No abstract

No abstract

1 Capsaicin sensitive a erent nerves play an important role in gastric mucosal defensive mechanisms. Capsaicin stimulates a erent nerves and enhances the release of calcitonin gene-related peptide (CGRP), which seems to be the predominant neurotransmitter of spinal a erents in the rat stomach, exerting many pharmacological e ects by a direct mechanism or indirectly through second messengers such as nitric oxide (NO). 2 Lafutidine is a new type of anti-ulcer drug, possessing both an antisecretory e ect, exerted via histamine H 2 receptor blockade, and gastroprotective activities. Studies with certain antagonists or chemical dea erentation techniques suggest the gastroprotective actions of lafutidine to be mediated by capsaicin sensitive a erent nerves, but this is an assumption based on indirect techniques. In order to explain the direct relation of lafutidine to a erent nerves, we conducted the following studies.3 We determined CGRP and NO release from rat stomach and speci®c [ 3 H]-resiniferatoxin (RTX) binding to gastric vanilloid receptor subtype 1 (VR1), which binds capsaicin, using EIA, a microdialysis system and a radioreceptor assay, respectively. 4 Lafutidine enhanced both CGRP and NO release from the rat stomach induced by a submaximal dose of capsaicin, but had no e ect on speci®c [ 3 H]-RTX and capsaicin binding to VR1. 5 In conclusion, our ®ndings demonstrate that lafutidine modulates the activity of capsaicin sensitive a erent nerves in the rat stomach, which may be a key mechanism involved in its gastroprotective action.

Abstract.Helicobacter pylori (H. pylori) infection of gastric epithelial cells has been shown to induce interleukin (IL)-8 production, but the signal transduction mechanism leading to IL-8 production has not been clearly defined. Here, we investigate the role of protein kinase C (PKC) in the mechanism of induction of IL-8 release by H. pylori in human gastric epithelial cells. In MKN45 cells, H. pylori-induced IL-8 release was enhanced by treatment with PKC inhibitors (GF109203X and calphostin C) and PKC depletion, which completely inhibited PKC activity. Moreover, PKC inhibitors and PKC depletion increased extracellular signal-regulated kinase (ERK) activity and phosphorylation, but not calcium / calmodulin-dependent protein kinase II (CaMK II) activity, in response to H. pylori infection. PKC activated by H. pylori inhibited activation of ERK induced by H. pylori without affecting the CaMK II activity and negatively regulated IL-8 production in human gastric epithelial cells.

These results suggest that lafutidine inhibits IL-8 release by inhibiting H. pylori adherence to gastric epithelial cells, indicating a novel mechanism by which lafutidine protects against the mucosal inflammation associated with H. pylori infection.

Helicobacter pylori (H. pylori) is a pathogen responsible for chronic gastritis and peptic ulcer diseases. It colonises the gastric mucus layer and adheres to the gastric epithelial cell surface. As this adherence is the first step of infection, it is important to study the adherence mechanism. The aim of this study was to analyse the specific binding assay of H. pylori to HEp-2 cells and three gastric phenotype cell lines, AGS, MKN-45 and AZ-521. H. pylori NCTC 11637 grown on agar plates was harvested and used in experiments. H. pylori was inoculated to pre-cultured cell monolayers. Adhered bacteria were labelled with an anti-H. pylori antibody and an FITC-conjugated secondary antibody and quantified by using a fluorescent plate reader. Microbial adherence to HEp-2 cells increased with incubation time and incubated concentration of H. pylori. No further increase was obtained with four or more hours of incubation or with a concentration of 4 x 10(7) bacteria/well or more. Scatchard analysis revealed a linear plot and the Bmax value was 88.3. Similar adherence patterns were obtained when AGS, AZ-521 and MKN-45 cells were used for adherence assays, but they had a lower binding affinity than HEp-2 cells and AZ-521. MKN-45 cells had less receptors than HEp-2 and AGS cells. In conclusion, H. pylori adhered to the cell surface could be quantified by this assay method. H. pylori adhesion to cell surfaces has a single population of binding site and one type of binding site on HEp-2, AGS, AZ-521 and MKN-45 cells.

No abstract

No abstract