Nicotinamide mononucleotide (NMN) ameliorated Nonylphenol-induced learning and memory impairment in rats via the central 5-HT system and the NAD+/SIRT1/MAO-A pathway

E1231/NMN protects against experimental metabolic syndrome: the central role of SIRT1 in modulating AKT/Nrf2/NFκB signaling

Metabolic syndrome (MetS) is a cluster of several disorders where many challenges hinder effective treatment. The downregulation of SIRT1 or inhibition of its activity is implicated in its pathophysiology. We hypothesized that the combined SIRT1 direct activator E1231 and the SIRT1 stabilizer nicotinamide mononucleotide (NMN) could offer a novel approach to mitigate the pathophysiological features of MetS. Our results revealed that E1231 alone or combined with NMN increased SIRT1 level and activity. This SIRT1 activation was accompanied by upregulation in the IRS-1 and activation of AKT. In parallel, the Nrf2 level and activity were increased while the NFκB activity and subsequent inflammatory cytokines were decreased. Additionally, SIRT1 activation was associated with improved insulin resistance, blood pressure, lipid profile, fasting blood glucose, glucose tolerance, and kidney and liver functions. Moreover, improved liver histology, decreased hepatic fibrosis markers, and increased survival rates were observed. These protective functions were counteracted when EX527, a SIRT1 inhibitor, was dually administered with E1231. Furthermore, correlation analysis revealed that SIRT1 was negatively correlated with NFκB, insulin resistance, and oxidative stress, while positive correlations were observed between SIRT1, p-AKT, and Nrf2 activity. Random Forest regression algorithm and partial dependence plots highlighted the significant roles of SIRT1, IRS-1, p-AKT, and NFκB in predicting MetS severity. These analyses underscore the strong interconnections between these signals. This reinforces the central role of SIRT1 in coordinating a multifaceted protective response against MetS. To conclude, SIRT1 alleviates MetS by modulating AKT/Nrf2/NFκB signaling and their interactions. Further research is necessary to validate these findings.

Targeting sirtuins in neurological disorders: A comprehensive review

The sirtuin (SIRT) family is a group of seven conserved nicotinamide adenine dinucleotide-dependent histone deacetylases (SIRT1-SIRT7), which play crucial roles in various fundamental biological processes, including metabolism, aging, stress responses, inflammation, and cell survival. The role of SIRTs in neuro-pathophysiology has recently attracted significant attention. Notably, SIRT1-SIRT3 have been identified as key players in neuroprotection as they reduce neuroinflammation and regulate mitochondrial function. This review summarizes the latest research advancements in the role of the SIRT family in neurological diseases, mainly including neurodegenerative diseases, ischemia-related diseases, bleeding-related diseases, nervous system injury and other nervous system diseases, emphasizing their critical functions and associated signaling pathways, (e.g., AMPK/SIRT1/PGC-1α, AMPK/SIRT1/IL-1β/NF-κB, STAT2-SIRT4-mTOR, SIRT3/FOXO3α, and other signaling pathways in disease progression, particularly their protective roles in neurodegenerative diseases, ischemic injuries, and neural damage. Additionally, this review discusses progress in clinical studies targeting SIRT-specific small-molecule agonists and inhibitors. Further research on SIRTs may provide new insights into potential therapeutic strategies for the prevention and treatment of neurological disorders.

Nicotinamide mononucleotide mitigates neuroinflammation by enhancing GPX4-mediated ferroptosis defense in microglia

BACKGROUND

Numerous neurological diseases involving neuroinflammation, particularly microglia, contribute to neuronal death. Ferroptosis is implicated in various diseases characterized by neuronal injury. Studies showed that nicotinamide mononucleotide (NMN) inhibits both neuroinflammation and ferroptosis. However, the mechanisms of NMN in both ferroptosis and neuroinflammation remain unclear. We aimed to explore the effects of NMN on neuroinflammation and the susceptibility of microglia to ferroptosis.

METHODS

Ferroptosis markers in macroglia exposed to lipopolysaccharides (LPS) were analyzed using CCK8, flow cytometry, ELISA, and quantitative RT-PCR. The effects of NMN on LPS-induced ferroptosis in microglia were evaluated through flow cytometry, western blot, and immunofluorescence staining. RT-PCR analysis assessed the inflammatory cytokine production of microglia subjected to Ferrostatin-1-regulated ferroptosis. RNA sequencing elucidated the underlying mechanism of NMN-involved microglia ferroptosis under LPS induction. In BV2 microglia, an inhibitor of GPX4, RSL3, was employed to suppress GPX4 expression. Intracerebroventricular injection of LPS was performed to evaluate neuroinflammation and microglia activation in vivo.

RESULTS

NMN effectively rescued LPS-induced ferroptosis and improved cell viability in microglia. Co-administration of NMN and ferrostatin-1 significantly reduced proinflammatory cytokine production in microglia following the introduction of LPS stimuli. Mechanistically, NMN facilitated glutathione (GSH) production, and enhanced resistance to lipid peroxidation occurred in a manner dependent on GPX4, repressing cytokine transcription and protecting cells from ferroptosis. RNA sequencing elucidated the underlying mechanism of NMN-associated microglia ferroptosis under LPS induction. Furthermore, simultaneous injection of NMN ameliorated LPS-induced ferroptosis and neuroinflammation in mouse brains. The data from the present study indicated that NMN enhances GPX4-mediated ferroptosis defense against LPS-induced ferroptosis in microglia by recruiting GSH, thereby inhibiting neuroinflammation.

CONCLUSION

Therapeutic approaches to effectively target ferroptosis in diseases using NMN, consideration should be given to both its anti-ferroptosis and anti-inflammatory effects to attain optimal outcomes, presenting promising strategies for treating neuroinflammation-related diseases or disorders.

ERβ activation improves nonylphenol-induced depression and neurotransmitter secretion disruption via the TPH2/5-HT pathway

The aim of this study is to investigate the role of estrogen receptor β (ERβ) in nonylphenol (NP) - induced depression - like behavior in rats and its impact on the regulation of the TPH2/5-HT pathway. In the in vitro experiment, rat basophilic leukaemia cells (RBL-2H3) cells were divided into the four groups: blank group, NP group (20 μM), ERβ agonist group (0.01 μM), and NP＋ERβ agonist group (20 μM＋0.01 μM). For the in vivo experiment, 72 adult male Sprague-Dawley rats were randomly divided into following six groups: the Control, NP (40 mg/kg) group, ERβ agonist (2 mg/kg, Diarylpropionitrile (DPN)) group, ERβ inhibitor (0.1 mg/kg, 4-(2-phenyl-5,7-bis(trifluoromethyl)pyrazolo[1,5-a]pyrimidin-3-yl) phenol (PHTPP)) group, NP+ERβ agonist (40 mg/kg NP ＋ 2 mg/kg DPN) group, and NP+ERβ inhibitor (40 mg/kg NP + 0.1 mg/kg PHTPP) group, with 12 rats in each group. Each rat in drug group were given NP by gavage and/or received a single intraperitoneal injection of DPN 2 mg/kg or PHTPP 0.1 mg/kg. Both in vivo and in vitro, NP group showed a decrease in the expression levels of ERβ, tryptophan hydroxylase (TPH1), and tryptophan hydroxylase-2 (TPH2) genes and proteins, and reduced levels of DA, NE, and 5-hydroxytryptophan (5-HT) neurotransmitters. RBL-2H3 cells showed signs of cell shrinkage, with rounded cells, increased suspension and more loosely arranged cells. The effectiveness of the ERβ agonist stimulation exhibited an increase exceeding 60% in RBL-2H3 cells. The application of ERβ agonist resulted in an alleviation the aforementioned alterations. ERβ agonist activated the TPH2/5-HT signaling pathways. Compared to the control group, the NP content in the brain tissue of the NP group was significantly increased. The latency to eat for the rats was longer and the amount of food consumed was lower, and the rats had prolonged immobility time in the behavioral experiment of rats. The expression levels of ERβ, TPH1, TPH2, 5-HT and 5-HITT proteins were decreased in the NP group, suggesting NP-induced depression-like behaviours as well as disturbances in the secretion of serum hormones and monoamine neurotransmitters. In the NP group, the midline raphe nucleus showed an elongated nucleus with a dark purplish-blue colour, nuclear atrophy, displacement and pale cytoplasm. ERβ might ameliorate NP-induced depression-like behaviors, and secretion disorders of serum hormones and monoamine neurotransmitters via activating TPH2/5-HT signaling pathways.

The identification of new roles for nicotinamide mononucleotide after spinal cord injury in mice: an RNA-seq and global gene expression study

Background

Nicotinamide mononucleotide (NMN), an important transforming precursor of nicotinamide adenine dinucleotide (NAD+). Numerous studies have confirmed the neuroprotective effects of NMN in nervous system diseases. However, its role in spinal cord injury (SCI) and the molecular mechanisms involved have yet to be fully elucidated.

Methods

We established a moderate-to-severe model of SCI by contusion (70 kdyn) using a spinal cord impactor. The drug was administered immediately after surgery, and mice were intraperitoneally injected with either NMN (500 mg NMN/kg body weight per day) or an equivalent volume of saline for seven days. The central area of the spinal cord was harvested seven days after injury for the systematic analysis of global gene expression by RNA Sequencing (RNA-seq) and finally validated using qRT-PCR.

Results

NMN supplementation restored NAD+ levels after SCI, promoted motor function recovery, and alleviated pain. This could potentially be associated with alterations in NAD+ dependent enzyme levels. RNA sequencing (RNA-seq) revealed that NMN can inhibit inflammation and potentially regulate signaling pathways, including interleukin-17 (IL-17), tumor necrosis factor (TNF), toll-like receptor, nod-like receptor, and chemokine signaling pathways. In addition, the construction of a protein-protein interaction (PPI) network and the screening of core genes showed that interleukin 1β (IL-1β), interferon regulatory factor 7 (IRF 7), C-X-C motif chemokine ligand 10 (Cxcl10), and other inflammationrelated factors, changed significantly after NMN treatment. qRT-PCR confirmed the inhibitory effect of NMN on inflammatory factors (IL-1β, TNF-α, IL-17A, IRF7) and chemokines (chemokine ligand 3, Cxcl10) in mice following SCI.

Conclusion

The reduction of NAD+ levels after SCI can be compensated by NMN supplementation, which can significantly restore motor function and relieve pain in a mouse model. RNA-seq and qRT-PCR systematically revealed that NMN affected inflammation-related signaling pathways, including the IL-17, TNF, Toll-like receptor, NOD-like receptor and chemokine signaling pathways, by down-regulating the expression of inflammatory factors and chemokines.