia

Background/Aim: Upper gastrointestinal bleeding (UGIB) is one of the most frequent gastrointestinal complications after cardiac surgery with cardiopulmonary bypass (CPB). Endothelin expression and microcirculatory dysfunction have been shown to be involved in UGIB. The aim of this study was to analyze the effect of vasopressin during CPB on the gastric mucosal microcirculation and the involvement of the endothelin system. Methods: Eighteen pigs were randomized into three groups (n = 6 each): group I = sham, group II = CPB (1-hour CPB) and group III = CPB + vasopressin (1-hour CPB and vasopressin administration during CPB to maintain baseline arterial pressure). All animals were observed for a further 90 min after termination of CPB. Systemic hemodynamics as well as blood flow and oxygen saturation of the gastric mucosa were measured continuously. At the end of the experiment, the gastric mucosal expressions of endothelin-1 (ET-1) and its receptor subtypes A (ETA) and B (ETB) were determined by polymerase chain reaction. Gastric mucosal injury, apoptotic cell death and leukocytic infiltration were determined by histology and immunohistochemical analyses of cleaved caspase-3 and myeloperoxidase. Results: CPB decreased gastric microvascular perfusion, which was associated with an increased expression of ET-1 and ETA. Vasopressin aggravated the CPB-associated malperfusion, whereas it completely abrogated the upregulation of ET-1 and ETA. Interestingly, vasopressin did not induce gastric mucosal morphologic injury, leukocytic infiltration or apoptotic cell death. Conclusion: Vasopressin aggravates CPB-associated microvascular malperfusion of the gastric mucosa but does not induce gastric mucosal injury.

Gastric antisecretory and antiulcer activity of bovine hemoglobin

AIM: To investigate gastric antisecretory and gastroprotective activity of bovine hemoglobin (B-Hb) in rats.

METHODS: Adult Albino-Wistar rats were divided into groups of 6 animals each. B-Hb in doses of 100, 300 and 900 mg/kg body weight was tested for gastric acid secretion and antiulcer activity. Gastric secretions were measured 6 h after pylorus ligation in rats pretreated with B-Hb. The acidity was measured by titrating gastric contents against 0.01 mol/L NaOH to pH 7. Indomethacin ulcers were produced by oral administration of 30 mg/kg bw in the rats pretreated with B-Hb one hour before indomethacin. Six hours after indomethacin stomach removed and ulcer index was recorded. Ethanol ulcer were produced by 1 mL of ethanol in the rats pretreated with B-Hb 30 min before the ethanol. One hour after ethanol stomach were cut open to score ulcers. Histological examination and analysis of gastric wall mucus, non-protein sulfhydryl groups (NP-SH), and myeloperoxidase (MPO) were carried in gastric tissue following ethanol administration.

RESULTS: In control rats pylorus ligation for 6 h resulted in the accumulation of 8.1 ± 0.61 mL of gastric secretion. The treatment of the rats with 100, 300 and 900 mg/kg of B-Hb produced a significant decrease in the volume of gastric secretion 5.6 ± 0.63, 5.5 ± 0.75 and 4.7 ± 0.58 mL respectively as compared to the control group [analysis of variance (ANOVA) F = 4.77, P < 0.05]. The lesion area in the control group was found to be 22.4 ± 3.2 mm² six hours after the administration of indomethacin. Treatment of rats with B-Hb at doses of 100 mg/kg (24.3 ± 3.29 mm²), 300 mg/kg (16.2 ± 1.45 mm²) and 900 mg/kg (12.6 ± 1.85 mm²) produced a dose dependent decreased the lesion scores (ANOVA F = 4.50, P < 0.05). The ulcer index following one hour after 1 mL ethanol was 7.1 ± 0.31. Pretreatment of rats with B-Hb at the doses of 100 mg/kg (2.5 ± 0.42), 300 mg/kg (2.1 ± 0.4) and 900 mg/kg (0.7 ± 0.21) significantly inhibited the formation of gastric lesions (ANOVA F = 63.26, P < 0.0001). Histological examination of gastric mucosa following ethanol showed significant lesions in the form of gastric pits with detachment of the surface epithelium; vacuolation of epithelial cells and elongation of microvessels. The changes were dose-dependently attenuated by B-Hb. The treatment of rats with ethanol significantly decreased the Alcian blue binding capacity of gastric wall mucus (480 ± 25.6 μg Alcian blue/g of tissue) as compared to control rats (667 ± 25.8 μg). Pretreatment of rats with B-Hb at the doses of 100 mg/kg (516 ± 31.6 μg/g), 300 mg/kg (558 ± 28.8 μg/g) and 900 mg/kg (654 ± 33.8 μg/g) significantly attenuated ethanol induced depletion of gastric wall mucus (ANOVA F = 8.05, P < 0.005). A significant and dose dependent increase of gastric mucosal NP-SH (ANOVA F = 19.62, P < 0.001) and decrease in MPO activity (ANOVA F = 3.1, P < 0.05) was observed in B-Hb treated rats.

CONCLUSION: B-Hb possesses significant gastric antisecretory and gastroprotective activity against experimentally induced gastric lesion. The gastroprotective effects of B-Hb are accompanied by inhibition of neutrophils activity, reduction of oxidative stress and maintenance of mucosal integrity.

Anti-ulcerogenic activity of the root bark extract of the African laburnum "Cassia sieberiana" and its effect on the anti-oxidant defence system in rats

BACKGROUND

Despite the widespread use of roots of Cassia sieberiana in managing several health conditions including gastric ulcer disease, there is little scientific data to support the rational phytotherapeutics as an anti-ulcer agent. This paper reports an evaluation of the in vivo anti-oxidant properties of an aqueous root bark extract of C. sieberiana in experimental gastric ulcer rats in a bid to elucidate its mechanism of action.

METHODS

Fisher 344 (F(344)) rats received pretreatment of C. sieberiana root bark extract (500, 750, and 1000 mg/kg body wt.) for 7 days after which there was induction of gastric injury with absolute ethanol. The mean ulcer index (MUI) was calculated and serum total anti-oxidant level determined. Gastric mucosal tissues were prepared and the activity level of the enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and myeloperoxidase (MPO) were measured together with the level of lipid hydroperoxides (LPO). Statistical difference between treatment groups was analysed using one-way analysis of variance (ANOVA) followed by Dunnett's post hoc t test. Statistical significance was calculated at P< 0.05.

RESULTS

The administration of ethanol triggered severe acute gastric ulcer and pretreatment with C. sieberiana root bark extract significantly and dose dependently protected against this effect. The root bark extract also dose dependently and significantly inhibited the ethanol induced decrease in activity levels of the enzymes SOD, CAT and GPx. The extract also inhibited the ethanol-induced decrease in level of serum total anti-oxidant capacity. The increase in ethanol-induced LPO level and MPO activity were also significantly and dose-dependently inhibited by the root bark extract.

CONCLUSIONS

The gastro-cytoprotective effect, inhibition of decrease in activity of gastric anti-oxidant enzymes and MPO as well as the inhibition of gastric LPO level suggests that one of the anti-ulcer mechanisms of C. sieberiana is the anti-oxidant property.

2,3-Dimercaptopropanol, a thiol chelator, alleviates gastroduodenal ulcers in rats

Earlier studies have implicated reactive oxygen species and transitional metals in the pathogenesis of gastric lesions. In this study, we have evaluated the effect of 2,3-dimercaptopropanol (DMP), a thiol compound and metal chelator, on chemically induced gastroduodenal ulcers in rats. Acid secretion studies were undertaken using pylorus-ligated rats pretreated with DMP (3-100 mg/kg, i.p.). The effect of orally administered DMP on cysteamine-induced duodenal ulcers and ethanol-induced gastric ulcers was also tested. The level of nonprotein sulfhydryls (NP-SH) and gastric wall mucus was measured in the glandular stomach of rats treated with ethanol. None of the dose of DMP affected the volume or acidity of gastric secretion. Low doses of DMP (3 and 10 mg/kg) significantly reduced cysteamine-induced duodenal ulcers, whereas the high doses (30 and 100 mg/kg) were ineffective in this model. All the doses of DMP significantly and dose dependently attenuated ethanol-induced gastric lesions. The adverse effects of ethanol on gastric wall mucus and NP-SH were significantly and dose dependently reversed by DMP. In conclusion, the protective effects of DMP appear to be independent of gastric acid secretion and may be associated with counteracting the oxidative stress by replenishing glutathione and reducing the pool of transition metals.

Protective effect of a cysteine prodrug and antioxidant, L-2-oxothiazolidine-4-carboxylate, against ethanol-induced gastric lesions in rats

Earlier studies have suggested an important role of glutathione (GSH) in cytoprotection against free radicals induced oxidative damage. This study reports gastroprotective effects of a cysteine precursor, L-2-oxothiazolidine-4-carboxylate (OTC), in experimental models of gastric secretion and ulceration. Acid secretion studies (volume and acidity) were undertaken in pylorus-ligated rats whereas the gastric lesions were induced by ethanol. Different groups of animals were treated with OTC (0, 100, 200 and 400 mg/kg). The levels of gastric wall mucus, nonprotein sulfhydryls (NP-SH) and myeloperoxidase (MPO) were measured in the glandular stomach of rats following ethanol-induced gastric lesions. Both medium and high doses of OTC significantly reduced the volume and acidity of gastric secretion in pylorus-ligated rats. Pretreatment with OTC significantly and dose-dependently attenuated the formation of ethanol-induced gastric lesion. OTC significantly protected the gastric mucosa against ethanol-induced depletion of gastric wall mucus, NP-SH and MPO. The gastroprotective effects of OTC may be attributed to its ability to inhibit neutrophils activity and replenish GSH demand.

Gastric submucosal microdialysis in the detection of rat stomach ischemia--a comparison of the 3H2O efflux technique with metabolic monitoring

Microdialysis has been utilized for nutritive blood flow measurements, but both the advantages and disadvantages of various approaches have not been evaluated in parallel in the stomach yet. Our aim was to compare the (3)H(2)O efflux technique with biochemical monitoring during temporary celiac artery occlusion in anesthetized rats. Microdialysis probes were implanted in the gastric submucosa and perfused with (3)H(2)O; samples were analyzed for β-activity, glucose, lactate, pyruvate and glycerol. Gastric mucosa and plasma were subjected to morphometry and analysis of myeloperoxidase, total thiols and lactatdehydrogenase. The most dramatic responses to ischemia were observed in lactate/pyruvate and lactate/glucose (%) ratios (6.1-9.3×, p < 0.0001); the changes in (3)H(2)O efflux and glycerol were less pronounced (1.1-1.7×, p < 0.0001 and < 0.01, respectively). (3)H(2)O efflux correlated best with the lactate/glucose ratio and glucose alone (r = 0.693 and -0.681, respectively, p < 0.0001). A correlation was also found between plasma lactatdehydrogenase and relative glycerol release (r = 0.600, p < 0.05). Myeloperoxidase, lactatdehydrogenase and histology score were increased by ischemia/reperfusion (0.06-0.12 nkat g(-1), p < 0.05, 0.26-0.44 nkat g(-1), p < 0.05 and 1.79-2.33, p < 0.05, respectively), macroscopy and plasma thiols remained unchanged. Microdialysis is useful in monitoring gastric ischemia, metabolic monitoring being superior to the (3)H(2)O efflux technique. The results question the efficacy of the utilized model to produce standardized major gastric damage.

Effects of esomeprazole on glutathione levels and mitochondrial oxidative phosphorylation in the gastric mucosa of rats treated with indomethacin

Proton pump inhibitors exert their preventive and healing effects on gastropathy induced by nonsteroidal anti-inflammatory drug (NSAIDs) by a dual action: the antisecretory and the antioxidant effect. The latter was investigated by using esomeprazole against indomethacin-induced gastric mucosa lesions in rats and assessed by a histomorphometric analysis. Treatment by intragastric gavage were 1% methocel as vehicle; esomeprazole 10, 30, or 60 micromol/kg; indomethacin 100 micromol/kg; and esomeprazole 10, 30, or 60 micromol/kg plus indomethacin 100 micromol/kg. The evaluation of glutathione (GSH) levels and respiratory chain complex activities [nicotinamide adenine dinucleotide, reduced (NADH)-ubiquinone oxidoreductase, succinate dehydrogenase, cytochrome C reductase, cytochrome oxidase] was performed in the isolated gastric mucosa. Esomeprazole (10-60 micromol/kg) dose dependently reversed, up to complete recovery, the inhibitory effect of indomethacin on GSH levels (approximately 60% inhibition) and mitochondrial enzyme activities (inhibition ranging from 60% to 75%). Indomethacin-induced mucosal injuries were reduced by esomeprazole. Thus, in addition to inhibiting acid secretion, the gastroprotective effect of esomeprazole can be ascribed to a reduction in gastric oxidative injury.

Gastric antisecretory and antiulcer effects of simvastatin in rats

BACKGROUND AND AIM

Recently, statins have appeared to have additional benefits beyond their lipid lowering effects, which has led to the interest in the use of this class of drugs outside the realm of cardiovascular disease. Simvastatin (SIM) is a commonly prescribed statin with anti-inflammatory and antioxidant properties. Excessive generation of oxygen-derived free radicals (ODFR) and proinflammatory mediators has been implicated in the pathogenesis of gastric ulcers. This investigation aimed to study the effect of SIM on experimentally induced gastric acid secretion and ulcer formation.

METHODS

Adult Wistar rats were divided into experimental groups containing six animals. Acid secretion studies were undertaken using pylorus-ligated rats pretreated with SIM (20, 40, and 60 mg/kg). The effect of orally administered SIM was also studied on indomethacin- and ethanol-induced gastric ulcers. The levels of myeloperoxidase (MPO), non-protein sulfhydryls (NP-SH), nitric oxide (NO), antioxidant enzymes, and gastric wall mucus were measured in the glandular stomach of rats following ethanol-induced gastric lesions.

RESULTS

Administration of SIM significantly and dose-dependently inhibited the volume of gastric secretion and the acidity. Pretreatment with SIM significantly reduced the formation of indomethacin- and ethanol-induced gastric lesions. The antiulcer activity of SIM was associated with significant attenuation of adverse effects of ethanol on gastric wall mucus, NP-SH and MPO. SIM modified the gastric NO levels and reversed the ethanol-induced decrease in glutathione-S-transferase and increase in superoxide dismutase and catalase.

CONCLUSIONS

These findings clearly suggest the involvement of proinflammatory agents and ODFR in the pathogenesis of gastric lesions. The gastroprotective effects of SIM are mediated by inhibition of neutrophils activity, reduction of oxidative stress, and maintenance of vascular integrity. This study was conducted in rats; its relevance to human gastric ulcers is not known and warrants further study.

Bromophenacyl bromide, a phospholipase A2 inhibitor attenuates chemically induced gastroduodenal ulcers in rats

AIM: To study the effect of bromophenacyl bromide (BPB), a phospholipase A₂ inhibitor on gastric secretion and to protect chemically induced gastric and duodenal ulcers in rats.

METHODS: Acid secretion studies were undertaken in pylorus-ligated rats with BPB treatment (0, 5, 15 and 45 mg/kg). Gastric and duodenal lesions in the rats were induced by ethanol and cysteamine respectively. The levels of gastric wall mucus, nonprotein sulfhydryls (NP-SH) and myeloperoxidase (MPO) were also measured in the glandular stomach of rats following ethanol induced gastric lesions.

RESULTS: BPB produced a dose-dependent inhibition of gastric acid secretion and acidity in rats. Pretreatment with BPB significantly attenuated the formation of ethanol induced gastric lesion. BPB also protected intestinal mucosa against cysteamine-induced duodenal ulcers. The antiulcer activity of BPB was associated with significant inhibition of ethanol-induced depletion of gastric wall mucus, NP-SH and MPO. These findings pointed towards the mediation of sulfhydryls in BPB induced gastrointestinal cytoprotection.

CONCLUSION: BPB possesses significant antiulcer and cytoprotective activity against experimentally induced gastroduodenal lesions.

The antioxidative and antihistaminic effect of Nigella sativa and its major constituent, thymoquinone on ethanol-induced gastric mucosal damage

The aim of this study was to assess the possible protective effects of Nigella sativa (NS) and its constituent, thymoquinone (TQ) on ethanol-induced gastric mucosal damage in an experimental model. Forty male rats aged four months were divided into four groups (each group containing ten animals); the control group received physiologic saline (10 ml kg(-1)) and the ethanol group had taken 1 ml (per rat) absolute alcohol by gavage. The third and fourth groups also received NS (500 mg kg(-1)) and TQ (10 mg kg(-1)) by gavage 1 h before alcohol administration, respectively. Both drugs (NS and TQ) could protect the gastric mucosa against the injurious effect of absolute alcohol and promote ulcer healing as evidenced from the ulcer index values. Gastric damage was confirmed histomorphometrically by significant increases in the number of mast cells (MC) and gastric erosions in ethanol treated rats. The NS treatment significantly decreased the number of MC and reduced the area of gastric erosions. Likewise, TQ treatment was also able to reduce the number of MC and the gravity of gastric mucosal lesions, but to lesser extent compared to NS. Gastric tissue histamine levels and myeloperoxidase activities were found to be increased in ethanol treated rats, and NS or TQ treatment reversed these increases. Results obtained from this study suggest that both drugs, particularly NS could partly protect gastric mucosa from acute alcohol-induced mucosal injury, and these gastroprotective effects could be due to their antiperoxidative, antioxidant and antihistaminic effects.

Mechanisms of protection by pantoprazole against NSAID-induced gastric mucosal damage

The use of nonsteroidal anti-inflammatory drugs (NSAIDs) can be associated with severe adverse digestive effects. In clinical settings, proton pump inhibitors have proven to be effective in preventing and healing NSAID-induced gastroduodenal lesions. The present study investigates the mechanisms of protection afforded by pantoprazole against gastric injury induced by different NSAIDs in rats. Animals were orally treated with indomethacin (100 micromol/kg), diclofenac (60 micromol/kg), piroxicam (150 micromol/kg) or ketoprofen (150 micromol/kg). Thirty minutes before NSAIDs, animals received pantoprazole 6 or 60 micromol/kg orally. Four hours after NSAIDs, the following parameters were assessed: histomorphometric evaluation of gastric mucosal damage; gastric mucosal levels of myeloperoxidase (MPO), malondialdehyde (MDA), reduced glutathione as an index of non-proteic sulfhydryl compounds (GSH), and prostaglandin E2 (PGE2); mucosal cyclooxygenase-1 and -2 (COX-1, COX-2) mRNA expression by reverse transcription-polymerase chain reaction (RT-PCR). Separate experiments were carried out to assay the effects of pantoprazole on gastric acid secretion in pylorus-ligated rats. The in vitro influence of pantoprazole (1-10 microM) on the oxidation of low density lipoproteins (LDLs) induced by copper sulphate was also examined. All NSAIDs elicited mucosal necrotic lesions associated with neutrophil infiltration and reduction of PGE2 levels. Increments of MPO and MDA contents, as well as a decrease in GSH levels, were detected in the gastric mucosa of indomethacin-, piroxicam- or ketoprofen-treated animals. Indomethacin enhanced mucosal COX-2 expression, while not affecting COX-1. At the oral dose of 6 micromol/kg pantoprazole did not affect NSAID-induced mucosal damage, whereas at 60 micromol/kg it markedly reduced injuries provoked by all test NSAIDs. Pantoprazole 60 micromol/kg also reversed the effects of NSAIDs on MPO, MDA, and GSH mucosal contents, without interfering with the decrease in PGE2 levels or indomethacin-induced COX-2 expression. However, at both doses, pantoprazole inhibited acid secretion in pylorus-ligated rats. Furthermore, pantoprazole concentration dependently reduced the in vitro oxidation of LDLs. Our results suggest that besides inhibiting acid secretion, the protection afforded by pantoprazole against NSAID-induced gastric damage depends on a reduction in mucosal oxidative injury, which may also account for an increment of sulfhydryl radical mucosal bioavailability. It is also suggested that pantoprazole does not influence the down-regulation of gastric prostaglandin production associated with NSAID treatment.

Lansoprazole prevents experimental gastric injury induced by non-steroidal anti-inflammatory drugs through a reduction of mucosal oxidative damage

AIM: This study investigated the mechanisms of protection afforded by the proton pump inhibitor lansoprazole against gastric injury induced by different non-steroidal anti-inflammatory drugs (NSAIDs) in rats.

METHODS: Male Sprague-Dawley rats were orally treated with indomethacin (100 µmol/kg), diclofenac (60 µmol/kg), piroxicam (150 µmol/kg) or ketoprofen (150 µmol/kg). Thirty minutes before NSAIDs, animals were orally treated with lansoprazole 18 or 90 µmol/kg. Four hours after the end of treatments, the following parameters were assessed: gastric mucosal PGE2, malondialdehyde (MDA), myeloperoxidase (MPO) or non-proteic sulfhydryl compounds (GSH) levels; reverse transcription-polymerase chain reaction (RT-PCR) of mucosal COX-2 mRNA; gastric acid secretion in pylorus-ligated animals; in vitro effects of lansoprazole (1-300 µmol/L) on the oxidation of low density lipoproteins (LDLs) induced by copper sulphate.

RESULTS: All NSAIDs elicited mucosal necrotic lesions which were associated with neutrophil infiltration and reduction of PGE2 levels. Increments of MPO and MDA contents, as well as a decrease in GSH levels were detected in the gastric mucosa of indomethacin- or piroxicam-treated animals. Indomethacin enhanced mucosal cyclooxygenase-2 expression, while not affecting cyclooxygenase-1. At the oral dose of 18 µmol/kg lansoprazole partly counteracted diclofenac-induced mucosal damage, whereas at 90 µmol/kg it markedly prevented injuries evoked by all test NSAIDs. Lansoprazole at 90 µmol/kg reversed also the effects of NSAIDs on MPO, MDA and GSH mucosal contents, without interfering with the decrease in PGE2 levels or indomethacin-induced cyclooxygenase-2 expression. However, both lansoprazole doses markedly inhibited acid secretion in pylorus-ligated rats. Lansoprazole concentration-dependently reduced the oxidation of LDLs in vitro.

CONCLUSION: These results suggest that, besides the inhibition of acid secretion, lansoprazole protection against NSAID-induced gastric damage depends on a reduction in mucosal oxidative injury, which is also responsible for an increment of sulfhydryl radical bioavailability. It is also suggested that lansoprazole does not influence the down-regulation of gastric prostaglandin production associated with NSAID treatment.

Menadione protects gastric mucosa against ethanol-induced ulcers

Previous studies have shown a definite role of mitogen activated protein kinase (MAPK) and epidermal growth factors (EGF) in the maintenance and repair of gastric mucosa. The aim of this study is to investigate the effect of menadione, an activator of MAPK pathway, on gastric acid secretion and experimentally induced gastric ulcer in rats. Acid secretion studies were undertaken using pylorus-ligated rats pretreated with menadione (5 - 45 mg/kg, i.p.). The effect of orally administered menadione on ethanol-induced gastric ulcers was also examined. The level of gastric wall mucus, non-protein sulfhydryls (NP-SH) and myeloperoxidase (MPO) was measured in the glandular stomach of rats following ethanol-induced gastric lesions. There was a significant inhibition of gastric acid secretion in the menadione treated rats. Pretreatment of rats with menadione significantly protected gastric mucosa against ethanol-induced gastric lesion. A significant attenuation of ethanol-induced reduction of gastric wall mucus, depletion of NP-SH and increase in gastric MPO activity was also observed in menadione treated rats. In conclusion, this study clearly showed acid antisecretory and antiulcer activity of menadione. Further studies are warranted to determine the mechanism of antiacid and gastroprotective effect of menadione.

Computer-assisted visualization and quantitation of experimental gastric lesions in rats

INTRODUCTION

Photography is commonly used to evaluate macroscopic morphology of experimental gastric lesions. The conventional methods for quantitation of these lesions tend to be highly subjective, error-prone, and tedious. This study reports a simple and novel method for visualization of experimental gastric lesions by direct scanning of stomach samples and their quantitation by using computer-assisted image analysis.

METHODS

Gastric mucosal lesions were produced by indomethacin or ethanol in male Wistar rats. The stomachs were removed, opened along the greater curvature, and washed. The flattened stomach samples were sandwiched within a transparent plastic folder and scanned. The captured image was saved and subjected to lesion quantitation using a freely accessible image analysis program, Scion Image. A macro subroutine was optimized for automation of the entire procedure for ease in frequent applications.

RESULTS

The images obtained by direct scanning of stomach samples showed excellent morphologic visualization of gastric lesions. The standard spots having variable areas of same density, or same areas of variable densities, showed a direct relation with signal intensity (pixels). A linear correlation was observed between measured and actual values of the known standard areas. The representative samples of indomethacin- and ethanol-induced gastric ulcers showed the total lesion areas of 4.62+/-0.74 and 169.26+/-13.23 mm(2), respectively.

DISCUSSION

Direct scanning of stomach samples is a simple, cost-effective, rapid, and efficient procedure for morphologic evaluation of experimental gastric lesions. The output images of scanned stomach samples are superior to scanned photographs, and can be instantly used for quantitative assessment of mucosal injury using the image analysis program.

Mechanisms of gastroprotection by lansoprazole pretreatment against experimentally induced injury in rats: role of mucosal oxidative damage and sulfhydryl compounds

This study investigated the mechanisms involved in the protective actions exerted by lansoprazole against experimental gastric injury. Following the intraluminal injection of ethanol-HCl, the histomorphometric analysis of rat gastric sections demonstrated a pattern of mucosal lesions associated with a significant increase in the mucosal contents of malondialdehyde and 8-iso-prostaglandin F(2alpha) (indices of lipid peroxidation), as well as a decrease in the levels of mucosal sulfhydryl compounds, assayed as reduced glutathione (GSH). Pretreatment with lansoprazole 90 micromol/kg, given intraduodenally as single dose or once daily by intragastric route for 8 days, significantly prevented ethanol-HCl-induced gastric damage. The concomitant changes in the mucosal levels of malondialdehyde, 8-iso-prostaglandin F(2alpha) and GSH elicited by ethanol-HCl were also counteracted by lansoprazole. In separate experiments, performed on animals undergoing 2-h pylorus ligation, lansoprazole did not enhance the concentration of prostaglandin E(2), bicyclo-prostaglandin E(2), or nitric oxide (NO) metabolites into gastric juice. Western blot analysis revealed the expression of both type 1 and 2 cyclooxygenase (COX) isoforms in the gastric mucosa of pylorus-ligated rats. These expression patterns were not significantly modified by single-dose or repeated treatment with lansoprazole. Lansoprazole also exhibited direct antioxidant properties by reducing 8-iso-prostaglandin F(2alpha) generation in an in vitro system where human native low-density lipoproteins were subjected to oxidation upon exposure to CuSO(4). The present results suggest that the protective effects of lansoprazole can be ascribed to a reduction of gastric oxidative injury, resulting in an increased bioavailability of mucosal sulfhydryl compounds. It is also proposed that lansoprazole does not exert modulator effects on the gastric expression of COX isoforms as well as on the activity of NO pathways.

Methimazole prevents stress and chemical induced gastropathy in rats

This investigation was undertaken to study the effect of methimazole (MMI) on gastric acid secretion and stress and chemically induced gastric ulcer in rats. Acid secretion studies were undertaken using pylorus-ligated rats pretreated with MMI (10-100 mg/kg, i.p.). The effect of orally administered MMI on water-immersion restraint (WIR) stress, indomethacin and ethanol-induced gastric ulcers was also tested. The level of myeloperoxidase (MPO), non-protein sulfhydryls (NP-SH) and gastric wall mucus was measured in the glandular stomach of rats following ethanol-induced gastric lesions. There was a dose-dependent inhibition of gastric acid secretion and ulcerogen induced gastric lesion formation in the MMI treated rats. Our morphological and histological studies showed a complete prevention of ethanol-induced lesions in the rats treated with high dose (100 mg/kg) of MMI. A significant attenuation of ethanol-induced increase in gastric MPO activity, depletion of NP-SH and reduction of gastric wall mucus was also observed in MMI treated rats. These findings clearly suggest the involvement of endogenous pro-inflammatory agents and oxidative stress in mediating the gastroprotective effect of MMI.