Nitric oxide donating compounds inhibit HCl-induced gastric mucosal lesions mainly via prostaglandin

The Related Study on the Pathogenesis of Gastrointestinal Diseases in Gastrointestinal Flora and the Risk of Gastric Ulcer Carcinogenesis

Gastrointestinal diseases are common diseases of many kinds. The pathogenesis of gastrointestinal disease has not been fully understood. In this study with gastric mucosa specimen, among the three groups of chronic gastritis, gastric ulcer, and duodenal ulcer, there were differences of Helicobacter pylori (H. pylori), Lactobacillus, Prevotella, Clostridium, B. fragilis, and Enterobacteriaceae. There was no significant difference in Lactobacillus among chronic gastritis, gastric ulcers, and duodenal ulcers with fecal specimens, but there was a significant difference between these three groups and the gastric cancer group. Correlation analysis showed that six kinds of flora had a negative correlation with H. pylori, procalcitonin (PCT), tumor necrosis factor α (TNF-α), cluster of differentiation 4 (CD4+), cluster of differentiation 8 (CD8+), immunoglobulin G (IgG), and immunoglobulin M (IgM) were different in different gastrointestinal diseases, and PCT, TNF-α and CD8+ were positively correlated with H. pylori and negatively correlated with CD4+, IgM and IgG. Logistic regression analysis showed that age, recurrent gastric ulcer times, atrophic gastritis, and H. pylori were independent risk factors of gastric ulcer canceration. Therefore, we believe that gastrointestinal flora, especially H. pylori, plays a vital role in the pathogenesis of gastrointestinal diseases, and H. pylori is an essential risk factor for gastric ulcer carcinogenesis.

Inorganic nitrite therapy: historical perspective and future directions

Over the past several years, investigators studying nitric oxide (NO) biology and metabolism have come to learn that the one-electron oxidation product of NO, nitrite anion, serves as a unique player in modulating tissue NO bioavailability. Numerous studies have examined how this oxidized metabolite of NO can act as a salvage pathway for maintaining NO equivalents through multiple reduction mechanisms in permissive tissue environments. Moreover, it is now clear that nitrite anion production and distribution throughout the body can act in an endocrine manner to augment NO bioavailability, which is important for physiological and pathological processes. These discoveries have led to renewed hope and efforts for an effective NO-based therapeutic agent through the unique action of sodium nitrite as an NO prodrug. More recent studies also indicate that sodium nitrate may also increase plasma nitrite levels via the enterosalivary circulatory system resulting in nitrate reduction to nitrite by microorganisms found within the oral cavity. In this review, we discuss the importance of nitrite anion in several disease models along with an appraisal of sodium nitrite therapy in the clinic, potential caveats of such clinical uses, and future possibilities for nitrite-based therapies.

Yogurt containing Lactobacillus gasseri OLL 2716 (LG21 yogurt) accelerated the healing of acetic acid-induced gastric ulcer in rats

We have reported that LG21 yogurt containing Lactobacillus gasseri OLL 2716 (LG21 yogurt) inhibits the formation of HCl-induced acute gastric lesions through the generation of prostaglandin E₂. This study aimed to determine the role of viable Lactobacillus in the healing of acetic acid-induced chronic gastric ulcer. LG21 yogurt or γ-ray radiated LG21 yogurt was administered orally twice a day for 10 d at a dose of 5 ml/kg. LG21 yogurt significantly accelerated the healing of the ulcer, but γ-ray radiated LG21 yogurt did not. However, both yogurts significantly inhibited HCl-induced gastric erosive lesions and enhanced the generation of gastric mucosal prostaglandin E₂. From the above results, it was found that viable bacteria are needed to accelerate the healing of chronic gastric ulcer, but not to inhibit gastric lesions.

Flavonoid-rich fraction of Maytenus ilicifolia Mart. ex. Reiss protects the gastric mucosa of rodents through inhibition of both H+,K+ -ATPase activity and formation of nitric oxide

Maytenus ilicifolia Mart. ex. Reissek (Celastraceae), a medicinal plant known in Brazil as "espinheira-santa" is commonly used to treat gastric disorders. The effect of the flavonoid-rich fraction separated from the leaves was evaluated for its gastroprotective properties and the mechanism(s) involved in this activity. Intraperitoneal administration of the flavonoid-rich fraction potently protected rats from experimentally induced chronic (ED(50)=79 mg/kg) and acute gastric lesions by ethanol (ED(50)=25mg/kg) and indomethacin (ED(50)=4 mg/kg) without altering the decreased amount of cytoprotective glutathione and mucus amount in the injured gastric mucosa. A potent reduction of gastric acid hypersecretion (ED(50)=7 mg/kg, i.p.) was accompanied by a reduction of nitric oxide release (ED(50)=1.6 mg/kg, i.p.) in the gastric secretion of 2h pylorus ligated rats which suggests an important role for nitric oxide-dependent mechanisms. Inhibition of gastric acid secretion in vivo was correlated with the in vitro inhibition of rabbit gastric H(+),K(+)-ATPase activity (IC(50)=41 microg/mL). Chemical investigation of the fraction showed galactitol (25%), epicatechin (3.1%) and catechin (2%) as the majoritary components. Collectively, the results show that the flavonoid-rich fraction of Maytenus ilicifolia potently protects animals from gastric lesions with high potency through inhibition of gastric acid secretion.

Role of nitric oxide in the protective effect of rabeprazole on gastric mucosal lesions in rats

AIM: To explore the role of nitric oxide (NO) in the protective effect of rabeprazole on the gastric mucosal lesions in rats.

METHODS: Before gastric mucosal lesion was made in rats by pure alcohol, rabeprazole (20 mg/kg) was administered into the gastric chamber and Nw-nitro-l-arginine methyl ester (l-NAME, 4 mg/kg), l-arginine (250 mg/kg) and d-arginine (250 mg/kg) were injected into the vein. Gastric mucosal blood flow (GMBF) was assessed with laser Doppler flowmetry (LDF); gastric mucosal and serum NO^-₂/NO^-₃ were measured by cadmium granulation reduction and colorimetric method; and the changes of ulcer index and the severity of tissue necrosis as well as neutrophil infiltration were observed.

RESULTS: The Ulcer index of the rabeprazole group was markedly lower than that in the controls (5.5 ± 0.5 vs 25.2 ± 2.3, P < 0.01), and the degrees of tissue necrosis and neutrophil infiltration were significantly milder (necrosis ++ - +++/≤+: 1/9 vs 8/2, P < 0.01; infiltration ++ - +++/≤+: 3/7 vs 9/1, P < 0.01). The protective effect of rabeprazole was significantly decreased by prior administration of l-NAME. The inhibitory effect of l-NAME was antagonized by prior administration of l-arginine, but not d-arginine. Rabeprazole administered into the gastric chamber obviously increased GMBF, gastric mucosal and serum NO^-₂/NO^-₃, which was prevented by pretreatment with l-NAME, but the antisecretory effect of rabeprazole was not affected by l-NAME.

CONCLUSION: Rabeprazole can exert important protection against gastric mucosal lesions in rats mediated by nitric oxide, and the action of rabeprazole against gastric acid secretion contributes little to the protective effect.

Protective effect of pantoprazole on gastric mucosal lesions in rats and its mechanism

AIM: To explore the protective effect of pantoprazole on the gastric mucosal lesions in rats and its related mechanism.

METHODS: Before the gastric mucosal lesion was in-duced by pure alcohol, the rats were intravenously injected with pantoprazole (20 mg/kg), Nω-nitro-L-arginine methyl ester (L-NAME, 4 mg/kg), and L-arginine (250 mg/kg). The gastric mucosal blood flow (GMBF) was detected by laser Doppler flowmetry (LDF), and the level of NO^-₂/NO^-₃ in the gastric mucosa and serum was measured by cadmium granulation reduction and colorimetric method. The ulcer index (UI), the severity of tissue necrosis, and neutrophils infiltration were observed.

RESULTS: Compared with that in the control group, the UI was significantly decreased (5.7±2.1 vs 25.4±2.5, P <0.01), and the degrees of tissue necrosis and neutrophils infiltration were markedly lightened. The protective effect of pantoprazole was significantly decreased by L-NAME. The inhibitory effect of L-NAME was antagonized by prior administration of L-arginine. The GMBF and the content of NO^-₂/NO^-₃ in gastric mucosa and serum were increased by the intravenous administration of pantoprazole. This effect was prevented by the pretreatment of L-NAME, but the antisecretion effect of pantoprazole was not affected by L-NAME.

CONCLUSION: Pantoprazole can protect gastric muc-osa against the lesions in rats by the mediation of nitric oxide (NO), and the protective effect has no relation with its antisecretory action of gastric acid.

Yogurt containing Lactobacillus gasseri OLL2716 exerts gastroprotective action against [correction of agaisnt] acute gastric lesion and antral ulcer in rats

Yogurt containing Lactobacillus gasseri OLL2716 (LG21 yogurt) is reported to improve Helicobacter pylori-induced gastric mucosal inflammation in clinical studies. However, other beneficial effects of LG21 yogurt have not been clarified. Therefore, we examined whether LG21 yogurt exhibits a gastroprotective action against acute gastric lesion or antral ulcer in rats. Moreover, the mechanism of gastroprotective action was also evaluated. After fasting, acute gastric lesions were induced by 0.6 M HCl. Gastric mucosal folds were stained by oral administration of methyl violet. Antral ulcers were induced by the combined administration of diethyldithiocarbamate and HCl in refed rats after fasting. LG21 yogurt was orally administered before HCl treatment or staining the mucosal folds. LG21 yogurt significantly and dose-dependently inhibited the formation of acute gastric lesions, and this gastroprotective action was attenuated by pretreatment with indomethacin. LG21 yogurt also significantly increased prostaglandin E2 generation in the gastric mucosa. Stained length of gastric mucosal fold was reduced by LG21 yogurt. Antral ulcer formation was also significantly inhibited by LG21 yogurt. From the above results, it was found that the ingestion of LG21 yogurt is useful for the prevention of gastric ulcer. Moreover, endogenous prostaglandin was suggested to be one of the gastroprotective mechanisms of LG21 yogurt.

The role of nitric oxide in tissue destruction

Nitric oxide (NO) is synthesized via the oxidation of arginine by a family of nitric oxide synthases (NOS), which are either constitutive (ie. endothelial (ec)NOS and neuronal (nc)NOS) or inducible (iNOS). The production of nitric oxide plays a vital role in the regulation of physiological processes, host defence, inflammation and immunity. Pro-inflammatory effects include vasodilation, oedema, cytotoxicity and the mediation of cytokine-dependent processes that can lead to tissue destruction. Nitric oxide-dependent tissue injury has been implicated in a variety of rheumatic diseases, including systemic lupus erythematosus (SLE), rheumatoid arthritis and osteoarthritis. Conversely, the production of NO by endothelial cell NOS may serve a protective, or anti-inflammatory, function by preventing the adhesion and release of oxidants by activated neutrophils in the microvasculature. In this chapter we describe the multifaceted role of nitric oxide in inflammation and address the potential therapeutic implications of NOS inhibition.

Nitric oxide and inflammatory mediators in the perpetuation of osteoarthritis

Articular chondrocyte production of nitric oxide (NO) and other inflammatory mediators, such as eicosanoids and cytokines, are increased in human osteoarthritis. The excessive production of nitric oxide inhibits matrix synthesis and promotes its degradation. Furthermore, by reacting with oxidants such as superoxide anion, nitric oxide promotes cellular injury and renders the chondrocyte susceptible to cytokine-induced apoptosis. PGE(2) exerts anabolic and catabolic effects on chondrocytes, depending on the microenvironment and physiologic condition. The increased expression of inducible NOS (iNOS) and cyclo-oxygenase-2 (COX-2) in OA chondrocytes is largely due to the increased expression of pro-inflammatory cytokines, particularly IL-1, which act in an autocrine/paracrine fashion to perpetuate a catabolic state that leads to progressive destruction of articular cartilage. The initiating factors for the production of inflammatory mediators include altered biomechanical forces; their continued production may be augmented by an increase in extracellular matrix proteins acting through ligation of surface integrins.