Everything below concerns redox cofactor. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-11-15. Numbers and descriptions here follow the published literature rather than marketing material.
The nicotinamide ring undergoes reversible reduction at the para position, converting NAD+ to NADH. This reaction transfers a hydride equivalent, not a free hydrogen atom or electron alone. Because the redox pair has a defined reduction potential, it links oxidation of fuels to respiratory chain activity. Many dehydrogenases use NAD+ as a co-substrate and produce NADH. The ratio of NAD+ to NADH reflects metabolic state and influences flux through several pathways.
NAD+ also serves as a substrate for enzymes that cleave it, including sirtuins, PARPs, and CD38. These enzymes consume NAD+ and release nicotinamide and ADP-ribose or related products. The dual roles as redox cofactor and signaling substrate connect NAD+ to DNA repair, circadian regulation, and calcium signaling. Cellular NAD+ concentrations vary by tissue, time of day, and stress exposure. How these consumption pathways interact with redox balance remains an active area of research.
Beyond redox chemistry, NAD+ serves as a substrate for enzymes that cleave the molecule and transfer its ADP-ribose moiety or remove acetyl groups. Sirtuins consume NAD+ during deacetylation, poly(ADP-ribose) polymerases use it in DNA damage responses, and CD38 enzymes hydrolyze it to signaling metabolites. These consumption pathways mean that NAD+ availability can influence gene regulation, DNA repair, and calcium signaling. Cellular NAD+ concentrations decline in some tissues with age in animal models, but whether this decline is a cause or consequence of aging in humans remains an active open question.
Nicotinamide adenine dinucleotide, commonly abbreviated NAD+, is a dinucleotide coenzyme built from an adenine nucleotide and a nicotinamide nucleotide joined by a pyrophosphate linkage. Its oxidized form carries a positive charge on the nicotinamide ring, while the reduced form, NADH, carries a hydride equivalent. The molecule participates in hundreds of oxidoreductase reactions, where it accepts or donates electrons and protons. Because it can cycle between oxidized and reduced states without net consumption, NAD+ functions as a reusable electron carrier rather than a fuel molecule.
| Property | Value | Notes |
|---|---|---|
| IUPAC name | Nicotinamide adenine dinucleotide | Oxidized dinucleotide form |
| CAS Registry Number | 53-84-9 | Common entry for beta-NAD+ |
| Molecular formula | C21H27N7O14P2 | Free acid form |
| Molar mass | 663.43 g/mol | Calculated for free acid |
| Water solubility | Freely soluble | Charged dinucleotide; less soluble in organic solvents |
In glycolysis, NAD+ accepts electrons during the oxidation of glyceraldehyde-3-phosphate, forming NADH. The tricarboxylic acid cycle and fatty acid oxidation also generate NADH, which donates electrons to the mitochondrial electron transport chain. This flow supports ATP synthesis and helps maintain the redox balance of the cell. Other dehydrogenases use NAD+ as a cofactor for biosynthetic reductions and detoxification reactions. NADH is later reoxidized to sustain continued flux through these pathways.
Beyond electron transfer, NAD+ serves as a substrate for enzymes that cleave the molecule and transfer ADP-ribose units. Sirtuins, poly(ADP-ribose) polymerases, and CD38 consume NAD+ in regulatory reactions. These activities link NAD+ availability to DNA repair, chromatin modification, calcium signaling, and metabolic stress responses. Because consumption can exceed biosynthesis under some conditions, cellular NAD+ levels are dynamic rather than fixed. Enzyme affinity and local synthesis also influence how much NAD+ is available for signaling.
Nicotinamide adenine dinucleotide, abbreviated NAD+, is a dinucleotide built from adenine, nicotinamide, two ribose sugars, and two phosphate groups. The oxidized form carries a positive charge on the nicotinamide ring, while the reduced form, NADH, is neutral. This pair acts as a reversible electron carrier in cells. NAD+ is present in bacteria, plants, animals, and fungi. Its structure allows it to accept and donate electrons without being consumed in the reactions it supports.
In redox reactions, NAD+ accepts a hydride ion, which consists of two electrons and one proton. The hydride adds to the nicotinamide ring at a specific carbon, converting NAD+ into NADH. Dehydrogenase enzymes use this step in glycolysis, the citric acid cycle, and fatty acid oxidation. NADH later donates electrons to the mitochondrial electron transport chain, helping to drive ATP synthesis. The balance between NAD+ and NADH reflects the metabolic state of a cell, and shifts in that balance can alter how pathways operate.
NAD+ stands for nicotinamide adenine dinucleotide, the oxidized form of a coenzyme found in all living cells. The molecule consists of two nucleotides, adenine and nicotinamide ribose, joined through phosphate groups. Its chemical formula is C21H27N7O14P2, and the free acid has a molar mass near 663.43 grams per mole. In redox reactions, NAD+ accepts a hydride ion and becomes NADH. The pair NAD+ and NADH participates in hundreds of metabolic reactions, including steps in glycolysis, the citric acid cycle, and oxidative phosphorylation.
In cells, NAD+ functions primarily as an electron carrier. Dehydrogenase enzymes in glycolysis and the citric acid cycle transfer hydride from substrates to NAD+, producing NADH. NADH then delivers electrons to the mitochondrial respiratory chain, supporting ATP synthesis. In fermentation, NADH is reoxidized to NAD+ so that glycolysis can continue. The balance between NAD+ and NADH helps set metabolic flux. Beyond redox, NAD+ serves as a substrate for enzymes that cleave it, including sirtuins, poly(ADP-ribose) polymerases, and CD38. These reactions consume NAD+ and release nicotinamide and ADP-ribose products.
Biosynthesis occurs through salvage, Preiss-Handler, and de novo pathways. In mammals, the salvage pathway from nicotinamide predominates, and NAMPT is often described as rate-limiting. Nicotinamide riboside and nicotinic acid enter related routes that converge on NAD+ production. Tissue NAD+ concentrations vary widely and are maintained by a balance of synthesis and consumption. Some studies report age-related declines in certain tissues, but whether these changes cause disease or can be reversed to improve human health remains an open question.
Methylnaltrexone bromide, naloxegol, and naldemedine all have similar structures, which is not far away from the chemical structure of morphine and other MOR-agonists. All contain a rigid pentacyclic structure that involves benzene ring (A), tetrahydrofuran ring (B), two cyclohexane rings (C and D) and a piperidine ring (E). The most important functional groups for the biological action of opioids are the hydroxyl group on the phenol, N-methyl group, ether bridge between C4 and C5, the double bond between carbon number C7 and C8 and the hydroxyl groups at C3 and C6. The phenolic ring and its 3-hydroxyl group is vital for the analgesic effects as the removal of the OH group decrease the analgesic activity 10-fold. There is another principle for the hydroxyl group on C6 as the removal enhances its activity. The increased activity is mainly because of the increased lipophilicity and the increased ability to cross the blood–brain barrier. Naldemedine has the hydroxyl group while methylnaltrexone bromide has a ketone group and naloxegol has an ester. The double bond between C7 and C8 is not required for the analgesic effect and reduction of the double bond will increase the activity. None of the antagonists has a double bond in their structure. The N-substituent on the skeleton is thought to determine the pharmacological behavior and its interaction with MOR. It is also thought to play a key role in distinguishing antagonists from agonists. Allyl group, a methylcyclopropyl group or a methylcyclobutyl as N-substituent groups are thought to lead antagonist activity.
== Research directions == Vaccines intended to reduce the effects of addictive drugs have been investigated since the early 2000s. The approach conjugates the drug molecule to a carrier protein so that the immune system produces antibodies that bind the drug in the bloodstream, reducing the amount that reaches the brain. Candidates have been tested against nicotine, cocaine, opioids and fentanyl. No such vaccine is licensed for use in any country. A Cochrane review found no evidence that nicotine vaccines improve long-term smoking cessation, and two phase III trials of NicVAX reported quit rates of approximately 11% in both the vaccine and the placebo groups. Anti-cocaine vaccine development has likewise not produced an approved product, and as of 2023 no pharmacological treatment for cocaine dependence had been approved. GLP-1 receptor agonist medications such as semaglutide, developed for type 2 diabetes and obesity, have attracted interest as possible treatments for substance use disorders because they act on the brain's reward system and reduce reward-driven behavior. Large observational studies have associated their use with lower rates of alcohol- and opioid-related harm; however, the small number of completed randomized controlled trials has not yet confirmed a consistent benefit, and as of 2023 specialists described these medications as promising but unproven for this indication.
Copper silicate based chemical gardens have been shown to exhibit resistive switching behavior and synaptic functions, including paired-pulse facilitation and potentiation/depression, while operating with low energy consumption using solution-based fabrication methods. That broadens the applications potential of non-equilibrium structures.
The Neuman systems model is a nursing theory based on the individual's relationship to stress, the reaction to it, and reconstitution factors that are dynamic in nature. The theory was developed by Betty Neuman, a community health nurse, professor and counselor. The central core of the model consists of energy resources (normal temperature range, genetic structure, response pattern, organ strength or weakness, ego structure, and knowns or commonalities) that are surrounded by several lines of resistance, the normal line of defense, and the flexible line of defense. The lines of resistance represent the internal factors that help the patient defend against a stressor, the normal line of defense represents the person's state of equilibrium, and the flexible line of defense depicts the dynamic nature that can rapidly alter over a short period of time. The purpose of the nurse is to retain this system's stability through the three levels of prevention:
Astrocytes are linked by gap junctions, creating an electrically coupled (functional) syncytium. Because of this ability of astrocytes to communicate with their neighbors, changes in the activity of one astrocyte can have repercussions on the activities of others that are quite distant from the original astrocyte. An influx of Ca2+ ions into astrocytes is the essential change that ultimately generates calcium waves. Because this influx is directly caused by an increase in blood flow to the brain, calcium waves are said to be a kind of hemodynamic response function. An increase in intracellular calcium concentration can propagate outwards through this functional syncytium. Mechanisms of calcium wave propagation include diffusion of calcium ions and IP3 through gap junctions and extracellular ATP signalling. Calcium elevations are the primary known axis of activation in astrocytes, and are necessary and sufficient for some types of astrocytic glutamate release. Given the importance of calcium signaling in astrocytes, tight regulatory mechanisms for the progression of the spatio-temporal calcium signaling have been developed. Via mathematical analysis it has been shown that localized inflow of Ca2+ ions yields a localized raise in the cytosolic concentration of Ca2+ ions. Moreover, cytosolic Ca2+ accumulation is independent of every intracellular calcium flux and depends on the Ca2+ exchange across the membrane, cytosolic calcium diffusion, geometry of the cell, extracellular calcium perturbation, and initial concentrations.
Sources: en.wikipedia.org
=== Infiltration to spinal cord === Infiltration from the subarachnoid space into the spinal cord occurs primarily along the perivascular tissues that surround blood vessels at the brain entrance. Infiltration from the anterior median fissure, a 3mm deep furrow on the anterior side of the spinal cord, to the anterior horn of the spinal cord, the ventral grey matter of the spinal cord, is found along the central artery. Direct infiltration of the nerve roots is also observed, mostly from the dorsal roots (the afferent sensory root of the spinal nerve) than the ventral roots (the efferent motor root of a spinal nerve). With mild infiltration, tumor cells are found diffusely in the subarachnoid space from the cervical to sacral levels. In some cases however there are no differences between spine levels. Infiltration from the subarachnoid space into the spinal cord occurs mainly along the perivascular space of the white matter. However, in some cases, direct infiltration into the spinal cord parenchyma is found together with destruction of the pia mater.
== Mechanism == Several immunological variables have been linked to MCTD and may play a role in disease etiology. The 70-kD peptide of the U1-RNP antigen appears to be a dominant autoantigen in MCTD, consisting of a 437 residue polypeptide that noncovalently binds with U1-RNA via an RNA binding region on the polypeptide spanning residues 92-202. The U1 70-kD polypeptide and RNP undergo a range of potential and demonstrated structural alterations, each of which may influence the antigenicity of the RNP complex. Autoantibodies are generally recognized as a feature of several rheumatic illnesses, including MCTD. Two investigations have provided evidence that anti-RNP antibodies have a role in the development of MCTD by linking antibody emergence to clinical illness. Beyond antibody formation, B cells can serve in a variety of other important immunological pathways, including as antigen presentation, pathogenic cytokine secretion, and tissue harm via antibody-directed mechanisms. T cells appear to have a key role in the pathophysiology of MCTD. RNP-reactive CD4+ T cells have been detected in the peripheral blood of MCTD patients. Both anti-RNP and anti-U1-RNA antibodies identified in patients' serum have typically undergone isotope shift to immunoglobulin G (IgG) subtypes. In addition, there is intense lymphocyte infiltration, with many T cells detected in the locations of tissue injury at autopsy and in patient biopsy specimens. In vitro studies have also revealed that human RNP reactive T cells can aid in the generation of anti-RNP autoantibodies.
On February 19, 2019, Pritzker signed into law a bill that raises the state minimum wage to $15 an hour by 2025, making Illinois the fifth state in the nation and first state in the Midwest to do so. The bill includes a tax credit for small businesses to help them deal with higher costs of labor and maintains the ability of restaurant owners to count tips toward pay. On April 12, 2019, Pritzker signed the Collective Bargaining Freedom Act, which protects the right of employers, employees, and their labor organizations to collectively bargain, ensuring that Illinois complies with the National Labor Relations Act. On May 17, 2019, Pritzker signed legislation to help workers exposed to toxic substances. In July 2019, Pritzker signed House Bill 2028, which passed both the Senate and House of Illinois unanimously. This bill doubles the compensation rate for families of police officers and firefighters killed in the line of duty from $10,000 to $20,000. On March 13, 2023, Pritzker signed the Paid Leave for All Workers Act, which requires employers to give employees at least an hour of paid leave for every 40 hours of work, up to 40 hours per year, which employees can use for any reason. It went into effect in 2024.
By the early 1970s, widespread civil unrest had spurred the re-emergence of anarchy as a topic of discussion and study. The viability of anarchy increasingly became a subject of research, including by those that disregarded it as undesirable. Discussions of the viability of anarchy gained traction in academic circles following the publication of American political philosopher Robert Nozick's 1974 work Anarchy, State, and Utopia. Nozick issued a challenge to mainstream political philosophy, which had become preoccupied with the question of how a state should be organised; he questioned how the existence of the state can be justified and whether anarchy was a viable alternative. Nozick suggested that anarchism be examined by political philosophy, but himself would end up advocating for a minimal state that upheld human rights, instead of complete anarchy. Public choice economists of the time, such as James M. Buchanan and Gordon Tullock, also explored anarchy's viability as a means to maintain social order, but came to characterise it in terms of lawlessness and violent social disorder. In his 1976 work Anarchy and Co-operation, American political scientist Michael Taylor argued that social order exists in counter-position to the state; and in his 1982 Community, Anarchy, and Liberty, he posited that anarchy could only exist in a stable form by maintaining social equality.
Sources: en.wikipedia.org
NAD+ is the oxidized form, while NADH is the reduced form carrying an added hydride. The two form a redox pair that cells use in many energy-yielding reactions.
NAD+ is a small organic cofactor, not a protein or enzyme. It binds temporarily to enzymes such as dehydrogenases to assist electron transfer.
Intact NAD+ is generally not taken up efficiently by most cells because it is charged and water-soluble. Cells often rely on precursors such as nicotinamide or nicotinamide riboside to produce NAD+ internally.
NAD+ is an oxidized dinucleotide coenzyme that carries electrons in metabolic reactions. It is also consumed by signaling enzymes, including sirtuins and PARPs. Its reduced form is NADH.