Sayuri Kato

Induction of a 72-kDa heat-shock protein in cultured rat gastric mucosal cells and rat gastric mucosa by zinc L-carnosine.

An antiulcer drug, zinc l-carnosine (polaprezinc), provides gastric mucosal protection against various irritants. In this study, we evaluated the effects of zinc l-carnosine on expression of 72-kDa heat shock protein (HSP72, stress inducible HSP70), which is known as an endogenous cytoprotectant in a wide variety of cells, including rat gastric mucosa in vitro and in vivo. Expression of HSP72 after exposure to zinc l-carnosine, zinc sulfate, or l-carnosine (1–300 μM) in rat gastric mucosal cells (RGM1) and intragastric administration of zinc l-carnosine, zinc sulfate (30 or 100 mg/kg) and l-carnosine (76 mg/kg) was investigated by western blotting and densitometric analysis. Exposure to zinc l-carnosine and zinc sulfate increased the expression of HSP72 significantly in RGM1 cells. Intragastric administration of zinc l-carnosine and zinc sulfate showed significant increment in HSP72 in rat gastric mucosa also in vivo. The ability to induce HSP72 is significantly higher in zinc l-carnosine compared with zinc sulfate based on molecular concentration in vivo. However, l-carnosine did not increase the expression of HSP72 in vitro and in vivo. Zinc derivatives, especially zinc l-carnosine, could be a strong HSP72 (chaperon) inducer, which has been known to enhance mucosal protective ability.

Systemic stress increases serum leptin level.

Background and Aim:  Leptin, the product of the obese (ob) gene, is a circulating peptide mainly synthesized by adipocytes. Leptin inhibits food intake and decreases body weight. A recent report has suggested that the gastric mucosa is also the source of leptin, and that the stomach leptin also contributes to the regulation of the serum leptin level. The aim of the present study was to investigate the effect of water‐immersion stress on serum, stomach and adipose tissue leptin levels to understand the relationship between stress and eating behavior.

FR167653, a potent suppressant of interleukin-1 and tumor necrosis factor-alpha production, ameliorates colonic lesions in experimentally induced acute colitis.

Background: Interleukin‐1 (IL‐1) and tumor necrosis factor‐α (TNF‐α) are believed to play a significant role in the pathogenesis of inflammatory bowel disease (IBD). Interleukin‐1 and TNF‐α possess overlapping and synergetic activities inducing the production in cascade of other cytokines, adhesion molecules, arachidonic acid metabolites, as well as activating immune and non‐immune cells. FR167653 (C24H18FN5O2.H2SO4.H2O) is a newly synthesized organic compound with a potent inhibitory effect on IL‐1β and TNF‐α production. We hypothesized that the suppression of IL‐1 and TNF‐α induced by FR167653 could effectively attenuate experimentally induced colonic damage.

Effects of cyclosporin A on water-immersion stress-induced gastric lesion and gastric secretion in rats.

Abstract: Cyclosporin A is an immunosuppressive agent which is well known as a specific inhibitor of calcineurin (protein phosphatase 2B). In this study, we investigated the effects of cyclosporin A on water-immersion stress-induced gastric ulcer formation and gastric acid secretion in rats. We also examined the localization of calcineurin immunohistochemically. Calcineurin was specifically expressed in gastric parietal cells and chief cells of the gastric mucosa. The intraperitoneal administration of cyclosporin A dose-dependently suppressed the development of gastric mucosal lesions induced by water-immersion stress and inhibited gastric acid secretion, as assessed by pylorus ligation. These results indicated that calcineurin may play an important role in gastric acid secretion.

Corticosteroid pretreatment prevents small intestinal mucosal damage induced by acetic acid-perfusion model in rats

One of the important problems in experimentally induced small intestinal lesions is that there is no reproducible model of diffuse and stable mucosal lesion. In this paper, we studied in detail the effects of continuous perfusion of various concentrations of acetic acid on the rat small intestinal mucosa. In order to evaluate its applicability for screening of the preventive effect of drugs on gut damage, we also evaluated the efficacy of corticosteroid pretreatment in preventing acetic acid-induced mucosal lesion. Male Sprague-Dawley rats were fasted for 12 hr, and the small intestinal lumen was perfused with 1%, 1.5%, 2.5%, 3%, 3.75% (pH 2.4–2.6) acetic acid or saline (control) at 1 ml/min for 15 min. In separate experiments, the effect of preadministration of budesonide (0.5 or 0.75 mg/kg/day) and prednisone (0.75 mg/kg/day) on 1.5% acetic acid-induced mucosal damage was investigated. Macroscopic and microscopic lesions occurred diffusely in a concentration-dependent fashion. Histological findings revealed signs of transmural inflammation characterized by mucosal–submucosal edema, ulceration, and neutrophil infiltration. Mucosal–submucosal height had an inverse relation with the acetic acid concentrations perfused. Myeloperoxidase activity levels increased several-fold in the acetic acid-perfused groups. Corticosteroid pretreatment prevented microscopic damage and was associated with reduction of MPO activity levels in 1.5% acetic acid-perfused rats. We conclude that this simple and reproducible model could be applied for the screening of new drugs in the gastrointestinal tract in which large numbers of animals are taken into account.