Biology of nitrogen oxides in the gastrointestinal tract

Abstract

Throughout the human gastrointestinal tract a variety of reactive nitrogen oxides are continuously formed as a result of a complex interplay between the host, commensal bacteria and dietary factors. These compounds include nitric oxide, nitrite, nitrate, peroxynitrite, S-nitrosothiols, nitrated fatty acids and N-nitrosamines, all of which are bioactive with the potential to affect physiological and pathological processes locally in the gut as well as systemically after absorption. Historically, the literature has been dominated by studies on the formation of potentially carcinogenic nitrosamines, but the focus was shifted in the 1980s with the seminal discovery of the L-arginine-nitric oxide pathway and its profound impact on normal physiological functions. More recently, a nitrate-nitrite-nitric oxide pathway has been discovered, with implications for local host defence and gut mucosal integrity and, intriguingly, also for systemic regulation of cardiovascular and metabolic function. This review discusses recent advances in the understanding of the formation, biochemistry, physiology and pathophysiology of reactive nitrogen oxides in the gastrointestinal tract. In addition, opportunities for nitric oxide-based pharmacological or dietary interventions are highlighted.

Characterization of the motor inhibitory role of colonic mucosa under chemical stimulation in mice

“…The lack of effects of the mucosal extracts and the reduction of motility evoked by the addition of a mucosa strip nearby the MF strip indicates that gaseous molecules should be the mediators. NO, H 2 S, and CO have been described as gaseous neurotransmitters in the enteric nervous system and also play a role in the response to gastrointestinal injury (5,8,15). Our result with specific inhibitors of their synthetic enzymes clearly demonstrates that the three of them are involved in the effects of the mucosa, which is reinforced for the lack of effects of mucosal strips previously treated with these inhibitors.…”

Protection from hypertension in mice by the Mediterranean diet is mediated by nitro fatty acid inhibition of soluble epoxide hydrolase

“…It is also plausible that some of the effects of nitrite and nitrate may also be mediated by nitroalkene formation, as the host diet, intrinsic biosynthetic mechanisms, and commensal bacteria can produce an array of unsaturated fatty acids (46,47).…”

Nitric Oxide, Its Metabolites, and Glutathione System in Children With Chronic Viral Hepatitis В and С

“…Существенное значение оксид азота и его метаболиты имеют и для различных отделов системы пищеварения [3]. Так, установлено, что у лиц с заболеваниями верхнего отдела пищеварительного тракта имеет место положи-тельная корреляция между содержанием оксида азота и объемом базальной и стимулированной желудочной секреции, т.е.…”