Chizuko Kawaguchi

Helicobacter pylori-associated gastric pro- and antioxidant formation in Mongolian gerbils

Helicobacter pylori colonized gastric mucosa is manifest in a significant neutrophil infiltration with an extensive level of oxyradical formation. Mongolian gerbil is one of the excellent models for H. pylori-infection. The present study was designed to investigate pro- and antioxidant formation in the stomach of H. pylori-positive gerbils. Fourteen male Mongolian gerbils (MGS/Sea) were orally inoculated with H. pylori (ATCC43504) (Hp group) and 15 gerbils were inoculated with the culture media (Control). H. pylori infection was confirmed by the serum anti-H. pylori IgG test. Each gerbil was evaluated 6 or 12 weeks after the inoculation. Neutrophil infiltration was assessed by the tissue MPO activity. Mucosal oxidative stress was evaluated by thiobarbituric acid-reactive substances (TBARS), total glutathione contents, glutathione peroxidase (GSHPx) activity and Cu-, Zn-superoxide dismutase (SOD) activity. In Hp group, the H. pylori was persistently infected until 12 weeks. The level of MPO activity was significantly higher in Hp group at 6 and 12 weeks. Although the levels of TBARS and total glutathione were within the same range as controls at 6 weeks, they were significantly increased at 12 weeks. However, GSHPx activity was significantly increased at 6 weeks, but became the same range with the controls at 12 weeks. SOD activity showed no significant increase in Hp group at 6 and 12 weeks. In conclusion, H. pylori inoculation induced gastric mucosal neutrophil activation and pro-oxidant formation and also increased total glutathione contents, one of the mucosal antioxidants in gerbils.

Rat CXC chemokine GRO/CINC-1 paradoxically stimulates the growth of gastric epithelial cells

Background: CXC chemokines such as interleukin (IL)‐8 are neutrophil chemoattractants, the levels of which increase in Helicobacter pylori‐infected gastric mucosa. Many investigators have focused on the chemotactic aspects of IL‐8; however, CXC chemokines are also reported to have angiogenic activity and to serve as remodelling factors. Rat GRO/CINC‐1 is a rodent counterpart of human GROα, a member of the family of CXC chemokines. Gastric mucosa infected with H. pylori is in a state of hyperproliferation, with increases in the amounts of growth factors such as hepatocyte growth factor (HGF).

Ethanol intake preceding Helicobacter pylori inoculation promotes gastric mucosal inflammation in Mongolian gerbils

Background : Mongolian gerbils have been reported to be a suitable model for Helicobacter pylori‐associated gastric mucosal injury, including gastric cancer. Although ethanol is known to be one of the harmful substances in the gastric mucosa, the relationship between ethanol and H. pylori infection remains unknown. The aim of the present study is to investigate the effect of ethanol treatment prior to H. pylori inoculation on associated gastric mucosal injury.

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

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