Reactive oxygen species have been implicated in brain injury after ischemic stroke. These oxidants can react and damage the cellular macromolecules by virtue of the reactivity that leads to cell injury and necrosis. Oxidants are also mediators in signaling involving mitochondria, DNA repair enzymes, and transcription factors that may lead to apoptosis after cerebral ischemia. Transgenic or knockout mice with cell- or site-specific prooxidant and antioxidant enzymes provide useful tools in dissecting the events involving oxidative stress in signaling and damage in ischemic brain injury.

https://journals.sagepub.com/doi/pdf/10.1097/00004647-200101000-00002

Reactive oxygen radicals in signaling and damage in the ischemic brain.

Nitric oxide (NO) is a potent vasodilator that was initially described as the mediator of endothelium-dependent relaxation (endothelium-derived relaxing factor, EDRF). It is now known that NO is produced by a variety of other cell types.Endothelium produces NO (EDRF) under basal conditions and in response to a variety of vasoactive stimuli in large cerebral arteries and the cerebral microcirculation. Endothelium-dependent relaxation is impaired in the presence of several pathophysiological conditions. This impairment may contribute to cerebral ischemia or stroke. Activation of glutamate receptors appears to be a major stimulus for production of NO by neurons. Neuronally derived NO may mediate local increases in cerebral blood flow during increases in cerebral metabolism. NO synthase-containing neurons also innervate large cerebral arteries and cerebral arterioles on the brain surface. Activation of parasympathetic fibers that innervate cerebral vessels produces NO-dependent increases in cerebral blood flo...

Nitric oxide and the cerebral circulation.

The discovery that nitric oxide (NO) functions as a signalling molecule in the nervous system has radically changed the concept of neural communication. Indeed, the adoption of the term nitrergic for nerves whose transmitter function depends on the release of NO or for transmission mechanisms brought about by NO (Moncada et al., 1997) emphasizes the specific characteristics of this mediator. The physical properties of NO prevent its storage in lipid-lined vesicles and metabolism by hydrolytic degradatory enzymes. Therefore, unlike established neurotransmitters, NO is synthesized on demand and is neither stored in synaptic vesicles nor released by exocytosis, but simply diffuses from nerve terminals. The distance of this NO diffusion (40 – 300 μm in diameter) implies that structures in the vicinity of the producing cell, both neuronal and non-neuronal, are influenced following its release. This suggests that, as well as acting as a neurotransmitter, NO has a neuromodulatory role (Garthwaite & Boulton, 1995). In addition, it diffuses into rather than binds with protein receptors on adjacent cells, and most of its known actions are the consequence of interplay with intracellular targets that would usually be regarded as secondary messengers. The activity of conventional neurotransmitters is terminated either by re-uptake mechanisms or enzymatic degradation while inactivation of NO follows reaction with a substrate. There are multiple points at which biological control can be exerted over the production and activity of conventional neurotransmitters. However, control of the synthesis of NO is the key to regulating its activity.

Endothelial NOS (eNOS) and inducible NOS (iNOS) are present in the nervous system and will be duly addressed here. However, neuronal NOS (nNOS) is the principal isoform present in said system and will be the main focus of this review. All nNOS positive neurones exhibit α-nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase activity, which has become the histochemical marker of nitrergic neurones. However, early results demonstrating this may have been limited by inappropriate fixation procedures and should be viewed with caution (Wolf, 1997). The original cloning of full-length nNOS produced what is now designated as nNOSα, and which accounts for the majority of nNOS activity in nervous tissue (Bredt et al., 1991). In addition, four splice variants have recently been identified (nNOSβ, nNOSγ, nNOSμ and nNOS-2) and these appear to exhibit distinct cellular and tissue locations (Gibson, 2001; Nakane et al., 1993; Silvagno et al., 1996; Alderton et al., 2001). In particular, there is growing evidence that nNOS biosynthesis in excitable tissues is not restricted to neurones while substantial amounts of this enzyme have been identified in skeletal muscle, where it is involved in the regulation of metabolism and muscle contractility (Stamler & Meissner, 2001).

The magnitude of literature dealing with the role of NO in the nervous system is so great that it would be impossible to include in this review the entirety of the research carried out. For logistical reasons, only groundbreaking references have been quoted, but when necessary, recent reviews dealing with specific areas within the field have been included and are intended to act as a guideline for further reading.

https://bpspubs.onlinelibrary.wiley.com/doi/pdf/10.1038/sj.bjp.0704569

NO as a signalling molecule in the nervous system

Bioimaging of nitric oxide.

Mononuclear phagocytes (monocytes, macrophages, and dendritic cells) play major roles in human immunodeficiency virus (HIV) persistence and disease pathogenesis. Macrophage antigen presentation and effector cell functions are impaired by HIV-1 infection. Abnormalities of macrophage effector cell function in bone marrow, lung, and brain likely result as a direct consequence of cellular activation and HIV replication. To further elucidate the extent of macrophage dysfunction in HIV-1 disease, a critical activation-specific regulatory molecule, nitric oxide (NO.), which may contribute to diverse pathology, was studied. Little, if any, NO. is produced by uninfected human monocytes. In contrast, infection with HIV-1 increases NO. production to modest, but significant levels (2-5 microM). Monocyte activation (with lipopolysaccharide, tumor necrosis factor alpha, or through interactions with astroglial cells) further enhances NO. production in HIV-infected cells, whereas its levels are diminished by interleukin 4. These results suggest a possible role for NO. in HIV-associated pathology where virus-infected macrophages are found. In support of this hypothesis, RNA encoding the inducible NO synthase (iNOS) was detected in postmortem brain tissue from one pediatric AIDS patient with advanced HIV encephalitis. Corresponding iNOS mRNA was not detected in brain tissue from five AIDS patients who died with less significant brain disease. These results demonstrate that HIV-1 can influence the expression of NOS in both cultured human monocytes and brain tissue. This newly described feature of HIV-macrophage interactions suggests previously unappreciated mechanisms of tissue pathology that result from productive viral replication.

https://rupress.org/jem/article-pdf/181/2/735/1106292/735.pdf

Regulation of nitric oxide synthase activity in human immunodeficiency virus type 1 (HIV-1)-infected monocytes: implications for HIV-associated neurological disease.

Potentiation of nitric oxide formation following bilateral carotid occlusion and focal cerebral ischemia in the rat: in vivo detection of the nitric oxide radical by electron paramagnetic resonance spin trapping

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Ohnishi St

Author Tools

Chat about Author

Papers

Potentiation of nitric oxide formation following bilateral carotid occlusion and focal cerebral ischemia in the rat: in vivo detection of the nitric oxide radical by electron paramagnetic resonance spin trapping