Nicotine Modulates Mitochondrial Dynamics in Hippocampal Neurons

Mdivi-1 alleviates nicotine-induced human periodontal ligament cells injury by inhibiting mitochondrial fission and dysfunction through the JNK/Drp1 pathway

BACKGROUND

Nicotine, a major component of tobacco, is implicated in the pathogenesis of periodontitis. However, the exact mechanisms through which nicotine exerts its harmful effects remain incompletely understood. This study investigates the impact of nicotine-induced mitochondrial fission on human periodontal ligament cells (hPDLCs).

METHODS

A range of assays, including MTT, immunofluorescence staining, flow cytometry, and western blotting, were utilized to evaluate hPDLC viability, apoptosis, mitochondrial fission, and function.

RESULTS

Nicotine decreases hPDLC viability in a dose-dependent manner, leading to apoptosis, an elevated BAX/BCL-2 ratio, and cellular injury. Furthermore, nicotine induces phosphorylation of Drp1 at Ser616, which facilitates mitochondrial fission, elevates mitochondrial ROS production, reduces mitochondrial membrane potential, and lowers ATP generation, resulting in mitochondrial dysfunction. Inhibition of Drp1 phosphorylation by Mdivi-1 significantly alleviates mitochondrial fission and dysfunction, reduces nicotine-induced apoptosis, and promotes osteogenic differentiation.

CONCLUSION

Nicotine activates c-Jun N-terminal kinase (JNK), and the inhibition of JNK activity with SP600125 effectively prevents nicotine-induced mitochondrial fission, enhances cell viability, and inhibits Drp1 phosphorylation.

Nicotine-induced transcriptional changes and mitochondrial dysfunction in the ventral tegmental area revealed by single-nucleus transcriptomics

Nicotine is widely recognized as the primary contributor to tobacco dependence. Previous studies have indicated that molecular and behavioral responses to nicotine are primarily mediated by ventral tegmental area (VTA) neurons, and accumulating evidence suggests that glia play prominent roles in nicotine addiction. However, VTA neurons and glia have yet to be characterized at the transcriptional level during the progression of nicotine self-administration. Here, a male mouse model of nicotine self-administration is established and the timing of three critical phases (pre-addiction, addicting, and post-addiction phase) is characterized. Single-nucleus RNA sequencing in the VTA at each phase is performed to comprehensively classify specific cell subtypes. Adaptive changes occurred during the addicting and post-addiction phases, with the addicting phase displaying highly dynamic neuroplasticity that profoundly impacts the transcription in each cell subtype. Furthermore, significant transcriptional changes in energy metabolism-related genes are observed, accompanied by notable structural alterations in neuronal mitochondria during the progression of nicotine self-administration. The results provide insights into mechanisms underlying the progression of nicotine addiction, serving as an important resource for identifying potential molecular targets for nicotine cessation.

Preventive Effects of Crocin, a Key Carotenoid Component in Saffron, Against Nicotine-Triggered Neurodegeneration in Rat Hippocampus: Possible Role of Autophagy and Apoptosis

Background

Nicotine is a behavioral stimulant that in high doses, through the neuro-inflammatory and oxidative stress pathway, can induce apoptosis and autophagy leading to cell death. Previous data indicate that crocin has neuroprotective properties. The aim of the current study is to investigate crocin's neuroprotective effects against nicotine-triggered neuro-inflammation, apoptosis, and autophagy in rat hippocampus.

Methods

Seventy adult male Wistar rats were divided into the following seven groups: Group one received normal saline (0.2 ml/rat), group two was treated with nicotine 10 mg/kg intraperitoneally, groups 3 to 6 were treated simultaneously with nicotine and crocin (10, 20, 40, and 80 mg/kg, intraperitoneally), group 7 was treated with crocin-alone (80 mg/kg, intraperitoneally). The period of the mentioned agent administration was 21 days. On the 22nd day, an open field test (OFT) was used for evaluation of anxiety and motor activity changes. Inflammatory and oxidative stress factors and also apoptosis and autophagy biomarkers were evaluated.

Results

All mentioned doses of crocin could decrease the nicotine-induced OFT behavioral changes. Crocin also could decrease levels of hippocampal TNF/TNF-α (tumor necrosis factor), IL1B/IL-1β (interleukin 1 beta), oxidized glutathione (GSSG), unphosphorylated and phosphorylated forms of JNK, BECN1 (beclin 1), BAX (BCL2 associated X, apoptosis regulator), and phosphorylated/inactive forms of BCL2 (BCL2 apoptosis regulator) in nicotine-dependent rats. Crocin treatments also caused increases in the reduced form of glutathione (GSH) content and activity of CAT (catalase) and mitochondrial complex enzymes in nicotine-addicted subjects.

Conclusions

Crocin can modulate JNK-BCL2-BECN1 or JNK-BCL2-BAX signaling pathways and reduce neuronal oxidative stress, neuro-inflammation, and mitochondrial respiratory chain enzymes and exert neuroprotective effects against nicotine-induced neurodegeneration.

Metabolic network analysis of pre-ASD newborns and 5-year-old children with autism spectrum disorder

Classical metabolomic and new metabolic network methods were used to study the developmental features of autism spectrum disorder (ASD) in newborns (n = 205) and 5-year-old children (n = 53). Eighty percent of the metabolic impact in ASD was caused by 14 shared biochemical pathways that led to decreased anti-inflammatory and antioxidant defenses, and to increased physiologic stress molecules like lactate, glycerol, cholesterol, and ceramides. CIRCOS plots and a new metabolic network parameter,V ° net, revealed differences in both the kind and degree of network connectivity. Of 50 biochemical pathways and 450 polar and lipid metabolites examined, the developmental regulation of the purine network was most changed. Purine network hub analysis revealed a 17-fold reversal in typically developing children. This purine network reversal did not occur in ASD. These results revealed previously unknown metabolic phenotypes, identified new developmental states of the metabolic correlation network, and underscored the role of mitochondrial functional changes, purine metabolism, and purinergic signaling in autism spectrum disorder.

Nicotinic acetylcholine receptors in cancer: Limitations and prospects

Nicotinic acetylcholine receptors (nAChRs) have long been considered to solely mediate neurotransmission. However, their widespread distribution in the human body suggests a more diverse physiological role. Additionally, the expression of nAChRs is increased in certain cancers, such as lung cancer, and has been associated with cell proliferation, epithelial-to-mesenchymal cell transition, angiogenesis and apoptosis prevention. Several compounds that interact with these receptors have been identified as potential therapeutic agents. They have been tested as drugs for treating nicotine addiction, alcoholism, depression, pain and Alzheimer's disease. This review focuses on nAChR-mediated signalling in cancer, presenting opportunities for the development of innovative nAChR-based anticancer drugs. It displays the differences in expression of each nAChR subunit between normal and cancer cells for selected cancer types, highlighting their possible involvement in specific cases. Antagonists of nAChRs that could complement existing cancer therapies are summarised and critically discussed. We hope that this review will stimulate further research on the role of nAChRs in cancer potentially leading to innovative cancer therapies.

Mitochondria oxidative stress mediated nicotine-promoted activation of pancreatic stellate cells by regulating mitochondrial dynamics

Nicotine, one of the main ingredients of cigarettes, promotes activation of pancreatic stellate cells(PSCs) and exacerbates pancreatic fibrosis in previous studies. Here we focus on the inner relationship between mitochondrial oxidative stress and mitochondrial dynamics to explore the possible mechanism. Primary human PSCs were stimulated by nicotine. The effect of nicotine on oxidative stress and mitochondrial dynamics was analyzed by reactive oxygen species (ROS) assay, quantitative real-time PCR, and western blotting. Mitochondrial morphology was observed. Antioxidant and small interfering RNA transfection were applied to explore the interrelationship between oxidative stress and mitochondrial dynamics, as well as its effect on PSCs activation. Nicotine exposure significantly increased Intracellular and mitochondrial ROS of hPSCs and promoted mitochondrial fission by upregulating dynamin-related protein 1(DRP1). Knockdown Drp1 reversed mitochondrial fragmentation and hPSCs activation that promoted by nicotine, but fail to alleviate oxidative stress. A mitochondrial-targeted antioxidant could reverse all the above changes. Our finding suggests that mitochondria oxidative stress mediated nicotine-promoted activation of PSCs by inducing Drp1-mediated mitochondrial fission, provides a new perspective on the possible mechanism by which nicotine affects PSCs, and reveals a potential therapeutic strategy.

Alterations of Mitochondrial Network by Cigarette Smoking and E-Cigarette Vaping

Toxins present in cigarette and e-cigarette smoke constitute a significant cause of illnesses and are known to have fatal health impacts. Specific mechanisms by which toxins present in smoke impair cell repair are still being researched and are of prime interest for developing more effective treatments. Current literature suggests toxins present in cigarette smoke and aerosolized e-vapor trigger abnormal intercellular responses, damage mitochondrial function, and consequently disrupt the homeostasis of the organelle's biochemical processes by increasing reactive oxidative species. Increased oxidative stress sets off a cascade of molecular events, disrupting optimal mitochondrial morphology and homeostasis. Furthermore, smoking-induced oxidative stress may also amalgamate with other health factors to contribute to various pathophysiological processes. An increasing number of studies show that toxins may affect mitochondria even through exposure to secondhand or thirdhand smoke. This review assesses the impact of toxins present in tobacco smoke and e-vapor on mitochondrial health, networking, and critical structural processes, including mitochondria fission, fusion, hyper-fusion, fragmentation, and mitophagy. The efforts are focused on discussing current evidence linking toxins present in first, second, and thirdhand smoke to mitochondrial dysfunction.

Targeting Mitochondria by Plant Secondary Metabolites: A Promising Strategy in Combating Parkinson's Disease

Parkinson’s disease (PD) is one of the most prevalent and debilitating neurodegenerative conditions, and is currently on the rise. Several dysregulated pathways are behind the pathogenesis of PD; however, the critical targets remain unclear. Accordingly, there is an urgent need to reveal the key dysregulated pathways in PD. Prevailing reports have highlighted the importance of mitochondrial and cross-talked mediators in neurological disorders, genetic changes, and related complications of PD. Multiple pathophysiological mechanisms of PD, as well as the low efficacy and side effects of conventional neuroprotective therapies, drive the need for finding novel alternative agents. Recently, much attention has been paid to using plant secondary metabolites (e.g., flavonoids/phenolic compounds, alkaloids, and terpenoids) in the modulation of PD-associated manifestations by targeting mitochondria. In this line, plant secondary metabolites have shown promising potential for the simultaneous modulation of mitochondrial apoptosis and reactive oxygen species. This review aimed to address mitochondria and multiple dysregulated pathways in PD by plant-derived secondary metabolites.

Schisandrin Restores the Amyloid β-Induced Impairments on Mitochondrial Function, Energy Metabolism, Biogenesis, and Dynamics in Rat Primary Hippocampal Neurons

INTRODUCTION

Schisandrin which is derived from Schisandra chinensis has shown multiple pharmacological effects on various diseases including Alzheimer's disease (AD). It is demonstrated that mitochondrial dysfunction plays an essential role in the pathogenesis of neurodegenerative disorders.

OBJECTIVE

Our study aims to investigate the effects of schisandrin on mitochondrial functions and metabolisms in primary hippocampal neurons.

METHODS

In our study, rat primary hippocampal neurons were isolated and treated with indicated dose of amyloid β1-42 (Aβ1-42) oligomer to establish a cell model of AD in vitro. Schisandrin (2 μg/mL) was further subjected to test its effects on mitochondrial function, energy metabolism, mitochondrial biogenesis, and dynamics in the Aβ1-42 oligomer-treated neurons.

RESULTS AND CONCLUSIONS

Our findings indicated that schisandrin significantly alleviated the Aβ1-42 oligomer-induced loss of mitochondrial membrane potential and impaired cytochrome c oxidase activity. Additionally, the opening of mitochondrial permeability transition pore and release of cytochrome c were highly restricted with schisandrin treatment. Alterations in cell viability, ATP production, citrate synthase activity, and the expressions of glycolysis-related enzymes demonstrated the relief of defective energy metabolism in Aβ-treated neurons after the treatment of schisandrin. For mitochondrial biogenesis, elevated expression of peroxisome proliferator-activated receptor γ coactivator along with promoted mitochondrial mass was found in schisandrin-treated cells. The imbalance in the cycle of fusion and fission was also remarkably restored by schisandrin. In summary, this study provides novel mechanisms for the protective effect of schisandrin on mitochondria-related functions.

Systematic Review of Nicotine Exposure's Effects on Neural Stem and Progenitor Cells

While various modalities of chronic nicotine use have been associated with numerous negative consequences to human health, one possible benefit of nicotine exposure has been uncovered. The discovery of an inverse correlation between smoking and Parkinson's disease, and later Alzheimer's disease as well, motivated investigation of nicotine as a neuroprotective agent. Some studies have demonstrated that nicotine elicits improvements in cognitive function. The hippocampus, along with the subventricular zone (SVZ), is a distinct brain region that allow for ongoing postnatal neurogenesis throughout adulthood and plays a major role in certain cognitive behaviors like learning and memory. Therefore, one hypothesis underlying nicotine-induced neuroprotection is possible effects on neural stem cells and neural precursor cells. On the other hand, nicotine withdrawal frequently leads to cognitive impairments, particularly in hippocampal-dependent behaviors, possibly suggesting an impairment of hippocampal neurogenesis with nicotine exposure. This review discusses the current body of evidence on nicotine's effects on neural stem cells and neural progenitors. Changes in neural stem cell proliferation, survival, intracellular dynamics, and differentiation following acute and chronic nicotine exposure are examined.

C-Phycocyanin Ameliorates Mitochondrial Fission and Fusion Dynamics in Ischemic Cardiomyocyte Damage

Mitochondrial dysfunction is a predominant risk factor in ischemic heart disease, in which the imbalance of mitochondrial fusion and fission deteriorates mitochondrial function and might lead to cardiomyocyte death. C-phycocyanin (C-pc), an active component from blue-green algae, such as Spirulina platensis, has been reported to have anti-apoptosis and anti-oxidation functions. In this study, the effects of C-pc on mitochondrial dynamics of cardiomyocytes was examined using an oxygen–glucose deprivation/reoxygenation (OGD/R) model in H9c2 cells, an in vitro model to study the ischemia in the heart. Cell viability assay showed that C-pc dose-dependently reduced OGD/R-induced cell death. Intracellular reactive oxygen species production induced by OGD/R was decreased in C-pc-treated groups in a dose-dependent manner as well. H9c2 cells subjected to OGD/R showed excessive mitochondrial fission and diminished mitochondrial fusion. C-pc treatment significantly ameliorated unbalanced mitochondrial dynamics induced by OGD/R and regulated mitochondrial remodeling through inhibiting mitochondrial fission while promoting fusion. The enhanced expressions of dynamin 1-like protein and mitochondrial fission 1 protein induced by OGD/R were suppressed by C-pc, while the subdued expressions of mitochondrial fusion proteins mitofusins 1 and 2 and optic atrophy 1 induced by OGD/R increased in C-pc-treated groups. Triple immunofluorescence staining revealed that C-pc treatment reduced the recruitment of dynamin 1-like protein from cytoplasm to mitochondrial membranes. Furthermore, C-pc protected H9c2 cells against OGD/R-induced cytochrome c/apoptotic protease activating factor-1 intrinsic apoptosis and suppressed the phosphorylations of extracellular signal-regulated kinase and c-Jun N-terminal kinase. These results suggest that C-pc protects cardiomyocytes from ischemic damage by affecting mitochondrial fission and fusion dynamics and reducing apoptosis and, thus, may be of potential as a prophylactic or therapeutic agent for ischemic heart disease.

Mitochondria as a possible target for nicotine action

Mitochondria are multifunctional and dynamic organelles deeply integrated into cellular physiology and metabolism. Disturbances in mitochondrial function are involved in several disorders such as neurodegeneration, cardiovascular diseases, metabolic diseases, and also in the aging process. Nicotine is a natural alkaloid present in the tobacco plant which has been well studied as a constituent of cigarette smoke. It has also been reported to influence mitochondrial function both in vitro and in vivo. This review presents a comprehensive overview of the present knowledge of nicotine action on mitochondrial function. Observed effects of nicotine exposure on the mitochondrial respiratory chain, oxidative stress, calcium homeostasis, mitochondrial dynamics, biogenesis, and mitophagy are discussed, considering the context of the experimental design. The potential action of nicotine on cellular adaptation and cell survival is also examined through its interaction with mitochondria. Although a large number of studies have demonstrated the impact of nicotine on various mitochondrial activities, elucidating its mechanism of action requires further investigation.

Betaine enhances the cellular survival via mitochondrial fusion and fission factors, MFN2 and DRP1

Betaine is a key metabolite of the methionine cycle and known for attenuating alcoholic steatosis in the liver. Recent studies have focused on the protection effect of betaine in mitochondrial regulation through the enhanced oxidative phosphorylation system. However, the mechanisms of its beneficial effects have not been clearly identified yet. Mitochondrial dynamics is important for the maintenance of functional mitochondria and cell homeostasis. A defective mitochondrial dynamics and oxidative phosphorylation system have been closely linked to several pathologies, raising the possibility that novel drugs targeting mitochondrial dynamics may present a therapeutic potential to restore the cellular homeostasis. In this study, we investigated betaine’s effect on mitochondrial morphology and physiology and demonstrated that betaine enhances mitochondrial function by increasing mitochondrial fusion and improves cell survival. Furthermore, it rescued the unbalance of the mitochondrial dynamics from mitochondrial oxidative phosphorylation dysfunction induced by oligomycin and rotenone. The elongation properties by betaine were accompanied by lowering DRP1 and increasing MFN2 expression. These data suggest that betaine could play an important role in remodeling mitochondrial dynamics to enhance mitochondrial function and cell viability.