Quercetin attenuates cell apoptosis in focal cerebral ischemia rat brain via activation of BDNF-TrkB-PI3K/Akt signaling pathway

Astragaloside IV plays a neuroprotective role by promoting PPARγ in cerebral ischemia-reperfusion rats

BACKGROUND

Cerebral ischemia-reperfusion injury (CIRI) usually occurs during the treatment phase of ischemic disease, which is closely related to high morbidity and mortality. Promoting neurogenesis and synaptic plasticity are effective neural recovery strategies for CIRI. Astragaloside IV (AS-IV) has been shown to play a neuroprotective role in some neurological diseases. In the current study, we evaluated the effect and possible mechanism of AS-IV in CIRI rats.

METHODS

The middle cerebral artery occlusion reperfusion (MCAO/R) model was established in rats to simulate the occurrence of human CIRI. First, we determined the cerebral injury on the 1st, 3rd, 5th and 7th day after cerebral ischemia-reperfusion (I/R) surgery by neurological deficit detection, TTC staining, TUNEL staining and Western blot analysis. Furthermore, rats were pre administered with AS-IV and then subjected to cerebral I/R surgery. Brains were collected on the 3rd day to evaluate the neuroprotective effect of AS-IV.

RESULTS

Our results showed that on the 3rd day after I/R, the neurological impairment score and infarct volume were highest, the levels of apoptosis and expression of Caspase3 and Bax reached the peak. AS-IV treatment apparently attenuated neurological dysfunction, reduced infarct volume and pathological damage, promoted the neurogenesis, and alleviated the pathological damage caused by cerebral I/R involved in thickening and blurring of synaptic membranes, reduction of microtubules and synaptic vesicles, and loss of synaptic cleft. Our study also showed that AS-IV promoted the transcription and expression of the peroxisome proliferators-activated receptors γ (PPARγ) and brain-derived neurotrophic factor (BDNF), increased the expression of phosphorylation of tyrosine kinase receptor B (TrkB) and downstream PI3K/Akt/mTOR pathway proteins. Notably, when GW9662, an inhibitor of PPARγ was administered with AS-IV, the neuroprotective effect of AS-IV was reduced.

CONCLUSIONS

These findings suggested that AS-IV has neuroprotective function in CIRI rats, and its molecular mechanism may depend on the phosphatidylinositide 3-kinase (PI3K)/protein kinase B (PKB)/Akt signalling pathway activated by PPARγ. AS-IV could be an effective therapeutic drug candidate for CIRI treatment.

A comprehensive and systematic review of the potential neuroprotective effect of quercetin in rat models of spinal cord injury

CONTEXT

Spinal cord injury (SCI) is a potentially fatal neurological disease with severe complications and a high disability rate. An increasing number of animal experimental studies support the therapeutic effect of quercetin, which is a natural anti-inflammatory and antioxidant bioflavonoid.

OBJECTIVE

This paper reviewed the therapeutic effect of quercetin on a rat SCI model and summarized the relevant mechanistic research.

DATA SOURCES

PubMed, EMBASE, Web of Science, Science Direct, WanFang Data, SinoMed databases, the China National Knowledge Infrastructure, and the Vip Journal Integration Platform were searched from their inception to April 2023 for animal experiments applying quercetin to treat SCI.

STUDY SELECTION

Based on the PICOS criteria, a total of 18 eligible studies were included, of which 14 were high quality.

RESULTS

In this study, there was a gradual increase in effect based on the Basso, Beattie, and Bresnahan (BBB) score after three days (p < 0.0001). Furthermore, gender differences also appeared in the efficacy of quercetin; males performed better than females (p = 0.008). Quercetin was also associated with improved inclined plane test score (p = 0.008). In terms of biochemical indicators, meta-analysis showed that MDA (p < 0.0001) and MPO (p = 0.0002) were significantly reduced after quercetin administration compared with the control group, and SOD levels were increased (p = 0.004). Mechanistically, quercetin facilitates the inhibition of oxidative stress, inflammation, autophagy and apoptosis that occur after SCI.

CONCLUSIONS

Generally, this systematic review suggests that quercetin has a neuroprotective effect on SCI.

Red Pine Bark Extract Alleviates Akt/GSK-3β Signaling Disruption in the Hippocampus of Streptozotocin-Induced Diabetic Sprague-Dawley Rats

This study investigates whether red pine (Pinus densiflora Sieb. et Zucc.) bark extract (PBE) can alleviate diabetes and abnormal apoptosis signaling pathways in the hippocampus of streptozotocin (STZ)-induced diabetic Sprague-Dawley (SD) rats. Two dosages of PBE (15 and 30 mg/kg of body weight/day) were administered orally to STZ-induced diabetic SD rats for 20 days. Blood glucose level and body weight were measured once per week. After 20 days of oral administration of PBE, the rat hippocampus was collected, and the production of Akt, p-Akt, GSK-3β, p-GSK-3β, tau, p-tau, Bax, and Bcl-2 proteins were determined by western blot analysis. A decrease in blood glucose level and recovery of body weight were observed in PBE-treated diabetic rats. In the Akt/GSK-3β/tau signaling pathway, PBE inhibited diabetes-induced Akt inactivation, GSK-3β inactivation, and tau hyperphosphorylation. The protein production ratio of Bax/Bcl-2 was restored to the control group level. These results suggest that PBE, rich in phenolic compounds, can be used as a functional food ingredient to ameliorate neuronal apoptosis in diabetes mellitus.

Localization of truncated TrkB and co-expression with full-length TrkB in the cerebral cortex of adult mice

Brain-derived neurotrophic factor (BDNF), one of the neurotrophins, and its specific receptor TrkB, are abundantly distributed in the central nervous system (CNS) and have a variety of biological effects, such as neural survival, neurite elongation, neural differentiation, and enhancing synaptic functions. Currently, there are two TrkB subtypes: full-length TrkB (TrkB-FL), which has a tyrosine kinase in the intracellular domain, and TrkB-T1, which is a tyrosine kinase-deficient form. While TrkB-FL is a typical tyrosine kinase receptor, TrkB-T1 is a main form expressed in the CNS of adult mammals, but its function is unknown. In this study, we performed fluorescent staining of the cerebral cortex of adult mice, by using TrkB-T1 antiserum and various antibodies of marker molecules for neurons and glial cells. We found that TrkB-T1 was expressed not only in neurons but also in astrocytes. In contrast, little expression of TrkB-T1 was found in oligodendrocytes and microglia. TrkB-T1 was expressed in almost all of the cells expressing TrkB-FL, indicating the direct interaction between TrkB subtypes. These findings suggest that a part of various functions of BDNF-TrkB signaling might be due to the interaction and cellular localization of TrkB subtypes in the cerebral cortex.

Therapeutic efficacy and pharmacological mechanism of Yindan Xinnaotong soft capsule on acute ischemic stroke: a meta-analysis and network pharmacology analysis

Yindan Xinnaotong soft capsule (YDXNT), a traditional Chinese medicine preparation, has shown a promising effect in the treatment of acute ischemic stroke (AIS). The goal of this study was to investigate the therapeutic effects and pharmacological mechanisms of YDXNT on AIS. Randomized controlled trials were searched and screened. Review Manager 5.4 was used for a meta-analysis. Active ingredients and targets of YDXNT were extracted from the Traditional Chinese Medicine Systems Pharmacology Database, Bioinformatics Analysis Tool for Molecular mechANism of Traditional Chinese Medicine, and Encyclopaedia of Traditional Chinese Medicine. AIS-related targets were retrieved from GeneCards, OMIM, and DrugBank databases. We constructed PPI and ingredient-target networks, performed Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses, and conducted molecular docking. The YDXNT group had a higher total effective rate and a higher Barthel Index score. YDXNT reduced the low-density lipoprotein cholesterol and the whole blood viscosity at high and shear rates. Our study identified 313 ingredients and 1196 common targets. The key ingredients were mainly quercetin, neocryptotanshinone II, miltionone I, neotanshinone C, and tanshiquinone B, and the key targets were mainly SRC, MAPK3, AKT1, MAPK1, and JUN. GO analysis showed that the core targets mainly involved in atherosclerosis and neural apoptosis. The core pathways were lipid and atherosclerosis, PI3K-Akt, MAPK, and other pathways. Key ingredients exhibited robust binding interactions with core targets. YDXNT could effectively improve the total effective rate, ability of daily life, blood lipids, and blood viscosity. Antiatherosclerotic and neuroprotective effects are the main pharmacological mechanisms.Registration number: CRD42023400127.

Therapeutic Potential of Natural Compounds from Herbs and Nutraceuticals in Alleviating Neurological Disorders: Targeting the Wnt Signaling Pathway

As an important signaling pathway in multicellular eukaryotes, the Wnt signaling pathway participates in a variety of physiological processes. Recent studies have confirmed that the Wnt signaling pathway plays an important role in neurological disorders such as stroke, Alzheimer's disease, and Parkinson's disease. The regulation of Wnt signaling by natural compounds in herbal medicines and nutraceuticals has emerged as a potential strategy for the development of new drugs for neurological disorders. Purpose: The aim of this review is to evaluate the latest research results on the efficacy of natural compounds derived from herbs and nutraceuticals in the prevention and treatment of neurological disorders by regulating the Wnt pathway in vivo and in vitro. A manual and electronic search was performed for English articles available from PubMed, Web of Science, and ScienceDirect from the January 2010 to February 2023. Keywords used for the search engines were "natural products,″ "plant derived products,″ "Wnt+ clinical trials,″ and "Wnt+,″ and/or paired with "natural products″/″plant derived products", and "neurological disorders." A total of 22 articles were enrolled in this review, and a variety of natural compounds from herbal medicine and nutritional foods have been shown to exert therapeutic effects on neurological disorders through the Wnt pathway, including curcumin, resveratrol, and querctrin, etc. These natural products possess antioxidant, anti-inflammatory, and angiogenic properties, confer neurovascular unit and blood-brain barrier integrity protection, and affect neural stem cell differentiation, synaptic formation, and neurogenesis, to play a therapeutic role in neurological disorders. In various in vivo and in vitro studies and clinical trials, these natural compounds have been shown to be safe and tolerable with few adverse effects. Natural compounds may serve a therapeutic role in neurological disorders by regulating the Wnt pathway. This summary of the research progress of natural compounds targeting the Wnt pathway may provide new insights for the treatment of neurological disorders and potential targets for the development of new drugs.

Multimodal investigation reveals the neuroprotective mechanism of Angong Niuhuang pill for intracerebral hemorrhage: Converging bioinformatics, network pharmacology, and experimental validation

ETHNOPHARMACOLOGICAL RELEVANCE

Angong Niuhuang Pill (ANP) is a traditional Chinese medicine formula that has been used clinically for many years in the treatment of cerebral hemorrhage. It is composed of ingredients such as calculus bovis, moschus, and others. Ancient texts have documented that ANP's multiple components possess properties such as heat-clearing, detoxification, and sedation, which can be effective in treating conditions such as coma and stroke. However, the underlying mechanisms of ANP's potential actions are still under investigation.

AIM OF THE STUDY

ANP is a Chinese medicine widely utilized for the treatment of intracerebral hemorrhage (ICH). However, the precise mechanism underlying the therapeutic effects remains largely elusive. The present study aims to unravel the effects and pharmacological molecular mechanisms of ANP in combatting ICH, employing a comprehensive network pharmacology approach and experimental validation.

MATERIALS AND METHODS

The molecular targets of ANP and ICH were obtained from various databases, followed by the construction of protein-protein interaction (PPI) networks using the STRING database. Further, gene ontology (GO) enrichment and Kyoto encyclopedia of genes and genomes (KEGG) analyses were conducted using the Metascape database and Cytoscape, respectively. Finally, molecular docking was performed. We performed a series of behavioral tests, immunohistochemical staining, TUNEL staining, and Western Blot to verify the effects of ANP.

RESULTS

IL-6, JUN, MMP9, IL-1β, VEGFA were the main candidate targets and were associated with fluid shear stress and atherosclerosis, TNF signaling pathway, etc. It is suggested that the potential mechanism of ANP against ICH may be mainly related to pyroptosis, inflammation. In vivo validation showed that ANP treatment significantly reduced the number of TUNEL-positive cells and ANP inhibited the activation of Iba-1 positive neurons, and suppressed the expression of inflammatory factors and pyroptosis indicators. In addition, ANP improved the cognitive level and motor ability of ICH mice.

CONCLUSION

The results of the study combined with virtual screening and experimental validation showed that ANP has an important contribution in protecting the brain from neuronal damage by regulating the pathways of inflammation and pyroptosis, laying the foundation and innovative ideas for future studies.

Flavonoids and ischemic stroke-induced neuroinflammation: Focus on the glial cells

Ischemic stroke is one of the most cases worldwide, with high rate of morbidity and mortality. In the pathological process of ischemic stroke, neuroinflammation is an essential process that defines the functional prognosis. After stroke onset, microglia, astrocytes and the infiltrating immune cells contribute to a complicated neuroinflammation cascade and play the complicated roles in the pathophysiological variations of ischemic stroke. Both microglia and astrocytes undergo both morphological and functional changes, thereby deeply participate in the neuronal inflammation via releasing pro-inflammatory or anti-inflammatory factors. Flavonoids are plant-specific secondary metabolites and can protect against cerebral ischemia injury via modulating the inflammatory responses. For instances, quercetin can inhibit the expression and release of pro-inflammatory cytokines, such as tumor necrosis factor (TNF)-α, IL-6 and IL-1β, in the cerebral nervous system (CNS). Apigenin and rutin can promote the polarization of microglia to anti-inflammatory genotype and then inhibit neuroinflammation. In this review, we focused on the dual roles of activated microglia and reactive astrocyte in the neuroinflammation following ischemic stroke and discussed the anti-neuroinflammation of some flavonoids. Importantly, we aimed to reveal the new strategies for alleviating the cerebral ischemic stroke.

Advances of phytotherapy in ischemic stroke targeting PI3K/Akt signaling

The pathogenesis of ischemic stroke is complex, and PI3K/Akt signaling is considered to play a crucial role in it. The PI3K/Akt pathway regulates inflammation, oxidative stress, apoptosis, autophagy, and vascular endothelial homeostasis after cerebral ischemia; therefore, drug research targeting the PI3K/Akt pathway has become the focus of scientists. In this review, we analyzed the research reports of antiischemic stroke drugs targeting the PI3K/Akt pathway in the past two decades. Because of the rich sources of natural products, increasing studies have explored the value of natural compounds, including Flavonoids, Quinones, Alkaloids, Phenylpropanoids, Phenols, Saponins, and Terpenoids, in alleviating neurological impairment and achieved satisfactory results. Herbal extracts and medicinal formulas have been applied in the treatment of ischemic stroke for thousands of years in East Asian countries. These precious clinical experiences provide a new avenue for research of antiischemic stroke drugs. Finally, we summarize and discuss the characteristics and shortcomings of the current research and put forward prospects for further in-depth exploration.

Polyherbal and Multimodal Treatments: Kaempferol- and Quercetin-Rich Herbs Alleviate Symptoms of Alzheimer's Disease

Alzheimer's Disease (AD) is a progressive neurodegenerative disorder impairing cognition and memory in the elderly. This disorder has a complex etiology, including senile plaque and neurofibrillary tangle formation, neuroinflammation, oxidative stress, and damaged neuroplasticity. Current treatment options are limited, so alternative treatments such as herbal medicine could suppress symptoms while slowing cognitive decline. We followed PRISMA guidelines to identify potential herbal treatments, their associated medicinal phytochemicals, and the potential mechanisms of these treatments. Common herbs, including Ginkgo biloba, Camellia sinensis, Glycyrrhiza uralensis, Cyperus rotundus, and Buplerum falcatum, produced promising pre-clinical results. These herbs are rich in kaempferol and quercetin, flavonoids with a polyphenolic structure that facilitate multiple mechanisms of action. These mechanisms include the inhibition of Aβ plaque formation, a reduction in tau hyperphosphorylation, the suppression of oxidative stress, and the modulation of BDNF and PI3K/AKT pathways. Using pre-clinical findings from quercetin research and the comparatively limited data on kaempferol, we proposed that kaempferol ameliorates the neuroinflammatory state, maintains proper cellular function, and restores pro-neuroplastic signaling. In this review, we discuss the anti-AD mechanisms of quercetin and kaempferol and their limitations, and we suggest a potential alternative treatment for AD. Our findings lead us to conclude that a polyherbal kaempferol- and quercetin-rich cocktail could treat AD-related brain damage.

Potential of Quercetin to Protect Cadmium Induced Cognitive Deficits in Rats by Modulating NMDA-R Mediated Downstream Signaling and PI3K/AKT-Nrf2/ARE Signaling Pathways in Hippocampus

Exposure to cadmium, a heavy metal distributed in the environment is a cause of concern due to associated health effects in population around the world. Continuing with the leads demonstrating alterations in brain cholinergic signalling in cadmium induced cognitive deficits by us; the study is focussed to understand involvement of N-Methyl-D-aspartate receptor (NMDA-R) and its postsynaptic signalling and Nrf2-ARE pathways in hippocampus. Also, the protective potential of quercetin, a polyphenolic bioflavonoid, was assessed in cadmium induced alterations. Cadmium treatment (5 mg/kg, body weight, p.o., 28 days) decreased mRNA expression and protein levels of NMDA receptor subunits (NR1, NR2A) in rat hippocampus, compared to controls. Cadmium treated rats also exhibited decrease in levels of NMDA-R associated downstream signalling proteins (CaMKIIα, PSD-95, TrkB, BDNF, PI3K, AKT, Erk1/2, GSK3β, and CREB) and increase in levels of SynGap in hippocampus. Further, decrease in protein levels of Nrf2 and HO1 associated with increase in levels of Keap1 exhibits alterations in Nrf2/ARE signalling in hippocampus of cadmium treated rats. Degeneration of pyramidal neurons in hippocampus was also evident on cadmium treatment. Simultaneous treatment with quercetin (25 mg/kg body weight p.o., 28 days) was found to attenuate cadmium induced changes in hippocampus. The results provide novel evidence that cadmium exposure may disrupt integrity of NMDA receptors and its downstream signaling targets by affecting the Nrf2/ARE signaling pathway in hippocampus and these could contribute in cognitive deficits. It is further interesting that quercetin has the potential to protect cadmium induced changes by modulating Nrf2/ARE signaling which was effective to control NMDA-R and PI3K/AKT cell signaling pathways.

Natural coumarins from Murraya paniculata as mixed-type inhibitors of cholinesterases: In vitro and in silico investigations

Currently, acetylcholinesterase (AChE) inhibiting drugs in clinical use, such as tacrine, donepezil, rivastigmine, and galanthamine, are associated with serious side effects and short half-lives. In recent years, numerous phytochemicals have been identified as inhibitors of cholinesterases with potential applications in the management of Alzheimer’s disease (AD). In this study three natural coumarins, 2′-O-ethylmurrangatin (1), murranganone (2), and paniculatin (3) isolated previously by our group from the leaves of Murraya paniculata, were tested against the two cholinesterases (ChE) enzymes, AChE and butyrylcholinesterase (BChE) using in vitro assay. Molecular docking was performed to highlight the structural properties that contribute to the molecular recognition pattern in the inhibition of ChE and the structural differences resulting in the selectivity of these compounds toward AChE. Classical enzyme inhibition kinetics data suggested that compounds 2 and 3 were potent inhibitors of AChE and BChE, while 1 was found inactive against both enzymes. The findings from molecular docking studies revealed the competitive and non-competitive inhibition mechanisms of compounds 2 and 3 against both enzymes. Molecular docking and simulations have revealed that hydrogen bonding, mediated by ketone and hydroxyl functionalities in various positions, significantly contributes to the binding of the inhibitor to the receptor. According to MD simulation studies, the stability of the ligand-AChE complex for the most active compound (3) is found to be comparable to that of the widely used drug Tacrine. In addition, to evaluate the drug-likeness of compounds, in silico ADME evaluation was performed, and the compounds presented good ADME profiles. Data suggested that the coumarin nucleus having diverse side chains at the C-8 position can serve as a potential inhibitor of cholinesterases and can act as a lead to develop a new semisynthetic drug for the treatment of AD.

Esketamine improves propofol-induced brain injury and cognitive impairment in rats

As an intravenous anesthetic, propofol has been indicated to induce neurotoxicity in both animal and human brains. It is of great significance to better understand the potential mechanism of propofol-induced neurotoxicity to eliminate the side effects of propofol. Esketamine is a sedative that has been proven to have an antidepressant effect. However, its effect on propofol-induced neurotoxicity and the underlying mechanism remain unclear. Herein, we investigated the role of esketamine in propofol-induced brain injury. A rat model of propofol-induced brain injury was established with or without the treatment of esketamine. The results demonstrated that propofol-induced impairment in spatial learning and memory of rats and promoted oxidative stress, neuronal injury and apoptosis in rat hippocampal tissues. The effects caused by propofol were attenuated by esketamine. Esketamine activated the mature brain-derived neurotrophic factor/tropomyosin receptor kinase B/phosphatidylinositide 3-kinase (mBDNF/TrkB/PI3K) signaling pathway in propofol-administrated rats. Moreover, knocking down BDNF partially reversed esketamine-mediated activation of the mBDNF/TrkB/PI3K signaling pathway and inhibition of neuronal apoptosis in propofol-induced rats. Overall, esketamine mitigates propofol-induced cognitive dysfunction and brain injury in rats by activating mBDNF/TrkB/PI3K signaling.

Quercetin Is An Active Agent in Berries against Neurodegenerative Diseases Progression through Modulation of Nrf2/HO1

Berries are well-known fruits for their antioxidant effects due to their high content of flavonoids, and quercetin is one of the potent bioactive flavonoids. Although oxidative stress is an inevitable outcome in cells due to energy uptake and metabolism and other factors, excessive oxidative stress is considered a pivotal mediator for the cell death and leads to the progression of neurodegenerative diseases (NDDs). Furthermore, oxidative stress triggers inflammation that leads to neuronal cell loss. Alzheimer's, Parkinson's, Huntington's disease, amyotrophic lateral sclerosis, multiple sclerosis, and so on are the main neurodegenerative diseases. Hence, AD and PD are the most affected NDDs and cause the most lethality without any effective cure. Since AD and PD are the most common NDDs, therefore, in this study, we will describe the effect of oxidative stress on AD and PD. Targeting oxidative stress could be a very effective way to prevent and cure NDDs. Thus, the nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO1) are potent endogenous antioxidant modulatory pathways, which also show cytoprotective activities. Modulation of Nrf2/HO1 signaling pathways through a biological approach could be an effective way to treat with NDDs. Quercetin is a natural polyphenol, which protects neurodegeneration, remarkably by suppressing oxidative stress and inflammation. Thus, quercetin could be a very effective agent against NDDs. We will discuss the benefits and challenges of quercetin to treat against NDDs, focusing on molecular biology.

Multifaceted role of polyphenols in the treatment and management of neurodegenerative diseases

Neurodegenerative diseases (NDDs) are conditions that cause neuron structure and/or function to deteriorate over time. Genetic alterations may be responsible for several NDDs. However, a multitude of physiological systems can trigger neurodegeneration. Several NDDs, such as Huntington's, Parkinson's, and Alzheimer's, are assigned to oxidative stress (OS). Low concentrations of reactive oxygen and nitrogen species are crucial for maintaining normal brain activities, as their increasing concentrations can promote neural apoptosis. OS-mediated neurodegeneration has been linked to several factors, including notable dysfunction of mitochondria, excitotoxicity, and Ca²⁺ stress. However, synthetic drugs are commonly utilized to treat most NDDs, and these treatments have been known to have side effects during treatment. According to providing empirical evidence, studies have discovered many occurring natural components in plants used to treat NDDs. Polyphenols are often safer and have lesser side effects. As, epigallocatechin-3-gallate, resveratrol, curcumin, quercetin, celastrol, berberine, genistein, and luteolin have p-values less than 0.05, so they are typically considered to be statistically significant. These polyphenols could be a choice of interest as therapeutics for NDDs. This review highlighted to discusses the putative effectiveness of polyphenols against the most prevalent NDDs.

Ruta graveolens water extract (RGWE) ameliorates ischemic damage and improves neurological deficits in a rat model of transient focal brain ischemia

INTRODUCTION AND AIMS

The limited therapeutic options for ischemic stroke treatment render necessary the identification of new strategies. In recent years, it has been shown that natural compounds may represent a valid therapeutic opportunity. Therefore, the present study aimed to evaluate the protective effect of Ruta graveolens water extract (RGWE) in an in vivo experimental model of brain ischemia.

METHODS

RGWE effects on ischemic damage and neurological function were evaluated in adult rats subjected to transient occlusion of the Middle Cerebral Artery (tMCAO), receiving two intraperitoneal injections of RGWE, 100 and 300 min after the induction of ischemia. In addition, astroglial and microglial activation was measured as GFAP and IBA-1 expression by immunofluorescence and confocal microscopy analysis.

RESULTS

Treatment with RGWE containing 10 mg/kg of Rutin, the major component, ameliorates the ischemic damage and improves neurological performances. Interestingly, the pro-inflammatory states of astrocytes and microglia, respectively detected by using C3 and iNOS markers, were significantly reduced in ipsilateral cortical and striatal areas in ischemic RGWE-treated rats.

CONCLUSIONS

RGWE shows a neuroprotective effect on brain infarct volume extent in a transient focal cerebral ischemia model and this effect was paralleled by the prevention of pro-inflammatory astroglial and microglial activation. Collectively, our findings support the idea that natural compounds may represent potential therapeutic opportunities against ischemic stroke.

Polyphenols Targeting Oxidative Stress in Spinal Cord Injury: Current Status and Future Vision

A spinal cord injury (SCI) occurs when the spinal cord is deteriorated or traumatized, leading to motor and sensory functions lost even totally or partially. An imbalance within the generation of reactive oxygen species and antioxidant defense levels results in oxidative stress (OS) and neuroinflammation. After SCI, OS and occurring pathways of inflammations are significant strenuous drivers of cross-linked dysregulated pathways. It emphasizes the significance of multitarget therapy in combating SCI consequences. Polyphenols, which are secondary metabolites originating from plants, have the promise to be used as alternative therapeutic agents to treat SCI. Secondary metabolites have activity on neuroinflammatory, neuronal OS, and extrinsic axonal dysregulated pathways during the early stages of SCI. Experimental and clinical investigations have noted the possible importance of phenolic compounds as important phytochemicals in moderating upstream dysregulated OS/inflammatory signaling mediators and axonal regeneration's extrinsic pathways after the SCI probable significance of phenolic compounds as important phytochemicals in mediating upstream dysregulated OS/inflammatory signaling mediators. Furthermore, combining polyphenols could be a way to lessen the effects of SCI.

BDNF Therapeutic Mechanisms in Neuropsychiatric Disorders

Brain-derived neurotrophic factor (BDNF) is the most abundant neurotrophin in the adult brain and functions as both a primary neurotrophic signal and a neuromodulator. It serves essential roles in neuronal development, maintenance, transmission, and plasticity, thereby influencing aging, cognition, and behavior. Accumulating evidence associates reduced central and peripheral BDNF levels with various neuropsychiatric disorders, supporting its potential utilization as a biomarker of central pathologies. Subsequently, extensive research has been conducted to evaluate restoring, or otherwise augmenting, BDNF transmission as a potential therapeutic approach. Promising results were indeed observed for genetic BDNF upregulation or exogenous administration using a multitude of murine models of neurological and psychiatric diseases. However, varying mechanisms have been proposed to underlie the observed therapeutic effects, and many findings indicate the engagement of disease-specific and other non-specific mechanisms. This is because BDNF essentially affects all aspects of neuronal cellular function through tropomyosin receptor kinase B (TrkB) receptor signaling, the disruptions of which vary between brain regions across different pathologies leading to diversified consequences on cognition and behavior. Herein, we review the neurophysiology of BDNF transmission and signaling and classify the converging and diverging molecular mechanisms underlying its therapeutic potentials in neuropsychiatric disorders. These include neuroprotection, synaptic maintenance, immunomodulation, plasticity facilitation, secondary neuromodulation, and preservation of neurovascular unit integrity and cellular viability. Lastly, we discuss several findings suggesting BDNF as a common mediator of the therapeutic actions of centrally acting pharmacological agents used in the treatment of neurological and psychiatric illness.

Quercetin Can Improve Spinal Cord Injury by Regulating the mTOR Signaling Pathway

The pathogenesis of spinal cord injury (SCI) is complex. At present, there is no effective treatment for SCI, with most current interventions focused on improving the symptoms. Inflammation, apoptosis, autophagy, and oxidative stress caused by secondary SCI may instigate serious consequences in the event of SCI. The mammalian target of rapamycin (mTOR), as a key signaling molecule, participates in the regulation of inflammation, apoptosis, and autophagy in several processes associated with SCI. Quercetin can reduce the loss of myelin sheath, enhance the ability of antioxidant stress, and promote axonal regeneration. Moreover, quercetin is also a significant player in regulating the mTOR signaling pathway that improves pathological alterations following neuronal injury. Herein, we review the therapeutic effects of quercetin in SCI through its modulation of the mTOR signaling pathway and elaborate on how it can be a potential interventional agent for SCI.

A Flavonoid on the Brain: Quercetin as a Potential Therapeutic Agent in Central Nervous System Disorders

Quercetin is one of the most common, naturally occurring flavonoids, structurally classified to the flavonol subfamily. This compound, found in many edible and medicinal plants either as a free or glycosidated form, has been scientifically exploited for many years, and one could hardly expect it could be a hero of some additional story. Commonly recognized as an anti-inflammatory agent, quercetin not only limits capillary vessel permeability by inhibiting hyaluronidase but also blocks cyclooxygenases and lipoxygenases. As a typical flavonoid, it is also known for its antioxidant effect, which was confirmed by many in vitro and in vivo studies. Throughout the years, numerous other activities were reported for quercetin, including antidiabetic, anti-proliferative, or anti-viral. Of note, recent data have revealed its potential role as a therapeutic agent for several central nervous system disorders. This review provides an overview of available experimental data on quercetin and its complexes with respect to central nervous system diseases, with a main focus on some aspects that were not discussed previously, such as anti-anxiolytic effects, anti-Huntington’s disease activity, or therapeutic potential in brain cancer. Moreover, quercetin’s protective role in some of these diseases is discussed, especially as an anti-neuroinflammatory agent. Bearing in mind the poor bioavailability of this compound, possible options that would enhance its delivery to the site of action are also presented.

Neuroprotective effect of Morin via TrkB/Akt pathway against diabetes mediated oxidative stress and apoptosis in neuronal cells

Long term Diabetes mellitus results in neuronal damage by increased intracellular glucose leading to oxidative stress. This condition is known as diabetic encephalopathy. Morin is a bioflavonoid, has significant antidiabetic, antioxidant and anti-inflammatory activities. The present study investigated whether the antioxidant properties of morin has beneficial effects on structural brain damage, neuronal apoptosis and dysregulation of TrkB/Akt signalling associated with diabetes. Adult male Sprague Dawley rats were induced diabetes by an intraperitoneal injection of 40mg/kg of streptozotocin and kept untreated for 30 days to induce DE. Cognitive performance was assessed using the Morris water maze test followed by morin and metformin administration at the doses of 50 and 100mg/kg, respectively, for 60 days. After 60 days of treatment, animals were subjected to the behavioural test and sacrificed to collect blood and brain and checked biochemical parameters.The treatment with Morin could significantly reduce the escape latency time in Morris water maze test, blood glucose level, HbA1C, toxicity markers, lipid peroxidation products and protein carbonyl content, downregulated the expression of Bax, Caspase 3 and Cytochrome C and upregulated Bcl-2, Bcl-XL, Akt, BDNF and TrkB expressions. Besides, enhanced the activities of antioxidant enzymes, plasma insulin level. Histomorphological observations also confirmed the protective effect of morin on neuronal degeneration. Morin 50mg once daily for 60 days was the most effective dose with a significant reduction in diabetes mediated complications in the brain associated with neuronal apoptosis and dysregulation of TrkB/Akt signalling.

Exploring Active Compounds and Mechanisms of Angong Niuhuang Wan on Ischemic Stroke Based on Network Pharmacology and Molecular Docking

Methods

The chemical ingredients of ANW were retrieved from TCMSP, TCMID, and literature. We predicted the potential targets of active ingredients by PubChem, Swiss Target Prediction, and STITCH databases. The targets related to ischemic stroke were retrieved using GeneCards, DisGeNET, DrugBank, TTD, and GEO databases. Subsequently, Venn diagrams were used to identify common targets of active ingredients and ischemic stroke. Protein-protein interaction (PPI) network was structured with STRING platform and Cytoscape 3.8.2. Gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses of key targets were performed in the Metascape database. Finally, molecular docking was conducted by AutoDock Tools and PyMOL software.

Results

A total of 2391 targets were identified for 230 active ingredients of ANW, and 1386 of them overlapped with ischemic stroke targets. The key active ingredients were mainly quercetin, β-estradiol, berberine, wogonin, and β-sitosterol, and the key targets were also identified, including IL-6, AKT1, MAPK3, PIK3CA, and TNF. The biological process (BP) results indicated that ANW may have therapeutic effects through response oxidative stress, inflammatory response, cellular response to lipid, and response to nutrient levels. Furthermore, the ingredients of ANW were predicted to have therapeutic effects on ischemic stroke via the HIF-1 signaling pathway, FoxO signaling pathway, chemokine signaling pathway, fluid shear stress and atherosclerosis, and neurotrophin signaling pathway. The molecular docking results all showed that the core ingredients were strong binding activity with the core targets.

Conclusion

In conclusion, the bioinformatics and pharmacological results reveal that counteracting oxidative stress, suppressing inflammation, inhibiting the development of AS, and even protecting neurological function are critical pathways for ANW in the treatment of ischemic stroke. These results may help to elucidate the mechanism of ANW on ischemic stroke for experimental studies and clinical applications.

Loranthus regularis Ameliorates Neurodegenerative Factors in the Diabetic Rat Retina

Diabetic retinopathy remains a primary source of blindness with the growing pandemic of diabetes. Numerous studies have shown that early neurodegeneration caused by elevated oxidative stress may initiate microvascular damage in the diabetic retina during the last few decades. A variety of preventive and treatment strategies using phytochemicals that possess high antioxidants have shown great promise in reducing diabetes-induced neurodegeneration retinal damage. In this investigation, we employed an extract of Loranthus regularis, a traditional medicinal herb which is found to improve diabetes and associated complications in experimental studies. We orally treated STZ-induced diabetic rats with L. regularis and analyzed the neurodegenerative factors in the retina. After treatments, we used Western blotting techniques to analyze the protein content of neurotrophic factors (NGF, BDNF, TrkB), apoptotic factors (cytochrome c, Bcl-2, Bax), and phosphorylation of AKT in the diabetic retina. Additionally, we used ELISA methods to measure the contents of BDNF and the activity of Caspase-3 and biochemical procedures to determine the levels of glutathione and lipid peroxidation (TBARS). Our findings show that L. regularis treatments resulted in a considerable increase in neurotrophic factors and a decrease in apoptotic factors in the diabetic retina. Furthermore, in diabetic retina treated with L. regularis, the level of Bcl-2 protein increased, while the phosphor-AKT signaling improved. As a result, L. regularis may protect against diabetic-induced retinal neuronal damage by increasing neurotrophic support and reducing oxidative stress and apoptosis. Therefore, this study suggests that in diabetic retinopathy, L. regularis could be a potential therapy option for preventing neuronal cell death.

Effect and Mechanisms of Quercetin for Experimental Focal Cerebral Ischemia: A Systematic Review and Meta-Analysis

Quercetin, a naturally occurring flavonoid, is mainly extracted from tea, onions, and apples. It has the underlying neuroprotective effect on experimental ischemic stroke. A systematic review and meta-analysis were used to assess quercetin’s efficacy and possible mechanisms in treating focal cerebral ischemia. Compared with the control group, twelve studies reported a remarkable function of quercetin in improving the neurological function score (NFS) ( $P<0.05$ ), and twelve studies reported a significant effect on reducing infarct volume ( $P<0.05$ ). Moreover, two and three studies showed that quercetin could alleviate blood-brain barrier (BBB) permeability and brain water content, respectively. The mechanisms of quercetin against focal cerebral ischemia are diverse, involving antioxidation, antiapoptotic, anti-inflammation, and calcium overload reduction. On the whole, the present study suggested that quercetin can exert a protective effect on experimental ischemic stroke. Although the effect size may be overestimated because of the quality of studies and possible publication bias, these results indicated that quercetin might be a promising neuroprotective agent for human ischemic stroke. This study is registered with PROSPERO, number CRD 42021275656.

Inhibition of Brain GTP Cyclohydrolase I Attenuates 3-Nitropropionic Acid-Induced Striatal Toxicity: Involvement of Mas Receptor/PI3k/Akt/CREB/ BDNF Axis

GTP cyclohydrolase I (GTPCH I) is the rate-limiting enzyme for tetrahydrobiopterin (BH4) biosynthesis; the latter is an essential factor for iNOS activation that contributes neuronal loss in Huntington’s disease (HD). The aim of the study was to investigate the neuroprotective effect of 2,4-diamino-6-hydroxypyrimidine (DAHP), GTPCH I enzyme inhibitor, against neuronal loss in 3-nitropropinic acid (3-NP)-induced HD in rats and to reveal the possible involved mechanisms mediated through PI3K/Akt axis and its correlation to Mas receptor (MasR). Rats received 3-NP (10 mg/kg/day; i.p.) with or without administration of DAHP (0.5 g/kg/day; i.p.) or wortmannin (WM), a PI3K inhibitor, (15 μg/kg/day; i.v.) for 14 days. DAHP improved cognitive, memory, and motor abnormalities induced by 3-NP, as confirmed by striatal histopathological specimens and immunohistochemical examination of GFAP. Moreover, DAHP treatment inhibited GTPCH I activity, resulting in decreased BH4 levels and iNOS activation. Also, DAHP upregulated the protein expression of survival protein; p85/p55 (pY458/199)-PI3K and pS473-Akt that, in turn, boosted the activation of striatal neurotrophic factors and receptor, pS133-CREB, BDNF and pY515-TrKB, which positively affect MasR protein expression and improve mitochondrial dysfunction, as indicated by enhancing both SDH and PGC-1α levels. Indeed, DAHP attenuates oxidative stress by increasing SOD activity and Nrf2 expression in addition to reducing neuro-inflammatory status by inhibiting NF-κB p65 and TNF-α expression. Interestingly, all the previous effects were blocked by co-administration of WM with DAHP. In conclusion, DAHP exerts neuroprotective effect against neuronal loss induced by 3-NP administration via inhibition of GTPCH I and iNOS activity and activation of MasR/PI3K/Akt/CREB/BDNF/TrKB axis besides its antioxidant and anti-inflammatory effect.

Effects of Polyphenols on Oxidative Stress, Inflammation, and Interconnected Pathways during Spinal Cord Injury

Despite the progression in targeting the complex pathophysiological mechanisms of neurodegenerative diseases (NDDs) and spinal cord injury (SCI), there is a lack of effective treatments. Moreover, conventional therapies suffer from associated side effects and low efficacy, raising the need for finding potential alternative therapies. In this regard, a comprehensive review was done regarding revealing the main neurological dysregulated pathways and providing alternative therapeutic agents following SCI. From the mechanistic point, oxidative stress and inflammatory pathways are major upstream orchestras of cross-linked dysregulated pathways (e.g., apoptosis, autophagy, and extrinsic mechanisms) following SCI. It urges the need for developing multitarget therapies against SCI complications. Polyphenols, as plant-derived secondary metabolites, have the potential of being introduced as alternative therapeutic agents to pave the way for treating SCI. Such secondary metabolites presented modulatory effects on neuronal oxidative stress, neuroinflammatory, and extrinsic axonal dysregulated pathways in the onset and progression of SCI. In the present review, the potential role of phenolic compounds as critical phytochemicals has also been revealed in regulating upstream dysregulated oxidative stress/inflammatory signaling mediators and extrinsic mechanisms of axonal regeneration after SCI in preclinical and clinical studies. Additionally, the coadministration of polyphenols and stem cells has shown a promising strategy for improving post-SCI complications.

A preparation of Ginkgo biloba L. leaves extract inhibits the apoptosis of hippocampal neurons in post-stroke mice via regulating the expression of Bax/Bcl-2 and Caspase-3

ETHNOPHARMACOLOGICAL RELEVANCE

Shuxuening injection (SXNI) is a Chinese medicine of Ginkgo biloba L. leaves extract (GBE), which is widely used clinically for cardiovascular diseases such as stroke and myocardial infarction, but the pharmacological mechanism of its therapeutic effect is not fully understood.

AIM OF THE STUDY

Preclinical studies suggested that inhibition of neuronal apoptosis effectively improves brain damage after ischemic stroke. The purpose of this study was to investigate the inhibitory effect of SXNI on neuronal apoptosis in post-stroke mice and its underlying mechanism.

MATERIALS AND METHODS

A mouse cerebral ischemia-reperfusion injury (CIRI) model was constructed by middle cerebral artery occlusion (MCAO) and treated with 3 mL/kg SXNI. TUNEL and immunohistochemistry experiments were performed on brain slices on the 7th day after stroke. The protein was extracted from the hippocampus region of the brain for western-blot assay. To simulate the in vivo ischemia-reperfusion process, the hippocampal neuron cell line HT-22 was subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) in vitro, and 200 μg/mL SXNI was administered. The HT-22 cells were then studied by RT-PCR and immunocytochemistry.

RESULTS

In vivo, SXNI treatment significantly reduced hippocampal neuronal apoptosis. Immunohistochemistry showed that SXNI inhibited the activation of Caspase-3 protein in the hippocampus after ischemic stroke. Western blot analysis further confirmed that SXNI regulated the expression of the antagonizing protein pair Bax and Bcl-2 to exert anti-apoptotic effect in addition to reducing the expression of Cleaved-Caspase-3 in the hippocampus. In vitro, 200 μg/mL SXNI treatment significantly improved HT-22 apoptosis caused by OGD/R. Further RT-PCR and immunocytochemistry study showed that 200 μg/mL SXNI inhibited apoptosis of hippocampal neurons by regulating the mRNA and protein expressions of apoptotic molecules Bax, Bcl-2 and Caspase-3.

CONCLUSIONS

CIRI can induce hippocampal neuronal apoptosis, which is inhibited by SXNI via regulating Bax/Bcl-2 and blocking Caspase-3 activation. Therefore, SXNI may be a promising treatment strategy to improve the prognosis of ischemic stroke.

Neuroprotective Effect of Quercetin during Cerebral Ischemic Injury Involves Regulation of Essential Elements, Transition Metals, Cu/Zn Ratio, and Antioxidant Activity

Cerebral ischemia results in increased oxidative stress in the affected brain. Accumulating evidence suggests that quercetin possesses anti-oxidant and anti-inflammatory properties. The essential elements magnesium (Mg), zinc (Zn), selenium (Se), and transition metal iron (Fe), copper (Cu), and antioxidants superoxide dismutase (SOD) and catalase (CAT) are required for brain functions. This study investigates whether the neuroprotective effects of quercetin on the ipsilateral brain cortex involve altered levels of essential trace metals, the Cu/Zn ratio, and antioxidant activity. Rats were intraperitoneally administered quercetin (20 mg/kg) once daily for 10 days before ischemic surgery. Cerebral ischemia was induced by ligation of the right middle cerebral artery and the right common carotid artery for 1 h. The ipsilateral brain cortex was homogenized and the supernatant was collected for biochemical analysis. Results show that rats pretreated with quercetin before ischemia significantly increased Mg, Zn, Se, SOD, and CAT levels, while the malondialdehyde, Fe, Cu, and the Cu/Zn ratio clearly decreased as compared to the untreated ligation subject. Taken together, our findings suggest that the mechanisms underlying the neuroprotective effects of quercetin during cerebral ischemic injury involve the modulation of essential elements, transition metals, Cu/Zn ratio, and antioxidant activity.

Polyphenols as adjunctive treatments in psychiatric and neurodegenerative disorders: Efficacy, mechanisms of action, and factors influencing inter-individual response

The pathophysiology of psychiatric and neurodegenerative disorders is complex and multifactorial. Polyphenols possess a range of potentially beneficial mechanisms of action that relate to the implicated pathways in psychiatric and neurodegenerative disorders. The aim of this review is to highlight the emerging clinical trial and preclinical efficacy data regarding the role of polyphenols in mental and brain health, elucidate novel mechanisms of action including the gut microbiome and gene expression, and discuss the factors that may be responsible for the mixed clinical results; namely, the role of interindividual differences in treatment response and the potentially pro-oxidant effects of some polyphenols. Further clarification as part of larger, well conducted randomized controlled trials that incorporate precision medicine methods are required to inform clinical efficacy and optimal dosing regimens.

Quercetin: A Bioactive Compound Imparting Cardiovascular and Neuroprotective Benefits: Scope for Exploring Fresh Produce, Their Wastes, and By-Products

Quercetin, a bioactive secondary metabolite, holds incredible importance in terms of bioactivities, which has been proved by in vivo and in vitro studies. The treatment of cardiovascular and neurological diseases by quercetin has been extensively investigated over the past decade. Quercetin is present naturally in appreciable amounts in fresh produce (fruits and vegetables). However, today, corresponding to the growing population and global demand for fresh fruits and vegetables, a paradigm shift and focus is laid towards exploring industrial food wastes and/or byproducts as a new resource to obtain bioactive compounds such as quercetin. Based on the available research reports over the last decade, quercetin has been suggested as a reliable therapeutic candidate for either treating or alleviating health issues, mainly those of cardiovascular and neurological diseases. In the present review, we have summarized some of the critical findings and hypotheses of quercetin from the available databases foreseeing its future use as a potential therapeutic agent to treat cardiovascular and neurological diseases. It is anticipated that this review will be a potential reference material for future research activities to be undertaken on quercetin obtained from fresh produce as well as their respective processing wastes/byproducts that rely on the circular concept.

Localised delivery of quercetin by thermo-sensitive PLGA-PEG-PLGA hydrogels for the treatment of brachial plexus avulsion

Accumulating evidence indicates that oxidative stress and inflammation are implicated in brachial plexus avulsion (BPA). Quercetin has anti-inflammatory, anti-oxidant, anti-apoptotic, and neuroprotective properties. This study investigated the therapeutic efficacy of a temperature-sensitive poly(D,L-lactide-co-glycolide)-poly(ethylene-glycol)-poly(D,L-lactide-co-glycolide) (PLGA-PEG-PLGA) hydrogel sustained-release system of quercetin in BPA. In situ injections of the hydrogel loaded with different concentrations of quercetin were conducted in a rat model of BPA. Significantly reduced reactive oxygen species and interleukin-6 levels in the injured spinal cord 24 h post-surgery, increased number of anterior horn motor and functional neurons in the spinal cord 6 weeks post-surgery, thickened biceps muscle fibres and enlarged endplate area with clear structure, reduced demyelinated peripheral nerves, and significantly increased Terzis grooming test scores were found in the groups with 50 or 100 mg/mL quercetin-loaded hydrogels compared with the control and blank hydrogel groups. In conclusion, the temperature-sensitive quercetin loaded PLGA-PEG-PLGA hydrogel sustained-release system can alleviate oxidative damage and inflammation in the spinal cord, increase neuron survival rate, and promote nerve regeneration and motor function recovery in rats with early BPA. The findings suggest that this drug-loaded hydrogel has potential applications in the clinical treatment of BPA.

Circulating lncRNAs HIF1A-AS2 and LINLK-A: Role and Relation to Hypoxia-Inducible Factor-1α in Cerebral Stroke Patients

Long noncoding RNAs (lncRNAs) have been recently recognized as key players of gene expression in cerebral pathogenesis. Thus, their potential use in stroke diagnosis, prognosis, and therapy is actively pursued. Due to the complexity of the disease, identifying stroke-specific lncRNAs remains a challenge. This study investigated the expression of lncRNAs HIF1A-AS2 and LINK-A, and their target gene hypoxia-inducible factor-1 (HIF-1) in Egyptian stroke patients. It also aimed to determine the molecular mechanism implicated in the disease. A total of 75 stroke patients were divided into three clinical subgroups, besides 25 healthy controls of age-matched and sex-matched. Remarkable upregulation of lncRNA HIF1A-AS2 and HIF1-α along with a downregulation of lncRNA LINK-A was noticed in all stroke groups relative to controls. Serum levels of phosphatidylinositol 3-kinase (PI3K), phosphorylated-Akt (p-Akt), vascular endothelial growth factor (VEGF), and angiopoietin-1 (ANG1) as well as their receptors, malondialdehyde (MDA), and total antioxidant capacity (TAC) were significantly increased, whereas brain-derived neurotrophic factor (BDNF) levels were significantly decreased particularly in hemorrhagic stroke versus ischemic groups. Eventually, these findings support the role of lncRNAs HIF1A-AS2 and LINK-A as well as HIF1-α in activation of angiogenesis, neovascularization, and better prognosis of stroke, especially the hemorrhagic type.

Role of microbiota-derived short-chain fatty acids in nervous system disorders

During the past decade, accumulating evidence from the research highlights the suggested effects of bacterial communities of the human gut microbiota and their metabolites on health and disease. In this regard, microbiota-derived metabolites and their receptors, beyond the immune system, maintain metabolism homeostasis, which is essential to maintain the host's health by balancing the utilization and intake of nutrients. It has been shown that gut bacterial dysbiosis can cause pathology and altered bacterial metabolites' formation, resulting in dysregulation of the immune system and metabolism. The short-chain fatty acids (SCFAs), such as butyrate, acetate, and succinate, are produced due to the fermentation process of bacteria in the gut. It has been noted remodeling in the gut microbiota metabolites associated with the pathophysiology of several neurological disorders, such as Alzheimer's disease, multiple sclerosis, Parkinson's disease, amyotrophic lateral sclerosis, stress, anxiety, depression, autism, vascular dementia, schizophrenia, stroke, and neuromyelitis optica spectrum disorders, among others. This review will discuss the current evidence from the most significant studies dealing with some SCFAs from gut microbial metabolism with selected neurological disorders.

Tenacissoside H promotes neurological recovery of cerebral ischaemia/reperfusion injury in mice by modulating inflammation and oxidative stress via TrkB pathway

Cerebral ischaemia/reperfusion (I/R)-induced acute brain injury remains a troublesome condition in clinical practice. The present study aimed to investigate the protective effect of tenacissoside H (TH) on I/R-induced cerebral injury in mice. Here, a mouse model of middle cerebral artery occlusion (MCAO) was established by an improved Longa-Zea method. TH was given by intraperitoneal injection once a day within 1 week before establishing the mouse MCAO model. The neurological functions of mice were evaluated and the apoptosis of neurons was also detected by the TUNEL method and Nissl's staining. ELISA and western blot were used to detect the expression of inflammatory factors, oxidation factors and proteins in the cerebral ischaemic cortex. The results revealed that TH dose-dependently reduced neurological impairment, neuron apoptosis and brain oedema induced by MCAO. Furthermore, TH attenuated the expression of pro-inflammatory cytokines (including interleukin (IL)-1β, IL-6 and tumour necrosis factor (TNF)-α), iNOS and nuclear factor (NF)-κB while increased production of anti-inflammatory cytokines (IL-4, IL-10 and BDNF) and proteins of tropomyosin-related kinase receptor B (TrkB) and PPARγ. Nevertheless, after the addition of TrkB inhibitor, the effects of TH above were mostly restrained. In conclusion, TH can protect mice against I/R-induced neurological impairments via modulating inflammation and oxidative stress through TrkB signalling.

Shexiang Baoxin Pill, a Proprietary Multi-Constituent Chinese Medicine, Prevents Locomotor and Cognitive Impairment Caused by Brain Ischemia and Reperfusion Injury in Rats: A Potential Therapy for Neuropsychiatric Sequelae of Stroke

Ischemic stroke is a common type of cerebrovascular event and also the leading cause of disability. Post-stroke cognitive impairment occurs frequently in stroke survivors. Shexiang Baoxin Pill (SBP) is a proprietary Chinese medicine, initially used to treat cardiovascular diseases. Herein, we aim to explore the effects of SBP on oxygen glucose deprivation and reoxygenation (OGD/R) in neuronal cells (CATH.a) and cerebral ischemia/reperfusion injury induced post-stroke cognitive impairment in middle cerebral artery occlusion (MCAO) rat model. MCAO rats received two doses of oral SBP treatment (28 or 56 mg/kg) after 1 h of operation and once daily for 2 weeks continuously. Behavioral tests, immunoblotting, and immunofluorescence were examined after 14 days. Current data suggest that SBP enhanced cell viability and downregulated apoptosis via activating the PI3K/Akt signaling pathway in CATH. a cells. Furthermore, 14 days of SBP treatment promoted the recovery of learning and locomotor function in the MCAO rats. SBP up-regulated the expression of p-Akt, p-GSK3β, as well as the expression of NMDAR1, PSD-95, and AMPAR. Also, SBP down-regulated the expression of p-CaMKII. These results indicated that long-term SBP treatment might be a potential option for cognitive impairment induced by the ischemic stroke.

Nutraceuticals in the Prevention of Neonatal Hypoxia-Ischemia: A Comprehensive Review of their Neuroprotective Properties, Mechanisms of Action and Future Directions

Neonatal hypoxia-ischemia (HI) is a brain injury caused by oxygen deprivation to the brain due to birth asphyxia or reduced cerebral blood perfusion, and it often leads to lifelong limiting sequelae such as cerebral palsy, seizures, or mental retardation. HI remains one of the leading causes of neonatal mortality and morbidity worldwide, and current therapies are limited. Hypothermia has been successful in reducing mortality and some disabilities, but it is only applied to a subset of newborns that meet strict inclusion criteria. Given the unpredictable nature of the obstetric complications that contribute to neonatal HI, prophylactic treatments that prevent, rather than rescue, HI brain injury are emerging as a therapeutic alternative. Nutraceuticals are natural compounds present in the diet or used as dietary supplements that have antioxidant, anti-inflammatory, or antiapoptotic properties. This review summarizes the preclinical in vivo studies, mostly conducted on rodent models, that have investigated the neuroprotective properties of nutraceuticals in preventing and reducing HI-induced brain damage and cognitive impairments. The natural products reviewed include polyphenols, omega-3 fatty acids, vitamins, plant-derived compounds (tanshinones, sulforaphane, and capsaicin), and endogenous compounds (melatonin, carnitine, creatine, and lactate). These nutraceuticals were administered before the damage occurred, either to the mothers as a dietary supplement during pregnancy and/or lactation or to the pups prior to HI induction. To date, very few of these nutritional interventions have been investigated in humans, but we refer to those that have been successful in reducing ischemic stroke in adults. Overall, there is a robust body of preclinical evidence that supports the neuroprotective properties of nutraceuticals, and these may represent a safe and inexpensive nutritional strategy for the prevention of neonatal HI encephalopathy.

Quercetin attenuates the reduction of parvalbumin in middle cerebral artery occlusion animal model

Background

Calcium is a critical factor involved in modulation of essential cellular functions. Parvalbumin is a calcium buffering protein that regulates intracellular calcium concentrations. It prevents rises in calcium concentrations and inhibits apoptotic processes during ischemic injury. Quercetin exerts potent antioxidant and anti-apoptotic effects during brain ischemia. We investigated whether quercetin can regulate parvalbumin expression in cerebral ischemia and glutamate toxicity-induced neuronal cell death. Adult male rats were treated with vehicle or quercetin (10 mg/kg) 30 min prior to middle cerebral artery occlusion (MCAO) and cerebral cortical tissues were collected 24 h after MCAO. We used various techniques including Western blot, reverse transcription-PCR, and immunohistochemical staining to elucidate the changes of parvalbumin expression.

Results

Quercetin ameliorated MCAO-induced neurological deficits and behavioral changes. Moreover, quercetin prevented MCAO-induced a decrease in parvalbumin expression.

Conclusions

These findings suggest that quercetin exerts a neuroprotective effect through regulation of parvalbumin expression.

The Therapeutic Potential of Quercetin in Parkinson's Disease: Insights into its Molecular and Cellular Regulation

Parkinson's disease (PD) is a chronic and progressive neurodegenerative disorder characterized by the progressive death of dopaminergic neurons in the substantia nigra pars compacta (SNc). PD is a multifactorial disorder, with several different factors being suggested to play a synergistic pathophysiological role, including oxidative stress, autophagy, underlying pro-inflammatory events and neurotransmitters abnormalities. Overall, PD can be viewed as the product of a complex interaction of environmental factors acting on a given genetic background. The importance of this subject has gained more attention to discover novel therapies to prevent as well as treat PD. According to previous research, drugs used to treat PD have indicated significant limitations. Therefore, the role of flavonoids has been extensively studied in PD treatment. Quercetin, a plant flavonol from the flavonoid group, has been considered as a supplemental therapy for PD. Quercetin has pharmacological functions in PD by controlling different molecular pathways. Although few studies intended to evaluate the basis for the use of quercetin in the context of PD have been conducted so far, at present, there is very little evidence available addressing the underlying mechanisms of action. Various principal aspects of these treatment procedures remain unknown. Here, currently existing knowledge supporting the use of quercetin for the clinical management of PD has been reviewed.

Quercetin exerts antidepressant and cardioprotective effects in estrogen receptor α-deficient female mice via BDNF-AKT/ERK1/2 signaling

Brain-derived neurotrophic factor (BDNF) is the potential link between depression and cardiovascular disease and estrogen receptor α (ERα), an estrogen-mediated major regulator, plays an important role in protecting against depression and cardiovascular disease. However, the relationship between BDNF and ERα remains obscure. Herein, quercetin (QUE), a kind of plant flavonoids and existed in many vegetables and fruits, was found to simultaneously reverse ERα-/--induced depression-like and cardiac dysfunction by reducing immobility time in the tail suspension test (TST) and forced swimming test (FST), and decreasing systolic blood pressure and activating the apoptosis-related proteins, BDNF, tropomyosin-related kinase B (TrkB), protein kinase B (AKT), and extracellular regulatory protein kinase (ERK1/2) in the hippocampal and cardiac tissues of female mice. These findings suggested that ERα might be involved in the regulation of BDNF activity, thereby regulating depression-like and cardiovascular responses in female mice, and QUE exerted significant antidepressant and cardioprotective effects, at least in part, through BDNF-TrkB-AKT/ERK1/2 to effectively inhibit ERα-/--induced hippocampal and cardiac dysfunction.

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.

MicroRNA-204-5p mediates sevoflurane-induced cytotoxicity in HT22 cells by targeting brain-derived neurotrophic factor

BACKGROUND

Sevoflurane is widely used as an inhalational anesthetic in clinical practice. However, sevoflurane can cause cytotoxicity and induce learning capacity decline in patients. A previous publication indicated that miR-204-5p might have a close relationship with sevoflurane-induced neurotoxicity. When exposed to sevoflurane, the expression of miR-204-5p in neonatal hippocampus of rats was significantly increased. Hence, we aimed to investigate the role of miR-204-5p in sevoflurane-induced neurotoxicity using a mouse hippocampal neuronal cell line (HT22).

METHODS

The levels of miR-204-5p in HT22 cells were detected by RT-qPCR. In addition, the effects of miR-204-5p on cell viability, apoptosis and proliferation were evaluated by CCK-8, flow cytometric, and immunofluorescence assay, respectively. Western blotting was used to detect expressions of Bax, Bcl-2, active caspase 3, BDNF, TrkB, p-TrkB, Akt and p-Akt in HT22 cells. ELISA assay was used to examine the levels of total superoxide dismutase (SOD), reduced glutathione (GSH), malondialdehyde (MDA) and reactive oxygen species (ROS) in cells. Meanwhile, the dual luciferase reporter system assay was employed to explore the interaction of miR-204-5p and BDNF in cells.

RESULTS

The level of miR-204-5p was increased in sevoflurane-treated HT22 cells. Moreover, downregulation of miR-204-5p inhibited sevoflurane-induced apoptosis and promoted cell proliferation by upregulating the proteins of Bcl-2 and downregulating the expressions of Bax and active caspase-3 in HT22 cells. In addition, inhibition of miR-204-5p alleviated sevoflurane-induced oxidative injuries in HT22 cells via decline of ROS and MDA and upregulation of SOD and GSH. Furthermore, bioinformatics and dual luciferase assay demonstrated that miR-204-5p can inhibit the TrkB/Akt pathway by targeting BDNF.

CONCLUSION

Our findings indicated that downregulation of miR-204-5p can decrease oxidative status in HT22 cells and alleviate sevoflurane-induced cytotoxicity through stimulating the BDNF/TrkB/Akt pathway. Therefore, miR-204-5p might be a potential biomarker and therapeutic target for the treatment of sevoflurane-induced neurotoxicity.

Quercetin attenuates diabetic neuropathic pain by inhibiting mTOR/p70S6K pathway-mediated changes of synaptic morphology and synaptic protein levels in spinal dorsal horn of db/db mice

Numerous studies indicate that the changes of synaptic morphology and synaptic protein levels in spinal dorsal horn neurons contributes to the development and maintenance of neuropathic pain. Quercetin, a bioflavonoid compound, has been shown to have analgesic effect in several pain models. However, the underlying mechanism for quercetin to allieviate pain is unclear. Therefore, in this study, we observed the effect of quercetin on diabetic neuropathic pain in db/db mice and explored the underlying mechanisms. Our results showed that chronic quercetin treatment alleviated thermal hyperalgesia in db/db mice. Moreover, quercetin administration significantly reduced the total dendritic length, the number of dendritic branches, and the dendritic spine density in the spinal dorsal horn neurons of db/db mice. Meanwhile, the up-regulated expressions of synaptic plasticity-associated proteins postsynaptic density protein 95 (PSD-95) and synaptophysin in spinal dorsal horn of db/db mice were decreased by quercetin treatment. In addition, quercetin treatment reduced the phosphorylated levels of mammalian target of rapamycin (mTOR) and p70 ribosomal S6 kinase (p70S6K) in spinal dorsal horn of db/db mice. These results demonstrate that quercetin may alleviate diabetic neuropathic pain by inhibiting mTOR/p70S6K pathway-mediated changes of synaptic morphology and synaptic protein levels in spinal dorsal horn neurons of db/db mice. These findings suggest that quercetin may be a promising therapeutic drug in neuropathic pain.