Dr. NO and Mr. Toxic – the versatile role of nitric oxide

Abstract

Nitric oxide (NO) is present in various organisms from humans, to plants, fungus and bacteria. NO is a fundamental signaling molecule implicated in major cellular functions. The role of NO ranges from an essential molecule to a potent mediator of cellular damages. The ability of NO to react with a broad range of biomolecules allows on one hand its regulation and a gradient concentration and on the other hand to exert physiological as well as pathological functions. In humans, NO is implicated in cardiovascular homeostasis, neurotransmission and immunity. However, NO can also contribute to cardiovascular diseases (CVDs) or septic shock. For certain denitrifying bacteria, NO is part of their metabolism as a required intermediate of the nitrogen cycle. However, for other bacteria, NO is toxic and harmful. To survive, those bacteria have developed processes to resist this toxic effect and persist inside their host. NO also contributes to maintain the host/microbiota homeostasis. But little is known about the impact of NO produced during prolonged inflammation on microbiota integrity, and some pathogenic bacteria take advantage of the NO response to colonize the gut over the microbiota. Taken together, depending on the environmental context (prolonged production, gradient concentration, presence of partners for interaction, presence of oxygen, etc.), NO will exert its beneficial or detrimental function. In this review, we highlight the dual role of NO for humans, pathogenic bacteria and microbiota, and the mechanisms used by each organism to produce, use or resist NO.

Evaluation of Indigo carmine on hepatic ischemia and reperfusion injury

“…Also, blocking calcium channels to avoid such overload proved to be able to mitigate the liver's IRI 42 . It is described in the literature the ability to block the calcium ionophores A23187 by the IC, in addition to being able to inhibit the synthesis of endothelial NO through the activation of transmembrane receptors, whose activation cascades involve calcium 18,22,43 . Since IC acts on endothelial cells by a couple of ways, being them transmembrane receptors and calcium channel, that culminates in inhibition of NO production 18 .…”

“…It is known that the control of calcium concentrations in the cytosol is critical, both in the production of NO by endothelial cells, which implies calcium increase for enzymatic process, and in the smooth muscle cell, where the relaxation of smooth muscle fiber occurs by calcium levels decrease 21 , 22 .…”

Nitric Oxide: From Gastric Motility to Gastric Dysmotility

“…In the central nervous system, nNOS is localized in the cerebellum and the brain. NO is involved in many functions, including neuronal plasticity, which helps in memory and learning processes [ 8 ].…”

“…However, it should be taken into account that the modulation of NO production is a complex mechanism complicated by the fact that there are a variety of stimuli of different nature (e.g., dietary component, inflammation, bacteria) that may also affect NOS expression [ 4 , 8 , 42 , 56 , 57 , 58 , 59 ]. Thus, some aspects on central and peripheral role of NO in health and disease that remained unsolved could be elucidated by further integrated studies, including those on gut neuro-immune interactions and bi-directional microbiota-gut-brain axis.…”

Implication of a Key Region of Six Bacillus cereus Genes Involved in Siroheme Synthesis, Nitrite Reductase Production and Iron Cluster Repair in the Bacterial Response to Nitric Oxide Stress

“…Nitric oxide (NO) stress is an important component of the eukaryotic immune response. NO is a free radical, which can be a powerful oxidizing and nitrating agent, and can react with many components of the bacterial cell [ 1 ]. In particular, it can bind and modify the properties of nucleic acids, lipids, sugars and proteins.…”