Apoptosis of rat gastric mucosa and of primary cultures of gastric epithelial cells by indomethacin: role of inducible nitric oxide synthase and interleukin-8.

In order to gain insights into indomethacin-induced gastric injury, rats were fed with indomethacin (20 mg/kg), or alternatively, the primary cultures of rat gastric epithelial cells were cultured with different doses of indomethacin (1-1000 microM). Light microscopy, electron microscopy, fluorescence microscopy, TdT-mediated dUTP-biotin nick end labelling staining, ssDNA staining and DNA fragmentation assay were employed to evaluate the levels of gastric injury and apoptosis. Cells expressing inducible nitric oxide synthase (iNOS) and interleukin (IL)-8 were localized at the rat gastric mucosa by immunohistochemistry. Administration of indomethacin to rats caused apoptosis and injury of the gastric mucosal epithelial cells. Indomethacin also induced apoptosis of primary cultures of gastric epithelial cells in a dose-dependent manner. Cells expressing iNOS and IL-8 were detected at and around the sites of gastric injury in the indomethacin-fed rats, but not in the control rats. The induction of apoptosis by indomethacin in the primary cultures of gastric epithelial cells suggests that the direct apoptotic capacity of indomethacin. iNOS and IL-8 may be involved in this process.