Neuroprotective Mechanisms of Resveratrol in Alzheimer's Disease: Role of SIRT1

Deciphering therapeutic options for neurodegenerative diseases: insights from SIRT1

Silent information regulator 1 (SIRT1) is a nicotinamide adenine dinucleotide (NAD +)-dependent protein deacetylase that exerts biological effects through nucleoplasmic transfer. Recent studies have highlighted that SIRT1 deacetylates protein substrates to exert its neuroprotective effects, including decreased oxidative stress and inflammatory, increases autophagy, increases levels of nerve growth factors (correlated with behavioral changes), and maintains neural integrity (affects neuronal development and function) in aging or neurological disorder. In this review, we highlight the molecular mechanisms underlying the protective role of SIRT1 in modulating neurodegeneration, focusing on protein homeostasis, aging-related signaling pathways, neurogenesis, and synaptic plasticity. Meanwhile, the potential of targeting SIRT1 to block the occurrence and progression of neurodegenerative diseases is also discussed. Taken together, this review provides an up-to-date evaluation of our current understanding of the neuroprotective mechanisms of SIRT1 and also be involved in the potential therapeutic opportunities of AD and related neurodegenerative diseases.

Hippocampus and its involvement in Alzheimer's disease: a review

Hippocampus is the significant component of the limbic lobe, which is further subdivided into the dentate gyrus and parts of Cornu Ammonis. It is the crucial region for learning and memory; its sub-regions aid in the generation of episodic memory. However, the hippocampus is one of the brain areas affected by Alzheimer's (AD). In the early stages of AD, the hippocampus shows rapid loss of its tissue, which is associated with the functional disconnection with other parts of the brain. In the progression of AD, atrophy of medial temporal and hippocampal regions are the structural markers in magnetic resonance imaging (MRI). Lack of sirtuin (SIRT) expression in the hippocampal neurons will impair cognitive function, including recent memory and spatial learning. Proliferation, differentiation, and migrations are the steps involved in adult neurogenesis. The microglia in the hippocampal region are more immunologically active than the other regions of the brain. Intrinsic factors like hormones, glia, and vascular nourishment are instrumental in the neural stem cell (NSC) functions by maintaining the brain's microenvironment. Along with the intrinsic factors, many extrinsic factors like dietary intake and physical activity may also influence the NSCs. Hence, pro-neurogenic lifestyle could delay neurodegeneration.

Antioxidants in Alzheimer's Disease: Current Therapeutic Significance and Future Prospects

Alzheimer's disease (AD) rate is accelerating with the increasing aging of the world's population. The World Health Organization (WHO) stated AD as a global health priority. According to the WHO report, around 82 million people in 2030 and 152 million in 2050 will develop dementia (AD contributes 60% to 70% of cases), considering the current scenario. AD is the most common neurodegenerative disease, intensifying impairments in cognition, behavior, and memory. Histopathological AD variations include extracellular senile plaques' formation, tangling of intracellular neurofibrils, and synaptic and neuronal loss in the brain. Multiple evidence directly indicates that oxidative stress participates in an early phase of AD before cytopathology. Moreover, oxidative stress is induced by almost all misfolded protein lumps like α-synuclein, amyloid-β, and others. Oxidative stress plays a crucial role in activating and causing various cell signaling pathways that result in lesion formations of toxic substances, which foster the development of the disease. Antioxidants are widely preferred to combat oxidative stress, and those derived from natural sources, which are often incorporated into dietary habits, can play an important role in delaying the onset as well as reducing the progression of AD. However, this approach has not been extensively explored yet. Moreover, there has been growing evidence that a combination of antioxidants in conjugation with a nutrient-rich diet might be more effective in tackling AD pathogenesis. Thus, considering the above-stated fact, this comprehensive review aims to elaborate the basics of AD and antioxidants, including the vitality of antioxidants in AD. Moreover, this review may help researchers to develop effectively and potentially improved antioxidant therapeutic strategies for this disease as it also deals with the clinical trials in the stated field.

Sodium-calcium exchanger isoform-3 targeted Withania somnifera (L.) Dunal therapeutic intervention ameliorates cognition in the 5xFAD mouse model of Alzheimer's disease

The third isoform of the Na+-Ca2+ exchanger (NCX3) is crucial for a physiological fine-tuning of the Ca2+ fluxes in excitable tissues. In this view, the NCX3 accounts for the aberrant Ca2+ influx seen during neuronal excitotoxicity, such as in Alzheimer's disease (AD). However, little is known about NCX3 regulation and functional properties. Withania somnifera (L.) Dunal (W. somnifera), a traditional indigenous plant widely recognized for having numerous medicinal values, was undertaken to determine its potential therapeutic benefit against aggregated Aβ1-42-induced NCX3 dysregulation and the thereof cognition impairment in 5xFAD mice. The undertaken sourced dried roots of authenticated W. somnifera physicochemical compositional tests satisfied standards of pharmacognostic quality, and further phytochemical analysis of the roots methanol extract revealed the roots constitute several antioxidants. Following an intra-gastric gavage administration of synthesized W. somnifera roots methanolic extract from postnatal day 30 (P30) to P75, in vivo cognitional studies and then neurochemical examinations of the NCX3 expression level, Aβ plaque deposition, and antioxidant activities in the AD-associated brain regions of 4-month-old 5xFAD mice suggests that the oxidative stress normalizing effects of W. somnifera constituents, operating on the NCX3, may have a therapeutic role in the improvement of cognition in AD.

Lycium barbarum extract promotes M2 polarization and reduces oligomeric amyloid-β-induced inflammatory reactions in microglial cells

Lycium barbarum (LB) is a traditional Chinese medicine that has been demonstrated to exhibit a wide variety of biological functions, such as antioxidation, neuroprotection, and immune modulation. One of the main mechanisms of Alzheimer's disease is that microglia activated by amyloid beta (Aβ) transform from the resting state to an M1 state and release pro-inflammatory cytokines to the surrounding environment. In the present study, immortalized microglial cells were pretreated with L. barbarum extract for 1 hour and then treated with oligomeric Aβ for 23 hours. The results showed that LB extract significantly increased the survival of oligomeric Aβ-induced microglial cells, downregulated the expression of M1 pro-inflammatory markers (inducible nitric oxide synthase, tumor necrosis factor α, interleukin-6, and interleukin-1β), and upregulated the expression of M2 anti-inflammatory markers (arginase-1, chitinase-like protein 3, and interleukin-4). LB extract also inhibited the oligomeric Aβ-induced secretion of tumor necrosis factor α, interleukin-6, and interleukin-1β in microglial cells. The results of in vitro cytological experiments suggest that, in microglial cells, LB extract can inhibit oligomeric Aβ-induced M1 polarization and concomitant inflammatory reactions, and promote M2 polarization.

Potential Mechanism Underlying Exercise Upregulated Circulating Blood Exosome miR-215-5p to Prevent Necroptosis of Neuronal Cells and a Model for Early Diagnosis of Alzheimer's Disease

Exercise is crucial for preventing Alzheimer's disease (AD), although the exact underlying mechanism remains unclear. The construction of an accurate AD risk prediction model is beneficial as it can provide a theoretical basis for preventive exercise prescription. In recent years, necroptosis has been confirmed as an important manifestation of AD, and exercise is known to inhibit necroptosis of neuronal cells. In this study, we extracted 67 necroptosis-related genes and 32 necroptosis-related lncRNAs and screened for key predictive AD risk genes through a random forest analysis. Based on the neural network Prediction model, we constructed a new logistic regression-based AD risk prediction model in order to provide a visual basis for the formulation of exercise prescription. The prediction model had an area under the curve (AUC) value of 0.979, indicative of strong predictive power and a robust clinical application prospect. In the exercise group, the expression of exosomal miR-215-5p was found to be upregulated; miR-215-5p could potentially inhibit the expressions of IDH1, BCL2L11, and SIRT1. The single-cell SCENIC assay was used to identify key transcriptional regulators in skeletal muscle. Among them, CEBPB and GATA6 were identified as putative transcriptional regulators of miR-215. After "skeletal muscle removal of load," the expressions of CEBPB and GATA6 increased substantially, which in turn led to the elevation of miR-215 expression, thereby suggesting a putative mechanism for negative feedback regulation of exosomal homeostasis.

Modulation of Sirt1-mTORC1 Pathway in Microglia Attenuates Retinal Ganglion Cell Loss After Optic Nerve Injury

Purpose

Optic nerve injury (ONI) causes neuroinflammation and neurodegeneration leading to visual deficits. The response of microglia has emerged as an impactful component of etiology in neurodegeneration. This study aimed to investigate the effect of SIRT1-mTORC1 signaling pathway in microglia regulation after ONI.

Methods

Cx3Cr1-Cre^ERT2/Raptor^F/F and Cx3Cr1-Cre^ERT2/Sirt1^F/F mice were used to delete Raptor and Sirt1 in microglia, respectively. Optic nerve crush (ONC) model was established to mimic ONI. PLX5622, a highly specific inhibitor of the colony-stimulating factor 1 receptor (CSF1R), is used to eliminate microglia in optic nerve. Ionized calcium binding adaptor molecule 1 (Iba1) immunostaining was used to detect microglial activation. Retinal ganglion cells (RGCs) were quantified by Nissl staining and retinal whole-mount immunostaining with RNA-binding protein with multiple splicing (RBPMS). Axonal damage was valued by transmission electron microscopy (TEM).

Results

Microglial activation emerged on day 3 post ONC and was earlier than RGCs loss which occurred at day 5 after injury. Depleting microglia with PLX5622 could attenuate the loss of RGCs and axon damage after ONC. Gain- and loss-of-function studies revealed that SIRT1 determined the activation of microglia in optic nerve. In addition, microglia-specific deletion of Raptor resulted in decreased microglial activation. Interestingly, activating mTORC1 with CCT007093 could reverse the function of SIRT1 in regulating the process of microglial activation mediated RGCs loss.

Conclusion

Our study reveals a potential novel mechanism of SIRT1-mTORC1 pathway in microglia regulation, and indicates a therapeutic potential for the protection of RGCs in ONI.

Soybean isoflavones protect SH-SY5Y neurons from atrazine-induced toxicity by activating mitophagy through stimulation of the BEX2/BNIP3/NIX pathway

Atrazine (ATR) is a widely used herbicide that can induce the degeneration of dopaminergic (DAergic) neurons in the substantia nigra, resulting in a Parkinson's disease-like syndrome. Despite the high risk of environmental exposure, few studies have investigated strategies for the prevention of ATR neurotoxicity. Our previous studies demonstrated that ATR can impair mitochondrial function, leading to metabolic failure. Cells maintain mitochondrial quality through selective autophagic elimination, termed mitophagy. Soybean isoflavones (SI) possess multiple beneficial bioactivities, including preservation of mitochondria function, so it was hypothesized that SI can protect neurons against ATR toxicity by promoting mitophagy. Pretreatment of SH-SY5Y neurons with SI prevented ATR-induced metabolic failure and cytotoxicity as assessed by intracellular ATP, Na+-K+-ATPase activity, mitochondrial membrane potential, and cell viability assays. The neuroprotective efficacy of SI was superior to the major individual components genistein, daidzein, and glycitein. Ultrastructural analyses revealed that ATR induced mitochondrial damage, while SI promoted the sequestration of damaged mitochondria into autophagic vesicles. Soybean isoflavones also induced mitophagy as evidenced by upregulated expression of BNIP3/NIX, BEX2, and LC3-II, while co-treatment with the mitophagy inhibitor Mdivi-1 blocked SI-mediated neuroprotection and prevented SI from reversing ATR-induced BEX2 downregulation. Furthermore, BEX2 knockdown inhibited SI-induced activation of the BNIP3/NIX pathway, mitophagy, and neuroprotection. These findings suggest that SI protects against ATR-induced mitochondrial dysfunction and neurotoxicity by activating the BEX2/BNIP3/NIX pathway.

Molecular Insight Into the Therapeutic Potential of Long Non-coding RNA-Associated Competing Endogenous RNA Axes in Alzheimer's Disease: A Systematic Scoping Review

Alzheimer’s disease (AD) is a heterogeneous degenerative brain disorder with a rising prevalence worldwide. The two hallmarks that characterize the AD pathophysiology are amyloid plaques, generated via aggregated amyloid β, and neurofibrillary tangle, generated via accumulated phosphorylated tau. At the post-transcriptional and transcriptional levels, the regulatory functions of non-coding RNAs, in particular long non-coding RNAs (lncRNAs), have been ascertained in gene expressions. It is noteworthy that a number of lncRNAs feature a prevalent role in their potential of regulating gene expression through modulation of microRNAs via a process called the mechanism of competing endogenous RNA (ceRNA). Given the multifactorial nature of ceRNA interaction networks, they might be advantageous in complex disorders (e.g., AD) investigations at the therapeutic targets level. We carried out scoping review in this research to analyze validated loops of ceRNA in AD and focus on ceRNA axes associated with lncRNA. This scoping review was performed according to a six-stage methodology structure and PRISMA guideline. A systematic search of seven databases was conducted to find eligible articles prior to July 2021. Two reviewers independently performed publications screening and data extraction, and quantitative and qualitative analyses were conducted. Fourteen articles were identified that fulfill the inclusion criteria. Studies with different designs reported nine lncRNAs that were experimentally validated to act as ceRNA in AD in human-related studies, including BACE1-AS, SNHG1, RPPH1, NEAT1, LINC00094, SOX21-AS1, LINC00507, MAGI2-AS3, and LINC01311. The BACE1-AS/BACE1 was the most frequent ceRNA pair. Among miRNAs, miR-107 played a key role by regulating three different loops. Understanding the various aspects of this regulatory mechanism can help elucidate the unknown etiology of AD and provide new molecular targets for use in therapeutic and clinical applications.

Block copolymers in Alzheimer's disease therapy: A perceptive to revolutionize biomaterials

Alzheimer's disease is a fatal illness associated with two persistent problems in treatment i. ineffective drug transportation across the bio-membranes and ii. on-site targeting. Such problems originate from the combinational factors for non-specific targets, physicochemical limitations in the delivery of the active agents and insignificant permeability across blood-brain-barrier. In this context, block copolymers such as PLGA-PEG, PEG-PLA, Poloxamers, PLGA-PEG-PLGA triblock copolymers, etc. present interesting potential in the development of nano-sized carrier systems like polymerosomes, polymeric micelles, etc. for the management and treatment of Alzheimer's disease. Modifications of block copolymers display improvement in solubility and reduction in toxicity due to the process of complexation, functionalization, dose reduction and modification of kinetics for the rate of release. This review article focuses on new insights into different copolymers and their superiority over conventional polymers in Alzheimer's disease for long-term therapy in the body. Association of block copolymers to therapy of Alzheimer's disease overcome the limitations of drug delivery by offering attributes such as smaller molecular size (less than 150 nm), higher solubility owing to hydrophilic interactions between polymeric components and systemic environment, better entrapment efficiency (above 80%) due to large effective surface area and long-term stability for sensitive actives such as peptides, monoclonal antibodies, curcumin, resveratrol, catechins, etc. With such multifunctional features, block copolymers actively permeate the bio-membrane as polymeric nanoparticles, nanomicelles and polymerosomes using different mechanisms such as transcellular- and receptor-mediated transportation to reach target neural network as well as extra-neuronal amyloid-β plaques for anti-Alzheimer's disease activity with neuroprotective action. These polymers emerge as important components for personalized therapy with potential applications in biosensing, drug delivery, theranostics, etc. for qualitative and quantitative predictions in the detection and treatment of Alzheimer's disease.

Neuroprotective Role of Nutritional Supplementation in Athletes

BACKGROUND

Neurodegenerative disorders belong to different classes of progressive/chronic conditions that affect the peripheral/central nervous system. It has been shown through studies that athletes who play sports involving repeated head trauma and sub-concussive impacts are more likely to experience neurological impairments and neurodegenerative disorders in the long run.

AIMS

The aim of the current narrative review article is to provide a summary of various nutraceuticals that offer promise in the prevention or management of sports-related injuries, especially concussions and mild traumatic brain injuries.

METHODS

This article reviews the various potential nutraceutical agents and their possible mechanisms in providing a beneficial effect in the injury recovery process. A thorough survey of the literature was carried out in the relevant databases to identify studies published in recent years. In the present article, we have also highlighted the major neurological disorders along with the associated nutraceutical(s) therapy in the management of disorders.

RESULTS

The exact pathological mechanism behind neurodegenerative conditions is complex as well as idiopathic. However, mitochondrial dysfunction, oxidative stress as well as intracellular calcium overload are some common reasons responsible for the progression of these neurodegenerative disorders. Owing to the multifaceted effects of nutraceuticals (complementary medicine), these supplements have gained importance as neuroprotective. These diet-based approaches inhibit different pathways in a physiological manner without eliciting adverse effects. Food habits and lifestyle of an individual also affect neurodegeneration.

CONCLUSION

Studies have shown nutraceuticals (such as resveratrol, omega-3-fatty acids) to be efficacious in terms of their neuroprotection against several neurodegenerative disorders and to be used as supplements in the management of traumatic brain injuries. Protection prior to injuries is needed since concussions or sub-concussive impacts may trigger several pathophysiological responses or cascades that can lead to long-term complications associated with CNS. Thus, the use of nutraceuticals as prophylactic treatment for neurological interventions has been proposed.

The role of traditional Chinese medicine in the treatment of cognitive dysfunction in type 2 diabetes

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetic cognitive dysfunction (DCD) is mainly one of the complications of type 2 diabetes mellitus (T2DM) with complex and obscure pathogenesis. Extensive evidence has demonstrated the effectiveness and safety of traditional Chinese medicine (TCM) for DCD management.

AIM OF THE STUDY

This review attempted to systematically summarize the possible pathogenesis of DCD and the current Chinese medicine on the treatment of DCD.

MATERIALS AND METHODS

We acquired information of TCM on DCD treatment from PubMed, Web of Science, Science Direct and CNKI databases. We then dissected the potential mechanisms of currently reported TCMs and their active ingredients for the treatment of DCD by discussing the deficiencies and giving further recommendations.

RESULTS

Most TCMs and their active ingredients could improve DCD through alleviating insulin resistance, microvascular dysfunction, abnormal gut microbiota composition, inflammation, and the damages of the blood-brain barrier, cerebrovascular and neurons under hyperglycemia conditions.

CONCLUSIONS

TCM is effective in the treatment of DCD with few adverse reactions. A large number of in vivo and in vitro, and clinical trials are still needed to further reveal the potential quality markers of TCM on DCD treatment.

Multifaced role of protein deacetylase sirtuins in neurodegenerative disease

Sirtuins, a class III histone/protein deacetylase, is a central regulator of metabolic function and cellular stress response. This plays a pivotal role in the pathogenesis and progression of diseases such as cancer, neurodegeneration, metabolic syndromes, and cardiovascular disease. Sirtuins regulate biological and cellular processes, for instance, mitochondrial biogenesis, lipid and fatty acid oxidation, oxidative stress, gene transcriptional activity, apoptosis, inflammatory response, DNA repair mechanism, and autophagic cell degradation, which are known components for the progression of the neurodegenerative diseases (NDDs). Emerging evidence suggests that sirtuins are the useful molecular targets against NDDs like, Alzheimer's Disease (AD), Parkinson's Disease (PD), Huntington's Disease (HD), and Amyotrophic Lateral Sclerosis (ALS). However, the exact mechanism of neuroprotection mediated through sirtuins remains unsettled. The manipulation of sirtuins activity with its modulators, calorie restriction (CR), and micro RNAs (miR) is a novel therapeutic approach for the treatment of NDDs. Herein, we reviewed the current putative therapeutic role of sirtuins in regulating synaptic plasticity and cognitive functions, which are mediated through the different molecular phenomenon to prevent neurodegeneration. We also explained the implications of sirtuin modulators, and miR based therapies for the treatment of life-threatening NDDs.

Dietary Antioxidants in Age-Related Macular Degeneration and Glaucoma

Age-related macular degeneration (AMD) and glaucoma are ophthalmic neurodegenerative diseases responsible for irreversible vision loss in the world population. Only a few therapies can be used to slow down the progression of these diseases and there are no available treatment strategies for reversing the degeneration of the neural retina. In AMD, the pathological process causes the malfunction and damage of the retinal pigmented epithelium and photoreceptors in the macula. In glaucoma, damage of the retinal ganglion cells and their axons is observed and treatment strategies are limited to intraocular pressure lowering. Therefore, other prophylactic and/or therapeutic methods are needed. Oxidative stress is involved in the neurodegenerative process accompanying both AMD and glaucoma; therefore, the use of antioxidant agents would clearly be beneficial, which is supported by the decreased prevalence and progression of AMD in patients adherent to a diet naturally rich in antioxidants. Dietary antioxidants are easily available and their use is based on the natural route of administration. Many preclinical studies both in vitro and using animal models of retinal degeneration showed the efficacy of dietary antioxidants, which was further proved in clinical trials. Resveratrol is beneficial both in AMD and glaucoma animal models, but confirmed only among AMD patients. For AMD, carotenoids and omega-3 fatty acids were also proved to be sufficient in preventing neurodegeneration. For glaucoma, coenzyme Q10 and alpha-lipoic acid showed efficacy for decreasing retinal ganglion cell loss and inhibiting the accompanying destructive processes. Interestingly, the benefits of vitamins, especially vitamin E was not confirmed, neither in preclinical nor in clinical studies.

Resveratrol shortens the chronological lifespan of Saccharomyces cerevisiae by a pro-oxidant mechanism

The antioxidant phenotype caused by resveratrol has been recognized as a key piece in the health benefits exerted by this phytochemical in diseases related to aging. It has recently been proposed that a mitochondrial pro-oxidant mechanism could be the cause of resveratrol antioxidant properties. In this regard, the hypothesis that resveratrol impedes electron transport to complex III of the electron transport chain as its main target suggests that resveratrol could increase reactive oxygen species (ROS) generation through reverse electron transport or by the semiquinones formation. This idea also explains that cells respond to resveratrol oxidative damage, inducing their antioxidant systems. Moreover, resveratrol pro-oxidant properties could accelerate the aging process, according to the free radical theory of aging, which postulates that organism's age due to the accumulation of the harmful effects of ROS in cells. Nonetheless, there is no evidence linking the chronological lifespan (CLS) shorten occasioned by resveratrol with a pro-oxidant mechanism. Hence, this study aimed to evaluate whether resveratrol shortens the CLS of Saccharomyces cerevisiae due to a pro-oxidant activity. Herein, we provide evidence that supplementation with 100 μM of resveratrol at 5% glucose: (1) shortened the CLS of ctt1Δ and yap1Δ strains; (2) decreased ROS levels and increased the catalase activity in WT strain; (3) maintained unaffected the ROS levels and did not change the catalase activity in ctt1Δ strain; and (4) lessened the exponential growth of ctt1Δ strain, which was restored with the adding of reduced glutathione. These results indicate that resveratrol decreases CLS by a pro-oxidant mechanism.

Resveratrol ameliorates thoracic blast exposure-induced inflammation, endoplasmic reticulum stress and apoptosis in the brain through the Nrf2/Keap1 and NF-κB signaling pathway

Blast injuries include the various types of internal and external trauma caused by the impact force of high-speed blast waves with multiple mechanisms involved. Thoracic blast exposure could induce neurotrauma as well, but effective therapies are lacking. Resveratrol is a polyphenol flavonoid secreted by plants and has been shown to provide cardiovascular protection and play anti-inflammatory, anti-oxidation and anti-cancer roles. However, the effects of resveratrol on thoracic blast exposure-induced brain injury have not been investigated. To explore this, a mouse model of thoracic blast exposure-induced brain injury was established. Sixty C57BL/6 wild type mice were randomly divided equally into four groups (one control group, one model group, and model groups with 25 or 50 mg/kg resveratrol injected intraperitoneally). As traumatic brain injury often accompanied by mental symptoms, cognitive dysfunction and anxious behavior were evaluated by Y maze, elevated plus maze and open field test. We also examined the mice for histopathological changes by hematoxylin-eosin staining; the expressions of inflammatory-related factors by ELISA; endoplasmic reticulum stress in brain tissue via the generation of reactive oxygen species (ROS) and the expressions of inositol-requiring enzyme-α (IRE-α) and C/EBP homologous protein (CHOP); apoptosis by measuring levels of Bax, p53 and Bcl-2. In addition, proteins of related pathways were also studied by western blotting. We found that resveratrol significantly reduced the levels of inflammatory-related factors, including interleukin (IL)-1β, IL-4, and high mobility group box protein 1(HMGB1), and increased the level of anti-inflammatory-related factor, IL-10, under thoracic blast exposure (P < 0.05). Cognitive dysfunction and anxious behavior were also ameliorated by resveratrol. In brain tissue, resveratrol significantly attenuated thoracic blast exposure-induced generation of ROS and expressions of IRE-α and CHOP, lowered the expressions of Bax and p53, and maintained Bcl-2 expression (P < 0.05). Additionally, resveratrol significantly ameliorated thoracic blast exposure-induced increases of Kelch-like ECH-associated protein 1 (Keap1) and nuclear factor (NF)-κB and the decrease in nuclear factor erythroid 2-related factor 2(Nrf2) expression in the brain (P < 0.05). Our results indicate that resveratrol has a protective effect on thoracic blast exposure-induced brain injury that is likely mediated through the Nrf2/Keap1 and NF-κB signaling pathways.

lncRNA SNHG1 Knockdown Alleviates Amyloid-β-Induced Neuronal Injury by Regulating ZNF217 via Sponging miR-361-3p in Alzheimer's Disease

BACKGROUND

Long noncoding RNAs have been proven to play an important role in the progression of Alzheimer's disease (AD). However, the function of small nucleolar RNA host gene 1 (SNHG1) in AD progression remains to be studied.

OBJECTIVE

To explore the role of SNHG1 in AD progression and clarify its potential mechanism.

METHODS

Amyloid β-protein (Aβ) was used to construct an AD cell model in vitro. The expression levels of SNHG1 and miR-361-3p were determined by quantitative real-time polymerase chain reaction. Cell viability and apoptosis were measured by cell counting kit 8 assay and flow cytometry. The levels of apoptosis-related proteins and zinc finger gene 217 (ZNF217) protein were evaluated by western blot analysis. Additionally, the contents of inflammatory cytokines and oxidative stress markers were tested by enzyme-linked immunosorbent assay. Furthermore, dual-luciferase reporter and RNA immunoprecipitation assays were used to verify the interaction between miR-361-3p and SNHG1 or ZNF217.

RESULTS

Aβ could induce cell injury, while resveratrol could reverse this effect. SNHG1 expression was positively regulated by Aβ and negatively regulated by resveratrol. SNHG1 knockdown could reverse the promotion effect of Aβ on cell injury. Moreover, SNHG1 sponged miR-361-3p, and miR-361-3p targeted ZNF217. Additionally, miR-361-3p overexpression reversed the promotion effect of SNHG1 overexpression on cell injury, and ZNF217 silencing also reversed the promotion effect of miR-361-3p inhibitor on cell injury.

CONCLUSION

SNHG1 promoted cell injury by regulating the miR-361-3p/ZNF217 axis, which might provide a theoretical basis for molecular therapy of AD.

Comprehensive Investigation of Stereoselective Food Drug Interaction Potential of Resveratrol on Nine P450 and Six UGT Isoforms in Human Liver Microsomes

The stereoselectivity of the food drug inhibition potential of resveratrol on cytochrome P450s and uridine 5'-diphosphoglucuronosyl transferases was investigated in human liver microsomes. Resveratrol enantiomers showed stereoselective inhibition of CYP2C9, CYP3A, and UGT1A1. The inhibitions of CYP1A2, CYP2B6, and CYP2C19 by resveratrol were stereo-nonselective. The estimated K_i values determined for CYP1A2 were 13.8 and 9.2 μM for trans- and cis-resveratrol, respectively. Trans-resveratrol noncompetitively inhibited CYP3A and UGT1A1 activities with K_i values of 23.8 and 27.4 μM, respectively. Trans-resveratrol inhibited CYP1A2, CYP2C19, CYP2E1, and CYP3A in a time-dependent manner with K_i shift values >2.0, while cis-resveratrol time-dependently inhibited CYP2C19 and CYP2E1. The time-dependent inhibition of trans-resveratrol against CYP3A4, CYP2E1, CYP2C19, and CYP1A2 was elucidated using glutathione as a trapping reagent. This information helped the prediction of food drug interaction potentials between resveratrol and co-administered drugs which are mainly metabolized by UGT1A1, CYP1A2, CYP2C19, CYP2E1, and CYP3A.

Cannabinoid receptor 2 selective agonists and Alzheimer's disease: An insight into the therapeutic potentials

Endocannabinoid system has been extensively studied in recent decades, particularly the cannabinoid receptors CB1 and CB2, due to their important role in neuroinflammation. Among these, CB2 has gained prominence due to its selective overexpression in glial cells during neuroinflammation. In contrast to CB1 agonists, CB2 agonists have no side effects such as ataxia, hypothermia, euphoria, psychological, or addiction liabilities. CB2 and its selective agonists' above-mentioned unique properties have become a research focus in neurodegenerative disorders such as Alzheimer's disease (AD). The review discusses the neuroprotective role of CB receptors, particularly CB2, in AD, as well as the significance and limitations of this research.

Effects of manganese on microglia M1/M2 polarization and SIRT1-mediated transcription of STAT3-dependent genes in mouse

Overexposure to manganese (Mn) can lead to neurological diseases, characterized by behavioral and motor impairments. Microglia-mediated neuroinflammation is involved in the pathogenesis and progression of neurodegenerative diseases. Microglial M1 and M2 phenotypes play pro-inflammatory and anti-inflammatory roles, respectively, in response to microenvironmental disturbances. Silent information regulator (SIRT1) has been demonstrated to play an important role in the neuroinflammatory response by deacetylating various transcription factors, such as proliferator-activated receptor γ coactivator 1α (PGC-1α), nuclear factor kappa B (NF-κB), and signal transducer and activator of transcription 3 (STAT3). In addition, PGC-1α and STAT3 have been implicated in microglial polarization and inflammatory response. In this study, Mn exposure (50, 100, 200 μmol/kg) induced neuroinflammatory injury and interfered with microglial M1/M2 polarization in mice, as indicated by the upregulated expression of M1 polarization marker mRNA (IL-1β, IL-6, TNF-α, and iNOS), whereas changes in M2 polarization markers (IL-4, TGF-β, and Arg1) varied, with some increasing and some decreasing, in response to increasing Mn doses, which was consistent with the flow cytometry results used to detect the percentages of each microglial type. We found that Mn could downregulate SIRT1 expression and activate NF-κB signaling. Following mice in the 200 μmol/kg Mn treatment, STAT3 and PGC-1α levels in the nuclear fraction both significantly decreased, and the interaction between the proteins decreased, affecting the transcription of STAT3-mediated genes. These findings provide new insights regarding the role played by Mn neurotoxicity in the suppression of neuroinflammation through the regulation of microglial polarization.

A multitude of signaling pathways associated with Alzheimer's disease and their roles in AD pathogenesis and therapy

The exact molecular mechanisms associated with Alzheimer's disease (AD) pathology continue to represent a mystery. In the past decades, comprehensive data were generated on the involvement of different signaling pathways in the AD pathogenesis. However, the utilization of signaling pathways as potential targets for the development of drugs against AD is rather limited due to the immense complexity of the brain and intricate molecular links between these pathways. Therefore, finding a correlation and cross-talk between these signaling pathways and establishing different therapeutic targets within and between those pathways are needed for better understanding of the biological events responsible for the AD-related neurodegeneration. For example, autophagy is a conservative cellular process that shows link with many other AD-related pathways and is crucial for maintenance of the correct cellular balance by degrading AD-associated pathogenic proteins. Considering the central role of autophagy in AD and its interplay with many other pathways, the finest therapeutic strategy to fight against AD is the use of autophagy as a target. As an essential step in this direction, this comprehensive review represents recent findings on the individual AD-related signaling pathways, describes key features of these pathways and their cross-talk with autophagy, represents current drug development, and introduces some of the multitarget beneficial approaches and strategies for the therapeutic intervention of AD.

High-Fat and Resveratrol Supplemented Diets Modulate Adenosine Receptors in the Cerebral Cortex of C57BL/6J and SAMP8 Mice

Neurodegenerative disorders are devastating diseases in which aging is a major risk factor. High-fat diet (HFD) seems to contribute to cognition deterioration, but the underlying mechanisms are poorly understood. Moreover, resveratrol (RSV) has been reported to counteract the loss of cognition associated with age. Our study aimed to investigate whether the adenosinergic system and plasma membrane cholesterol are modulated by HFD and RSV in the cerebral cortex of C57BL/6J and SAMP8 mice. Results show that HFD induced increased A₁R and A_2AR densities in C57BL/6J, whereas this remained unchanged in SAMP8. Higher activity of 5′-Nucleotidase was found as a common effect induced by HFD in both mice strains. Furthermore, the effect of HFD and RSV on A_2BR density was different depending on the mouse strain. RSV did not clearly counteract the HFD-induced effects on the adenosinergic system. Besides, no changes in free-cholesterol levels were detected in the plasma membrane of cerebral cortex in both strains. Taken together, our data suggest a different modulation of adenosine receptors depending on the mouse strain, not related to changes in plasma membrane cholesterol content.

Resveratrol: A Vital Therapeutic Agent with Multiple Health Benefits

Resveratrol (RSV), the most effective stilbene phytoalexin synthesized naturally or induced in plants as part of their defense mechanism, is a key component of natural phenolic compounds and is being considered as a treatment option for a variety of diseases. RSV was discovered in the skin of red grapes, mulberries, peanuts, pines, and Polygonum cuspidatum weed root extracts. It was first extracted from white hellebore (Veratrum grandiflorum O. Loes) roots in 1940, then from Polygonum cuspidatum roots in 1963. However, RSV's use as a drug is limited due to its initial conformational strength and poor stability. The research focused on a set of RSV biological activity data. RSV has been the subject of growing concern, despite its wide range of biological and therapeutic applications. According to the literature, RSV has antioxidant, anti-cancer, cardioprotective, neuroprotective, anti- inflammatory, anti-microbial, immunomodulatory, and radioprotective properties. The current analysis summarized biological applications of RSV, their mechanisms of action, and recent scientific development in the area of their delivery. It is possible to infer that RSV has many effects on infected cells' cellular functions.

Icariin ameliorate Alzheimer's disease by influencing SIRT1 and inhibiting Aβ cascade pathogenesis

Of all types of dementia, Alzheimer's disease is the type that has the highest proportion of cases and is the cause of substantial medical and economic burden. The mechanism of Alzheimer's disease is closely associated with the aggregation of amyloid-β protein and causes neurotoxicity and extracellular accumulation in the brain and to intracellular neurofibrillary tangles caused by tau protein hyperphosphorylation in the brain tissue. Previous studies have demonstrated that sirtuin1 downregulation is involved in the pathological mechanism of Alzheimer's disease. The decrease of sirtuin1 level would cause Alzheimer's disease by means of promoting the amyloidogenic pathway to generate amyloid-β species and thereby triggering amyloid-β cascade reaction, such as tau protein hyperphosphorylation, neuron autophagy, neuroinflammation, oxidative stress, and neuron apoptosis. Currently, there is no effective treatment for Alzheimer's disease, it is necessary to develop new treatment strategies. According to the theory of traditional Chinese medicine and based on the mechanism of the disease, tonifying the kidneys is one of the principles for the treatment of Alzheimer's disease and Epimedium is a well-known Chinese medicine for tonifying kidney. Therefore, investigating the influence of the components of Epimedium on the pathological characteristics of Alzheimer's disease may provide a reference for the treatment of Alzheimer's disease in the future. In this article, we summarise the effects and mechanism of icariin, the main ingredient extracted from Epimedium, in ameliorating Alzheimer's disease by regulating sirtuin1 to inhibit amyloid-β protein and improve other amyloid-β cascade pathogenesis.

Diabetes and Alzheimer's Disease: Might Mitochondrial Dysfunction Help Deciphering the Common Path?

A growing number of clinical and epidemiological studies support the hypothesis of a tight correlation between type 2 diabetes mellitus (T2DM) and the development risk of Alzheimer's disease (AD). Indeed, the proposed definition of Alzheimer's disease as type 3 diabetes (T3D) underlines the key role played by deranged insulin signaling to accumulation of aggregated amyloid beta (Aβ) peptides in the senile plaques of the brain. Metabolic disturbances such as hyperglycemia, peripheral hyperinsulinemia, dysregulated lipid metabolism, and chronic inflammation associated with T2DM are responsible for an inefficient transport of insulin to the brain, producing a neuronal insulin resistance that triggers an enhanced production and deposition of Aβ and concomitantly contributes to impairment in the micro-tubule-associated protein Tau, leading to neural degeneration and cognitive decline. Furthermore, the reduced antioxidant capacity observed in T2DM patients, together with the impairment of cerebral glucose metabolism and the decreased performance of mitochondrial activity, suggests the existence of a relationship between oxidative damage, mitochondrial impairment, and cognitive dysfunction that could further reinforce the common pathophysiology of T2DM and AD. In this review, we discuss the molecular mechanisms by which insulin-signaling dysregulation in T2DM can contribute to the pathogenesis and progression of AD, deepening the analysis of complex mechanisms involved in reactive oxygen species (ROS) production under oxidative stress and their possible influence in AD and T2DM. In addition, the role of current therapies as tools for prevention or treatment of damage induced by oxidative stress in T2DM and AD will be debated.

H2S Attenuates Sleep Deprivation-Induced Cognitive Impairment by Reducing Excessive Autophagy via Hippocampal Sirt-1 in WISTAR RATS

Sleep deprivation (SD) is widespread in society causing serious damage to cognitive function. Hydrogen sulfide (H2S), the third gas signal molecule, plays important regulatory role in learning and memory functions. Inhibition of excessive autophagy and upregulation of silent information regulator 1 (Sirt-1) have been reported to prevent cognitive dysfunction. Therefore, this present work was to address whether H2S attenuates the cognitive impairment induced by SD in Wistar rats and whether the underlying mechanisms involve in inhibition of excessive autophagy and upregulation of Sirt-1. After treatment with SD for 72 h, the cognitive function of Wistar rats was evaluated by Y-maze, new object recognition, object location, and Morris water maze tests. The results shown that SD-caused cognitive impairment was reversed by treatment with NaHS (a donor of H2S). NaHS also prevented SD-induced hippocampal excessive autophagy, as evidenced by the decrease in autophagosomes, the down-regulation of Beclin1, and the up-regulation of p62 in the hippocampus of SD-exposed Wistar rats. Furthermore, Sirtinol, an inhibitor of Sirt-1, reversed the inhibitory roles of NaHS in SD-induced cognitive impairment and excessive hippocampal autophagy in Wistar rats. Taken together, our results suggested that H2S improves the cognitive function of SD-exposed rats by inhibiting excessive hippocampal autophagy in a hippocampal Sirt-1-dependent way.

Therapeutic potentials of resveratrol in combination with radiotherapy and chemotherapy during glioblastoma treatment: a mechanistic review

Glioblastoma, WHO grade IV astrocytoma, is the most aggressive type of brain tumors. These cancerous cells have a rapid growth rate, tendency to penetrate vital brain structures, molecular heterogeneity, etc. and this cancer is associated with a poor prognosis and low survival rate. Due to the resistance of glioblastoma cells to conventional therapeutic modalities (such as radiation therapy and chemotherapy) as well as the adverse effects of these modalities, the researchers have attempted to discover an appropriate alternative or adjuvant treatment for glioblastoma. Resveratrol, as an herbal and natural polyphenolic compound, has anti-tumoral property and has shown to be effective in GBM treatment. Resveratrol exerts its anti-tumoral effect through various mechanisms such as regulation of cell cycle progression and cell proliferation, autophagy, oxidant system, apoptosis pathways, and so on. Resveratrol in combination with radiation therapy and chemotherapy has also been used. In the present study, we summarized the current findings on therapeutic potentials of resveratrol in glioblastoma radiotherapy and chemotherapy.

Comparison of malondialdehyde levels and superoxide dismutase activity in resveratrol and resveratrol/donepezil combination treatment groups in Alzheimer's disease induced rat model

The aim of this study was to determine the malondialdehyde (MDA) level and superoxide dismutase (SOD) activity in colchicine induced Alzheimer’s disease (AD), resveratrol (RS) treated and RS + donepezil (DPZ) treated rat models. The objective was to compare the MDA level and SOD activity among these rat models. The present study included 3 months old male albino Wistar rats, which were in-house bred and weighting about 220–250 g. The rats were divided into nine subgroups which included control, sham, AD induced, RS treated and DPZ treated groups in different doses and combinations. The lipid peroxidation product for MDA in the brain homogenate was measured by estimating the levels of thiobarbituric acid reactive substance. Estimation of SOD was done by the method of autoxidation of pyrogallol by Marklund and Marklund. There was a marked increase in the MDA levels in AD induced group in comparison to the control group (p < 0.05). The SOD activity was higher in the RS 10 and RS 20 treated groups in contrast to the AD group (p < 0.05). In DPZ + RS group, there was a substantial increase in the SOD activity (p < 0.05). It is also observed that the RS 20 treatment group showed higher SOD activity than the RS 10 group (p < 0.05). This study showed that, AD induced group had elevated levels of MDA, which indicates the poor oxidative stress–defence mechanism. The RS 10 and RS 20 groups showed higher SOD activity in comparison to the AD group, which indicated the improved oxidative stress–defence mechanism. The RS + DPZ group showed higher SOD activity, indicating a synergistic effect of DPZ and RS.

Resveratrol Alleviates Levodopa-Induced Dyskinesia in Rats

Dyskinesia is a serious complication of Parkinson’s disease during levodopa (L-DOPA) treatment. The pathophysiology of L-DOPA-induced dyskinesia (LID) is complex and not fully illuminated. At present, treatment of dyskinesia is quite limited. Recent studies demonstrated neuroinflammation plays an important role in development of LID. Thus, inhibition of neuroinflammation might open a new avenue for LID treatment. Resveratrol (RES) is the most well-known polyphenolic stilbenoid and verified to possess a large variety of biological activities. DA neurotoxicity was assessed via behavior test and DA neuronal quantification. The movement disorders of dyskinesia were detected by the abnormal involuntary movements scores analysis. Effects of RES on glial cells-elicited neuroinflammation were also explored. Data showed that RES attenuated dyskinesia induced by L-DOPA without affecting L-DOPA’s anti-parkinsonian effects. Furthermore, RES generated neuroprotection against long term treatment of L-DOPA-induced DA neuronal damage. Meanwhile, RES reduced protein expression of dyskinesia molecular markers, ΔFOS B and ERK, in the striatum. Also, there was a strong negative correlation between DA system damage and ΔFOS B level in the striatum. In addition, RES inhibited microglia and astroglia activation in substantia nigra and subsequent inflammatory responses in the striatum during L-DOPA treatment. RES alleviates dyskinesia induced by L-DOPA and these beneficial effects are closely associated with protection against DA neuronal damage and inhibition of glial cells-mediated neuroinflammatory reactions.

Resveratrol Alleviates 27-Hydroxycholesterol-Induced Senescence in Nerve Cells and Affects Zebrafish Locomotor Behavior via Activation of SIRT1-Mediated STAT3 Signaling

The oxysterol 27-hydroxycholesterol (27HC) is the first identified endogenous selective estrogen receptor modulator (SERM), which like endogenous estrogen 17β-estradiol (E₂) induces the proliferation of estrogen receptor- (ER-) positive breast cancer cells in vitro. However, 27HC differs from E₂ in that it shows adverse effects in the nervous system. Our previous study confirmed that 27HC could induce neural senescence by activating phosphorylated signal transducer and activator of transcription, which E₂ could not. The purpose of the present study is to investigate whether STAT3 acetylation was involved in 27HC-induced neural senescence. Microglia (BV2 cells) and rat pheochromocytoma cells (PC12 cells) were used in vitro to explore the effect of resveratrol (REV) on 27HC-induced neural senescence. Senescence-associated β-galactosidase (SA-β-Gal) staining was performed using an SA-β-Gal Staining Kit in cells and zebrafish larvae. Zebrafish were used in vivo to assess the effect of 27HC on locomotor behavior and aging. We found that 27HC could induce senescence in neural cells, and REV, which has been employed as a Sirtuin-1 (SIRT1) agonist, could attenuate 27HC-induced senescence by inhibiting STAT3 signaling via SIRT1. Moreover, in the zebrafish model, REV attenuated 27HC-induced locomotor behavior disorder and aging in the spinal cord of zebrafish larvae, which was also associated with the activation of SIRT1-mediated STAT3 signaling. Our findings unveiled a novel mechanism by which REV alleviates 27HC-induced senescence in neural cells and affects zebrafish locomotor behavior by activating SIRT1-mediated STAT3 signaling.

Vitamin K2 Modulates Organelle Damage and Tauopathy Induced by Streptozotocin and Menadione in SH-SY5Y Cells

Vitamin K2, known for its antioxidative and anti-inflammatory properties, can act as a potent neuroprotective molecule. Despite its action against mitochondrial dysfunction, the mechanism underlying the links between the protective effects of vitamin K2 and endoplasmic reticulum (ER) stress along with basal levels of total tau protein and amyloid-beta 42 (Aβ42) has not been elucidated yet. To understand the neuroprotective effect of vitamin K2 during metabolic complications, SH-SY5Y cells were treated with streptozotocin for 24 h and menadione for 2 h in a dose-dependent manner, followed by post-treatment of vitamin K2 for 5 h. The modulating effects of vitamin K2 on cell viability, lactate dehydrogenase release, reactive oxygen species (ROS), mitochondrial membrane potential, ER stress marker (CHOP), an indicator of unfolded protein response (UPR), inositol requiring enzyme 1 (p-IRE1α), glycogen synthase kinase 3 (GSK3α/β), total tau and Aβ42 were studied. Results showed that vitamin K2 significantly reduces neuronal cell death by inhibiting cytotoxicity and ROS levels and helps in the retainment of mitochondrial membrane potential. Moreover, vitamin K2 significantly decreased the expression of CHOP protein along with the levels and the nuclear localization of p-IRE1α, thus showing its significant role in inhibiting chronic ER stress-mediated UPR and eventually cell death. In addition, vitamin K2 significantly down-regulated the expression of GSK3α/β together with the levels of total tau protein, with a petite effect on secreted Aβ42 levels. These results suggested that vitamin K2 alleviated mitochondrial damage, ER stress and tauopathy-mediated neuronal cell death, which highlights its role as new antioxidative therapeutics targeting related cellular processes.

Role of Polyphenols on Gut Microbiota and the Ubiquitin-Proteasome System in Neurodegenerative Diseases

Today, neurodegenerative diseases have become a remarkable public health challenge due to their direct relation with aging. Accordingly, understanding the molecular and cellular mechanisms occurring in the pathogenesis of them is essential. Both protein aggregations as a result of the ubiquitin-proteasome system (UPS) inefficiency and gut microbiota alternation are the main pathogenic hallmarks. Polyphenols upregulating this system may decrease the developing rate of neurodegenerative diseases. Most of the dietary intake of polyphenols is converted into other microbial metabolites, which have completely different biological properties from the original polyphenols and should be thoroughly investigated. Herein, several prevalent neurodegenerative diseases are pinpointed to explain the role of gut microbiota alternations and the role of molecular changes, especially UPS down-regulation in their pathogenesis. Some of the most important polyphenols found in our diet are explained along with their microbial metabolites in the body.

Personalizing the Care and Treatment of Alzheimer's Disease: An Overview

Alzheimer's disease (AD) is a progressive, complex, and multifactorial neurodegenerative disorder, still without effective and stable therapeutic strategies. Currently, available medications for AD are based on symptomatic therapy, which include acetylcholinesterase (AChE) inhibitors and N-methyl-D-aspartate (NMDA) receptor antagonist. Additionally, medications such as antipsychotic drugs, antidepressants, sedative, and hypnotic agents, and mood stabilizers are used for the management of behavioral and psychological symptoms of dementia (BPSD). Clinical research has been extensively investigated treatments focusing on the hallmark pathology of AD, including the amyloid deposition, tau hyperphosphorylation, neuroinflammation, and vascular changes; however, so far without success, as all new potential drugs failed to show significant clinical benefit. The underlying heterogeneous etiology and diverse symptoms of AD suggest that a precision medicine strategy is required, which would take into account the complex genetic, epigenetic, and environmental landscape of each AD patient. The article provides a comprehensive overview of the literature on AD, the current and potential therapy of both cognitive symptoms as well as BPSD, with a special focus on gut microbiota and epigenetic modifications as new emerging drug targets. Their specific patterns could represent the basis for novel individually tailored approaches aimed to optimize precision medicine strategies for AD prevention and treatment. However, the successful application of precision medicine to AD demands a further extensive research of underlying pathological processes, as well as clinical and biological complexity of this multifactorial neurodegenerative disorder.

Impact of dietary polyphenols on neuroinflammation-associated disorders

Neurodegenerative disorders like Alzheimer's, Parkinson's, and associated dementia typically originate with altered protein folding and aggregation of their β structures in the neurons. This self-aggregation leads to glial activation in the brain, causing neuroinflammation and leads to neuronal death. According to statistics provided by WHO, there are around 50 million people with dementia worldwide and every year, 10 million more cases are projected to increase. Also, around 5-8 percentage of people who are aged above 60 globally has dementia or associated disorders. Over 82 million in 2030 and 152 in 2050 are expected to have dementia. Most of these patients fall into low-middle-income countries which makes it even more essential to find an affordable and effective treatment method. Polyphenols of different origin are studied for their potential role as anti-neuro-inflammatory molecules. This review would summarize recent advances in three widely researched dietary polyphenols projected as potential therapeutic agents for disorders like Alzheimer's, Parkinson's, etc. They are Resveratrol, Catechins, and Tannins. The review would discuss the recent advances and challenges in using these polyphenols using specific examples as potential therapeutic agents against neuroinflammation associated disorders. An abstract of neuroinflammation-associated events and the effects by selected polyphenols.

Resveratrol, Metabolic Dysregulation, and Alzheimer's Disease: Considerations for Neurogenerative Disease

Alzheimer’s disease (AD) has traditionally been discussed as a disease where serious cognitive decline is a result of Aβ-plaque accumulation, tau tangle formation, and neurodegeneration. Recently, it has been shown that metabolic dysregulation observed with insulin resistance and type-2 diabetes actively contributes to the progression of AD. One of the pathologies linking metabolic disease to AD is the release of inflammatory cytokines that contribute to the development of brain neuroinflammation and mitochondrial dysfunction, ultimately resulting in amyloid-beta peptide production and accumulation. Improving these metabolic impairments has been shown to be effective at reducing AD progression and improving cognitive function. The polyphenol resveratrol (RSV) improves peripheral metabolic disorders and may provide similar benefits centrally in the brain. RSV reduces inflammatory cytokine release, improves mitochondrial energetic function, and improves Aβ-peptide clearance by activating SIRT1 and AMPK. RSV has also been linked to improved cognitive function; however, the mechanisms of action are less defined. However, there is evidence to suggest that chronic RSV-driven AMPK activation may be detrimental to synaptic function and growth, which would directly impact cognition. This review will discuss the benefits and adverse effects of RSV on the brain, highlighting the major signaling pathways and some of the gaps surrounding the use of RSV as a treatment for AD.

UGT84F9 is the major flavonoid UDP-glucuronosyltransferase in Medicago truncatula

Mammalian phase II metabolism of dietary plant flavonoid compounds generally involves substitution with glucuronic acid. In contrast, flavonoids mainly exist as glucose conjugates in plants, and few plant UDP-glucuronosyltransferase enzymes have been identified to date. In the model legume Medicago truncatula, the major flavonoid compounds in the aerial parts of the plant are glucuronides of the flavones apigenin and luteolin. Here we show that the M. truncatula glycosyltransferase UGT84F9 is a bi-functional glucosyl/glucuronosyl transferase in vitro, with activity against a wide range of flavonoid acceptor molecules including flavones. However, analysis of metabolite profiles in leaves and roots of M. truncatula ugt84f9 loss of function mutants revealed that the enzyme is essential for formation of flavonoid glucuronides, but not most flavonoid glucosides, in planta. We discuss the use of plant UGATs for the semi-synthesis of flavonoid phase II metabolites for clinical studies.

Resveratrol Improves Mitochondrial Biogenesis Function and Activates PGC-1α Pathway in a Preclinical Model of Early Brain Injury Following Subarachnoid Hemorrhage

Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) has been shown to play a pivotal role in the regulation of mitochondrial biogenesis in diseases. Resveratrol (RSV), a natural polyphenolic reagent, has powerful antioxidant properties and the ability to scavenge mitochondrial reactive oxygen species (ROS) in a variety of central nervous system diseases. However, the underlying molecular mechanisms of RSV on mitochondrial biogenesis in early brain injury (EBI) following subarachnoid hemorrhage (SAH) remain poorly understood. This study aimed to explore the potential neuroprotective effects of RSV on mitochondrial biogenesis and function by activation of the PGC-1α signaling pathway in a prechiasmatic cistern SAH model. PGC-1α expression and related mitochondrial biogenesis were detected. Amounts of nuclear respiratory factor 1 (NRF1) and mitochondrial transcription factor A (TFAM) were determined to evaluate the extent of mitochondrial biogenesis. Increased PGC-1α and mitochondrial biogenesis after SAH were observed in the temporal cortex. Resveratrol increased the expression of PGC-1α, NRF1, and TFAM, and promoted PGC-1α nuclear translocation. Moreover, RSV could scavenge excess ROS, increase the activity of superoxide dismutase (SOD), enhance the potential of mitochondrial membrane and ATP levels, reduce the number of mitochondrial DNA copy, and decrease the level of malondialdehyde (MDA). RSV significantly ameliorated the release of apoptosis-related cytokines, namely P53, cleaved caspase-3, cytochrome c, and BAX, leading to the amelioration of neuronal apoptosis, brain edema, and neurological impairment 24 h after SAH. These results indicate that resveratrol promotes mitochondrial biogenesis and function by activation of the PGC-1α signaling pathway in EBI following SAH.

Tetrahydroxystilbene glucoside alleviates angiotensin II induced HUVEC senescence via SIRT1

Tetrahydroxystilbene glucoside (TSG), an active ingredient of Polygonum multiflorum, has been known for certain anti-aging effects. In this study, the possible protective mechanism of TSG on human umbilical vein endothelial cell (HUVEC) senescence induced by angiotensin II (Ang II) was investigated. The results revealed that TSG pretreatment could reduce the percentage of senescence-associated β-galactosidase (SA-β-gal) positive cells and decrease the expression levels of the cellular senescence biomarker proteins p53 and PAI-1. At the same time, the expression of SIRT1 in senescent cells showed an upward trend due to TSG treatment. When inhibiting the expression of SIRT1 by EX527, our results showed that TSG reversed the effect of EX527 by promoting the expression level of SIRT1, reducing the expression of SA-β-gal positive cells and the expression level of p53 and PAI-1 proteins. The present study demonstrated that TSG could protect against HUVEC senescence induced by Ang II, potentially through modulation of SIRT1 activity.

Sirt-1 Regulates Physiological Process and Exerts Protective Effects against Oxidative Stress

BACKGROUND

Recent studies suggest a correlation between the reduced Sirt-1 expression with Alzheimer's diseases (AD) and depression, respectively, suggesting a possible pathogenic role of the altered Sirt-1 expression in neuronal degenerative diseases, such as AD and depression. However, the molecular mechanisms underlying how Sirt-1 reduction impairs neuronal functions remain unknown.

METHODS

We used the SK-N-SH neuroblastoma cells to study the role of Sirt-1 expression on physiological roles in neuronal cells. Gain of Sirt-1 was achieved by transiently transfecting Sirt-1 expression plasmid. Sirt-1-specific shRNA was used to elucidate the role of Sirt-1 loss of function. CCK-8 (Cell Counting Kit-8) assay and flow cytometry were used to evaluate cell proliferation. Semiquantitative western blotting was used to detect relative protein levels. A further luciferase reporter gene assay was employed to examine the effect of Sirt-1 expression on the transcriptional activity of p53. RT-qPCR was used to determine the mRNA levels of p21, Bax, and Bcl-2, which were the downstream target genes of p53.

RESULTS

Sirt-1 suppressed the p53 downstream gene p21 transcription, while shRNA-mediated Sirt-1 knockdown resulted in a significant increase in p21 expression, implying a possibility that Sirt-1 promotes neuron proliferation through suppressing p53 transcriptional activity. The mRNA and protein levels of p53 were not affected by the altered Sirt-1 expression, suggesting that Sirt-1 regulates the transcriptional regulatory activity of p53 rather than p53 expression. Indeed, we further confirmed that Sirt-1 appeared to inhibit p53 transcriptional activity by attenuating its acetylation and resulted in a decrease of p53's binding to the p21 promoter. Overexpressed Sirt-1 scavenged reactive oxygen species (ROS) production in SK-N-SH with H2O2. Knockdown of Sirt-1 presented opposite effect; the addition of EX527 (Sirt-1 inhibitor) increased ROS accumulation.

CONCLUSIONS

Oxidative stress induces Sirt-1 in neuron cells, and Sirt-1 promotes proliferation in SK-N-SH cells, which protects them from oxidative stress-induced cell death, potentially via suppressing the transcriptional activity of p53. These results provide a molecular explanation underlying how the reduced Sirt-1 potentially causes the AD and depression-related diseases, supporting the idea that Sirt-1 can possibly be used as a diagnostic biomarker and/or therapeutic drug target for the AD and depression-related diseases.

Buccal Resveratrol Delivery System as a Potential New Concept for the Periodontitis Treatment

The health benefits of resveratrol have been proven to inhibit the development of numerous diseases. A frequent limitation in its use is a low bioavailability stemming from a poor solubility and fast enterohepatic metabolism. Thus, the aim of the research was to investigate the possibility to formulate mucoadhesive cyclodextrin- and xanthan gum-based buccal tablets in order to increase the solubility of resveratrol and to eliminate bypass enterohepatic metabolism. Systems of resveratrol with α-cyclodextrin (α-CD), β-cyclodextrin (β-CD), γ-cyclodextrin (γ-CD) and 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) prepared by the dry mixing method (ratio 1:1) were selected for the of tablets where xanthan gum was used as a mucoadhesive agent. They were identified on the basis of PXRD, FT-IR analysis. Tablets F1 (with α-CD), F2 (with β-CD) and F3 (with γ-CD) were characterized by the highest compactibility as well as by favorable mucoadhesive properties. Resveratrol release from these tablets was delayed and controlled by diffusion. The tablets prepared in the course of this study appear to constitute promising resveratrol delivery systems and are recommended to increase the effectiveness of the treatment in many diseases, particularly periodontitis.

3,5-Dimethoxy-4-hydroxy myricanol attenuated oxidative stress-induced toxicity on cardiomyoblast cells

Myocardial ischemia is the main reason for ischemic heart diseases. Antioxidant treatment is considered as a possible approach to prevent myocardial ischemia injury, because oxidative stress is a key factor triggering it. This study was to investigate the protective effects of 3,5-dimethoxy-4-hydroxy myricanol (DHM) against oxidative stress-induced cytotoxicity on H9c2 cells and further explore its mechanisms. The oxidative stress and inflammatory response markers were detected by H2DCFDA fluorescent measurement, enzyme-linked immunosorbent assay (ELISA), real-time PCR and Western blot. Results showed DHM exerted inhibitory effects against H9c2 cell damage. Furthermore, DHM decreased oxidative stress in H9c2 cells through up-regulating protein expression of heme oxygenase-1 (HO-1) and nuclear factor (erythroid-derived 2)-like 2 (Nrf2). Moreover, DHM inhibited inflammatory responses through down-regulating the protein expression of mitogen-activated protein kinases (MAPKs) and nuclear factor kappa B (NF-κB). DHM exerted protective activities against oxidative stress-induced cell damage, at least through decreasing oxidative stress and inhibiting inflammatory responses, indicating that DHM have the potential to be developed as therapeutic agents for the treatment of myocardial ischemia.

Sirt1 Activity in the Brain: Simultaneous Effects on Energy Homeostasis and Reproduction

Diet deeply impacts brain functions like synaptic plasticity and cognitive processes, neuroendocrine functions, reproduction and behaviour, with detrimental or protective effects on neuronal physiology and therefore consequences for health. In this respect, the activity of metabolic sensors within the brain is critical for the maintenance of health status and represents a possible therapeutic target for some diseases. This review summarizes the main activity of Sirtuin1 (Sirt1), a metabolic sensor within the brain with a focus on the link between the central control of energy homeostasis and reproduction. The possible modulation of Sirt1 by natural phytochemical compounds like polyphenols is also discussed.

An Insight into Molecular Mechanisms and Novel Therapeutic Approaches in Epileptogenesis

Epilepsy is the second most common neurological disease with abnormal neural activity involving the activation of various intracellular signalling transduction mechanisms. The molecular and system biology mechanisms responsible for epileptogenesis are not well defined or understood. Neuroinflammation, neurodegeneration and Epigenetic modification elicit epileptogenesis. The excessive neuronal activities in the brain are associated with neurochemical changes underlying the deleterious consequences of excitotoxicity. The prolonged repetitive excessive neuronal activities extended to brain tissue injury by the activation of microglia regulating abnormal neuroglia remodelling and monocyte infiltration in response to brain lesions inducing axonal sprouting contributing to neurodegeneration. The alteration of various downstream transduction pathways resulted in intracellular stress responses associating endoplasmic reticulum, mitochondrial and lysosomal dysfunction, activation of nucleases, proteases mediated neuronal death. The recently novel pharmacological agents modulate various receptors like mTOR, COX-2, TRK, JAK-STAT, epigenetic modulators and neurosteroids are used for attenuation of epileptogenesis. Whereas the various molecular changes like the mutation of the cell surface, nuclear receptor and ion channels focusing on repetitive episodic seizures have been explored by preclinical and clinical studies. Despite effective pharmacotherapy for epilepsy, the inadequate understanding of precise mechanisms, drug resistance and therapeutic failure are the current fundamental problems in epilepsy. Therefore, the novel pharmacological approaches evaluated for efficacy on experimental models of epilepsy need to be identified and validated. In addition, we need to understand the downstream signalling pathways of new targets for the treatment of epilepsy. This review emphasizes on the current state of novel molecular targets as therapeutic approaches and future directions for the management of epileptogenesis. Novel pharmacological approaches and clinical exploration are essential to make new frontiers in curing epilepsy.

miRNA and mRNA Profiling Links Connexin Deficiency to Deafness via Early Oxidative Damage in the Mouse Stria Vascularis

Pathogenic mutations in the non-syndromic hearing loss and deafness 1 (DFNB1) locus are the primary cause of monogenic inheritance for prelingual hearing loss. To unravel molecular pathways involved in etiopathology and look for early degeneration biomarkers, we used a system biology approach to analyze Cx30^−/− mice at an early cochlear post-natal developmental stage. These mice are a DFNB1 mouse model with severely reduced expression levels of two connexins in the inner ear, Cx30, and Cx26. Integrated analysis of miRNA and mRNA expression profiles in the cochleae of Cx30^−/− mice at post-natal day 5 revealed the overexpression of five miRNAs (miR-34c, miR-29b, miR-29c, miR-141, and miR-181a) linked to apoptosis, oxidative stress, and cochlear degeneration, which have Sirt1 as a common target of transcriptional and/or post-transcriptional regulation. In young adult Cx30^−/− mice (3 months of age), these alterations culminated with blood barrier disruption in the Stria vascularis (SV), which is known to have the highest aerobic metabolic rate of all cochlear structures and whose microvascular alterations contribute to age-related degeneration and progressive decline of auditory function. Our experimental validation of selected targets links hearing acquisition failure in Cx30^−/− mice, early oxidative stress, and metabolic dysregulation to the activation of the Sirt1–p53 axis. This is the first integrated analysis of miRNA and mRNA in the cochlea of the Cx30^−/− mouse model, providing evidence that connexin downregulation determines a miRNA-mediated response which leads to chronic exhaustion of cochlear antioxidant defense mechanisms and consequent SV dysfunction. Our analyses support the notion that connexin dysfunction intervenes early on during development, causing vascular damage later on in life. This study identifies also early miRNA-mediated biomarkers of hearing impairment, either inherited or age related.

A Review of Plant Extracts and Plant-Derived Natural Compounds in the Prevention/Treatment of Neonatal Hypoxic-Ischemic Brain Injury

Neonatal hypoxic-ischemic (HI) brain injury is one of the major drawbacks of mortality and causes significant short/long-term neurological dysfunction in newborn infants worldwide. To date, due to multifunctional complex mechanisms of brain injury, there is no well-established effective strategy to completely provide neuroprotection. Although therapeutic hypothermia is the proven treatment for hypoxic-ischemic encephalopathy (HIE), it does not completely chang outcomes in severe forms of HIE. Therefore, there is a critical need for reviewing the effective therapeutic strategies to explore the protective agents and methods. In recent years, it is widely believed that there are neuroprotective possibilities of natural compounds extracted from plants against HIE. These natural agents with the anti-inflammatory, anti-oxidative, anti-apoptotic, and neurofunctional regulatory properties exhibit preventive or therapeutic effects against experimental neonatal HI brain damage. In this study, it was aimed to review the literature in scientific databases that investigate the neuroprotective effects of plant extracts/plant-derived compounds in experimental animal models of neonatal HI brain damage and their possible underlying molecular mechanisms of action.

SIRT1 and SIRT2 Activity Control in Neurodegenerative Diseases

Sirtuins are NAD+ dependent histone deacetylases (HDAC) that play a pivotal role in neuroprotection and cellular senescence. SIRT1-7 are different homologs from sirtuins. They play a prominent role in many aspects of physiology and regulate crucial proteins. Modulation of sirtuins can thus be utilized as a therapeutic target for metabolic disorders. Neurological diseases have distinct clinical manifestations but are mainly age-associated and due to loss of protein homeostasis. Sirtuins mediate several life extension pathways and brain functions that may allow therapeutic intervention for age-related diseases. There is compelling evidence to support the fact that SIRT1 and SIRT2 are shuttled between the nucleus and cytoplasm and perform context-dependent functions in neurodegenerative diseases including Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD). In this review, we highlight the regulation of SIRT1 and SIRT2 in various neurological diseases. This study explores the various modulators that regulate the activity of SIRT1 and SIRT2, which may further assist in the treatment of neurodegenerative disease. Moreover, we analyze the structure and function of various small molecules that have potential significance in modulating sirtuins, as well as the technologies that advance the targeted therapy of neurodegenerative disease.

Tantalizing role of p53 molecular pathways and its coherent medications in neurodegenerative diseases

Neurodegenerative diseases are incongruous, commonly age-related disorders characterized by progressive neuronal loss, comprising the most prevalent being Alzheimer's disease, Parkinson's disease, and Huntington's disease. Perilous health states are anticipated following the neurodegeneration. Their etiology remains largely ambiguous, while various mechanisms are ascribed to their pathogenesis. A recommended conception is regarding the role of p53, as a transcription factor regulating numerous cellular pathways comprising apoptosis. Neuronal fates are a feasible occurrence that contributes to all neurodegenerative diseases. In this work, we review the research investigated the potential role of p53 in the pathogenesis of these diseases. We put special emphasis on intricate We not only describe aberrant changes in p53 level/activity observed in CNS regions affected by particular diseases but, most importantly, put special attention to the complicated reciprocal tuning connections prevailing between p53 and molecules considered in pathological hallmarks of these disorders. Natural and synthetic medications regulating p53 expression are regarded as well.

Resveratrol's Anti-Cancer Effects through the Modulation of Tumor Glucose Metabolism

Simple Summary

The prevention and treatment of cancer is an ongoing medical challenge. In the context of personalized medicine, the well-studied polyphenol resveratrol could complement classical tumor therapy. It may affect key processes such as inflammation, angiogenesis, proliferation, metastasis, glucose metabolism, and apoptosis in various cancers because resveratrol acts as a multi-targeting agent by modulating multiple signal transduction pathways. This review article focuses on resveratrol’s ability to modify tumor glucose metabolism and its associated therapeutic capacity. Resveratrol reduces glucose uptake and glycolysis by affecting Glut1, PFK1, HIF-1α, ROS, PDH, and the CamKKB/AMPK pathway. It also inhibits cell growth, invasion, and proliferation by targeting NF-kB, Sirt1, Sirt3, LDH, PI-3K, mTOR, PKM2, R5P, G6PD, TKT, talin, and PGAM. In addition, resveratrol induces apoptosis by targeting integrin, p53, LDH, and FAK. In conclusion, resveratrol has many potentials to intervene in tumor processes if bioavailability can be increased and this natural compound can be used selectively.

Abstract

Tumor cells develop several metabolic reprogramming strategies, such as increased glucose uptake and utilization via aerobic glycolysis and fermentation of glucose to lactate; these lead to a low pH environment in which the cancer cells thrive and evade apoptosis. These characteristics of tumor cells are known as the Warburg effect. Adaptive metabolic alterations in cancer cells can be attributed to mutations in key metabolic enzymes and transcription factors. The features of the Warburg phenotype may serve as promising markers for the early detection and treatment of tumors. Besides, the glycolytic process of tumors is reversible and could represent a therapeutic target. So-called mono-target therapies are often unsafe and ineffective, and have a high prevalence of recurrence. Their success is hindered by the ability of tumor cells to simultaneously develop multiple chemoresistance pathways. Therefore, agents that modify several cellular targets, such as energy restriction to target tumor cells specifically, have therapeutic potential. Resveratrol, a natural active polyphenol found in grapes and red wine and used in many traditional medicines, is known for its ability to target multiple components of signaling pathways in tumors, leading to the suppression of cell proliferation, activation of apoptosis, and regression in tumor growth. Here, we describe current knowledge on the various mechanisms by which resveratrol modulates glucose metabolism, its potential as an imitator of caloric restriction, and its therapeutic capacity in tumors.