Neuroprotection by baicalein in ischemic brain injury involves PTEN/AKT pathway

Baicalein attenuates bleomycin-induced lung fibroblast senescence and lung fibrosis through restoration of Sirt3 expression

CONTEXT

Fibroblast senescence was reported to contribute to the pathological development of idiopathic pulmonary fibrosis (IPF), and baicalein is reported to attenuate IPF.

OBJECTIVE

This study explores whether baicalein attenuates lung fibrosis by regulating lung fibroblast senescence.

MATERIALS AND METHODS

Institute of Cancer Research (ICR) mice were randomly assigned to control, bleomycin (BLM), baicalein and BLM + baicalein groups. Lung fibrosis was established by a single intratracheal dose of BLM (3 mg/kg). The baicalein group received baicalein orally (100 mg/kg/day). Sirtuin 3 (Sirt3) siRNA (50 μg) was injected through the tail vein once a week for 2 weeks to explore its effect on the anti-pulmonary fibrosis of baicalein.

RESULTS

BLM-treated mice exhibited obvious lung fibrosis and fibroblast senescence by showing increased levels of collagen deposition (27.29% vs. 4.14%), hydroxyproline (208.05 vs. 40.16 ng/mg), collagen I (25.18 vs. 9.15 μg/mg), p53, p21, p16, MCP-1, PAI-1, TNF-α, MMP-10 and MMP-12 in lung tissues, which were attenuated by baicalein. Baicalein also mitigated BLM-mediated activation of TGF-β1/Smad signalling pathway. Baicalein restored the BLM-induced downregulation of Sirt3 expression in lung tissues and silencing of Sirt3 abolished the inhibitory role of baicalein against BLM-induced lung fibrosis, fibroblast senescence and activation of TGF-β1/Smad signalling pathway.

CONCLUSIONS

Baicalein preserved the BLM-induced downregulation of lung Sirt3 expression, and thus the suppression of TGF-β1/Smad signalling pathway and lung fibrosis, which might provide an experimental basis for treatment of IPF.

Neuron-secreted NLGN3 ameliorates ischemic brain injury via activating Gαi1/3-Akt signaling

We here tested the potential activity and the underlying mechanisms of neuroligin-3 (NLGN3) against ischemia-reperfusion-induced neuronal cell injury. In SH-SY5Y neuronal cells and primary murine cortical neurons, NLGN3 activated Akt-mTOR and Erk signalings, and inhibited oxygen and glucose deprivation (OGD)/re-oxygenation (OGD/R)-induced cytotoxicity. Akt activation was required for NLGN3-induced neuroprotection. Gαi1/3 mediated NLGN3-induced downstream signaling activation. NLGN3-induced Akt-S6K1 activation was largely inhibited by Gαi1/3 silencing or knockout. Significantly, NLGN3-induced neuroprotection against OGD/R was almost abolished by Gαi1/3 silencing or knockout. In vivo, the middle cerebral artery occlusion (MCAO) procedure induced NLGN3 cleavage and secretion, and increased its expression and Akt activation in mouse brain tissues. ADAM10 (A Disintegrin and Metalloproteinase 10) inhibition blocked MCAO-induced NLGN3 cleavage and secretion, exacerbating ischemic brain injury in mice. Neuronal silencing of NLGN3 or Gαi1/3 in mice also inhibited Akt activation and intensified MCAO-induced ischemic brain injury. Conversely, neuronal overexpression of NLGN3 increased Akt activation and alleviated MCAO-induced ischemic brain injury. Together, NLGN3 activates Gαi1/3-Akt signaling to protect neuronal cells from ischemia-reperfusion injury.

The pivotal role of JAK/STAT and IRS/PI3K signaling pathways in neurodegenerative diseases: Mechanistic approaches to polyphenols and alkaloids

BACKGROUND

Neurodegenerative diseases (NDDs) are characterized by progressive neuronal dysfunctionality which results in disability and human life-threatening events. In recent decades, NDDs are on the rise. Besides, conventional drugs have not shown potential effectiveness to attenuate the complications of NDDs. So, exploring novel therapeutic agents is an urgent need to combat such disorders. Accordingly, growing evidence indicates that polyphenols and alkaloids are promising natural candidates, possessing several beneficial pharmacological effects against diseases. Considering the complex pathophysiological mechanisms behind NDDs, Janus kinase (JAK), insulin receptor substrate (IRS), phosphoinositide 3-kinase (PI3K), and signal transducer and activator of transcription (STAT) seem to play critical roles during neurodegeneration/neuroregeneration. In this line, modulation of the JAK/STAT and IRS/PI3K signaling pathways and their interconnected mediators by polyphenols/alkaloids could play pivotal roles in combating NDDs, including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), stroke, aging, multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), depression and other neurological disorders.

PURPOSE

Thus, the present study aimed to investigate the neuroprotective roles of polyphenols/alkaloids as multi-target natural products against NDDs which are critically passing through the modulation of the JAK/STAT and IRS/PI3K signaling pathways.

STUDY DESIGN AND METHODS

A systematic and comprehensive review was performed to highlight the modulatory roles of polyphenols and alkaloids on the JAK/STAT and IRS/PI3K signaling pathways in NDDs, according to the PRISMA guideline, using scholarly electronic databases, including Scopus, PubMed, ScienceDirect, and associated reference lists.

RESULTS

In the present study 141 articles were included from a total of 1267 results. The results showed that phenolic compounds such as curcumin, epigallocatechin-3-gallate, and quercetin, and alkaloids such as berberine could be introduced as new strategies in combating NDDs through JAK/STAT and IRS/PI3K signaling pathways. This is the first systematic review that reveals the correlation between the JAK/STAT and IRS/PI3K axis which is targeted by phytochemicals in NDDs. Hence, this review highlighted promising insights into the neuroprotective potential of polyphenols and alkaloids through the JAK/STAT and IRS/PI3K signaling pathway and interconnected mediators toward neuroprotection.

CONCLUSION

Amongst natural products, phenolic compounds and alkaloids are multi-targeting agents with the most antioxidants and anti-inflammatory effects possessing the potential of combating NDDs with high efficacy and lower toxicity. However, additional reports are needed to prove the efficacy and possible side effects of natural products.

Baicalein limits osteoarthritis development by inhibiting chondrocyte ferroptosis

Osteoarthritis (OA) is a common degenerative disease of articular cartilage, and there is currently no effective treatment. Baicalein, a flavonoid extracted from plants of the Scutellaria genus, has frequently been used in the past as an anti-inflammatory and anti-allergic therapy. This study investigated the effect of baicalein on OA development. For in vivo study, a destabilization of the medial meniscus (DMM)-induced OA model was established in 8-week-old wild-type (WT) and AMPKα-knockout (KO) mice, while an in vitro study was performed using chondrocytes in an OA microenvironment induced by interleukin-1β (IL-1β) exposure. We found that baicalein alleviated OA development in vivo and exerted a chondroprotective effect in vitro by suppressing chondrocyte ferroptosis. Baicalein reduced OA-related pain sensitivity by inhibiting ferroptosis of chondrocytes in OA mice. Baicalein also facilitated AMPK holoenzyme assembly, stability, and activity and suppressed ferroptosis by inducing AMPKα phosphorylation in chondrocyte. In addition, AMPKα preserved nuclear factor erythroid 2-related factor 2(Nrf2) abundance in chondrocytes and induced Nrf2 into nucleus by promoting Keap1 degradation. Meanwhile, Nrf2 increased expression of heme oxygenase-1(HO-1) to inhibit chondrocyte lipid ROS. Taken together, these results showed that baicalein alleviated OA development by improving the activity of AMPK/Nrf2/HO-1 signaling to inhibit chondrocyte ferroptosis, revealing baicalein to be a potential therapeutic strategy for OA.

Neuroprotective Strategies for Stroke by Natural Products: Advances and Perspectives

Cerebral ischemic stroke is a disease with high prevalence and incidence. Its management focuses on rapid reperfusion with intravenous thrombolysis and endovascular thrombectomy. Both therapeutic strategies reduce disability, but the therapy time window is short, and the risk of bleeding is high. Natural products (NPs) have played a key role in drug discovery, especially for cancer and infectious diseases. However, they have made little progress in clinical translation and pose challenges to the treatment of stroke. Recently, with the investigation of precise mechanisms in cerebral ischemic stroke and the technological development of NP-based drug discovery, NPs are addressing these challenges and opening up new opportunities in cerebral stroke. Thus, in this review, we first summarize the structure and function of diverse NPs, including flavonoids, phenols, terpenes, lactones, quinones, alkaloids, and glycosides. Then we propose the comprehensive neuroprotective mechanism of NPs in cerebral ischemic stroke, which involves complex cascade processes of oxidative stress, mitochondrial damage, apoptosis or ferroptosis-related cell death, inflammatory response, and disruption of the blood-brain barrier (BBB). Overall, we stress the neuroprotective effect of NPs and their mechanism on cerebral ischemic stroke for a better understanding of the advances and perspective in NPs application that may provide a rationale for the development of innovative therapeutic regimens in ischemic stroke.

Buyang Huanwu decoction improves neural recovery after spinal cord injury in rats through the mTOR signaling pathway and autophagy

BACKGROUND

Spinal cord injury (SCI) refers to the interruption of the tracts inside the spinal cord caused by various factors. The repair of damaged axons has always been a difficult point in clinical treatment and neuroscience research. The treatment of SCI with Buyang huanwu decoction (BYHWD), a well-known recipe for invigorating Qi (a vital force forming part of any living entity in traditional Chinese culture) and promoting blood circulation, shows a good effect.

METHODS

The rubrospinal tract (RST) transection model in rats was established in this study and rats were administrated with low (BL), medium (BM), or high (BH) doses of BYHWD.

RESULTS

Compared with the SCI group, BL, BM moderately, and BH significantly improved the motor function of forelimbs and increased the number of red nucleus neurons in SCI rats. As for the possible molecular mechanism, BL, BM moderately, and BH significantly increased mTOR whereas decreased Beclin-1 and LC3 in the red nucleus.

CONCLUSION

In conclusion, low, medium, and high doses of BYHWD could promote neural recovery in SCI rats through improving motor function and neuron survival in the red nucleus. The neuroprotective effects of BYHWD might be associated with affecting the mTOR signaling pathway and autophagy.

Neuroprotective Effect of Corosolic Acid Against Cerebral Ischemia-Reperfusion Injury in Experimental Rats

Several therapeutic approaches were also urgently needed as ischaemic stroke was one of the most common brain disorders. Many phytochemicals have recently been discovered for the advancement of lead-like libraries that are concentrated on the peripheral and central nervous systems. Science does not yet understand how these drugs work, nor do they comprehend their in vivo characteristics. We investigated the potential benefits of corosolic acid (CA) in the treatment of brain injury caused by ischemia/reperfusion (I/R) in adult male Sprague-Dawley rats. Injury occurs after a 2-hour transient occlusion of the posterior cerebral artery and subsequent reperfusion (after 20 hours). Furthermore, the experiment assessed the size of the infarct, the amount of brain water present, as well as the neurofunctional conditions in rats. In the study, several markers of inflammation and cytokines associated with brain injury were measured. The Elisa kit was used in this study to measure the mRNA expression of interleukin-6 (IL-6), interleukin-10 (IL-10), interleukin 1β, TNF-α (tumor necrosis factor), cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE2), and nitrous oxide (NO). The CA treatment significantly reduced brain water content, brain infarction volume, neurological scores, and Evans blue leakage (p < 0.001 and p < 0.001). Experimental rats were treated with CA after a significantly reduced level of anti-inflammatory, pro-inflammatory, and oxidative stress mediators was noted in their body tissues and serum (p < 0.001). By suppressing inflammatory responses in rats, CA demonstrated anti-inflammatory and neuroprotective properties.

Morin and isoquercitrin protect against ischemic neuronal injury by modulating signaling pathways and stimulating mitochondrial biogenesis

OBJETIVE

The search for the etiology of Alzheimer's disease has revealed dysregulation of amyloid protein precursors, β-secretase, mitophagy, apoptosis, and Tau protein genes after ischemic brain injury. Due to this and the fact that some flavonoids have demonstrated anti-amyloidogenic effects on AD targets, we aimed to investigate whether they are effective against an ischemic neuronal injury not only by its antioxidant effects and clarify their mechanism.We simulated the energy depletion that characterizes ischemic processes using iodoacetic acid on HT22 cells. In vitro ischemic assays were also performed under OXPHOS inhibition using inhibitors of the different mitochondrial complexes and intracellular ATP, NADH and NADPH levels were determined. The signaling pathways of MAP kinase (MAPK) and of the PI3K/Akt mTOR were analyzed for its close association with post-ischemic survival.

RESULTS

Morin and isoquercitrin showed a significant neuroprotective effect against IAA toxicity, favored the activity of the mitochondrial complexes and prevented the decrease in ERK phosphorylation and activation of the stress proteins JNK and p38 caused by IAA treatment, as well as prevented satisfactorily mTOR and p70 dephosphorylation. They provide a considerable resistance to ischemic brain injury by modulating signaling pathways that stimulate mitochondrial biogenesis and promoting the activity of electron transport chain.

Neurodegenerative Diseases and Flavonoids: Special Reference to Kaempferol

Neurodegenerative diseases like Alzheimer's disease, Parkinson's disease, Huntington's disease, Multiple Sclerosis and Ischemic stroke have become a major health problem worldwide. Pre-clinical studies have demonstrated the beneficial effects of flavonoids on neurodegenerative diseases and suggest them to be used as therapeutic agents. Kaempferol is found in many plants such as tea, beans, broccoli, strawberries, and neuroprotective effects against the development of many neurodegenerative diseases such as Parkinson, Alzheimer's disease and Huntington's disease. The present study summarizes the neuroprotective effects of kaempferol in various models of neurodegenerative diseases. Kaempferol delays the initiation as well as the progression of neurodegenerative disorders by acting as a scavenger of free radicals and preserving the activity of various antioxidant enzymes. Kaempferol can cross the Blood-Brain Barrier (BBB), and therefore results in an enhanced protective effect. The multi-target property of kaempferol makes it a potential dietary supplement in preventing and treating neurodegenerative diseases.

An overview of pharmacological activities of baicalin and its aglycone baicalein: New insights into molecular mechanisms and signaling pathways

The flavonoids, baicalin, and its aglycone baicalein possess multi-fold therapeutic properties and are mainly found in the roots of Oroxylum indicum (L.) Kurz and Scutellaria baicalensis Georgi. These flavonoids have been reported to possess various pharmacological properties, including antibacterial, antiviral, anticancer, anticonvulsant, anti-oxidant, hepatoprotective, and neuroprotective effects. The pharmacological properties of baicalin and baicalein are due to their abilities to scavenge reactive oxygen species (ROS) and interaction with various signaling molecules associated with apoptosis, inflammation, autophagy, cell cycle, mitochondrial dynamics, and cytoprotection. In this review, we summarized the molecular mechanisms underlying the chemopreventive and chemotherapeutic applications of baicalin and baicalein in the treatment of cancer and inflammatory diseases. In addition, the preventive effects of baicalin and baicalein on mitochondrial dynamics and functions were highlighted with a particular emphasis on their anti-oxidative and cytoprotective properties. The current review highlights could be useful for future prospective studies to further improve the pharmacological applications of baicalein and baicalin. These studies should define the threshold for optimal drug exposure, dose optimization and focus on therapeutic drug monitoring, objective disease markers, and baicalin/baicalein drug levels.

Baicalein ameliorates ischemic brain damage through suppressing proinflammatory microglia polarization via inhibiting the TLR4/NF-κB and STAT1 pathway

Microglial polarization mediated neuroinflammation plays an important role in the pathological process of stroke. The aim of this study is to determine whether baicalein indirectly ameliorates neuronal injury through modulating microglial polarization after stroke and if so, then by what mechanism. The effects of baicalein on microglial polarization were revealed through the middle cerebral artery occlusion mouse model (MCAO, n = 6), the lipopolysaccharide (LPS) + interferon-γ (IFN-γ) and oxygen-glucose deprivation (OGD) induced neuroinflammatory microglia model (BV2, n = 3), respectively. Mice were treated with baicalein (100 mg/kg, i.g.) after reperfusion, and followed by daily administrations for 3 days. Results showed that the infarct volumes at 3 d in vehicle and baicalein-treated MCAO mice were 91.18 ± 4.02% and 55.36 ± 4.10%. Baicalein improved sensorimotor functions (p < 0.01) after MCAO. Real-time PCR revealed that baicalein decreased proinflammatory markers expression (p < 0.05), while elevated the anti-inflammatory markers (p < 0.05) in vivo and in vitro. Both western blot and immunofluorescent staining further confirmed that baicalein reduced proinflammatory marker CD16 levels (p < 0.01) and enhanced anti-inflammatory marker CD206 or Arg-1 levels (p < 0.05). Notably, baicalein suppressed the release of proinflammatory cytokines (p < 0.05) and nitric oxide (NO, p < 0.001). Mechanistically, baicalein prevented increases in TLR4 protein levels (p < 0.001), the phosphorylation of IKBα and p65 (p < 0.01), and the nuclear translocation of NF-κB p65 (p < 0.05). The NF-κB inhibitor, BAY 11-7085, enhanced the inhibitory effect of baicalein on the proinflammatory microglial polarization. Baicalein also inhibited the phosphorylation of signal transducer and activator of transcription 1 (STAT1, p < 0.001). A microglia-neuron co-culture system revealed that baicalein driven neuroprotection against OGD induced neuronal damage through modulating microglial polarization (p < 0.05). Baicalein indirectly ameliorates neuronal injury after stroke by polarizing microglia toward the anti-inflammatory phenotype via inhibition of the TLR4/NF-κB pathway and down-regulation of phosphorylated STAT1, suggesting that baicalein might serve a potential therapy for stroke.

Immunostimulant and Antidepressant Effect of Natural Compounds in the Management of Covid-19 Symptoms

In recent years, the use of natural compounds as adjuvant treatments and alternatives to traditional pharmacological therapies has become increasingly popular. These compounds have a wide range of biological effects, such as: antioxidant, anti-aging, hypocholesterolizing, hypoglycemic, antitumoral, antidepressant, anxiolytic activity, etc. Almost all of these compounds are easily available and are contained in different foods. At the end of 2019 the Coronavirus SARS-CoV-2 appeared in China and quickly spread throughout the world, causing a pandemic. The most common symptoms of this infection are dry cough, fever, dyspnea, and in severe cases bilateral interstitial pneumonia, with consequences that can lead to death. The nations, in trying to prevent the spread of infection, have imposed social distancing and lockdown measures on their citizens. This had a strong psychological-social impact, leading to phobic, anxious and depressive states. Pharmacological therapy could be accompanied by treatment with several natural compounds, such as vitamins, baicalein, zinc and essential oils. These compounds possess marked immunostimulant activity, strengthening the immune response and mitigating interactions between the virus and the host cell. They also have an antidepressant effect, acting on certain neurotransmitters.

Baicalein, Baicalin, and Wogonin: Protective Effects against Ischemia-Induced Neurodegeneration in the Brain and Retina

Ischemia is a common pathological condition present in many neurodegenerative diseases, including ischemic stroke, retinal vascular occlusion, diabetic retinopathy, and glaucoma, threatening the sight and lives of millions of people globally. Ischemia can trigger excessive oxidative stress, inflammation, and vascular dysfunction, leading to the disruption of tissue homeostasis and, ultimately, cell death. Current therapies are very limited and have a narrow time window for effective treatment. Thus, there is an urgent need to develop more effective therapeutic options for ischemia-induced neural injuries. With emerging reports on the pharmacological properties of natural flavonoids, these compounds present potent antioxidative, anti-inflammatory, and antiapoptotic agents for the treatment of ischemic insults. Three major active flavonoids, baicalein, baicalin, and wogonin, have been extracted from Scutellaria baicalensis Georgi (S. baicalensis); all of which are reported to have low cytotoxicity. They have been demonstrated to exert promising pharmacological capabilities in preventing cell and tissue damage. This review focuses on the therapeutic potentials of these flavonoids against ischemia-induced neurotoxicity and damage in the brain and retina. The bioactivity and bioavailability of baicalein, baicalin, and wogonin are also discussed. It is with hope that the therapeutic potential of these flavonoids can be utilized and developed as natural treatments for ischemia-induced injuries of the central nervous system (CNS).

Baicalein attenuates caspase-independent cells death via inhibiting PARP-1 activation and AIF nuclear translocation in cerebral ischemia/reperfusion rats

It is reported that baicalein can activate PI3K/AKT pathway, inhibit caspase activation and reduce cerebral infarct volume in middle cerebral artery occlusion (MCAO) rats. However, a caspase-independent mechanism initiated by poly (ADP-ribose) polymerase-1 (PARP-1) activation has been reported to make more contribution to cells death after ischemic stroke. In the present study, we established a cerebral ischemia/reperfusion (I/R) rat model through middle cerebral artery occlusion following reperfusion to investigate the mechanisms of ischemic tissue recovery following baicalein treatment. The data showed that baicalein treatment at dose of 100 mg/kg for 7 days significantly inhibited the release of cytokines, activation of PARP-1, nuclear translocation of apoptosis-inducing factor (AIF) and macrophage migration inhibitory factor (MIF) in cerebral I/R rats, therefore decreased cerebral infarct volume and neurological scores. Then, we further investigated the signal transduction mechanisms of ischemic tissue protection by baicalein in vitro. Following oxygen and glucose deprivation (OGD) in SH-SY5Y cells, the mitochondrial AIF was translocated into nucleus after 12 h. The co-immunoprecipitation analysis showed that the interaction between AIF and MIF was activated by OGD and subsequently resulted in MIF nuclear translocation. Also, the baicalein inhibited apoptosis, reduced oxidative stress, protected mitochondrial function and restored mitochondrial membrane potential in OGD cells. The results obtained from both in vivo and in vitro study demonstrated the PARP-1/AIF pathway involved in mechanisms of baicalein to protect the cerebral tissues from ischemic injury.

Network Pharmacology and Molecular Docking Analysis on Molecular Targets and Mechanisms of Buyang Huanwu Decoction in the Treatment of Ischemic Stroke

Methods

The bioactive components and potential targets of BHD were screened by TCMSP, BATMAN-TCM, ETCM, and SymMap databases. Besides, compounds that failed to find the targets from the above databases were predicted through STITCH, SwissTargetPrediction, and SEA. Moreover, six databases were searched to mine targets of IS. The intersection targets were obtained and analyzed by GO and KEGG enrichment. Furthermore, BHD-IS PPI network, compound-target network, and herb-target-pathway network were constructed by Cytoscape 3.6.0. Finally, AutoDock was used for molecular docking verification.

Results

A total of 235 putative targets were obtained from 59 active compounds in BHD. Among them, 62 targets were related to IS. PPI network showed that the top ten key targets were IL6, TNF, VEGFA, AKT1, etc. The enrichment analysis demonstrated candidate BHD targets were more frequently involved in TNF, PI3K-Akt, and NF-kappa B signaling pathway. Network topology analysis showed that Radix Astragali was the main herb in BHD, and the key components were quercetin, beta-sitosterol, kaempferol, stigmasterol, etc. The results of molecular docking showed the active components in BHD had a good binding ability with the key targets.

Conclusions

Our study demonstrated that BHD exerted the effect of treating IS by regulating multitargets and multichannels with multicomponents through the method of network pharmacology and molecular docking.

Therapeutic modulation of the phosphatidylinositol 3-kinases (PI3K) pathway in cerebral ischemic injury

The cerebral ischemic reperfusion injury may leads to morbidity and mortality in patients. phosphatidylinositol 3-kinase (PI3K) signaling pathway has been believed to work in association with its downstream targets, other receptors, and pathways that may offer antioxidant, anti-inflammatory, anti-apoptotic effects, neuroprotective role in neuronal excitotoxicity. This review elaborates the mechanistic interventions of the PI3K pathway in cerebral ischemic injury in context to nuclear factor erythroid 2-related factor 2 (Nrf2) regulation, Hypoxia-inducible factor 1 signaling (HIF-1), growth factors, Endothelial NOS (eNOS) proinflammatory cytokines, Erythropoietin (EPO), Phosphatase and tensin homologous protein of chromosome 10 gene (PTEN) signaling, NF-κB/Notch signaling, c-Jun N-terminal kinase (JNK) and Glycogen synthase kinase-3β (GSK-3β) signaling pathway. Evidences showing the activation of PI3K inhibits apoptotic pathway, which results in its neuroprotective effect in ischemic injury. Despite discussing the therapeutic role of the PI3K pathway in treating cerebral ischemic injury, the review also enlighten the selective modulation of PI3K pathway with activators and inhibitors which may provide promising results in clinical and preclinical settings.

Mild hypothermia protects rat cortical neurons against oxygen-glucose deprivation/reoxygenation injury via the PI3K/Akt pathway

Ischemic stroke is the most frequent cause of long-term morbidity and mortality in the elderly worldwide. Mild hypothermia (32-35°C) has been found to have a neuroprotective effect against ischemic stroke. However, the protective mechanisms remain unclear. In the present study, we explore the neuroprotective effect of mild hypothermia in neuron-astrocyte cocultures by oxygen-glucose deprivation/reoxygenation (OGD/R) as well as the underlying mechanisms. Thionin staining was performed and cell viability, extracellular glutamate concentration and the phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt) pathway-related proteins were detected after OGD/R. The results indicated that mild hypothermia significantly alleviated damage to Nissl bodies and increased the viability of neurons, which alleviated OGD/R-triggered neuronal injury. Furthermore, mild hypothermia significantly enhanced the phosphorylation of Akt (pAkt) and glutamate transporter-1 (GLT-1) and reduced extracellular glutamate concentration after OGD/R. When the PI3K inhibitor LY294002 was added, neuronal viability and the expression of pAkt and GLT-1 decreased, and extracellular glutamate concentration increased. The protective effect of mild hypothermia was counteracted by LY294002. There was no significant change in neuronal viability or the expression of pAkt and GLT-1 in the group treated with dihydrokainate, an inhibitor of GLT-1-function, compared with the mild hypothermia + OGD/R (HOGD) group, but extracellular glutamate concentration was increased. Consequently, mild hypothermia promoted glutamate clearance by regulating GLT-1 expression via the PI3K/Akt pathway, providing a neuroprotective effect against OGD/R injury.

Natural Products for the Treatment of Neurodegenerative Diseases

Neurodegenerative diseases are a heterogeneous group of disorders characterized by the progressive degeneration of the structure and function of the central nervous system or peripheral nervous system. Alzheimer's Disease (AD), Parkinson's Disease (PD) and Spinal Cord Injury (SCI) are the common neurodegenerative diseases, which typically occur in people over the age of 60. With the rapid development of an aged society, over 60 million people worldwide are suffering from these uncurable diseases. Therefore, the search for new drugs and therapeutic methods has become an increasingly important research topic. Natural products especially those from the Traditional Chinese Medicines (TCMs), are the most important sources of drugs, and have received extensive interest among pharmacist. In this review, in order to facilitate further chemical modification of those useful natural products by pharmacists, we will bring together recent studies in single natural compound from TCMs with neuroprotective effect.

A Network Pharmacology Technique to Investigate the Synergistic Mechanisms of Salvia miltiorrhiza and Radix puerariae in Treatment of Cardio-Cerebral Vascular Diseases

Objective

This study is aimed to analyze the active ingredients, drug targets, and related pathways in the combination of Salvia miltiorrhiza (SM) and Radix puerariae (RP) in the treatment of cardio-cerebral vascular diseases (CCVDs).

Method

The ingredients and targets of SM and RP were obtained from Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP), and the disease targets were obtained from Therapeutic Target Database (TTD), National Center for Biotechnology Information (NCBI), and Online Mendelian Inheritance in Man (OMIM) Database. The synergistic mechanisms of the SM and RP were evaluated by gene ontology (GO) enrichment analyses and Kyoto encyclopedia of genes and genomes (KEGG) path enrichment analyses.

Result

A total of 61 active ingredients and 58 common targets were identified in this study. KEGG pathway enrichment analysis results showed that SM- and RP-regulated pathways were mainly inflammatory processes, immunosuppression, and cardiovascular systems. The component-target-pathway network indicated that SM and RP exert a synergistic mechanism for CCVDs through PTGS2 target in PI3k-Akt, TNF, and Jak-STAT signaling pathways.

Conclusion

In summary, this study clarified the synergistic mechanisms of SM and RP, which can provide a better understanding of effect in the treatment of CCVDs.

Upregulation of C Terminus of Hsc70-Interacting Protein Attenuates Apoptosis and Procoagulant Activity and Facilitates Brain Repair After Traumatic Brain Injury

Traumatic brain injury (TBI) could highly induce coagulopathy through breaking the dynamic balance between coagulation and fibrinolysis systems, which may be a major contributor to the progressive secondary injury cascade that occurs after TBI. Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) inhibition is reported to exert neuroprotection in TBI, making it a potential regulatory target involved in TBI-induced coagulation disorder. PTEN level is controlled in a major way by E3 ligase-mediated degradation through the ubiquitin-proteasome system. The C terminus of Hsc70-interacting protein (CHIP) has been shown to regulate proteasomal degradation and ubiquitination level of PTEN. In the present study, CHIP was overexpressed and knocked down in mouse brain microvascular endothelial cells (bEnd.3) and tissues during the early phase of TBI. In vitro cell proliferation, cell apoptosis, migration capacity, and invasion capacity were determined. The changes of procoagulant and apoptosis molecules after TBI were also detected as well as the micrangium density and blood-brain barrier permeability after in vivo TBI. In vitro results demonstrated that CHIP overexpression facilitated bEnd.3 cell proliferation, migration, and invasion and downregulated cell apoptosis and the expressions of procoagulant molecules through promoting PTEN ubiquitination in a simulated TBI model with stretch-induced injury treatment. In vivo experiments also demonstrated that CHIP overexpression suppressed post-TBI apoptosis and procoagulant protein expressions, as well as increased microvessel density, reduced hemorrhagic injury, and blood-brain barrier permeability. These findings suggested that the upregulation of CHIP may attenuate apoptosis and procoagulant activity, facilitate brain repair, and thus exerts neuroprotective effects in TBI.

Neuroprotective effects of miR-532-5p against ischemic stroke

Stroke can cause death and disability and has a high incidence with many complications. So far, effective treatment options for stroke are still limited. MicroRNA-532-5p (miR-532-5p) is significantly downregulated in stroke. However, the role of miR-532-5p in ischemic stroke is still unclear. In this study, we established an in vivo middle cerebral artery occlusion (MCAO) model in mice. The expression level of miR-532-5p, neurological score, infarct area, neuronal apoptosis, and phosphoinositide 3-kinase (PI3K)/Akt signaling pathway-related molecules were examined. Low miR-532-5p levels and high phosphatase and tensin homolog deleted on chromosome 10 (PTEN) levels were detected in the mouse MCAO model. MiR-532-5p overexpression improved neurological dysfunction, reduced the infarct area, attenuated neuronal injury and apoptosis, and promoted the activation of the PI3K/Akt signaling pathway in MCAO mice. In vitro, we treated mouse neuroblastoma cells (N2a) with oxygen-glucose deprivation and reperfusion (OGD/R). The expression level of miR-532-5p, cell viability, cell apoptosis, and the PI3K/Akt signaling pathway-related molecules were detected. Consistent with the in vivo tests, the miR-532-5p level was decreased and the PTEN level was increased in OGD-treated N2a cells in vitro. The miR-532-5p mimic increased cell viability, decreased cell apoptosis, and activated the PI3K/Akt signaling pathway. Furthermore, PTEN was verified as a target gene of miR-532-5p by luciferase reporter assay. PTEN overexpression attenuated the protective effect of miR-532-5p in OGD-treated N2a cells. In summary, these findings reveal that miR-532-5p protects against ischemic stroke by inhibiting PTEN and activating the PI3K/Akt signaling pathway and may serve as a novel therapeutic target for ischemic stroke.

Bone mesenchymal stem cell-derived exosomal microRNA-29b-3p prevents hypoxic-ischemic injury in rat brain by activating the PTEN-mediated Akt signaling pathway

BACKGROUND

Mesenchymal stem cells (MSCs) are suspected to exert neuroprotective effects in brain injury, in part through the secretion of extracellular vesicles like exosomes containing bioactive compounds. We now investigate the mechanism by which bone marrow MSCs (BMSCs)-derived exosomes harboring the small non-coding RNA miR-29b-3p protect against hypoxic-ischemic brain injury in rats.

METHODS

We established a rat model of middle cerebral artery occlusion (MCAO) and primary cortical neuron or brain microvascular endothelial cell (BMEC) models of oxygen and glucose deprivation (OGD). Exosomes were isolated from the culture medium of BMSCs. We treated the MCAO rats with BMSC-derived exosomes in vivo, and likewise the OGD-treated neurons and BMECs in vitro. We then measured apoptosis- and angiogenesis-related features using TUNEL and CD31 immunohistochemical staining and in vitro Matrigel angiogenesis assays.

RESULTS

The dual luciferase reporter gene assay showed that miR-29b-3p targeted the protein phosphatase and tensin homolog (PTEN). miR-29b-3p was downregulated and PTEN was upregulated in the brain of MCAO rats and in OGD-treated cultured neurons. MCAO rats and OGD-treated neurons showed promoted apoptosis and decreased angiogenesis, but overexpression of miR-29b-3p or silencing of PTEN could reverse these alterations. Furthermore, miR-29b-3p could negatively regulate PTEN and activate the Akt signaling pathway. BMSCs-derived exosomes also exerted protective effects against apoptosis of OGD neurons and cell apoptosis in the brain samples from MCAO rats, where we also observed promotion of angiogenesis.

CONCLUSION

BMSC-derived exosomal miR-29b-3p ameliorates ischemic brain injury by promoting angiogenesis and suppressing neuronal apoptosis, a finding which may be of great significance in the treatment of hypoxic-ischemic brain injury.

SIRT1 is required for the neuroprotection of resveratrol on retinal ganglion cells after retinal ischemia-reperfusion injury in mice

PURPOSE

Retinal ganglion cells (RGCs) loss is closely related to visual impairment in glaucoma, so the neuroprotection on RGCs is important and novel for glaucoma research. SIRT1, a family member of sirtuins, is implicated in many crucial processes of eye diseases. The purpose of this study is to determine the neuroprotection of SIRT1 on RGCs and to investigate the underlying mechanisms of these effects in an experimental model for acute glaucoma.

METHODS

Retinal ischemia-reperfusion (IR) injury was induced in C57BL/6J mice. Resveratrol (RSV, activator of SIRT1) and sirtinol (inhibitor of SIRT1) were injected intravitreally 1 day before IR injury. RGCs survival rate was quantified by immunofluorescence staining. RGCs apoptosis was evaluated by the staining of TUNEL and cleaved caspase-3, and SIRT1 level was detected by western blot. Expressions of phospho-Akt, Akt, Bax, and Bcl-2 were further determined by western blot to investigate the neuroprotective mechanisms of SIRT1.

RESULTS

RGCs survival rates and SIRT1 levels were decreased over time after IR injury. Intravitreal injection of RSV remarkably attenuated RGCs loss in a dose-dependent manner, and the most effective concentration of RSV was 100 μM. Up-regulation of SIRT1 by RSV significantly inhibited RGCs apoptosis, increased p-Akt level, decreased Bax and cleaved caspase-3 expressions, and all these effects were diminished by 100 μM sirtinol. Moreover, there were no significant changes in total Akt and Bcl-2 levels.

CONCLUSION

SIRT1 activation by RSV confers neuroprotection on RGCs in retinal IR injury through the activation of Akt pathway and subsequent suppression of mitochondrial apoptotic pathway. Determination of the effective concentration of intravitreal injection of RSV also provides a theoretical basis for the clinical application of RSV.

Dietary Polyphenols: A Multifactorial Strategy to Target Alzheimer's Disease

Ageing is an inevitable fundamental process for people and is their greatest risk factor for neurodegenerative disease. The ageing processes bring changes in cells that can drive the organisms to experience loss of nutrient sensing, disrupted cellular functions, increased oxidative stress, loss of cellular homeostasis, genomic instability, accumulation of misfolded protein, impaired cellular defenses and telomere shortening. Perturbation of these vital cellular processes in neuronal cells can lead to life threatening neurological disorders like Alzheimer's Disease, Parkinson's Disease, Huntington's Disease, Lewy body dementia, etc. Alzheimer's Disease is the most frequent cause of deaths in the elderly population. Various therapeutic molecules have been designed to overcome the social, economic and health care burden caused by Alzheimer's Disease. Almost all the chemical compounds in clinical practice have been found to treat symptoms only limiting them to palliative care. The reason behind such imperfect drugs may result from the inefficiencies of the current drugs to target the cause of the disease. Here, we review the potential role of antioxidant polyphenolic compounds that could possibly be the most effective preventative strategy against Alzheimer's Disease.

Retracted: Protection of miR-19b in hypoxia/reoxygenation-induced injury by targeting PTEN

OBJECTIVE

To study the role and mechanism of microRNA 19b (miR-19b) in hypoxia/reoxygenation (H/R)-induced injury by targeting PTEN.

METHODS

PC12 and BV2 cells induced by H/R were treated with miR-19b mimics/inhibitors or small interfering PTEN (si-PTEN), respectively. Lactate dehydrogenase (LDH) level, malondialdehyde (MDA), and superoxide dismutase (SOD) content was detected. Besides, cell viability and apoptosis were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, Hoechst33342 staining, and flow cytometry, whereas mitochondrial membrane potential (MMP) tested by JC-1 assay, and reactive oxygen species (ROS) evaluated by the dichloro-dihydro-fluorescein diacetate assay. The ischemia/reperfusion (I/R) rats model was used to investigate the effects of miR-19b in vivo test. The infarct area and apoptosis rates in brain tissues were detected by 2,3,5-triphenyltetrazolium chloride and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling staining, respectively. miR-19b and PTEN/PI3K/Akt pathway-related proteins were detected by quantitative reverse-transcription polymerase chain reaction and western blot analysis.

RESULTS

miR-19b mimics could reduce LDH, MDA, and ROS levels and decline cell apoptosis, but enhance the viability, MMP, and SOD activity with decreased PTEN and cleaved caspase, as well as increased p-Akt/Akt and Bcl-2/Bax ratios in H/R-induced PC12 and BV2 cells. However, miR-19b inhibitors led to completely opposite results to aggravate H/R-induced cell injury. Meanwhile, si-PTEN could reverse the effect of miR-19b inhibitors on H/R-induced injury. Moreover, treatment with miR-19b agomir after I/R in vivo sufficiently decreased infarct area and reduced apoptosis rates by targeting PTEN through the regulation of the PI3K/Akt pathway.

CONCLUSION

miR-19b could inhibit oxidative stress, enhance cell MMP, promote cell survival, and inhibit cell apoptosis by targeting PTEN via the regulation of the PI3K/Akt pathway, thus playing the neuronal protective effects.

Nigella sativa and thymoquinone attenuate oxidative stress and cognitive impairment following cerebral hypoperfusion in rats

Nigella sativa, a plant widely used in traditional medicine, possesses anti-inflammatory, antioxidant and neuroprotective properties. In the present study, we investigated the effect of hydroalcoholic extract of N. sativa seeds (NSE) and its active constituent, thymoquinone (TQ), on learning and memory deficits, hippocampal acetylcholine esterase (AChE) activity, and markers of redox status, mainly lipid peroxidation and superoxide dismutase (SOD) activity following cerebral hypoperfusion in rats. Cerebral hypoperfusion was induced by permanent occlusion of bilateral common carotid arteries (2VO). Male Wistar rats were administered either a vehicle (sham group: 10 ml/kg/day, ip), NSE (100, 200, and 400 mg/kg/day, ip), TQ (10, 20, and 40 mg/kg/day, ip), or donepezil (5 mg/kg/day, ip) for 10 days (three days before and seven days after ligation). Spatial learning and memory deficits were investigated using the Morris water maze (MWM) task. 2VO produced significant learning and memory deficits as evidenced by increased latency time to reach the hidden platform, increased swimming time, and decreased time spent in the target quadrant in the probe trial in the MWM task. There was also a significant increase in the lipid peroxidation level and AChE activity, and a significant decrease in SOD activity in the hippocampal portion of hypoperfused rats, as compared with the sham group. Treatment with NSE (400 mg/kg/day; p < 0.001) and TQ (40 mg/kg/day; p < 0.001), as well as donepezil significantly prevented learning and memory impairments and alleviated changes in the hippocampal lipid peroxide level and SOD and AChE activities in this model. In conclusion, our data suggest that N. sativa and thymoquinone have a beneficial role in cerebrovascular insufficiency states and dementia.

Baicalein administered in the subacute phase ameliorates ischemia-reperfusion-induced brain injury by reducing neuroinflammation and neuronal damage

Ischemic stroke is a cerebrovascular disease with high morbidity, high mortality, and high disability, representing a serious threat to human life and health. Clinically, the extensive injury caused by ischemic stroke results from ischemia-reperfusion (I/R) injury thrombolytic treatment. However, there are few reports on the use of medications in the subacute stage of cerebral I/R. Baicalein (5,6,7-trihydroxyflavone) is a biologically active ingredient extracted from the root of Scutellaria baicalensis Georgi. In the present study, we investigated the therapeutic effect of baicalein administered in the subacute phase of cerebral I/R injury in a rat model of ischemia induced by occlusion of the middle cerebral artery (MCA). Rats were treated daily with baicalein (200 mg/kg, i.g.) in the subacute phase (24 h after reperfusion) for 7 days. The results showed that baicalein significantly reduced neurobehavioral deficits and decreased brain infarct volume from 18.99% to 7.41%. Immunofluorescence analysis of the ischemic penumbra showed that baicalein significantly reduced expression of the M1 marker, cluster of differentiation (CD) 16 and CD86, and increased expression of the M2 marker, CD 163 and CD206, indicating that baicalein inhibited M1 transformation and promoted M2 transformation of microglia/macrophage to inhibit neuroinflammation. Moreover, baicalein suppressed NF-κB signaling by reducing IκBα phosphorylation and nuclear translocation of NF-κB/p65, which decreased the release of the pro-inflammatory factors IL-6, IL-18, and TNF-α. In addition, baicalein reduced phosphorylation of JNK, ERK and p38, which are involved modulation of microglia/macrophage M1/M2 polarization. Western blot analysis of apoptosis- and autophagy-related proteins showed that baicalein increased the Bcl-2/Bax ratio and reduced caspase-3 expression to decrease neuronal apoptosis and ameliorate neuronal loss. Baicalein also decreased the LC3-II/LC3-I ratio and promoted phosphorylation of the PI3K/Akt/mTOR signaling pathway which implied inhibition of autophagy. These observations suggest that baicalein exerts neuroprotective effects by reducing neuroinflammation, apoptosis and autophagy, and protects against cerebral I/R injury in the subacute phase in vivo.

Neuroprotective Effects of Baicalein on Acrolein-induced Neurotoxicity in the Nigrostriatal Dopaminergic System of Rat Brain

Elevated levels of acrolein, an α,β-unsaturated aldehyde are detected in the brain of patients with Parkinson's disease (PD). In the present study, the neuroprotective effect of baicalein (a phenolic flavonoid in the dried root of Scutellaria baicalensis Georgi) on acrolein-induced neurodegeneration of nigrostriatal dopaminergic system was investigated using local infusion of acrolein in the substantia nigra (SN) of rat brain. Systemic administration of baicalein (30 mg/kg, i.p.) significantly attenuated acrolein-induced elevations in 4-hydroxy-2-noneal (a product of lipid peroxidation), N-(3-formyl-3,4-dehydropiperidino)lysine (a biomarker of acrolein-conjugated proteins), and heme-oxygenase-1 levels (a redox-regulated protein) in the infused SN, indicating that baicalein inhibited acrolein-induced oxidative stress and protein conjugation. Furthermore, baicalein reduced acrolein-induced elevations in glial fibrillary acidic protein (a biomarker of activated astrocytes), ED-1 (a biomarker of activated microglia), and mature cathepsin B levels (a cysteine lysosomal protease), suggesting that baicalein attenuated acrolein-induced neuroinflammation. Moreover, baicalein attenuated acrolein-induced caspase 1 activation (a pro-inflammatory caspase) and interleukin-1β levels, indicating that baicalein prevented acrolein-induced inflammasome activation. In addition, baicalein significantly attenuated acrolein-induced caspase 3 activation (a biomarker of apoptosis) as well as acrolein-induced elevation in receptor interacting protein kinase (RIPK) 3 levels (an initiator of necroptosis), indicating that baicalein attenuated apoptosis and necroptosis. At the same time, baicalein mitigated acrolein-induced reduction in dopamine levels in the striatum ipsilateral to acrolein-infused SN. In conclusion, our data suggest that baicalein is neuroprotective via inhibiting oxidative stress, protein conjugation, and inflammation. Furthermore, baicalein prevents acrolein-induced program cell deaths, suggesting that baicalein is therapeutically useful for slowing PD progression.

Changes in the levels of 12/15-lipoxygenase, apoptosis-related proteins and inflammatory factors in the cortex of diabetic rats and the neuroprotection of baicalein

This study was designed to investigate the neuroprotective effects of baicalein and the effect of the cortical 12/15-lipoxygenase (12/15-LOX) pathway on diabetic cognitive dysfunction. Our results showed that spatial learning and memory ability, as well as cortex neurons, were significantly impaired after the onset of diabetes. The fasting blood glucose and random blood glucose levels in the model group were significantly higher than those in the normal group. The levels of TG and TC in the plasma of the model group were significantly increased, but there was no significant difference in the LDL level. The insulin content in the plasma of diabetic rats was significantly lower than that of the normal group. The levels of inflammatory factors and 12(S)-HETE were significantly increased in diabetic rats, as were the protein expression levels of cPLA2, 12/15-LOX, p38MAPK, phospho-p38MAPK, caspase-3, caspase-9 and Aβ_1-42; by contrast, protein expression of Bcl-2 was significantly decreased. Administration of baicalein was shown to improve the spatial learning and memory ability and significantly decrease the levels of inflammatory cytokines. However, baicalein did not significantly influence the levels of blood glucose, lipids or insulin in rats. Baicalein treatment significantly protected diabetes rats from neuron death; significantly attenuated the overexpression of cPLA2, 12/15-LOX, p38MAPK, phospho-p38MAPK, caspase-3, caspase-9 and Aβ_1-42; and upregulated the expression of Bcl-2. These findings suggest that baicalein improves the cognitive function of diabetic rats by directly acting in the brain rather than by regulating the levels of blood glucose, lipids or insulin. In addition, baicalein can protect rat cortical neurons from damage caused by diabetes via inhibiting the 12/15-LOX pathway and relieving inflammation and apoptosis of the central nervous system.

Phytochemicals and cognitive health: Are flavonoids doing the trick?

Flavonoids constitute a large group of polyphenolic compounds with numerous effects on behaviour and cognition. These effects vary from learning and memory enhancement to an improvement of general cognition. Furthermore, flavonoids have been implicated in a) neuronal proliferation and survival, by acting on a variety of cellular signalling cascades, including the ERK/CREB/BDNF and PI3K/Akt pathway, b) oxidative stress reduction and c) relief from Alzheimer's disease-type symptoms. From an electrophysiological aspect, they promote long term potentiation in the hippocampus, supporting the hypothesis of synaptic plasticity mediation. Together, these actions reveal a neuroprotective effect of flavonoid compounds in the brain. Therefore, flavonoid intake could be a potential clinical direction for prevention and/or attenuation of cognitive decline deterioration which accompanies various brain disorders. The purpose of the current review paper was to summarise all these effects on cognition, describe the possible pathways via which they may act on a cellular level and provide a better picture for future research towards this direction.

Baicalein Enhances the Oral Bioavailability and Hepatoprotective Effects of Silybin Through the Inhibition of Efflux Transporters BCRP and MRP2

Although hepatoprotective properties of silybin are well documented, the clinical therapeutic efficacy is limited by its low bioavailability due to absorption rates, extensive phase II metabolism, and biliary excretion. As our previous study indicated that metabolic enzymes may have limited effects on the pharmacokinetic (PK) behavior of silymarin, here, we intended to increase the oral bioavailability and bio-efficacy of silybin through the inhibition of active efflux. In Caco-2 and transfected MDCKII cell models, flavone baicalein significantly inhibited the efflux of silybin as a BCRP and MRP2 inhibitor. In addition, baicalein reduced the biliary excretion index (BEI) and biliary clearance of silybin conjugates in the sandwich-cultured rat hepatocyte (SCH) model, indicating the inhibition of baicalein in biliary excretion of conjugated silybin metabolites. PK study demonstrated that baicalein significantly increased the area under the curve (AUC) and C_max of silybin and its conjugates, suggesting enhanced absorption in vivo. Moreover, coadministration of silybin with baicalein boosted the liver protective, antioxidant, and anti-inflammatory effects of silybin in the carbon tetrachloride (CCl₄)-induced liver injury model in comparison with silybin given alone. In summary, efflux transporters play a critical role in the low bioavailability of silybin, while inhibition of breast cancer resistance protein (BCRP) and multi-drug resistance protein 2 (MRP2) by baicalein can significantly increase the absorption and bio-efficacy of silybin, which provides a new combination therapeutic approach for the treatment of chronic liver diseases.

Effects of the traditional Chinese medicine baicalein on the viability of random pattern skin flaps in rats

Background

Random skin flaps are routinely placed during plastic and reconstructive surgery, but the distal areas often develop ischemia and necrosis. Baicalein, a major flavonoid extracted from the traditional Chinese herbal medicine huangqin, Scutellaria baicalensis Georgi, may improve flap viability.

Materials and methods

Rats were randomly divided into baicalein and control groups and they underwent placement of modified McFarlane flaps after intraperitoneal administration of baicalein or vehicle. Flap survival and water content were measured 7 days later, as were angiogenesis, apoptosis, and oxidative stress in ischemic flaps.

Results

Baicalein promoted flap survival, reduced edema, increased mean vessel density, and enhanced vascular endothelial growth factor production at both the translational and transcriptional levels. Baicalein reduced caspase 3 cleavage, increased superoxidase dismutase and glutathione levels, and decreased the malondialdehyde level.

Conclusion

Baicalein promoted flap viability by stimulating angiogenesis and inhibiting apoptosis and oxidation.

MicroRNA-21a-5p promotes fibrosis in spinal fibroblasts after mechanical trauma

Traumatic spinal cord injury (SCI) causes permanent disability to at least 180,000 people per year worldwide. Early regulation of spinal fibroblast proliferation may inhibit fibrotic scar formation, allowing the creation of a favorable environment for neuronal regeneration and thereby enhancing recovery from traumatic SCIs. In this study, we aimed to identify the role of microRNA-21a-5p (miR-21a-5p) in regulating spinal fibroblasts after mechanical trauma and to investigate the dysregulation of miR-21a-5p in the pathological process of spinal SCI. We investigated the differential expression of microRNAs in primary spinal fibroblasts after mechanical trauma and found that the expression of miR-21a-5p was higher in spinal fibroblasts after scratch damage (SD). In addition, mouse spinal fibroblasts were transfected with miR-21a-5p mimics/inhibitor, and the role of miR-21a-5p in spinal fibrogenic activation was analyzed. These experiments demonstrated that miR-21a-5p overexpression promoted fibrogenic activity in spinal fibroblasts after mechanical trauma, as well as enhancing proliferation and attenuating apoptosis in spinal fibroblasts. Finally, the potential role of miR-21a-5p in regulating the Smad signaling pathway was examined. MiR-21a-5p activated the Smad signaling pathway by enhancing Smad2/3 phosphorylation. These results suggest that miR-21a-5p promotes spinal fibrosis after mechanical trauma. Based on these findings, we propose a close relationship between miR-21a-5p and spinal fibrosis, providing a new potential therapeutic target for SCI.

Complete inhibition of phosphatase and tensin homolog promotes the normal and oxygen-glucose deprivation/reperfusion-injured PC12 cells to cell death

Introduction: Lipid phosphatase and tensin homolog deleted from chromosome 10 (PTEN) antagonizes phosphoinositide 3-kinase (PI3K)/AKT cell survival pathway. The effect of PTEN inhibitors has been rarely examined on cell survival following reperfusion injury. In this study, we investigated the neuroprotective effect of SF1670, as a new PTEN inhibitor, on an in vitro stroke-like model.

Methods: PC12 cells were exposed to oxygen-glucose deprivation/reperfusion (OGD/R). The cells were treated in five conditions as follows: normoxic normoglycemic (NO/NG); 60 minutes OGD; 60 minutes OGD and 6 h reperfusion (OGD/R); OGD/R treated with 10 µM SF1670 (OGD/R-SF), and NO/NG treated with 10 µM SF1670 (NO/NG-SF). Then, phosphorylation levels of AKT, P38 in PC12 cells were measured by immunoblotting. The cell viability was also determined by colorimetric assay.

Results: The results of immunoblotting revealed that following OGD/R the levels of phospho-AKT (p-AKT) significantly decreased, compared to NO/NG cells (P < 0.05). However, the ratio of p-AKT/total AKT significantly increased in the presence of SF1670 in the OGD/R-SF group, compared to the OGD/R condition. On the other hand, SF1670 significantly reduced the p-P38 MAPK and p-JNK levels, compared to OGD/R cells. Moreover, cell viability significantly decreased in the OGD and OGD/R condition compared to NO/NG cells. Surprisingly, SF-treated cells (OGD/R-SF and NO/NG-SF group) showed low cell viability compared to NO/NG condition.

Conclusion: Overall, our results demonstrated that complete inhibition of phosphatase activity of PTEN not only did not exhibit neuroprotective effect but also promoted PC12-deprived cells to death.

Baicalein Rescues Delayed Cooling via Preservation of Akt Activation and Akt-Mediated Phospholamban Phosphorylation

Cooling reduces the ischemia/reperfusion (I/R) injury seen in sudden cardiac arrest (SCA) by decreasing the burst of reactive oxygen species (ROS). Its cardioprotection is diminished when delay in reaching the target temperature occurs. Baicalein, a flavonoid derived from the root of Scutellaria baicalensis Georgi, possesses antioxidant properties. Therefore, we hypothesized that baicalein can rescue cooling cardioprotection when cooling is delayed. Two murine cardiomyocyte models, an I/R model (90 min ischemia/3 h reperfusion) and stunning model (30 min ischemia/90 min reperfusion), were used to assess cell survival and contractility, respectively. Cooling (32 °C) was initiated either during ischemia or during reperfusion. Cell viability and ROS generation were measured. Cell contractility was evaluated by real-time phase-contrast imaging. Our results showed that cooling reduced cell death and ROS generation, and this effect was diminished when cooling was delayed. Baicalein (25 µM), given either at the start of reperfusion or start of cooling, resulted in a comparable reduction of cell death and ROS production. Baicalein improved phospholamban phosphorylation, contractility recovery, and cell survival. These effects were Akt-dependent. In addition, no synergistic effect was observed with the combined treatments of cooling and baicalein. Our data suggest that baicalein may serve as a novel adjunct therapeutic strategy for SCA resuscitation.

Baicalein inhibits cell growth and increases cisplatin sensitivity of A549 and H460 cells via miR-424-3p and targeting PTEN/PI3K/Akt pathway

Lung cancer is the leading cause of death in individuals with malignant disease. Non‐small‐cell lung cancer (NSCLC) is the most common type of lung cancer, and chemotherapy drugs such as cisplatin are the most widely used treatment for this disease. Baicalein is a purified flavonoid compound that has been reported to inhibit cancer cell growth and metastasis and increase sensitization to chemotherapeutic drugs via different pathways. Therefore, we assessed the effects of baicalein on the proliferation, apoptosis and cisplatin sensitivity in the NSCLC A549 and H460 cell lines and determined the pathways through which baicalein exerts its effects. Baicalein was slightly toxic to normal human bronchial NHBE cells but inhibited growth, induced apoptosis and increased cisplatin sensitivity in A549 and H460 cells. Baicalein down‐regulated miR‐424‐3p, up‐regulated PTEN expression and down‐regulated expression of PI3K and p‐Akt in A549 and H460 cells. Dual‐luciferase reporter assay demonstrated that PTEN is a target gene of miR‐424‐3p, and overexpression of miR‐424‐3p or silencing of PTEN partially attenuated the effects of baicalein on A549 and H460 cells. Taken together, we concluded that baicalein inhibits cell growth and increases cisplatin sensitivity to A549 and H460 cells via down‐regulation of miR‐424‐3p and targeting the PTEN/PI3K/Akt pathway.

Neuroprotective effect of baicalin on focal cerebral ischemia in rats

Baicalin, a flavonoid compound from the root of the herb Scutellaria baicalensis Georgi, has been widely used to treat patients with inflammatory disease. The aim of this study was to assess the efficacy of baicalin in a rat model of focal cerebral ischemia. Adult male Sprague-Dawley rat models of cerebral artery occlusion were established and then randomly and equally divided into three groups: ischemia (cerebral ischemia and reperfusion), valproic acid (cerebral ischemia and reperfusion + three intraperitoneal injections of valproic acid; positive control), and baicalin (cerebral ischemia and reperfusion + intraperitoneal injection of baicalin for 21 days). Neurological deficits were assessed using the postural reflex test and forelimb placing test at 3, 7, 14, and 21 days after ischemia. Rat cerebral infarct volume was measured using 2,3,5-triphenyltetrazolium chloride (TTC) staining method. Pathological change of ischemic brain tissue was assessed using hematoxylin-eosin staining. In the baicalin group, rat neurological function was obviously improved, cerebral infarct volume was obviously reduced, and the pathological impairment of ischemic brain tissue was obviously alleviated compared to the ischemia group. Cerebral infarct volume was similar in the valproic acid and baicalin groups. These findings suggest that baicalin has a neuroprotective effect on cerebral ischemia.

The Effects of Baicalin and Baicalein on Cerebral Ischemia: A Review

Ischemic stroke, producing a high mortality and morbidity rate, is a common clinical disease. Enhancing the prevention and control of ischemic stroke is particularly important. Baicalin and its aglycon baicalein are flavonoids extracted from Scutellaria baicalensis, an important traditional Chinese herb. In recent years, a growing body of evidences has shown that baicalin and baicalein could be effective in the treatment of cerebral ischemia. Pharmacokinetic studies have shown that baicalin could penetrate the blood-brain barrier and distribute in cerebral nuclei. Through a variety of in vitro and in vivo models of ischemic neuronal injury, numerous studies have demonstrated that baicalin and baicalein have salutary effect for neuroprotection. Especially, the studies on the pharmacological mechanism showed that baicalin and baicalein have several pharmacological activities, which include antioxidant, anti-apoptotic, anti-inflammatory and anti-excitotoxicity effects, protection of the mitochondria, promoting neuronal protective factors expression and adult neurogenesis effects and many more. This review focuses on the neuroprotective effects of baicalin and baicalein in ischemia or stroke-induced neuronal cell death. We aimed at collecting all important information regarding the neuroprotective effect and its pharmacological mechanism of baicalin and baicalein in various in vivo and in vitro experimental models of ischemic neuronal injury.

CoQ10 Augments Rosuvastatin Neuroprotective Effect in a Model of Global Ischemia via Inhibition of NF-κB/JNK3/Bax and Activation of Akt/FOXO3A/Bim Cues

Statins were reported to lower the Coenzyme Q10 (CoQ10) content upon their inhibition of HMG-CoA reductase enzyme and both are known to possess neuroprotective potentials; therefore, the aim is to assess the possible use of CoQ10 as an adds-on therapy to rosuvastatin to improve its effect using global I/R model. Rats were allocated into sham, I/R, rosuvastatin (10 mg/kg), CoQ10 (10 mg/kg) and their combination. Drugs were administered orally for 7 days before I/R. Pretreatment with rosuvastatin and/or CoQ10 inhibited the hippocampal content of malondialdehyde, nitric oxide, and boosted glutathione and superoxide dismutase. They also opposed the upregulation of gp91^phox, and p47^phox subunits of NADPH oxidase. Meanwhile, both agents reduced content/expression of TNF-α, iNOS, NF-κBp65, ICAM-1, and MPO. Besides, all regimens abated cytochrome c, caspase-3 and Bax, but increased Bcl-2 in favor of cell survival. On the molecular level, they increased p-Akt and its downstream target p-FOXO3A, with the inhibition of the nuclear content of FOXO3A to downregulate the expression of Bim, a pro-apoptotic gene. Additionally, both treatments downregulate the JNK3/c-Jun signaling pathway. The effect of the combination regimen overrides that of either treatment alone. These effects were reflected on the alleviation of the hippocampal damage in CA1 region inflicted by I/R. Together, these findings accentuate the neuroprotective potentials of both treatments against global I/R by virtue of their rigorous multi-pronged actions, including suppression of hippocampal oxidative stress, inflammation, and apoptosis with the involvement of the Akt/FOXO3A/Bim and JNK3/c-Jun/Bax signaling pathways. The study also nominates CoQ10 as an adds-on therapy with statins.

Baicalein Preventive Treatment Confers Optimal Cardioprotection by PTEN/Akt/NO Activation

Baicalein is a flavonoid with excellent oxidant scavenging capability. It has been reported to protect against a variety of oxidative injuries including ischemia/reperfusion (I/R). However, the optimal treatment strategy for I/R injury and the protective mechanisms are not fully understood. In this study we employed an established chick cardiomyocyte model of I/R and investigated the effects of three baicalein treatment strategies on reactive oxygen species (ROS) scavenging, nitric oxide (NO) production and cell viability. The molecular signaling pathways were also explored. Compared to the I/R control (cell death 52.2[Formula: see text][Formula: see text][Formula: see text]2.0%), baicalein preventive treatment (25[Formula: see text][Formula: see text]M, pretreated for 72[Formula: see text]h and continued through I/R) conferred the best protection (19.5[Formula: see text][Formula: see text][Formula: see text]3.9%, [Formula: see text]), followed by I/R treatment (treated during I/R) and reperfusion treatment (treated at reperfusion only). Preventive and I/R treatments almost completely abolished ROS generation during both ischemic and reperfusion phases, and increased NO production and Akt phosphorylation. Reperfusion treatment reduced the ROS burst in the early reperfusion phase only, and had no effect on NO production and Akt activation. Further, the phosphorylation of phosphatase and tensin homolog (PTEN), a phosphatase negatively regulating Akt activation, was significantly increased by baicalein preventive treatment and slightly by the I/R treatment. PTEN protein expression was reduced in the same trend accordingly. Baicalein reperfusion treatment had no effects on PTEN phosphorylation and expression. Our results indicate that baicalein preventive treatment confers optimal cardioprotection against I/R injury, and this protection involves effective oxidant scavenging and the activation of PTEN/Akt/NO pathway.

The flavonoid Baicalein attenuates cuprizone-induced demyelination via suppression of neuroinflammation

Multiple sclerosis (MS) is a chronic demyelinating disease of the central nervous system characterized by recurrent and progressive demyelination/remyelination cycles, neuroinflammation, oligodendrocyte loss, and axonal pathology. Baicalein isolated from the roots of Scutellaria baicalensis has been shown to exert anti-inflammatory and antioxidant effects. The cuprizone model is an established mouse model of MS and causes demyelination and motor dysfunction and induces neuroinflammation, such as glial activation and pro-inflammatory cytokine production. To determine whether Baicalein attenuates cuprizone-induced demyelination, we administrated Baicalein to cuprizone-exposed mice. Baicalein attenuated weight loss (P<0.05) and motor dysfunction (P<0.05) in the cuprizone model mice. Baicalein treatment effectively suppressed the demyelination (P<0.01) and gene expressions of CNP (P<0.05) and MBP (P<0.05). Baicalein treatment also inhibited the cuprizone-induced increase in Iba1-positive microglia (P<0.001), GFAP-positive astrocytes (P<0.001), and the gene expressions of CD11b (P<0.01), GFAP (P<0.05), TNFα (P<0.05), IL-1β (P<0.05), and iNOS (p<0.01). We found that Baicalein treatment attenuated cuprizone-induced demyelination, glial activation, pro-inflammatory cytokine expression, and motor dysfunction. Our results suggest that Baicalein may be a useful therapeutic agent in demyelinating diseases to suppress neuroinflammation.

Baicalein as a potent neuroprotective agent: A review

In recent times, neurodegenerative diseases are the most challenging global health problems. Neuronal cell death or damage is a key factor for many neurodegenerative disorders. Therefore, there has been a growing interest in the development of effective neuroprotective agents, especially from natural sources. In particular, phytochemicals have shown high efficacy with low side effects in various in vitro and in vivo studies. In the various phytoconstituents, flavonoids are important bioactive products and mainly found in various vegetables and fruits. Among them, baicalein is one of the important flavones, which is mainly found in the root of Scutellaria baicalensis Georgi. A number of studies have reported that baicalein has potent neuroprotective properties under in vitro as well as in vivo systems. Hence, the purpose of this paper is to provide a review of the existing literature in connection with the neuroprotective effects of baicalein and its molecular mechanisms of action. The current review highlights could be useful to identify novel therapeutic agents in relation to the treatment of neurotoxicity-mediated diseases.