Effect of L‐tryptophan on cytoprotection against long term postprandial hyperglycemia‐induced esophageal damage in rats

Abstract

Beneficial effects of L‐tryptophan (L‐Try) have already been described by many activities in kynurenine and serotonin synthesis, redox reactions in all living cells which play key role for cancer invasion and proliferation. Recently we revealed that postprandial hyperglycemia (PPH) which characterized by hyperglycemic spikes leads to nitro‐oxidative stress and may predispose to foregut disorders. Nevertheless, the effect of L‐Try on PPH is unknown. In this study, we elaluated effect of L‐Try on NO/NOS expression in OM during PPH and abnormal PG/COX activity.Rats were used with without/with L‐Try treatment (400 mg/kg) and indomethacin (Indo, 5 mg/kg) during PPH (Kozar, 2009); oesophagus (OM) and lower oesophageal sphincter (LOS) lesions were investigated by histology score index (HIS); esophageal NO2, cNOS and iNOS via bioanalysis.PPH caused destructive lesions in the OM and LOS, accompanied by the up‐regulation of iNOS and down‐regulation of cNOS expressions, excessive NO2‐ while Indo significantly aggravated severity of these lesions; L‐Try prevented ulcerogenic response to PPH with potent up‐regulation of cNOS but did not affect synthesis NO2‐.These results suggest that L‐Try prevents L‐Try‐induced OM and LOS damage but oesophagoprotective‐promoting effect may be associated with the stimulation of endothelial metabolism, but not through an amelioration of PG/COX activity.