OBJECTIVETo determine whether the activation of p38 mitogen-activated protein kinase (MAPK) is involved in the pathogenesis of stress ulcer.

METHODSModel of stress ulcer was established with the treatment of rats with water-immersion restraint (WIR) stress. Ulcer index (UI) was macroscopically evaluated as a parameter of gastric mucosal lesions. Expression of phospho- and pan-p38 in gastric mucosa was detected using Western blot analysis. Tumor necrosis factor-alpha (TNF-alpha) and Interleukin 1beta (IL-1beta) gene expressions were analyzed by Northern blot analysis. As indicated in some experiments, rats were pretreated with intravenous injection of the specific p38 MAPK inhibitor CNI-1493 prior to WIR stress and then the changes of UI and TNF-alpha and IL-1beta mRNA expression were examined.

RESULTSThe p38 MAPK was persistently activated in the gastric mucosa of rats with WIR stress, with maximal activation after 1 h of stress [(6.8 +/- 3.2) fold of baseline levels, P < 0.01]. Inhibition of p38 MAPK activation with CNI-1493 led to a marked decrease in UI in WIR stress rats. Similarly, the increased gene expression of proinflammatory cytokines TNF-alpha and IL-1beta in gastric mucosa induced by WIR stress were significantly diminished by p38 MAPK inhibition.

CONCLUSIONp38 MAPK might have an important role in the pathogenesis of stress ulcer.