Neuroprotective Effect of Curcumin Against Cerebral Ischemia-Reperfusion Via Mediating Autophagy and Inflammation

Network Pharmacology and Molecular Docking-Based Mechanism Study to Reveal the Protective Effect of Salvianolic Acid C in a Rat Model of Ischemic Stroke

Salvianolic acid C (SAC) is a major bioactive component of Salvia miltiorrhiza Bunge (Danshen), a Chinese herb for treating ischemic stroke (IS). However, the mechanism by which SAC affects the IS has not yet been evaluated, thus a network pharmacology integrated molecular docking strategy was performed to systematically evaluate its pharmacological mechanisms, which were further validated in rats with cerebral ischemia. A total of 361 potential SAC-related targets were predicted by SwissTargetPrediction and PharmMapper, and a total of 443 IS-related targets were obtained from DisGeNET, DrugBank, OMIM, and Therapeutic Target database (TTD) databases. SAC-related targets were hit by the 60 targets associated with IS. By Gene ontology (GO) functional annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment combined with the protein-protein interaction (PPI) network and cytoHubba plug-ins, nine related signaling pathways (proteoglycans in cancer, pathways in cancer, PI3K-Akt signaling pathway, Focal adhesion, etc.), and 20 hub genes were identified. Consequently, molecular docking indicated that SAC may interact with the nine targets (F2, MMP7, KDR, IGF1, REN, PPARG, PLG, ACE and MMP1). Four of the target proteins (VEGFR2, MMP1, PPARγ and IGF1) were verified using western blot. This study comprehensively analyzed pathways and targets related to the treatment of IS by SAC. The results of western blot also confirmed that the SAC against IS is mainly related to anti-inflammatory and angiogenesis, which provides a reference for us to find and explore the effective anti-IS drugs.

Curcumin ameliorates H2O2‑induced inflammatory response in chondrocytes by inducing autophagy activation

Relapsing polychondritis (RP) is a clinical disease characterized by inflammation of cartilage tissue and chondrocytes. The principal curcuminoid curcumin is the most active component in turmeric and has been reported to have a chondroprotective effect, including anti-inflammatory activity, which is vitally important for mitigating RP symptoms and prognosis. However, the mechanisms underlying these actions have remained to be fully elucidated. In the present study, the chondroprotective mechanisms of curcumin on hydrogen peroxide (H₂O₂)-treated primary chondrocytes were examined in vitro. The viability of chondrocytes treated with H₂O₂ was significantly reduced in a dose- and time-dependent manner. Cotreatment of curcumin with H₂O₂ significantly decreased growth inhibition. It was observed that curcumin inhibited the expression levels of the inflammatory mediators interleukin (IL)-1β, IL-6 and inducible nitric oxide synthase and induced autophagy activation. Curcumin increased the protein levels of the autophagy marker beclin-1 and light chain 3-II and decreased the expression levels of P62 in H₂O₂-treated chondrocytes. The curcumin-induced anti-inflammatory effects were markedly abrogated by the autophagy inhibitor 3-methyladenine. In conclusion, the present study suggested that curcumin regulates inflammatory factors by activating autophagy in chondrocytes. The protective role of curcumin in chondrocytes was demonstrated, suggesting that it should be explored for the prophylactic treatment of RP in the clinic in the future.

Integrated Analysis of the Cecal Microbiome and Plasma Metabolomics to Explore NaoMaiTong and Its Potential Role in Changing the Intestinal Flora and Their Metabolites in Ischemic Stroke

Ischemic stroke (IS), as a leading cause of disability worldwide, affects intestinal bacterial communities and their metabolites, while recent discoveries have highlighted the importance of the intestinal microflora in the development of IS. Systematic investigations of complex intestinal bacterial communities and their metabolites during ischemic brain injury contribute to elucidate the promising therapeutic targets for IS. However, the associations between intestinal microbiota and related circulating metabolic processes in IS remained unclear. Hence, to identify the changed microflora and their metabolites in IS of NaoMaiTong (NMT), an effective clinical medication, we established the middle cerebral artery occlusion/reperfusion (MCAO/R) model using conventionalized and pseudo-germ-free (PGF) rats. Subsequently, we systematically screen the microflora and related metabolites changing in IS via an integrated approach of cecal 16S rRNA sequencing combined with plasma metabolomics. We found that NMT relied on intestinal flora to improve stroke outcome in conventionalized rats while the protection of NMT was reduced in PGF rats. Total 35 differential bacterial genera and 26 differential microbial metabolites were regulated by NMT. Furthermore, L-asparagine and indoleacetaldehyde were significantly negatively correlated with Lachnospiraceae_UCG.001 and significantly positively correlated with Lachnoclostridium. Indoleacetaldehyde also presented a negative correlation with Lactobacillus and Bifidobacterium. 2-Hydroxybutyric acid was strongly negatively correlated with Ruminococcus, Lachnospiraceae_UCG.001 and Lachnospiraceae_UCG.006. Creatinine was strongly negatively correlated with Akkermansia. In summary, the research provided insights into the intricate interaction between intestinal microbiota and metabolism of NMT in IS. We identified above differential bacteria and differential endogenous metabolites which could be as prebiotic and probiotic substances that can influence prognosis in stroke and have potential to be used as novel therapeutic targets or exogenous drug supplements.

Post-Ischemic Brain Neurodegeneration in the Form of Alzheimer's Disease Proteinopathy: Possible Therapeutic Role of Curcumin

For thousands of years, mankind has been using plant extracts or plants themselves as medicinal herbs. Currently, there is a great deal of public interest in naturally occurring medicinal substances that are virtually non-toxic, readily available, and have an impact on well-being and health. It has been noted that dietary curcumin is one of the regulators that may positively influence changes in the brain after ischemia. Curcumin is a natural polyphenolic compound with pleiotropic biological properties. The observed death of pyramidal neurons in the CA1 region of the hippocampus and its atrophy are considered to be typical changes for post-ischemic brain neurodegeneration and for Alzheimer’s disease. Additionally, it has been shown that one of the potential mechanisms of severe neuronal death is the accumulation of neurotoxic amyloid and dysfunctional tau protein after cerebral ischemia. Post-ischemic studies of human and animal brains have shown the presence of amyloid plaques and neurofibrillary tangles. The significant therapeutic feature of curcumin is that it can affect the aging-related cellular proteins, i.e., amyloid and tau protein, preventing their aggregation and insolubility after ischemia. Curcumin also decreases the neurotoxicity of amyloid and tau protein by affecting their structure. Studies in animal models of cerebral ischemia have shown that curcumin reduces infarct volume, brain edema, blood-brain barrier permeability, apoptosis, neuroinflammation, glutamate neurotoxicity, inhibits autophagy and oxidative stress, and improves neurological and behavioral deficits. The available data suggest that curcumin may be a new therapeutic substance in both regenerative medicine and the treatment of neurodegenerative disorders such as post-ischemic neurodegeneration.

Mechanistic Insight on Autophagy Modulated Molecular Pathways in Cerebral Ischemic Injury: From Preclinical to Clinical Perspective

Cerebral ischemia is one of the most devastating brain injuries and a primary cause of acquired and persistent disability worldwide. Despite ongoing therapeutic interventions at both the experimental and clinical levels, options for stroke-related brain injury are still limited. Several evidence suggests that autophagy is triggered in response to cerebral ischemia, therefore targeting autophagy-related signaling pathways can provide a new direction for the therapeutic implications in the ischemic injury. Autophagy is a highly conserved lysosomal-dependent pathway that degrades and recycles damaged or non-essential cellular components to maintain neuronal homeostasis. But, whether autophagy activation promotes cell survival against ischemic injury or, on the contrary, causes neuronal death is still under debate. We performed an extensive literature search from PubMed, Bentham and Elsevier for various aspects related to molecular mechanisms and pathobiology involved in autophagy and several pre-clinical studies justifiable further in the clinical trials. Autophagy modulates various downstream molecular cascades, i.e., mTOR, NF-κB, HIF-1, PPAR-γ, MAPK, UPR, and ROS pathways in cerebral ischemic injury. In this review, the various approaches and their implementation in the translational research in ischemic injury into practices has been covered. It will assist researchers in finding a way to cross the unbridgeable chasm between the pre-clinical and clinical studies.

The natural (poly)phenols as modulators of microglia polarization via TLR4/NF-κB pathway exert anti-inflammatory activity in ischemic stroke

Increasing evidences suggest that inflammation plays a key role in the pathogenesis of stroke, a devastating disease second only to cardiac ischemia as a cause of death worldwide. Microglia are the first non-neuronal cells on the scene during the innate immune response to acute ischemic stroke. Microglia respond to acute brain injury by activating and developing classic M1-like (pro-inflammatory) or alternative M2-like (anti-inflammatory) phenotypes. M1 microglia produce pro-inflammatory cytokines to exacerbate neural death, astrocyte apoptosis, and blood brain barrier (BBB) disruption, while M2 microglia play the opposite role. NF-κB, a central regulator of the inflammatory response, was responsible for microglia M1 and M2 polarization. NF-κB p65 and p50 form a heterodimer to initiate a pro-inflammatory cytokine response, which enhances M1 activation and impair M2 response of microglia. TLR4, expressed on the surface of microglia, plays an important role in activating NF-κB, ultimately causing the M1 response of microglia. Therefore, modulation of microglial phenotypes via TLR4/NF-κB signaling pathway may be a promising therapeutic approach for ischemic stroke. Dietary (poly)phenols are present in various foods, which have shown promising protective effects on ischemic stroke. In vivo studies strongly suggest that many (poly)phenols have a pronounced impact on ischemic stroke, as demonstrated by lower neuroinflammation. Thus, this review focuses on the anti-inflammatory properties of dietary (poly)phenols and discusses their effects on the polarization of microglia through modulating TLR4/NF-κB signaling pathway in the ischemic stroke.

Aromatherapy in Stroke Patients: Is it Time to Begin?

Stroke is the second largest cause of death worldwide, causing disease with long-term consequences and considerable healthcare costs. The application of new nursing interventions aimed at reducing distressing behaviors and at increasing patient comfort is an important part of the care and, until now, there are no defined guidelines. Aromatherapy has been demonstrated to be efficient in several other neurological disorders for the treatment of somatic and emotional diseases and to promote patient health. In the management of stroke patients, aromatherapy is still in its infancy. The first evidence coming from animal models demonstrated a consistent and reliable neuroprotective effect in reducing cerebral ischemia-reperfusion injury. In the last few years, some preliminary data being to be collected in humans revealed significant influence in reducing patients' pain and emotional distress. In this perspective study, we sought to summarize, for the first time, the main findings emerging from this new field of study, discussing the future opportunities to be translated into primary care practice.

Zinc finger E-Box binding homeobox 2 (ZEB2)-induced astrogliosis protected neuron from pyroptosis in cerebral ischemia and reperfusion injury

Ischemia injury can cause cell death or impairment of neuron and astrocytes, and thus induce loss of nerve function. central nervous systems injury induces an aberrant activation of astrocytes called astrogliosis. Pyroptosis, which is a kind of programmed cell death, was proved play an important role in ischemia injury. Zinc Finger E-Box Binding Homeobox 2 (ZEB2) promoted neuron astrogliosis, which play a protected role in neuron regeneration. However, its precise mechanism remains unclear. This study investigated the mechanism of ZEB2 on astrogliosis and neuron regeneration after cerebral ischemia reperfusion condition. To confirm our hypothesis, Neurons and astrocytes were isolated from fetal Sprague Dawley rats, in vivo Middle Cerebral Artery Occlusion/reperfusion (MCAO/R) rat model and in vitro oxygen-glucose deprivation/reperfusion (OGD/R)-treated astrocytes and neurocytes model were constructed. Our results showed that ZEB2 was expressed in nucleus of astrocyte and upregulated after OGD/R induction, ZEB2 promoted astrogliosis. Further upregulation of ZEB2 promoted the astrogliosis, which promoted neuron proliferation and regeneration by decreased pyroptosis. Moreover, this finding was further confirmed in vivo MCAO/R rat model. Overexpression of ZEB2 promoted astrogliosis, which decreased infarct volume and accumulated recovery of neurological function by alleviated pyroptosis. This finding revealed that ZEB2 was a regulator of the astrogliosis after ischemia/reperfusion injury, and then astrogliosis promoted neuron regeneration via decreased neuron pyroptosis. Therefore, ZEB2 may be a potential therapeutic target for ischemia/reperfusion injury.

Knocking Down Peroxiredoxin 6 Aggravates Cerebral Ischemia-Reperfusion Injury by Enhancing Mitophagy

Cerebral ischemia-reperfusion injury (IRI) is caused by reperfusion following ischemia. Mitophagy is closely related to cerebral IRI. Mitophagy disorder or excess may be harmful and lead to neuronal apoptosis. Peroxiredoxin 6 (PRDX6) is an antioxidant protein and plays an important role in ischemic stroke. However, the relationship between PRDX6 and mitophagy is not clear at present. In order to explore and solve this problem. We have established a middle cerebral artery occlusion (MCAO) model of cerebral ischemia-reperfusion in SD rats and knockdown PRDX6 and PINK1 with lentivirus. Knocking down PRDX6 led to further aggravation of cerebral IRI. Our research found that knockdown PRDX6 increased the expression of mitophagy-related and apoptosis-related proteins. Knocking down PINK1 relieved mitophagy and apoptosis caused by knocking down PRDX6. In conclusion, knockdown of PRDX6 could aggravate cerebral IRI by enhancing PINK1/PARKIN pathway mediated mitophagy, and this effect could increase neuronal apoptosis.

Evaluation and Characterization of Curcumin-β-Cyclodextrin and Cyclodextrin-Based Nanosponge Inclusion Complexation

Cyclodextrin polymers and cyclodextrin-based nanosponges have been widely investigated for increasing drug bioavailability. This study examined curcumin's complexation stability and solubilization with β-cyclodextrin and β-cyclodextrin-based nanosponge. Nanosponges were prepared through the cross-linking of β-cyclodextrin with different molar ratios of diphenyl carbonate. Phase solubility experiments were conducted to evaluate the formed complexes and evaluate the potential of using β-cyclodextrin and nanosponge in pharmaceutical formulations. Furthermore, physicochemical characterizations of the prepared complexes included PXRD, FTIR, NMR, and DSC. In addition, in vitro release studies were performed for the prepared formulations. The formation of β-cyclodextrin complexes enhanced curcumin solubility up to 2.34-fold compared to the inherent solubility, compared to a 2.95-fold increment in curcumin solubility when loaded in β-cyclodextrin-based nanosponges. Interestingly, the stability constant for curcumin nanosponges was (4972.90 M^-1), which was ten times higher than that for the β-cyclodextrin complex, where the value was 487.34 M^-1. The study results indicated a decrease in the complexation efficiency and solubilization effect with the increased cross-linker amount. This study's findings showed the potential of using cyclodextrin-based nanosponge and the importance of studying the effect of cross-linking density for the preparation of β-cyclodextrin-based nanosponges to be used for pharmaceutical formulations.

Curcumin Protects against Renal Ischemia/Reperfusion Injury by Regulating Oxidative Stress and Inflammatory Response

Objective

The aim of this study was to explore the pharmacological effects of curcumin on oxidative stress and inflammatory response of renal dysfunction induced by renal ischemia/reperfusion (RIRI).

Methods

Fifty male SD rats (Sprague Dawley) were randomly divided into the sham group, RIRI group, and curcumin group (low, medium, and high). The RIRI model was established by clipping the left renal artery for 45 min and then reperfusion for 24 h and resection of the contralateral kidney. In the curcumin group, curcumin was intraperitoneally injected once a day for 3 consecutive days using different dosage regimens. The RIRI group was intraperitoneally administered with normal saline. Renal injury was evaluated by measuring the concentration of creatinine (Cr) and urea nitrogen (BUN) in serum. Oxidative stress was assessed by assessing the level of malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione (GSH), and iron reduction/antioxidant capacity (FRAP) in tissues. In addition, the protective effect of RIRI was investigated by measuring Paller scores, the level of serum inflammatory factors and caspase-3, and the number of apoptotic cells.

Results

Ischemia/reperfusion resulted in increased levels of Cr and BUN in serum and MDA in tissues and decreased levels of SOD, CAT, GPx, GSH, and FRAP. Curcumin pretreatment strikingly increased the level of SOD, CAT, GPx, GSH, IL-10, IFN-γ, and FRAP and significantly decreased MDA, Cr, BUN, IL-8, TNF-α, IL-6, and myeloperoxidase (MPO) expressions in tissues.

Conclusion

Curcumin can relieve the degree of renal injury and improve renal function in ischemia-reperfusion, which may be related to the fact that curcumin can increase SOD content in serum and reduce MDA and FRAP levels in the rat model.

NETosis in ischemic/reperfusion injuries: An organ-based review

Neutrophil extracellular trap (NETosis), the web-like structures induced by neutrophil death, is an important inflammatory mechanism of the immune system leading to reactive oxygen species production/coagulopathy, endothelial dysfunction, atherosclerosis, and ischemia. NETosis exerts its role through different mechanisms such as triggering Toll-like receptors, inflammatory cytokines, platelet aggregation, neutrophil activation/infiltration, and vascular impairment. NETosis plays a key role in the prognosis of coronary artery disease, ischemic injury of kidney, lung, gastrointestinal tract and skeletal muscles. In this review, we explored the molecular mechanisms involved in NETosis, and ischemic/reperfusion injuries in body organs.

Curcumin Alleviates the Senescence of Canine Bone Marrow Mesenchymal Stem Cells during In Vitro Expansion by Activating the Autophagy Pathway

Senescence in mesenchymal stem cells (MSCs) not only hinders the application of MSCs in regenerative medicine but is also closely correlated with biological aging and the development of degenerative diseases. In this study, we investigated the anti-aging effects of curcumin (Cur) on canine bone marrow-derived MSCs (cBMSCs), and further elucidated the potential mechanism of action based on the modulation of autophagy. cBMSCs were expanded in vitro with standard procedures to construct a cell model of premature senescence. Our evidence indicates that compared with the third passage of cBMSCs, many typical senescence-associated phenotypes were observed in the sixth passage of cBMSCs. Cur treatment can improve cBMSC survival and retard cBMSC senescence according to observations that Cur (1 μM) treatment can improve the colony-forming unit-fibroblasts (CFU-Fs) efficiency and upregulated the mRNA expression of pluripotent transcription factors (SOX-2 and Nanog), as well as inhibiting the senescence-associated beta-galactosidase (SA-β-gal) activities and mRNA expression of the senescence-related markers (p16 and p21) and pro-inflammatory molecules (tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6)). Furthermore, Cur (0.1 μM~10 μM) was observed to increase autophagic activity, as identified by upregulation of microtubule-associated protein 1 light chain 3 (LC3), unc51-like autophagy-activating kinase-1 (ULK1), autophagy-related gene (Atg) 7 and Atg12, and the generation of type II of light chain 3 (LC3-II), thereby increasing autophagic vacuoles and acidic vesicular organelles, as well as causing a significant decrease in the p62 protein level. Moreover, the autophagy activator rapamycin (RAP) and Cur were found to partially ameliorate the senescent features of cBMSCs, while the autophagy inhibitor 3-methyladenine (3-MA) was shown to aggravate cBMSCs senescence and Cur treatment was able to restore the suppressed autophagy and counteract 3-MA-induced cBMSC senescence. Hence, our study highlights the important role of Cur-induced autophagy and its effects for ameliorating cBMSC senescence and provides new insight for delaying senescence and improving the therapeutic potential of MSCs.

Phenylboronic acid-based core-shell drug delivery platform clasping 1,3-dicarbonyl compounds by a coordinate interaction

Along with the successful commercialization of chemotherapeutics, such as doxorubicin and paclitaxel, numerous natural compounds have been investigated for clinical applications. Recently, curcumin (CUR), a natural compound with various therapeutic effects, has attracted attention for cancer immunotherapy. Most chemotherapeutics, however, have poor water solubility due to their hydrophobicity, which makes them less suited to biomedical applications; CUR is no exception because of its low bioavailability and extremely high hydrophobicity. In the present study, we developed an easy but effective strategy using the interaction between the 1,3-dicarbonyl groups of drugs and phenylboronic acid (PBA) to solubilize hydrophobic drugs. First, we verified the coordinate interaction between 1,3-dicarbonyl and PBA using 3,5-heptanedione as a model compound, followed by CUR as a model drug. A PBA-grafted hydrophilic polymer was used to form a nanoconstruct by coordination bonding with CUR, which then made direct administration of the nanoparticles possible. The nanoconstruct exhibited remarkable loading capability, uniform size, colloidal stability, and pH-responsive drug release, attributed to the formation of core-shell nanoconstructs by coordinate interaction. The therapeutic nanoconstructs successfully showed both chemotherapeutic and anti-PD-L1 anticancer effects in cellular and animal models. Furthermore, we demonstrated the applicability of this technique to other 1,3-dicarbonyl compounds. Overall, our findings suggest a facile, but expandable strategy by applying the coordinate interaction between 1,3-dicarbonyl and PBA, which enables high drug loading and stimuli-responsive drug release.

Neuroprotective Effect of Alpha-asarone on the Rats Model of Cerebral Ischemia-Reperfusion Stroke via Ameliorating Glial Activation and Autophagy

Alpha-asarone, a major active component isolated from Acorus gramineus, can affect brain functions and behaviors by multiple mechanisms. However, the effect of alpha-asarone on cerebral ischemia-reperfusion (CIR) stroke has not been reported. The present study aimed to investigate the neuroprotective effect of alpha-asarone and the involved mechanisms against CIR stroke. Rats were subjected to middle cerebral occlusion (MCAO) for 2 h. Then the drug or drug-free vehicle was intravenously injected to corresponding groups. After reperfusion for 24 h, the infarct volume was evaluated by Triphenyl Tetrazolium Chloride (TTC) staining. The neurofunctional recovery and post-stroke epilepsy were evaluated. Nissl and Hematoxylin-Eosin (H&E) staining were used for histological observation. We investigated the protective mechanism of alpha-asarone against the stroke. The results showed that alpha-asarone exhibited a desirable neuroprotective effect, manifested as reducing infarct volume and post-stroke epilepsy and improving neurological function. Histological and flow cytometry analysis revealed that alpha-asarone treatment alleviated cell injury and apoptosis in vivo and in vitro. Furthermore, alpha-asarone decreased GFAP, Iba-1, and LC3II/LC3I expression and increased the expression of p62. These results suggested that alpha-asarone attenuated the CIR stroke injury via ameliorating glial activation and autophagy.

Alpinia oxyphylla Miq extract reduces cerebral infarction by downregulating JNK-mediated TLR4/T3JAM- and ASK1-related inflammatory signaling in the acute phase of transient focal cerebral ischemia in rats

Background

Post-ischemic inflammation is a crucial component in stroke pathology in the early phase of cerebral ischemia–reperfusion (I/R) injury. Inflammation caused by microglia, astrocytes, and necrotic cells, produces pro-inflammatory mediators and exacerbates cerebral I/R injury. This study evaluated the effects of the Alpinia oxyphylla Miq [Yi Zhi Ren (YZR)] extract on cerebral infarction at 1 day after 90 min of transient middle cerebral artery occlusion (MCAo) and investigated the molecular mechanisms underlying the regulation of c-Jun N-terminal kinase (JNK)-mediated inflammatory cascades in the penumbral cortex. Rats were intraperitoneally injected with the YZR extract at the doses of 0.2 g/kg (YZR-0.2 g), 0.4 g/kg (YZR-0.4 g), or 0.8 g/kg (YZR-0.8 g) at MCAo onset.

Results

YZR-0.4 g and YZR-0.8 g treatments markedly reduced cerebral infarction, attenuated neurological deficits, and significantly downregulated the expression of phospho-apoptosis signal-regulating kinase 1 (p-ASK1)/ASK1, tumor necrosis factor receptor-associated factor 3 (TRAF3), TRAF3-interacting JNK-activating modulator (T3JAM), ionized calcium-binding adapter molecule 1 (Iba1), p-JNK/JNK, inducible nitric oxide synthase, cyclooxygenase-2, tumor necrosis factor-α, toll-like receptor 4 (TLR4), glial fibrillary acidic protein (GFAP), nuclear factor-kappa B (NF-κB), and interleukin-6 in the penumbral cortex at 1 day after reperfusion. SP600125 (SP), a selective JNK inhibitor, had the same effects. Furthermore, Iba1- and GFAP-positive cells were colocalized with TLR4, and colocalization of GFAP-positive cells was found with NF-κB in the nuclei.

Conclusion

YZR-0.4 g and YZR-0.8 g treatments exerted beneficial effects on cerebral ischemic injury by downregulating JNK-mediated signaling in the peri-infarct cortex. Moreover, the anti-infarction effects of YZR extract treatments were partially attributed to the downregulation of JNK-mediated TLR4/T3JAM- and ASK1-related inflammatory signaling pathways in the penumbral cortex at 1 day after reperfusion.

Effect of Co-Administration of Curcumin with Amlodipine in Hypertension

Curcumin, a curcuminoid known as the main bioactive compound of turmeric, is used in foods, cosmetics, and pharmaceutical products. Amlodipine is a general antihypertensive drug used in combination with various other antihypertensive agents. To date, no studies have examined the effects of the co-administration of amlodipine with curcumin. In this study, the vasodilatory effects of curcumin, amlodipine, and the co-administration of curcumin with amlodipine on isolated rat aortic rings pre-contracted with phenylephrine were evaluated, and the hypotensive effects were evaluated using the tail cuff method. To measure blood pressure, male spontaneously hypertensive rats were divided into four groups, each containing six rats, as follows: amlodipine 1 mg/kg alone treated, amlodipine 1 mg/kg with curcumin 30 mg/kg treated, amlodipine 1 mg/kg with curcumin 100 mg/kg treated, and amlodipine 1 mg/kg with curcumin 300 mg/kg treated groups. Amlodipine and curcumin were intraperitoneally injected, and systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured at 1, 2, 4, and 8 h after administration. The combined administration of curcumin and amlodipine induced a stronger vasorelaxant effect than amlodipine alone. However, co-administration did not significantly lower SBP and DBP compared to the single administration of amlodipine. The results of this study suggest that hypertensive patients taking amlodipine can consume curcumin or turmeric for food or other medical purposes without inhibiting the blood pressure-lowering effect of amlodipine.

Dexmedetomidine attenuates neuronal injury induced by cerebral ischemia‑reperfusion by regulating miR‑199a

As is well known, dexmedetomidine (DEX) serves a neuroprotective role in cerebral ischemia‑reperfusion (CIR) injury, and microRNA (miR)‑199a has been re‑ported to be associated with IR injury. However, the association between DEX and miR‑199a in CIR injury remains unknown. Thus, the aim of the present study was to verify whether the neuroprotective effect of DEX on cerebral ischemia‑reperfusion rats is associated with miR‑199a. A rat model of CIR was established, and the modified neurological severity score (mNSS) was evaluated. The effect of DEX on the patholog‑ical structure of the cerebral cortex in CIR rats was observed by hematoxylin and eosin and Nissl staining. Reverse transcription‑quantitative PCR was used to analyze the expression levels of miR‑199a in brain tissue following intracerebroventricular injection of miR‑199a antagomir. The co‑expression of NeuN and microtubule‑associated proteins 1A/1B light chain 3B in the cerebral cortex was analyzed by immunofluorescence staining. Western blotting and immunohistochemistry were performed to analyze the expression of autophagy‑associated proteins in the brain tissue. DEX inhibited the expression of miR‑199a, decreased the mNSS and improved pathological damage to the cerebral cortex. DEX also inhibited autophagy and expression levels of associated proteins and decreased nerve cell injury. In conclusion, DEX inhibited expression of miR‑199a and improved neurocyte injury induced by CIR.

Natural products attenuate PI3K/Akt/mTOR signaling pathway: A promising strategy in regulating neurodegeneration

BACKGROUND

As common, progressive, and chronic causes of disability and death, neurodegenerative diseases (NDDs) significantly threaten human health, while no effective treatment is available. Given the engagement of multiple dysregulated pathways in neurodegeneration, there is an imperative need to target the axis and provide effective/multi-target agents to tackle neurodegeneration. Recent studies have revealed the role of phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) in some diseases and natural products with therapeutic potentials.

PURPOSE

This is the first systematic and comprehensive review on the role of plant-derived secondary metabolites in managing and/or treating various neuronal disorders via the PI3K/Akt/mTOR signaling pathway.

STUDY DESIGN AND METHODS

A systematic and comprehensive review was done based on the PubMed, Scopus, Web of Science, and Cochrane electronic databases. Two independent investigators followed the PRISMA guidelines and included papers on PI3K/Akt/mTOR and interconnected pathways/mediators targeted by phytochemicals in NDDs.

RESULTS

Natural products are multi-target agents with diverse pharmacological and biological activities and rich sources for discovering and developing novel therapeutic agents. Accordingly, recent studies have shown increasing phytochemicals in combating Alzheimer's disease, aging, Parkinson's disease, brain/spinal cord damages, depression, and other neuronal-associated dysfunctions. Amongst the emerging targets in neurodegeneration, PI3K/Akt/mTOR is of great importance. Therefore, attenuation of these mediators would be a great step towards neuroprotection in such NDDs.

CONCLUSION

The application of plant-derived secondary metabolites in managing and/or treating various neuronal disorders through the PI3K/Akt/mTOR signaling pathway is a promising strategy towards neuroprotection.

Neuroprotective Effects of Curcumin in Cerebral Ischemia: Cellular and Molecular Mechanisms

Despite being a major global health concern, cerebral ischemia/stroke has limited therapeutic options. Tissue plasminogen activator (tPA) is the only available medication to manage acute ischemic stroke, but this medication is associated with adverse effects and has a narrow therapeutic time window. Curcumin, a polyphenol that is abundantly present in the rhizome of the turmeric plant (Curcuma longa), has shown promising neuroprotective effects in animal models of neurodegenerative diseases, including cerebral ischemia. In the central nervous system (CNS), neuroprotective effects of curcumin have been experimentally validated in Alzheimer's disease, Parkinson's disease, multiple sclerosis, and cerebral ischemia. Curcumin can exert pleiotropic effects in the postischemic brain including antioxidant, anti-inflammatory, antiapoptotic, vasculoprotective, and direct neuroprotective efficacies. Importantly, neuroprotective effects of curcumin has been reported in both ischemic and hemorrhagic stroke models. A broad-spectrum neuroprotective efficacy of curcumin suggested that curcumin can be an appealing therapeutic strategy to treat cerebral ischemia. In this review, we aimed to address the pharmacotherapeutic potential of curcumin in cerebral ischemia including its cellular and molecular mechanisms of neuroprotection revealing curcumin as an appealing therapeutic candidate for cerebral ischemia.

Curcumin Attenuates Cerebral Ischemia-reperfusion Injury Through Regulating Mitophagy and Preserving Mitochondrial Function

BACKGROUND

Curcumin, the complex extracted from the traditional edible herb, has a wide range of pharmacological effects. A great deal of studies has demonstrated that curcumin could protect against cerebral ischemia-reperfusion (I/R) injury. In the present study, we aimed to test the hypothesis that curcumin reduces brain damage via regulating mitophagy and preserving mitochondrial function. To clarify the potential effect and mechanism of curcumin on cerebral I/R, we utilize MCAO followed by reperfusion rats and OGD/R neurons as cerebral I/R in vivo and in vitro, respectively.

METHODS

We determined the cellular ROS levels and mitochondrial function, including mitochondrial membrane potential (MMP), ATP levels, state 3 respiration and state 4 respiration. We also detected the levels of mitophagy by immunofluorescent staining and western blotting.

RESULTS

Results found that curcumin decreased neurological deficit scores, infarct volume and morphological changes of neurons in rats after brain I/R injury. Curcumin also reduced the levels of ROS while increased MMP, ATP levels and state 3 respiration to prevent the impairment of mitochondrial function from cerebral I/R. Furthermore, curcumin enhanced the co-localization of LC3B and mitochondrial marker VDAC1, the ratio of LC3-II to LC3-I, improving cerebral I/Rinduced mitophagy.

CONCLUSION

In conclusion, our results suggest that curcumin protects against cerebral I/R injury by improving mitophagy and preserving mitochondrial function.

Pharmacological properties and underlying mechanisms of curcumin and prospects in medicinal potential

Curcumin, isolated from Curcuma longa L., is a fat-soluble natural compound that can be obtained from ginger plant tuber roots, which accumulative evidences have demonstrated that it can resist viral and microbial infection and has anti-tumor, reduction of blood lipid and blood glucose, antioxidant and removal of free radicals, and is active against numerous disorders various chronic diseases including cardiovascular, pulmonary, neurological and autoimmune diseases. In this article is highlighted the recent evidence of curcuminoids applied in sevral aspects of medical problem particular in COVID-19 pandemics. We have searched several literature databases including MEDLINE (PubMed), EMBASE, the Web of Science, Cochrane Library, Google Scholar, and the ClinicalTrials.gov website via using curcumin and medicinal properties as a keyword. All studies published from the time when the database was established to May 2021 was retrieved. This review article summarizes the growing confirmation for the mechanisms related to curcumin's physiological and pharmacological effects with related target proteins interaction via molecular docking. The purpose is to provide deeper insight and understandings of curcumin's medicinal value in the discovery and development of new drugs. Curcumin could be used in the prevention or therapy of cardiovascular disease, respiratory diseases, cancer, neurodegeneration, infection, and inflammation based on cellular biochemical, physiological regulation, infection suppression and immunomodulation.

Autophagy in vascular dementia and natural products with autophagy regulating activity

Chronic Cerebral Hypoperfusion(CCH)-induced vascular dementia(VD) is a common neurodegenerative disease which seriously affects the patient's quality of life. Therefore, it is critical to find an effective treatment of VD. Autophagy is a natural regulated mechanism that can remove dysfunctional proteins and organelles, however, over-activation or under-activation can of autophagy can induce the apoptosis of cells. Although autophagy plays a role in the central nervous system is unquestionable, the effects of autophagy in the ischemic brain are still controversial. Some autophagy regulators have been tested, suggesting that both activation and inhibition of autophagy can improve the cognitive function. This article reviews the role of autophagy in CCH-induced VD to discuss whether autophagy has the potential to become a target for drug development and provides several potential compounds for treating vascular dementia.

Normobaric Oxygen (NBO) Therapy Reduces Cerebral Ischemia/Reperfusion Injury through Inhibition of Early Autophagy

Objectives

Normobaric oxygen (NBO) therapy has great clinical potential in the treatment of ischemic stroke, but its underlying mechanism is unknown. Our study aimed to investigate the role of autophagy during the application of NBO on cerebral ischemia/reperfusion injury.

Methods

Male Sprague Dawley rats received 2 hours of middle cerebral artery occlusion (MCAO), followed by 2, 6, or 24 hours of reperfusion. At the beginning of reperfusion, rats were randomly given NBO (95% O₂) or room air (21% O₂) for 2 hours. In some animals, 3-methyladenine (3-MA, autophagy inhibitor) was administered 10 minutes before reperfusion. The severity of the ischemic injury was determined by infarct volume, neurological deficit, and apoptotic cell death. Western blotting was used to determine the protein expression of autophagy and apoptosis, while mRNA expression of apoptotic molecules was detected by real-time PCR.

Results

NBO treatment after ischemia/reperfusion significantly decreased infarct volume and neurobehavioral defects. The increased expression of the autophagy markers, including microtubule-associated protein 1A light chain 3 (LC3) and Beclin 1, after ischemia/reperfusion was reversed by NBO, while promoting Sequestosome 1 (p62/SQSTM1) expression. In addition, NBO reduced cerebral apoptosis in association with alleviated BAX expression and increased BCL-2 expression. 3-MA reduced autophagy and apoptotic death but did not further improve NBO-attenuated ischemic damage.

Conclusion

NBO induced remarkable neuroprotection from ischemic injury, which was correlated with blocked autophagy activity.

Turmeric and its bioactive constituents trigger cell signaling mechanisms that protect against diabetes and cardiovascular diseases

Turmeric, the rhizome of Curcuma longa plant belonging to the ginger family Zingiberaceae, has a history in Ayurvedic and traditional Chinese medicine for treatment of chronic diseases, including metabolic and cardiovascular diseases (CVD). This parallels a prevalence of age- and lifestyle-related diseases, especially CVD and type 2 diabetes (T2D), and associated mortality which has occurred in recent decades. While the chemical composition of turmeric is complex, curcuminoids and essential oils are known as two major groups that display bioactive properties. Curcumin, the most predominant curcuminoid, can modulate several cell signaling pathways involved in the etiology and pathogenesis of CVD, T2D, and related morbidities. Lesser bioactivities have been reported from other curcuminoids and essential oils. This review examines the chemical compositions of turmeric, and related bioactive constituents. A focus was placed on the cellular and molecular mechanisms that underlie the protective effects of turmeric and turmeric-derived compounds against diabetes and CVD, compiled from the findings obtained with cell-based and animal models. Evidence from clinical trials is also presented to identify potential preventative and therapeutic efficacies. Clinical studies with longer intervention durations and specific endpoints for assessing health outcomes are warranted in order to fully evaluate the long-term protective efficacy of turmeric.

Altered Properties of Neurons and Astrocytes and the Effects of Food Components in Stroke-Prone Spontaneously Hypertensive Rats

ABSTRACT

In stroke-prone spontaneously hypertensive rats (SHRSP), stroke induces neuronal vulnerability and neuronal death, while astrocytes show a weakened support function toward neurons. Moreover, certain food components have been demonstrated to prevent the occurrence of stroke. This review aims to explain the stroke-related properties of SHRSP-derived neurons and astrocytes. In addition, it describes the effects of particular dietary phytochemicals on SHRSP. In this study, we obtained information using PubMed, ScienceDirect, and Web of Science. We searched for the functions of neurons and astrocytes and the molecular mechanism of ischemic stroke induction. We summarized the recent literature on the underlying mechanisms of stroke onset in SHRSP and the alleviating effects of typical food-derived phytochemical components. Neuronal death in SHRSP is induced by hypoxia-reoxygenation, suggesting the involvement of oxidative stress. Furthermore, the production of lactate, l-serine, and glial cell line-derived neurotrophic factor in SHRSP-derived astrocytes was reduced compared with that in control Wistar-Kyoto rats. Vitamin E exerts an inhibitory effect on hypoxia-reoxygenation-induced neuronal death in SHRSP. Curcumin, epigallocatechin gallate, resveratrol, and carotenoids can prevent the development of stroke in SHRSP. In particular, the properties of SHRSP-derived neurons and astrocytes affect stroke-induced neuronal death. This review suggests the potential and therapeutic applications of dietary phytochemicals in reducing stroke risk and lowering blood pressure in SHRSP, respectively, by targeting various processes, including oxidative stress, apoptosis, and inflammation. Thus, future research on SHRSP brain cells with a genetic predisposition to stroke can consider using these food ingredients to develop approaches for stroke prevention.

Curcumin ameliorates ischemic stroke injury in rats by protecting the integrity of the blood-brain barrier

The blood-brain barrier (BBB) is critical for proper cerebral homeostasis and its dysfunction during ischemic stroke can result in significant neurological injury. The major goal of the present study was to identify whether curcumin pretreatment possessed protective effects on BBB integrity during the 24 h of acute ischemic brain injury. To investigate the protective effects of curcumin, male Sprague-Dawley rats were divided into multiple groups, including sham, middle cerebral artery occlusion/reperfusion (MCAO/R) vehicle and curcumin pretreated MCAO/R groups. The effects of curcumin were measured by analyzing neurological deficits, infarct size, BBB permeability and expression levels of permeability-related proteins in the brain. It was found that curcumin pretreatment significantly improved neurological scores, decreased infarct size, and protected synaptic remodeling of hippocampal neurons and upregulated the protein expression level of tight junction proteins, ZO-1, occludin and claudin-5 in ischemic rat brains. Furthermore, curcumin pretreatment before stroke was shown to downregulate the phosphorylation of NF-κB and MMP-9, which are central mediators of inflammation. The results from the present study indicated that curcumin pretreatment ameliorated ischemic stroke injury by protecting BBB integrity and synaptic remodeling, as well as inhibiting inflammatory responses.

Triblock Copolymer Nanomicelles Loaded with Curcumin Attenuates Inflammation via Inhibiting the NF-κB Pathway in the Rat Model of Cerebral Ischemia

AIM

Cerebral ischemic injury is one of the debilitating diseases showing that inflammation plays an important role in worsening ischemic damage. Therefore, studying the effects of some potential anti-inflammatory compounds can be very important in the treatment of cerebral ischemic injury.

METHODS

This study investigated anti-inflammatory effects of triblock copolymer nanomicelles loaded with curcumin (abbreviated as NC) in the brain of rats following transient cerebral ischemia/reperfusion (I/R) injury in stroke. After preparation of NC, their protective effects against bilateral common carotid artery occlusion (BCCAO) were explored by different techniques. Concentrations of free curcumin (C) and NC in liver, kidney, brain, and heart organs, as well as in plasma, were measured using a spectrofluorometer. Western blot analysis was then used to measure NF-κB-p65 protein expression levels. Also, ELISA assay was used to examine the level of cytokines IL-1β, IL-6, and TNF-α. Lipid peroxidation levels were assessed using MDA assay and H&E staining was used for histopathological examination of the hippocampus tissue sections.

RESULTS

The results showed a higher level of NC compared to C in plasma and organs including the brain, heart, and kidneys. Significant upregulation of NF-κB, IL-1β, IL-6, and TNF-α expressions compared to control was observed in rats after induction of I/R, which leads to an increase in inflammation. However, NC was able to downregulate significantly the level of these inflammatory cytokines compared to C. Also, the level of lipid peroxidation in pre-treated rats with 80mg/kg NC was significantly reduced.

CONCLUSION

Our findings in the current study demonstrate a therapeutic effect of NC in an animal model of cerebral ischemia/reperfusion (I/R) injury in stroke through the downregulation of NF-κB-p65 protein and inflammatory cytokines.

Mechanisms of neuronal cell death in ischemic stroke and their therapeutic implications

Ischemic stroke caused by arterial occlusion is the most common type of stroke, which is among the most frequent causes of disability and death worldwide. Current treatment approaches involve achieving rapid reperfusion either pharmacologically or surgically, both of which are time-sensitive; moreover, blood flow recanalization often causes ischemia/reperfusion injury. However, even though neuroprotective intervention is urgently needed in the event of stroke, the exact mechanisms of neuronal death during ischemic stroke are still unclear, and consequently, the capacity for drug development has remained limited. Multiple cell death pathways are implicated in the pathogenesis of ischemic stroke. Here, we have reviewed these potential neuronal death pathways, including intrinsic and extrinsic apoptosis, necroptosis, autophagy, ferroptosis, parthanatos, phagoptosis, and pyroptosis. We have also reviewed the latest results of pharmacological studies on ischemic stroke and summarized emerging drug targets with a focus on clinical trials. These observations may help to further understand the pathological events in ischemic stroke and bridge the gap between basic and translational research to reveal novel neuroprotective interventions.

Neuroprotective Phytochemicals in Experimental Ischemic Stroke: Mechanisms and Potential Clinical Applications

Ischemic stroke is a challenging disease with high mortality and disability rates, causing a great economic and social burden worldwide. During ischemic stroke, ionic imbalance and excitotoxicity, oxidative stress, and inflammation are developed in a relatively certain order, which then activate the cell death pathways directly or indirectly via the promotion of organelle dysfunction. Neuroprotection, a therapy that is aimed at inhibiting this damaging cascade, is therefore an important therapeutic strategy for ischemic stroke. Notably, phytochemicals showed great neuroprotective potential in preclinical research via various strategies including modulation of calcium levels and antiexcitotoxicity, antioxidation, anti-inflammation and BBB protection, mitochondrial protection and antiapoptosis, autophagy/mitophagy regulation, and regulation of neurotrophin release. In this review, we summarize the research works that report the neuroprotective activity of phytochemicals in the past 10 years and discuss the neuroprotective mechanisms and potential clinical applications of 148 phytochemicals that belong to the categories of flavonoids, stilbenoids, other phenols, terpenoids, and alkaloids. Among them, scutellarin, pinocembrin, puerarin, hydroxysafflor yellow A, salvianolic acids, rosmarinic acid, borneol, bilobalide, ginkgolides, ginsenoside Rd, and vinpocetine show great potential in clinical ischemic stroke treatment. This review will serve as a powerful reference for the screening of phytochemicals with potential clinical applications in ischemic stroke or the synthesis of new neuroprotective agents that take phytochemicals as leading compounds.

Neuroprotective Effect for Cerebral Ischemia by Natural Products: A Review

Natural products have a significant role in the prevention of disease and boosting of health in humans and animals. Stroke is a disease with high prevalence and incidence, the pathogenesis is a complex cascade reaction. In recent years, it’s reported that a vast number of natural products have demonstrated beneficial effects on stroke worldwide. Natural products have been discovered to modulate activities with multiple targets and signaling pathways to exert neuroprotection via direct or indirect effects on enzymes, such as kinases, regulatory receptors, and proteins. This review provides a comprehensive summary of the established pharmacological effects and multiple target mechanisms of natural products for cerebral ischemic injury in vitro and in vivo preclinical models, and their potential neuro-therapeutic applications. In addition, the biological activity of natural products is closely related to their structure, and the structure-activity relationship of most natural products in neuroprotection is lacking, which should be further explored in future. Overall, we stress on natural products for their role in neuroprotection, and this wide band of pharmacological or biological activities has made them suitable candidates for the treatment of stroke.

Neuroprotective Effects of Oxymatrine on PI3K/Akt/mTOR Pathway After Hypoxic-Ischemic Brain Damage in Neonatal Rats

Oxymatrine (OMT), a quinolizidine alkaloid extracted from traditional Chinese herb Sophora flavescens Ait, has drawn attention because of its beneficial bioactivities against hypoxic-ischemic brain damage (HIBD). However, the underlying molecular mechanism remains unclear. In this study, we determined the in vivo and in vitro effects of OMT on seven-day old Sprague-Dawley rats with HIBD and in a rat model of primary hippocampal neuron oxygen glucose deprivation reoxygenation (OGD/R). This study was aimed to evaluate whether OMT exerted neuroprotective effects mediated by the (phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin) PI3K/Akt/mTOR pathway after HIBD. Experimental results showed that the alkaloid significantly improved the early neurofunctional development, brain water content, abnormal pathological changes, and necrosis of neurons after HIBD. Moreover, OMT enhanced the cell viability and stabilized the mitochondrial permeability transition pore in the primary hippocampal neurons after OGD/R. OMT significantly decreased the autophagosome generation, elevated the expression of PI3K, Akt, and mTOR, and simultaneously reversed the mRNA expression of microtubule-associated protein 1-light chain 3 (LC3), Beclin-1, and sequestosomel (P62) induced by hypoxia and ischemia. However, these protective effects against HIBD could be suppressed when rapamycin, a specific inhibitor of mTOR, was included. Hence, the OMT exerted neuroprotective effects against HIBD by attenuating excessive autophagy by mediating the PI3K/Akt/mTOR pathway.

Neuroprotective Effect of Fisetin Against the Cerebral Ischemia-Reperfusion Damage via Suppression of Oxidative Stress and Inflammatory Parameters

It is well established that inflammatory reactions and oxidative stress play an imperial role in cerebral ischemia-reperfusion pathogenesis. Fisetin is a flavonoid and has an antioxidant and anti-inflammatory effect on various diseases. In this study, we have been working to examine the neuroprotective effect of fisetin in brain injuries triggered by cerebral ischemic-reperfusion and explore the potential role of nuclear factor kappa B (NF-κB) signaling. In vitro, fisetin was examined against the cell viability, lactate dehydrogenase (LDH) leakage, cytokines, and apoptosis after ischemia/reperfusion (I/R) induced in the cells. In vivo, I/R injury was induced in the brain via transient middle cerebral artery occlusion (2 h) and reperfusion (20 h). The infarction area, brain water content, and neurofunctional parameters were also estimated. Inflammatory cytokines and brain injury markers were scrutinized at the end of the study. Fisetin treatment alleviated cell injury and suppressed the inflammatory cytokines (interleukin-1 (IL-1), tumor necrosis factor- α (TNF-α), inducible nitric oxide synthase (iNOS), interleukin-1β (IL-1β), cyclooxygenase-2 (COX-2), interleukin-16 (IL-6), and prostaglandin E₂ (PGE₂)) and antioxidant parameters in a dose-dependent manner. Fisetin significantly (P < 0.001) reduced the infarct volume, brain water content. Fisetin significantly (P < 0.001) suppressed the neurological parameters and inflammatory cytokines such as IL-1, TNF-α, iNOS, IL-1β, COX-2, IL-6, PGE₂, and oxidative markers in a dose-dependent manner. Fisetin significantly (P < 0.001) reduced the inflammatory mediators including NF-κB and intercellular adhesion molecule 1 (ICAM-1). Further studies also showed that fisetin significantly inhibited the NF-κB activity via inflammatory and antioxidant pathways. In conclusion, by suppressing inflammatory cytokines, fisetin protected the brain tissue against I/R injury, and this effect could be due to reduced NF-κB activity.

Dl-3-n-butylphthalide inhibits neuroinflammation by stimulating foxp3 and Ki-67 in an ischemic stroke model

Dl-3-n-butylphthalide (NBP) has been widely used to treat ischemic stroke in China. To investigate the mechanisms underlying NBP activity, we established a permanent middle cerebral artery occlusion (pMCAO) rat model and injected the rats with 4 mg/kg/d NBP for nine days. We then assessed neuroinflammation, neovascularization and nerve regeneration within the brain. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry imaging (MALDI-TOF MSI) was used to determine the phospholipid distribution, while laser ablation-inductively coupled plasma mass spectrometry imaging (LA-ICP MSI) was used to measure Foxp3, Ki-67 and pCREB levels in the brain. Immunohistochemistry was used to investigate the expression of NLR family pyrin domain containing 3 (NLRP3) and its inflammatory products, caspase-1 and interleukin-1β, in brain tissues. NBP attenuated ischemic damage and ameliorated neurological deficits in rats with pMCAO. In the ischemic brain region, NBP reduced phosphatidylethanolamine (18:0), NLRP3, caspase-1 and interleukin-1β levels, but increased levels of Foxp3, Ki-67, pCREB and several phospholipids. In molecular docking analyses, NBP bound to NLRP3, interleukin-1β, caspase-1, Foxp3, and Ki-67. These results demonstrate that NBP reduces neuroinflammation in brain tissues and promotes nerve and blood vessel regeneration, thus protecting neuromorphology and function.

Apelin-13 inhibits apoptosis and excessive autophagy in cerebral ischemia/reperfusion injury

Apelin-13 is a novel endogenous ligand for an angiotensin-like orphan G-protein coupled receptor, and it may be neuroprotective against cerebral ischemia injury. However, the precise mechanisms of the effects of apelin-13 remain to be elucidated. To investigate the effects of apelin-13 on apoptosis and autophagy in models of cerebral ischemia/reperfusion injury, a rat model was established by middle cerebral artery occlusion. Apelin-13 (50 μg/kg) was injected into the right ventricle as a treatment. In addition, an SH-SY5Y cell model was established by oxygen-glucose deprivation/reperfusion, with cells first cultured in sugar-free medium with 95% N₂ and 5% CO₂ for 4 hours and then cultured in a normal environment with sugar-containing medium for 5 hours. This SH-SY5Y cell model was treated with 10^–7 M apelin-13 for 5 hours. Results showed that apelin-13 protected against cerebral ischemia/reperfusion injury. Apelin-13 treatment alleviated neuronal apoptosis by increasing the ratio of Bcl-2/Bax and significantly decreasing cleaved caspase-3 expression. In addition, apelin-13 significantly inhibited excessive autophagy by regulating the expression of LC3B, p62, and Beclin1. Furthermore, the expression of Bcl-2 and the phosphatidylinositol-3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway was markedly increased. Both LY294002 (20 μM) and rapamycin (500 nM), which are inhibitors of the PI3K/Akt/mTOR pathway, significantly attenuated the inhibition of autophagy and apoptosis caused by apelin-13. In conclusion, the findings of the present study suggest that Bcl-2 upregulation and mTOR signaling pathway activation lead to the inhibition of apoptosis and excessive autophagy. These effects are involved in apelin-13-induced neuroprotection against cerebral ischemia/reperfusion injury, both in vivo and in vitro. The study was approved by the Animal Ethical and Welfare Committee of Jining Medical University, China (approval No. 2018-JS-001) in February 2018.

Toll-like receptor 4/nuclear factor-kappa B pathway is involved in radicular pain by encouraging spinal microglia activation and inflammatory response in a rat model of lumbar disc herniation

Background

Lumbar disc herniation (LDH) is a common cause of radicular pain, but the mechanism is not clear. In this study, we investigated the engagement of toll-like receptor 4 (TLR4) and the nuclear factor-kappa B (NF-κB) in radicular pain and its possible mechanisms.

Methods

An LDH model was induced by autologous nucleus pulposus (NP) implantation, which was obtained from coccygeal vertebra, then relocated in the lumbar 4/5 spinal nerve roots of rats. Mechanical and thermal pain behaviors were assessed by using von Frey filaments and hotplate test respectively. The protein level of TLR4 and phosphorylated-p65 (p-p65) was evaluated by western blotting analysis and immunofluorescence staining. Spinal microglia activation was evaluated by immunofluorescence staining of specific relevant markers. The expression of pro- and anti-inflammatory cytokines in the spinal dorsal horn was measured by enzyme linked immunosorbent assay.

Results

Spinal expression of TLR4 and p-NF-κB (p-p65) was significantly increased after NP implantation, lasting up to 14 days. TLR4 was mainly expressed in spinal microglia, but not astrocytes or neurons. TLR4 antagonist TAK242 decreased spinal expression of p-p65. TAK242 or NF-κB inhibitor pyrrolidinedithiocarbamic acid alleviated mechanical and thermal pain behaviors, inhibited spinal microglia activation, moderated spinal inflammatory response manifested by decreasing interleukin (IL)-1β, IL-6, tumor necrosis factor-α expression and increasing IL-10 expression in the spinal dorsal horn.

Conclusions

The study revealed that TLR4/NF-κB pathway participated in radicular pain by encouraging spinal microglia activation and inflammatory response.

Neuroprotection Effect of Astragaloside IV from 2-DG-Induced Endoplasmic Reticulum Stress

Objective

Astragaloside IV shows neuroprotective activity, but its mechanism remains unclear. To investigate whether astragaloside IV protects from endoplasmic reticulum stress (ERS), we focus on the regulation of glycogen synthase kinase-3β (GSK-3β) and mitochondrial permeability transition pore (mPTP) by astragaloside IV in neuronal cell PC12.

Methods and Results

PC12 cells treated with different concentrations of ERS inductor 2-deoxyglucose (2-DG) (25-500 μM) showed a significant increase of glucose-regulated protein 78 (GRP 78) and GRP 94 expressions and a decrease of tetramethylrhodamine ethyl ester (TMRE) fluorescence intensity and mitochondrial membrane potential (∆Ψm), with the peak effect seen at 50 μM, indicating that 2-DG induces ERS and the mPTP opening. Similarly, 50 μM of astragaloside IV increased the GSK-3β phosphorylation at Ser9 most significantly. Next, we examined the neuroprotection of astragaloside IV by dividing the PC12 cells into control group, 2-DG treatment group, astragaloside IV plus 2-DG treatment group, and astragaloside IV only group. PC12 cells treated with 50 μM 2-DG for different time courses (0-36 hr) showed a significant increase of Cleaved-Caspase-3 with the peak at 6 hr. 2-DG significantly induced cell apoptosis and increased the green fluorescence intensity of Annexin V-FITC, and these effects were reversed by astragaloside IV. Such a result indicates that astragaloside IV protected neural cell survival from ERS. 2-DG treatment significantly increased the expressions of inositol-requiring ER-to-nucleus signal kinase 1 (IRE1), phosphor-protein kinase R-like ER kinase (p-PERK), but not affect the transcription factor 6 (ATF6) expression. 2-DG treatment significantly decreased the phosphorylation of GSK-3β and significantly reduced the TMRE fluorescence intensity and ∆Ψm, following mPTP open. Astragaloside IV significantly inhibited the above effects caused by 2-DG, except the upregulation of ATF6 protein. Taken together, astragaloside IV significantly inhibited the ERS caused by 2-DG.

Conclusion

Our data suggested that astragaloside IV protects PC12 cells from ERS by inactivation of GSK-3β and preventing the mPTP opening. The GRP 78, GRP 94, IRE1, and PERK signaling pathways but not ATF6 are responsible for GSK-3β inactivation and neuroprotection by astragaloside IV.

Potential Therapeutic Role of Phytochemicals to Mitigate Mitochondrial Dysfunctions in Alzheimer's Disease

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder characterized by a decline in cognitive function and neuronal damage. Although the precise pathobiology of AD remains elusive, accumulating evidence suggests that mitochondrial dysfunction is one of the underlying causes of AD. Mutations in mitochondrial or nuclear DNA that encode mitochondrial components may cause mitochondrial dysfunction. In particular, the dysfunction of electron transport chain complexes, along with the interactions of mitochondrial pathological proteins are associated with mitochondrial dysfunction in AD. Mitochondrial dysfunction causes an imbalance in the production of reactive oxygen species, leading to oxidative stress (OS) and vice versa. Neuroinflammation is another potential contributory factor that induces mitochondrial dysfunction. Phytochemicals or other natural compounds have the potential to scavenge oxygen free radicals and enhance cellular antioxidant defense systems, thereby protecting against OS-mediated cellular damage. Phytochemicals can also modulate other cellular processes, including autophagy and mitochondrial biogenesis. Therefore, pharmacological intervention via neuroprotective phytochemicals can be a potential strategy to combat mitochondrial dysfunction as well as AD. This review focuses on the role of phytochemicals in mitigating mitochondrial dysfunction in the pathogenesis of AD.

XingNaoJing injection ameliorates cerebral ischaemia/reperfusion injury via SIRT1-mediated inflammatory response inhibition

Context: XingNaoJing injection (XNJ), extracted from a traditional compound Chinese medicine Angong niuhuang pill, is well known for treating stroke in the clinic, but the specific effects and mechanisms remain unclear.Objective: We investigated the mechanistic basis for the protective effect of XNJ on cerebral ischaemia/reperfusion (I/R) injury.Materials and methods: Five groups of 10 SD rats underwent 2 h of middle cerebral artery occlusion (MCAO) followed by 24 h reperfusion. XNJ at 10 and 15 mL/kg was intraperitoneally administered 24 h before ischaemia and at the onset of reperfusion respectively. The silent information regulator 1 (SIRT1) inhibitor EX527 was intracerebroventricularly injected 0.5 h before reperfusion. Cerebral infarction size, neurological scores, morphological changes, and expression levels of inflammatory mediators and SIRT1 were measured. Furthermore, human brain microvascular endothelial cells (HBMECs) were subjected to 3 h oxygen and glucose deprivation (OGD) followed by 24 h reoxygenation to mimic cerebral I/R in vitro. EX527 pre-treatment occurred 1 h before OGD. SIRT1 and inflammatory mediator levels were analyzed.Results: Both XNJ doses significantly decreased cerebral infarct area (40.11% vs. 19.66% and 9.87%) and improved neurological scores and morphological changes. Inflammatory mediator levels were remarkably decreased in both model systems after XNJ treatment. XNJ also enhanced SIRT1 expression. Notably, the SIRT1 inhibitor EX527 attenuated the XNJ-mediated decrease in inflammation in vivo and in vitro.Conclusions: XNJ improved cerebral I/R injury through inhibiting the inflammatory response via the SIRT1 pathway, which may be a useful target in treating cerebral I/R injury.

Novel scorpion venom peptide HsTx2 ameliorates cerebral ischemic brain injury in rats via the MAPK signaling pathway

Ischemic stroke is a severe threat to human health due to its high recurrence, mortality, and disability rates. As such, how to prevent and treat ischemic stroke effectively has become a research hotspot in recent years. Here, we identified a novel peptide, named HsTx2 (AGKKERAGSRRTKIVMLKCIREHGH, 2 861.855 Da), derived from the scorpion Heterometrus spinifer, which showed obvious anti-apoplectic effects in rats with ischemic stroke. Results further demonstrated that HsTx2 significantly reduced formation of infarct area and improved behavioral abnormalities in ischemic stroke rats. These protective effects were likely exerted via activation of the mitogen-activated protein kinase (MAPK) signaling pathway, i.e., up-regulation of phosphorylated ERK1/2 in both rat cerebral cortex and activated microglia (AM); up-regulation of phosphorylated p38 (p-p38) in the cerebral cortex; and inhibition of phosphorylated JNK and p-p38 levels in the AM. In conclusion, this study highlights HsTx2 as a potential neuroprotective agent for stroke.

Assessing the influence of curcumin in sex-specific oxidative stress, survival and behavior in Drosophila melanogaster

Oxidative stress, which occurs from an imbalance of reactive oxygen and nitrogen species (RONS) and both endogenous and exogenous antioxidants, promotes aging and underlies sex-specific differences in longevity and susceptibility to age-related neurodegeneration. Recent evidence suggests that curcumin, a yellow pigment derived from turmeric and shown to exhibit antioxidant properties as a RONS scavenger, influences the regulation of genetic elements in endogenous antioxidant pathways. To investigate the role of curcumin in sex-specific in vivo responses to oxidative stress, Drosophila were reared on media supplemented with 0.25, 2.5 or 25 mmol l-1 curcuminoids (consisting of curcumin, demethoxycurcumin and bisdemethoxycurcumin) and resistance to oxidative stress and neural parameters were assessed. High levels of curcuminoids exhibited two sex-specific effects: protection from hydrogen peroxide as an oxidative stressor and alterations in turning rate in an open field. Taken together, these results suggest that the influence of curcuminoids as antioxidants probably relies on changes in gene expression and that sexual dimorphism exists in the in vivo response to curcuminoids.

Curcumin Formulations and Trials: What's New in Neurological Diseases

Curcumin’s pharmacological properties and its possible benefits for neurological diseases and dementia have been much debated. In vitro experiments show that curcumin modulates several key physiological pathways of importance for neurology. However, in vivo studies have not always matched expectations. Thus, improved formulations of curcumin are emerging as powerful tools in overcoming the bioavailability and stability limitations of curcumin. New studies in animal models and recent double-blinded, placebo-controlled clinical trials using some of these new formulations are finally beginning to show that curcumin could be used for the treatment of cognitive decline. Ultimately, this work could ease the burden caused by a group of diseases that are becoming a global emergency because of the unprecedented growth in the number of people aged 65 and over worldwide. In this review, we discuss curcumin’s main mechanisms of action and also data from in vivo experiments on the effects of curcumin on cognitive decline.

Curcumin promotes neurogenesis of hippocampal dentate gyrus via Wnt/β-catenin signal pathway following cerebral ischemia in mice

OBJECTIVES

To investigate whether curcumin promotes hippocampal neurogenesis in the cerebral ischemia (CI) mice via Wnt/β-catenin signaling pathway.

METHODS

Male C57BL/6 mice were randomly divided into groups: sham operation group (Sham), cerebral ischemic group (CI), curcumin treatment group (50, 100 mg/kg/d, i.p.) and curcumin (100 mg/kg/d) + DKK1 (a blocker of Wnt receptor, 200 ng/d, icv) group. CI was induced by bilateral common carotid arteries occlusion (BCCAO) for 20 min. The Morris water maze test was conducted to detect spatial learning and memory. Immunofluorescence staining was used to examine the proliferation and differentiation of immature neurons in the hippocampal dentate gyrus. The proteins involved in neurogenesis and Wnt signaling pathway were examined using Western blot assay.

RESULTS

Curcumin significantly alleviated cognitive deficits induced by CI. Curcumin dose-dependently increased the proliferation of neural stem cells and promoted the differentiation and maturation of newly generated neural cells into neurons. Curcumin also increased the expression of proteins involved in neurogenesis (including Ngn2, Pax6 and NeuroD 1) and the Wnt/β-catenin signaling pathway. Moreover, the forenamed effects of curcumin were abolished by pretreatment with DKK1, a blocker of Wnt receptor.

CONCLUSION

Curcumin promotes hippocampal neurogenesis by activating Wnt/β-catenin signaling pathway to ameliorate cognitive deficits after acute CI.

Nose-to-brain Delivery of Natural Compounds for the Treatment of Central Nervous System Disorders

BACKGROUND

Several natural compounds have demonstrated potential for the treatment of central nervous system disorders such as ischemic cerebrovascular disease, glioblastoma, neuropathic pain, neurodegenerative diseases, multiple sclerosis and migraine. This is due to their well-known antioxidant, anti-inflammatory, neuroprotective, anti-tumor, anti-ischemic and analgesic properties. Nevertheless, many of these molecules have poor aqueous solubility, low bioavailability and extensive gastrointestinal and/or hepatic first-pass metabolism, leading to a quick elimination as well as low serum and tissue concentrations. Thus, the intranasal route emerged as a viable alternative to oral or parenteral administration, by enabling a direct transport into the brain through the olfactory and trigeminal nerves. With this approach, the blood-brain barrier is circumvented and peripheral exposure is reduced, thereby minimizing possible adverse effects.

OBJECTIVE

Herein, brain-targeting strategies for nose-to-brain delivery of natural compounds, including flavonoids, cannabinoids, essential oils and terpenes, will be reviewed and discussed. Brain and plasma pharmacokinetics of these molecules will be analyzed and related to their physicochemical characteristics and formulation properties.

CONCLUSION

Natural compounds constitute relevant alternatives for the treatment of brain diseases but often require loading into nanocarrier systems to reach the central nervous system in sufficient concentrations. Future challenges lie in a deeper characterization of their therapeutic mechanisms and in the development of effective, safe and brain-targeted delivery systems for their intranasal administration.

Curcumin Improves the Renal Autophagy in Rat Experimental Membranous Nephropathy via Regulating the PI3K/AKT/mTOR and Nrf2/HO-1 Signaling Pathways

Membranous nephropathy (MN, also known as membranous glomerulopathy) is one of the many glomerular diseases causing nephrotic syndrome. The literature indicates that autophagy is associated with the homeostasis of podocytes in glomeruli. Curcumin, the main active component in turmeric, has drawn attention for its effective bioactivities against chronic kidney disease. The current study was aimed at assessing the effects of curcumin and exploring the underlying mechanism that mediates autophagy in an animal model of passive Heymann nephritis (PHN) in rats. Passive Heymann nephritis (PHN) was induced in male SD rats by intraperitoneal injection of anti-Fx1A serum. The rats were divided into 3 groups: control (n = 10, normal diet), model group (n = 10, 0.5% sodium carboxymethylcellulose), and curcumin (n = 10, 300 mg/kg/d). The kidney function and oxidative stress indicators were measured using commercial diagnostic kits, and the histomorphology of renal tissues was observed. The number of podocytes was measured by immunohistochemistry. Meanwhile, the autophagosomes in podocyte were analyzed by transmission electron microscopy and the immunofluorescence assay pointing to p62, an autophagic marker. Western blot analyzed the levels of apoptosis, autophagy, PI3K/AKT/mTOR, and Nrf2/HO-1 pathway-associated proteins. The total cholesterol (TC), triglycerides (TG), creatinine (Scr), blood urea nitrogen (BUN), urine volume, and urine albumin of PHN rats were significantly reduced by the administration of curcumin and attenuated renal histomorphological changes in model rats. Meanwhile, curcumin improved the oxidative stress response by decreasing MDA and increasing SOD, GSH, and CAT levels in the kidney of PHN rats. Furthermore, curcumin significantly ameliorated the podocyte loss, along with the fusion, and increased the autophagic vacuoles compared to the PHN control rats. In addition, curcumin downregulated the expression of Bax, Caspase-3, p62, PI3K, p-AKT, and p-mTOR proteins and upregulated the Bcl-2, beclin1, LC3, Nrf2, and HO-1 levels in this animal model. The results provide a scientific basis that curcumin could significantly alleviate the development of MN by inducing autophagy and alleviating renal oxidative stress through the PI3K/AKT/mTOR and Nrf2/HO-1 pathways.

Protective effects of natural compounds against oxidative stress in ischemic diseases and cancers via activating the Nrf2 signaling pathway: A mini review

Oxidative stress, an imbalance between reactive oxygen species and antioxidants, has been seen in the pathological states of many disorders such as ischemic diseases and cancers. Many natural compounds (NCs) have long been recognized to ameliorate oxidative stress due to their inherent antioxidant activities. The modulation of oxidative stress by NCs via activating the Nrf2 signaling pathway is summarized in the review. Three NCs, ursolic acid, betulinic acid, and curcumin, and the mechanisms of their cytoprotective effects are investigated in myocardial ischemia, cerebral ischemia, skin cancer, and prostate cancer. To promote the therapeutic performance of NCs with poor water solubility, the formulation approach, such as the nano drug delivery system, is elaborated as well in this review.

Turmeric and Its Major Compound Curcumin on Health: Bioactive Effects and Safety Profiles for Food, Pharmaceutical, Biotechnological and Medicinal Applications

Curcumin, a yellow polyphenolic pigment from the Curcuma longa L. (turmeric) rhizome, has been used for centuries for culinary and food coloring purposes, and as an ingredient for various medicinal preparations, widely used in Ayurveda and Chinese medicine. In recent decades, their biological activities have been extensively studied. Thus, this review aims to offer an in-depth discussion of curcumin applications for food and biotechnological industries, and on health promotion and disease prevention, with particular emphasis on its antioxidant, anti-inflammatory, neuroprotective, anticancer, hepatoprotective, and cardioprotective effects. Bioavailability, bioefficacy and safety features, side effects, and quality parameters of curcumin are also addressed. Finally, curcumin's multidimensional applications, food attractiveness optimization, agro-industrial procedures to offset its instability and low bioavailability, health concerns, and upcoming strategies for clinical application are also covered.

Rapamycin Pretreatment Alleviates Cerebral Ischemia/Reperfusion Injury in Dose-Response Manner Through Inhibition of the Autophagy and NFκB Pathways in Rats

Although rapamycin can attenuate cerebral ischemia/reperfusion (I/R) injury, the potential roles of rapamycin on cerebral I/R injury remain largely controversial. The present work aims to evaluate underlying molecular mechanisms of rapamycin pretreatment on I/R injury. In total, 34 Sprague-Dawley rats were randomly grouped to 3 groups: sham group (n = 2), vehicle group (n = 16), and rapamycin-pretreatment group (n = 16). Before the focal cerebral ischemia was induced, those rats in the pretreatment group were intraperitoneally injected rapamycin (1 mg/kg body) for 20 hours, while rats in the vehicle group received same-volume saline. Then, rats in these 2 groups received focal cerebral ischemia for 3 and 6 hours, respectively (n = 8 in each group), which was followed by the application of reperfusion for 4, 24, 72 hours, and 1 week (n = 2 in each group). The results showed that the rapamycin pretreatment improved the memory functions of rats after I/R injury, which was evaluated using a Y-maze test. Rapamycin pretreatment significantly reduced the size of triphenyltetrazolium chloride infarction and decreased the expression of I/R injury markers. Moreover, the expression of LC-3 and NFκB was also significantly reduced after rapamycin pretreatment. Taken together, rapamycin pretreatment may alleviate cerebral I/R injury partly through inhibiting autophagic activities and NFκB pathways in rats.