Search Results (57)

NAD⁺ is a fundamental molecule participating as a redox cofactor in several metabolic reactions and has a neuroprotective role associated with oxidate stress. Despite its critical role, NAD⁺ levels sharply decline with age, contributing to the pathogenesis of aging-related diseases. Supplementation with nicotinamide riboside (NR), also known as a form of vitamin B3, a biochemical precursor of NAD⁺, may replenish this depletion. Background/Objectives: Mounting evidence suggests that dietary supplementation with NR, a form of vitamin B3 and a biochemical precursor of NAD⁺, enhances NAD⁺ bioavailability and prevents the detrimental effects on sleep, cognitive function, mitochondrial function, and insulin sensitivity. However, there is a paucity of studies focused on how NR administration affects sleep patterns. This narrative review summarizes the current state of scientific knowledge on the effects of nicotinamide riboside supplementation on sleep. Results: Pre-clinical studies indicate that NR enhances the performance of the clock genes BMAL1 and PER2, and ameliorates chronic sleep deprivation-induced cognitive impairment, potentially by alleviating oxidative stress and mitochondrial impairment in microglia. NR supplementation also increased REM sleep and reduced NREM sleep by approximately 17%. In human studies, NR improved sleep efficiency in young and middle-aged male individuals with insomnia. It also improved sleep quality and reduced fatigue and drowsiness in older adults. More research is warranted to understand the impacts of NR on sleep for women. Conclusions: NR supplementation is a reliable and effective alternative to boost NAD⁺ levels and may ameliorate sleep patterns. Full article

Subclinical chronic kidney disease (sCKD) predisposes one to acute kidney injury (AKI) and chronic kidney disease (CKD). Reduced kidney functional reserve (KFR) detects sCKD in preclinical studies and predicts AKI after cardiac surgery. We evaluated renal protection in a rat model of kidney injury where ischaemia–reperfusion injury (IRI) was induced after sCKD. Dual treatment boosting nicotinamide adenine dinucleotide (NAD) by nicotinamide riboside (NR) combined with the mitochondria-targeted antioxidant SkQR1 protected the KFR and reduced structural kidney damage, including markers of vascular integrity and the relative blood volume (rBV). The dual treatment upregulated Sirt1 and Nrf2, increased the nuclear localisation of the mitochondrial biogenesis regulator PGC-1α and the mitochondrial protein marker COX4, and upregulated the antioxidant gene NOQ1. These observations suggest mitochondrial protection and modulation of the cellular redox state provided long-term structural and functional protection against kidney injury superimposed on background sCKD. Full article

Background: Nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR) are intermediary products in NAD+ metabolism. NMN and NR supplementation can elevate NAD+ levels in tissues, addressing health issues associated with aging and obesity. However, the impact of NMN and NR on atherosclerosis remains incompletely elucidated. Methods: C57BL/6J and Apolipoprotein E knockout (ApoE^−/−) mice were used to explore the impact of NMN and NR supplementation on serum lipids, fatty liver, and atherosclerosis. Additionally, various suppliers, administration protocols, and doses on ApoE^−/− mice were investigated. Results: The intragastric administration of NMN (300 mg/kg) and NR (230 mg/kg) reduced body weight, serum lipids, and fatty liver but aggravated atherosclerosis in ApoE^−/− mice after 4 months of administration with different suppliers. Atherosclerosis also deteriorated after 2 months of different NMN administration protocols (intragastric and water administration) in ApoE^−/− mice with existing plaques. The effects of NMN were dose-dependent, and doses around 100 mg/kg had little harmful effects on atherosclerosis. Conclusions: NMN and NR improve dyslipidemia and fatty liver but promote atherosclerosis in ApoE^−/− mice. These findings emphasize the safe dosage for the clinical trials of NMN. Full article

Dihydronicotinamide rioside (NRH), the reduced form of nicotinamide riboside (NR), is a recently identified, naturally occurring precursor of arguably the most crucial cofactor for cellular function, nicotinamide adenine dinucleotide (NAD+). Recent investigation suggests that NRH is more adept at increasing NAD+ stores than traditional NAD+ precursors, and such extreme NAD+ boosting via NRH supplementation induces cytotoxicity in certain cellular contexts. It has also been shown that the lack of functional BRCA protein in epithelial ovarian cancer (EOC) directly impacts intracellular NAD+ levels. Given that altered cellular metabolism and DNA repair mechanisms are central alterations in EOC, and these processes are functionally dependent on NAD+, we sought to assess whether NRH supplementation in EOC cell lines enhanced cellular cytotoxicity alone and in combination with standard therapeutic agents. Significant cytotoxicity was noted in NRH treated cells (~40%) with minimal cell death in the nicotinic acid (NA)-treated lines. Levels of NAD(P)H were confirmed to have increased with NRH supplementation, albeit at different levels among the different cell lines. Overall, the cytotoxicity associated with NRH supplementation appears to be independent of ROS generation. Strikingly, NRH supplementation enhanced cytotoxicity of carboplatin in OVCAR8, but not ES2 or SKOV3. Paclitaxel cytotoxicity was also enhanced by the addition of NRH in OVCAR8, but not ES2 or SKOV3 cell lines. NA supplementation had no effect on baseline treatment-induced cytotoxicity. PARP inhibition by olaparib requires NAD+. Interestingly, NRH supplementation enhanced olaparib cytotoxicity in SKOV3 and OVCAR8, but not ES2 cells. NRH in combination with olaparib completely altered mitochondrial respiration, thereby shutting down energy consumption, which would lead to cell death. Coupled together with expression data of key enzymes required for NRH/NAD metabolism, this could be key in understanding mechanisms of cell death with NRH supplementation. Here, we showed that in the context of EOC, exploitation of the NAD+ bioenergetic phenotype through NRH supplementation is a biologically feasible strategy to enhance the response of traditional therapy with potentially minimal toxicity. These data suggest several potential mechanisms by which cellular NAD+ availability impacts treatment efficacy and resistance and highlights the potential utility of NAD+ metabolomics as a biomarker to guide treatment decisions. Full article

Background/Objectives: Early postmortem mitochondrial function and apoptotic activation affect meat quality development. Nicotinamide riboside (NR) supplementation to pigs prior to harvest can improve pork color stability, but its mechanism remains unclear. This study aimed to evaluate the impact of NR supplementation on early postmortem mitochondrial functionality and apoptosis. Methods: Sixteen pigs (N = 16) were individually fed a control or NR-supplemented diet (30 mg·kg body weight⁻¹·d⁻¹) for 10 days prior to harvest. Longissimus dorsi muscle samples were collected at 45 min and 24 h postmortem and analyzed for mitochondrial functionality using high-resolution respirometry and apoptotic protein abundance (apoptosis regulator Bcl-2-associated X (BAX), apoptotic inducing factor (AIF), and caspase 3 (CASP3)) via immunoblotting. Results: NR-supplemented muscle exhibited lower proton leak-associated respiration at 45 min postmortem (p < 0.05), followed by a slower accumulation of mitochondrial outer membrane permeabilization (MOMP; p < 0.05) and a slower loss of mitochondrial integral function (p < 0.05) from 45 min to 24 h postmortem. NR supplementation decreased BAX abundance at 45 min postmortem but increased mature AIF abundance (62 kDa) at 24 h postmortem (p < 0.05). The abundance of CASP3 fragments (~29 kDa) decreased from 45 min to 24 h postmortem, independent of treatment (p < 0.05). Conclusions: NR supplementation demonstrated the potential to protect mitochondrial integral function and alleviate apoptotic activation in early postmortem porcine skeletal muscle, which might contribute to a higher meat color stability in NR-supplemented pork during retail display. Full article

Objectives: This study aims to observe the preventive effect of nicotinamide riboside (NR) on fructose-induced lipid metabolism disorders and explore its mechanism. Methods: Male C57BL/6J mice were fed a 20% fructose solution and given 400 mg/kg NR daily by gavage for 10 weeks. Results: The results indicated that NR supplementation significantly reduced the body weight, liver weight, white adipose tissue (WAT) weight, serum, and hepatic lipid levels. NR upregulated the protein expression levels of sirtuin-1 (SIRT1), AMP-activated protein kinase (AMPK), PR domain containing 16 (PRDM16), uncoupling protein 1 (UCP1), peroxisome proliferator-activated receptor-gamma coactiva-tor-1-alpha (PGC-1α), nuclear respiratory factor 1-encoding gene (NRF1), mitochondrial transcription factor A (TFAM), cluster of differentiation 137 (CD137), transmembrane protein 26 (TMEM26), and T-box 1 (TBX1). Moreover, NR enhanced the Actinobacteria and Enterorhabdus abundance. Spearman’s correlation analysis revealed that significant correlations exist between Firmicutes, Bacteroidetes, and Erysipelotrichaceae with browning-related indicators. Conclusions: In conclusion, NR could alleviate lipid metabolic abnormalities induced by fructose through activating SIRT1/AMPK-mediated browning of WAT. The mechanism by which NR improves fructose-induced lipid metabolism disorders may also be associated with the modulation of intestinal flora. Full article

Background: Targeting mitochondria and protecting the mitochondrial function of CD8⁺ T cells are crucial for enhancing the clinical efficacy of cancer immunotherapy. Objectives: In this study, our objective was to investigate the potential of nicotinamide riboside (NR) in preserving the mitochondrial function of CD8⁺ T cells and mitigating their exhaustion. Methods: We established two in vitro models to induce CD8⁺ T cell exhaustion either by tumor cell-conditioned medium (TCM) or by continuous stimulation with OVA_(257–264) peptide. CD8⁺ T cells were treated in the absence/presence of NR. Results: Our findings demonstrated that NR supplementation effectively inhibited CD8⁺ T cell exhaustion and preserved mitochondrial function in both models. Moreover, apoptosis of CD8⁺ T cells was reduced after NR treatment. Western blot data indicated that NR treatment upregulated Silent information regulator 1 (SirT1) expression. Further inhibition of Sirt1 activity using EX527 uncovered that the inhibitory effect of NR on CD8⁺ T cell exhaustion and its protective effect on mitochondria were attenuated. Conclusions: In conclusion, our results indicate that NR supplementation attenuates CD8⁺ T cell exhaustion, and its underlying mechanism is associated with increased mitochondrial function regulated by the SirT1 pathway. Our research provides evidence that NR may assist in enhancing the clinical efficacy of immunotherapy. Full article

Glioblastoma, a formidable brain tumor characterized by dysregulated NAD metabolism, poses a significant therapeutic challenge. The NAMPT inhibitor FK866, which induces NAD depletion, has shown promise in controlling tumor proliferation and modifying the tumor microenvironment. However, the clinical efficacy of FK866 as a single drug therapy for glioma is limited. In this study, we aim to disrupt NAD metabolism using fluorinated NAD precursors and explore their synergistic effect with FK866 in inducing cytotoxicity in glioblastoma cells. The synthesized analogue of nicotinamide riboside (NR), ara-F nicotinamide riboside (F-NR), inhibits nicotinamide ribose kinase (NRK) activity in vitro, reduces cellular NAD levels, and enhances FK866’s cytotoxicity in U251 glioblastoma cells, indicating a collaborative impact on cell death. Metabolic analyses reveal that F-NR undergoes conversion to fluorinated nicotinamide mononucleotide (F-NMN) and other metabolites, highlighting the intact NAD metabolic pathway in glioma cells. The activation of SARM1 by F-NMN, a potent NAD-consuming enzyme, is supported by the synergistic effect of CZ-48, a cell-permeable SARM1 activator. Temporal analysis underscores the sequential nature of events, establishing NAD depletion as a precursor to ATP depletion and eventual massive cell death. This study not only elucidates the molecular intricacies of glioblastoma cell death but also proposes a promising strategy to enhance FK866 efficacy through fluorinated NAD precursors, offering potential avenues for innovative therapeutic interventions in the challenging landscape of glioblastoma treatment. Full article

The objective of this study was to determine the daily dietary nicotinamide riboside (NR) dose required to maximize the delay of subjective muscle fatigue onset. Barrows (N = 100) were assigned to one of five treatments: a conventional swine finishing diet containing 0 (CON), 15 (15NR), 30 (30NR), 45 (45NR) mg·kg body weight⁻¹·d⁻¹ NR, or CON supplemented with 45 mg·kg body weight⁻¹·d⁻¹ NR by drench or cookie dough (DRE). All treatments were administered for the final 11 days of feeding. On supplementation d 10, barrows individually experienced a performance test at 1.09 m/s until they were subjectively exhausted. Wireless electromyography (EMG) sensors were affixed to the biceps femoris (BF), tensor fascia latae (TFL), and semitendinosus (ST) to measure real-time muscle activity. There were no treatment effects for barrow speed (p = 0.57), a tendency for a treatment effect (p = 0.07) for distance, and a treatment effect (p = 0.04) on time to exhaustion. Barrows of the 15NR and DRE treatments had greater (p = 0.05) distances to exhaustion than CON barrows but did not differ from other NR barrows (p > 0.11). Barrows in the 45NR treatment did not differ (p = 0.11) in distance from 30NR barrows but tended to have a greater (p = 0.07) distance compared to CON barrows. All other treatment comparisons did not differ (p > 0.27). Barrows in the DRE treatment moved for longer (p < 0.01) than CON barrows, but all other treatments did not differ from each other (p > 0.15). There was no treatment × period interaction for all muscles’ root mean square (RMS) values (p > 0.16), but there were Period effects for all muscles (p < 0.01) and a Treatment effect (p = 0.04) in the TFL. For all muscles, period 4 had greater RMS values than all other periods (p < 0.01), who did not differ from each other (p > 0.29). In the TFL, CON barrows had greater RMS values during the performance test compared to all NR treatments (p < 0.02), who did not differ from each other (p > 0.18). Overall, NR demonstrates potential in being a useful tool in fatigue prevention, but efficient administration of the compound needs further investigation. Full article

The URH1p enzyme from the yeast Saccharomyces cerevisiae has gained significant interest due to its role in nitrogenous base metabolism, particularly involving uracil and nicotinamide salvage. Indeed, URH1p was initially classified as a nucleoside hydrolase (NH) with a pronounced preference for uridine substrate but was later shown to also participate in a Preiss-Handler-dependent pathway for recycling of both endogenous and exogenous nicotinamide riboside (NR) towards NAD+ synthesis. Here, we present the detailed enzymatic and structural characterisation of the yeast URH1p enzyme, a member of the group I NH family of enzymes. We show that the URH1p has similar catalytic efficiencies for hydrolysis of NR and uridine, advocating a dual role of the enzyme in both NAD⁺ synthesis and nucleobase salvage. We demonstrate that URH1p has a monomeric structure that is unprecedented for members of the NH homology group I, showing that oligomerisation is not strictly required for the N-ribosidic activity in this family of enzymes. The size, thermal stability and activity of URH1p towards the synthetic substrate 5-fluoruridine, a riboside precursor of the antitumoral drug 5-fluorouracil, make the enzyme an attractive tool to be employed in gene-directed enzyme-prodrug activation therapy against solid tumours. Full article

Nicotinamide adenine dinucleotide (NAD) is one of the most important and essential components within an organism. Extensive ongoing research is aimed at harnessing its potential in managing diverse diseases by supplying various forms of NAD in its oxidized state, NAD⁺. Ultraviolet radiation (UVR) is the most common environmental exposure factor, but also carries many risks. UVR affects the epidermis and contributes to sunburn, photo-allergy, DNA damage, and certain cancers, notably melanoma. Research has shown that NAD⁺ precursors, including nicotinamide riboside (NR), reduce melanogenesis in aged melanocytes. In this study, we used NR to determine whether melanin hyperpigmentation was suppressed after light stimulation. We found that melanogenesis was inhibited when B16F10 cells treated with α-melanocyte-stimulating hormone were exposed to specific doses of NR. Additionally, tyrosinase activity (a key step in melanin production) was suppressed. However, there was no difference in the expression level of melanogenic genes. Ultraviolet B light directly stimulated HaCaT cells, inducing the RNA expression of metalloproteinases. Treatment with NR suppressed the corresponding gene expression and reduced cytotoxicity. This study demonstrates the possibility of using NR as a new skin-whitening ingredient due to its inhibitory effect on hyperpigmentation and ability to maintain skin layers affected by UVR. Full article

The administration of NAD⁺ precursors is a potential approach to protect against liver damage and metabolic dysfunction. However, the effectiveness of different NAD⁺ precursors in alleviating metabolic disorders is still poorly elucidated. The current study was performed to compare the effectiveness of four different NAD⁺ precursors, including nicotinic acid (NA), niacinamide (NAM), nicotinamide riboside (NR), and nicotinamide mononucleotide (NMN) in alleviating high-glucose-induced injury to hepatocytes in a fish model, Megalobrama amblycephala. An in vitro high-glucose model was successfully established to mimic hyperglycemia-induced damage to the liver, which was evidenced by the reduced cell viability, the increased transaminase activity, and the depletion of cellular NAD⁺ concentration. The NAD⁺ precursors all improved cell viability, with the maximal effect observed in NR, which also had the most potent NAD⁺ boosting capacity and a significant Sirt1/3 activation effect. Meanwhile, NR presented distinct and superior effects in terms of anti-oxidative stress, inflammation inhibition, and anti-apoptosis compared with NA, NAM, and NMN. Furthermore, NR could effectively benefit glucose metabolism by activating glucose transportation, glycolysis, glycogen synthesis and the pentose phosphate pathway, as well as inhibiting gluconeogenesis. Moreover, an oral gavage test confirmed that NR presented the most potent effect in increasing hepatic NAD⁺ content and the NAD⁺/NADH ratio among four NAD⁺ precursors. Together, the present study results demonstrated that NR is most effective in attenuating the high-glucose-induced injury to hepatocytes in fish compared to other NAD⁺ precursors. Full article

NAD⁺ boosting via nicotinamide riboside (NR) confers anti-inflammatory effects. However, its underlying mechanisms and therapeutic potential remain incompletely defined. Here, we showed that NR increased the expression of CC-chemokine receptor 7 (CCR7) in human M1 macrophages by flow cytometric analysis of cell surface receptors. Consequently, chemokine ligand 19 (CCL19, ligand for CCR7)-induced macrophage migration was enhanced following NR administration. Metabolomics analysis revealed that prostaglandin E2 (PGE2) was increased by NR in human monocytes and in human serum following in vivo NR supplementation. Furthermore, NR-mediated upregulation of macrophage migration through CCL19/CCR7 was dependent on PGE2 synthesis. We also demonstrated that NR upregulated PGE2 synthesis through SIRT3-dependent post-transcriptional regulation of cyclooxygenase 2 (COX-2). The NR/SIRT3/migration axis was further validated using the scratch-test model where NR and SIRT3 promoted more robust migration across a uniformly disrupted macrophage monolayer. Thus, NR-mediated metabolic regulation of macrophage migration and wound healing may have therapeutic potential for the topical management of chronic wound healing. Full article

Changes in intracellular nicotinamide adenine dinucleotide (NAD⁺) levels have been observed in various disease states. A decrease in NAD⁺ levels has been noted following spinal cord injury (SCI). Nicotinamide riboside (NR) serves as the precursor of NAD⁺. Previous research has demonstrated the anti-inflammatory and apoptosis-reducing effects of NR supplements. However, it remains unclear whether NR exerts a similar role in mice after SCI. The objective of this study was to investigate the impact of NR on these changes in a mouse model of SCI. Four groups were considered: (1) non-SCI without NR (Sham), (2) non-SCI with NR (Sham +NR), (3) SCI without NR (SCI), and (4) SCI with NR (SCI + NR). Female C57BL/6J mice aged 6–8 weeks were intraperitoneally administered with 500 mg/kg/day NR for a duration of one week. The supplementation of NR resulted in a significant elevation of NAD⁺ levels in the spinal cord tissue of mice after SCI. In comparison to the SCI group, NR supplementation exhibited regulatory effects on the chemotaxis/recruitment of leukocytes, leading to reduced levels of inflammatory factors such as IL-1β, TNF-α, and IL-22 in the injured area. Moreover, NR supplementation notably enhanced the survival of neurons and synapses within the injured area, ultimately resulting in improved motor functions after SCI. Therefore, our research findings demonstrated that NR supplementation had inhibitory effects on leukocyte chemotaxis, anti-inflammatory effects, and could significantly improve the immune micro-environment after SCI, thereby promoting neuronal survival and ultimately enhancing the recovery of motor functions after SCI. NR supplementation showed promise as a potential clinical treatment strategy for SCI. Full article

Abnormal NAD⁺ signaling has been implicated in axonal degeneration in diabetic peripheral neuropathy (DPN). We hypothesized that supplementing NAD⁺ precursors could alleviate DPN symptoms through increasing the NAD⁺ levels and activating the sirtuin-1 (SIRT1) protein. To test this, we exposed cultured Dorsal Root Ganglion neurons (DRGs) to Nicotinamide Riboside (NR) or Nicotinamide Mononucleotide (NMN), which increased the levels of NAD⁺, the SIRT1 protein, and the deacetylation activity that is associated with increased neurite growth. A SIRT1 inhibitor blocked the neurite growth induced via NR or NMN. We then induced neuropathy in C57BL6 mice with streptozotocin (STZ) or a high fat diet (HFD) and administered NR or NMN for two months. Both the STZ and HFD mice developed neuropathy, which was reversed through the NR or NMN administration: sensory function improved, nerve conduction velocities normalized, and intraepidermal nerve fibers were restored. The NAD⁺ levels and SIRT1 activity were reduced in the DRGs from diabetic mice but were preserved with the NR or NMN treatment. We also tested the effect of NR or NMN administration in mice that overexpress the SIRT1 protein in neurons (nSIRT1 OE) and found no additional benefit from the addition of the drug. These findings suggest that supplementing with NAD+ precursors or activating SIRT1 may be a promising treatment for DPN. Full article