Transcriptional up-regulation of nNOS in the dorsal vagal complex during low endotoxemia.

The present study analyses the expression and distribution of neuronal nitric oxide synthase (nNOS) in the brainstem of animals pre-treated with Escherichia coli or Helicobacter pylori LPS, at doses that modulate gastric motor function. Systemic administration of H. pylori LPS prevented in a dose-dependent manner (5, 40 and 100 microg kg(-1), i.v.) the increase in intragastric pressure induced by 2-deoxy-D-glucose (200 mg kg(-1), i.v.) in urethane-anaesthetized rats. Quantitative analysis showed a significant increase in the amount of nNOS mRNA induced by E. coli or H. pylori LPS (2 h later), in a segment of the brainstem containing the dorsal vagal complex (DVC). Immunohistochemical studies showed nNOS presence in the DVC of vehicle-treated rats. Both E. coli (40 microg kg(-1), i.p.) and H. pylori LPS (100 microg kg(-1), i.p.) significantly increased (2 h later) the number of nNOS immunoreactive cells in this area, mainly at the most rostral level. The present study shows that systemic administration of E. coli or H. pylori LPS induces a transcriptional up-regulation of the nNOS in the DVC of the brainstem and suggests a role for NO synthesis in this area in the control of gastric motor function under endotoxemia.