Ecabet sodium induces neuronal nitric oxide synthase-derived nitric oxide synthesis and gastric adaptive relaxation in the human stomach

Gastric adaptive relaxation (GAR) is a major factor of functional dyspepsia (FD). Nitric oxide (NO) could be the key molecule responsible for GAR. We previously reported that the physiological gastric reservoir ability can be evaluated by measuring the cross-sectional area of the proximal stomach by abdominal ultrasonography (US). Ecabet sodium (ES), a gastro-protective antiulcer agent, has been shown to improve symptoms in FD patients. We examined the effects of ES on GAR in humans and on NO synthesis in vitro. GAR was measured by US in 14 subjects, 8 of whom had a pressure sensor inserted into their stomach, after treatment with ES, placebo, or no drugs. NO was measured in SH-SY 5Y cells using a fluorescent indicator. Neuronal, endothelial and inducible NO synthase (nNOS, eNOS and iNOS, respectively) expressions were examined in SH-SY 5Y cells by Western blotting. Compared to placebo, ES induced significantly greater dilatation of the proximal stomach after the subjects drank 300-400 ml water (P < 0.05). After ES intake, the intragastric pressure did not change significantly, but it tended to be lower (n = 8; P = 0.15). ES increased NO production and nNOS expression, but not iNOS or eNOS expression, in SH-SY 5Y cells in vitro. Pretreatment with non-selective NO synthase (NOS) inhibitor, but not with iNOS-selective inhibitor, reduced NO production by ES. ES may promote GAR in humans through nNOS-related NO; therefore, it may be useful for patients with FD.