p-Hydroxybenzyl alcohol prevents brain injury and behavioral impairment by activating Nrf2, PDI, and neurotrophic factor genes in a rat model of brain ischemia

Clostridium butyricum MIYAIRI 588 alleviates periodontal bone loss in mice with diabetes mellitus

The gut microbiota is a bridge linking periodontitis and systemic diseases, such as diabetes mellitus (DM). The probiotic Clostridium butyricum MIYAIRI 588 (CBM588) is reportedly an effective therapeutic approach for gut dysbiosis. Here, in a mouse model, we explored the therapeutic effect of CBM588 on periodontal bone destruction in DM and DM-associated periodontitis (DMP), as well as the underlying mechanism. Micro-computed tomography revealed that DM and DMP both aggravated periodontal bone destruction, which was alleviated by intragastric supplementation with CBM588. Moreover, 16S rRNA sequencing and untargeted metabolite analysis indicated that CBM588 ameliorated DMP-triggered dysbiosis and led to reduced oxidative stress associated with elevated 4-hydroxybenzenemethanol (4-HBA) in serum. Furthermore, in vitro and in vivo experiments found that the metabolite 4-HBA promoted nuclear factor erythroid 2-related factor 2 (Nrf2) signaling activation and modulated the polarization of macrophages, thus ameliorating inflammatory bone destruction in DMP. Our study demonstrates the protective effects of CBM588 in DM-induced mice, with and without ligature-induced periodontitis. The mechanism involves regulation of the gut microbiota and restoration of the integrity of the gut barrier to alleviate oxidative damage by elevating serum 4-HBA. This study suggests the possibility of CBM588 as a therapeutic adjuvant for periodontal treatment in diabetes patients.

Exploring the Therapeutic Effect of Neurotrophins and Neuropeptides in Neurodegenerative Diseases: at a Glance

Neurotrophins and neuropeptides are the essential regulators of peripheral nociceptive nerves that help to induce, sensitize, and maintain pain. Neuropeptide has a neuroprotective impact as it increases trophic support, regulates calcium homeostasis, and reduces excitotoxicity and neuroinflammation. In contrast, neurotrophins target neurons afflicted by ischemia, epilepsy, depression, and eating disorders, among other neuropsychiatric conditions. Neurotrophins are reported to inhibit neuronal death. Strategies maintained for "brain-derived neurotrophic factor (BDNF) therapies" are to upregulate BDNF levels using the delivery of protein and genes or compounds that target BDNF production and boosting BDNF signals by expanding with BDNF mimetics. This review discusses the mechanisms of neurotrophins and neuropeptides against acute neural damage as well as highlighting neuropeptides as a potential therapeutic agent against Parkinson's disease (PD), Huntington's disease (HD), Alzheimer's disease (AD), and Machado-Joseph disease (MJD), the signaling pathways affected by neurotrophins and their receptors in both standard and diseased CNS systems, and future perspectives that can lead to the potent application of neurotrophins and neuropeptides in neurodegenerative diseases (NDs).

Systems metabolic engineering upgrades Corynebacterium glutamicum to high-efficiency cis, cis-muconic acid production from lignin-based aromatics

Lignin displays a highly challenging renewable. To date, massive amounts of lignin, generated in lignocellulosic processing facilities, are for the most part merely burned due to lacking value-added alternatives. Aromatic lignin monomers of recognized relevance are in particular vanillin, and to a lesser extent vanillate, because they are accessible at high yield from softwood-lignin using industrially operated alkaline oxidative depolymerization. Here, we metabolically engineered C. glutamicum towards cis, cis-muconate (MA) production from these key aromatics. Starting from the previously created catechol-based producer C. glutamicum MA-2, systems metabolic engineering first discovered an unspecific aromatic aldehyde reductase that formed aromatic alcohols from vanillin, protocatechualdehyde, and p- hydroxybenzaldehyde, and was responsible for the conversion up to 57% of vanillin into vanillyl alcohol. The alcohol was not re-consumed by the microbe later, posing a strong drawback on the producer. The identification and subsequent elimination of the encoding fudC gene completely abolished vanillyl alcohol formation. Second, the initially weak flux through the native vanillin and vanillate metabolism was enhanced up to 2.9-fold by implementing synthetic pathway modules. Third, the most efficient protocatechuate decarboxylase AroY for conversion of the midstream pathway intermediate protocatechuate into catechol was identified out of several variants in native and codon optimized form and expressed together with the respective helper proteins. Fourth, the streamlined modules were all genomically combined which yielded the final strain MA-9. MA-9 produced bio-based MA from vanillin, vanillate, and seven structurally related aromatics at maximum selectivity. In addition, MA production from softwood-based vanillin, obtained through alkaline depolymerization, was demonstrated.

Integrative Analyses of Biomarkers Associated with Endoplasmic Reticulum Stress in Ischemic Stroke

Background. Neuronal apoptosis, which is the primary pathological transform of cerebral injury following ischemic stroke (IS), is considered to be induced by endoplasmic reticulum stress (ERS) by numerous reports. However, ERS biomarkers in IS have not been fully identified yet. Consequently, the present study is aimed at exploring potential blood biomarkers by investigating the molecular mechanisms of ERS promoting neuronal apoptosis following IS development. Methods. A comprehensive analysis was performed with two free-accessible whole-blood datasets (GSE16561 and GSE37587) from the Gene Expression Omnibus database. Genetic information from 107 IS and 24 healthy controls was employed to analyze the differentially expressed genes (DEGs). Genes related to ERS (ERS-DEGs) were identified from the analysis. Enrichment analyses were performed to explore the biofunction and correlated signal pathways of ERS-DEGs. Protein-protein interaction (PPI) network and immune correlation analyses were performed to identify the hub genes along with their correspondent expressions and functions, all of which contributed to incremental diagnostic values. Results. A total of 60 IS-related DEGs were identified, of which 27 genes were confirmed as ERS-DEGs. GO and KEGG enrichment analysis corroborated that upregulated ERS-DEGs were principally enriched in pathways related to immunity, including neutrophil activation and Th17 cell differentiation. Moreover, the GSEA and GSVA indicated that T cell-related signal pathways were the most considerably immune pathways for ERS-DEG enrichment. A total of 10 hub genes were filtered out via the PPI network analysis. Immune correlation analysis confirmed that the expression of hub genes is associated with immune cell infiltration. Conclusions. By integrating and analyzing the two gene expression data profiles, it can be inferred that ERS may be involved in the development of neuronal apoptosis following IS via immune homeostasis. The identified hub genes, which are associated with immune cell infiltration, may serve as potential biomarkers for relative diagnosis and therapy.

Para-Hydroxybenzyl Alcohol Delays the Progression of Neurodegenerative Diseases in Models of Caenorhabditis elegans through Activating Multiple Cellular Protective Pathways

The traditional Chinese medicine Gastrodia elata (commonly called “Tianma” in Chinese) has been widely used in the treatment of rheumatism, epilepsy, paralysis, headache, and dizziness. Phenolic compounds, such as gastrodin, para-hydroxybenzyl alcohol (HBA), p-hydroxybenzaldehyde, and vanillin are the main bioactive components isolated from Gastrodia elata. These compounds not only are structurally related but also share similar pharmacological activities, such as antioxidative and anti-inflammatory activities, and effects on the treatment of aging-related diseases. Here, we investigated the effect of para-hydroxybenzyl alcohol (HBA) on neurodegenerative diseases and aging in models of Caenorhabditis elegans (C. elegans). Our results showed that HBA effectively delayed the progression of neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and Huntington's disease in models of C. elegans. In addition, HBA could increase the average lifespan of N2 worms by more than 25% and significantly improve the age-related physiological functions of worms. Moreover, HBA improved the survival rate of worms under stresses of oxidation, heat, and pathogenic bacteria. Further mechanistic investigation revealed that HBA could activate FOXO/DAF-16 and SKN-1 to regulate antioxidative and xenobiotic metabolism pathway. HBA could also activate HSF-1 to regulate proteostasis maintenance pathway, mitochondrial unfolded stress response, endoplasmic stress response and autophagy pathways. The above results suggest that HBA activated multiple cellular protective pathways to increase stress resistance and protect against aging and aging-related diseases. Overall, our study indicates that HBA is a potential candidate for future development of antiaging pharmaceutical application.

Unexpected Role of pH and Microenvironment on the Antioxidant and Synergistic Activity of Resveratrol in Model Micellar and Liposomal Systems

Experimental and theoretical studies indicate that resveratrol (RSV, dietary polyphenol that effectively reduces cellular oxidative stress) is a good scavenger of hydroxyl, alkoxyl, and peroxyl radicals in homogeneous systems. However, the role of RSV as a chain-breaking antioxidant is still questioned. Here, we describe pH dependent effectiveness of RSV as an inhibitor of peroxidation of methyl linoleate in Triton X-100 micelles and in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) liposomes, with the best effectiveness at pH 6 (stoichiometric factors, n, are 4.9 and 5.6, and the rate constants for reaction with peroxyl radicals, k_inh, are 1200 and 3300 M^–1 s^–1 in micellar and liposomal systems, respectively). We propose the mechanism in which RSV-derived radicals are coupled to dimers with recovered ability to trap lipidperoxyl radicals. The formation of such dimers is facilitated due to increased local concentration of RSV at the lipid–water interface. Good synergy of RSV with α-tocopherol analogue in micelles and liposomes is in contrast to the previously reported lack of synergy in non-polar solvents; however, the increased persistency of tocopheroxyl radicals in dispersed lipid/water systems and proximal localization of both antioxidants greatly facilitate the possible recovery of α-TOH by RSV.

ERO1-PDI Redox Signaling in Health and Disease

Significance: Protein disulfide isomerase (PDI) and endoplasmic reticulum oxidoreductase 1 (ERO1) are crucial for oxidative protein folding in the endoplasmic reticulum (ER). These enzymes are frequently overexpressed and secreted, and they contribute to the pathology of neurodegenerative, cardiovascular, and metabolic diseases. Recent Advances: Tissue-specific knockout mouse models and pharmacologic inhibitors have been developed to advance our understanding of the cell-specific functions of PDI and ERO1. In addition to their roles in protecting cells from the unfolded protein response and oxidative stress, recent studies have revealed that PDI and ERO1 also function outside of the cells. Critical Issues: Despite the well-known contributions of PDI and ERO1 to specific disease pathology, the detailed molecular and cellular mechanisms underlying these activities remain to be elucidated. Further, although PDI and ERO1 inhibitors have been identified, the results from previous studies require careful evaluation, as many of these agents are not selective and may have significant cytotoxicity. Future Directions: The functions of PDI and ERO1 in the ER have been extensively studied. Additional studies will be required to define their functions outside the ER.

The Nrf2 Pathway in Ischemic Stroke: A Review

Ischemic stroke, characterized by the sudden loss of blood flow in specific area(s) of the brain, is the leading cause of permanent disability and is among the leading causes of death worldwide. The only approved pharmacological treatment for acute ischemic stroke (intravenous thrombolysis with recombinant tissue plasminogen activator) has significant clinical limitations and does not consider the complex set of events taking place after the onset of ischemic stroke (ischemic cascade), which is characterized by significant pro-oxidative events. The transcription factor Nuclear factor erythroid 2-related factor 2 (Nrf2), which regulates the expression of a great number of antioxidant and/or defense proteins, has been pointed as a potential pharmacological target involved in the mitigation of deleterious oxidative events taking place at the ischemic cascade. This review summarizes studies concerning the protective role of Nrf2 in experimental models of ischemic stroke, emphasizing molecular events resulting from ischemic stroke that are, in parallel, modulated by Nrf2. Considering the acute nature of ischemic stroke, we discuss the challenges in using a putative pharmacological strategy (Nrf2 activator) that relies upon transcription, translation and metabolically active cells in treating ischemic stroke patients.

P- Hydroxybenzyl Alcohol Alleviates Oxidative Stress in a Nonalcoholic Fatty Liver Disease Larval Zebrafish Model and a BRL-3A Hepatocyte Via the Nrf2 Pathway

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, and it has gradually become the main disease burden in the world. However, the pathogenesis of NAFLD is complex, involving such things as dyslipidemia, oxidative stress, inflammation, etc. This brings to the table a significant challenge for drug development, and there is still no drug approved by the FDA on the market to treat the disease. GAS and HBA are active ingredients of the orchidaceae plant gastrodia elata and have exhibit effects in ameliorating nervous system diseases caused by oxidative stress. HBA is a metabolite of GAS that could perform lipid regulation and improve oxidative stress on HCD-induced NAFLD larval zebrafish, as reported by previous studies; we therefore explored the role of HBA in lipid regulation and oxidative stress on HCD-induced NAFLD larval zebrafish in vivo and FFA-induced BRL-3A hepatocyte in vitro. The gene expression of lipogenesis, inflammation, and oxidative stress were measured to investigate the underlying mechanism of HBA, and the potential protein target of HBA was explored by immunofluorescence. Altogether, our data highlight the role of HBA in improving NAFLD by use of its lipid-lowering and anti-oxidative properties via the Nrf2/HO-1 signaling pathway, providing a potential therapeutic compound for NAFLD treatment.

Insight into Medicinal Chemistry Behind Traditional Chinese Medicines: p-Hydroxybenzyl Alcohol-Derived Dimers and Trimers from Gastrodia elata

From an aqueous extract of "tian ma" (the steamed and dried rhizomes of Gastrodia elata), ten new compounds gastrodibenzins A-D (1-4) and gastrotribenzins A-F (5-10), along with known analogues (11-20), having structure features coupling between two and three p-hydroxybenzyl-derived units via carbon- and/or ether-bonds, were isolated and characterized by spectroscopic data analysis. Meanwhile, the new compounds 5a, 6a, 8a, 22, and 23, as well as the known derivatives 13a, 14a, 15, 17-21, 24, 25, and p-hydroxybenzyl aldehyde were isolated and identified from a refluxed aqueous solution of p-hydroxybenzyl alcohol. Methylation of 5a and 6a in methanol and ethylation of 6a, 8a, 13a, and 14a in ethanol produced 5 and 6 and 7, 8, 13, and 14, respectively. using ultra-performance liquid chromatography high-resolution electrospray ionization mass spectrometry (UPLC-HRESIMS) analysis of the refluxed solutions of p-hydroxybenzyl alcohol and the refluxed extracts of the fresh G. elata rhizome and "tian ma" extracts indicated consistent production and variation of the dimeric and trimeric derivatives of p-hydroxybenzyl alcohol upon extracting solvents and refluxing time. In various assays, the dimeric and trimeric derivatives showed more potent activities than p-hydroxybenzyl alcohol itself and gastrodin, which are the main known active constituents of "tian ma". These results revealed for the first time that the more effective dimers and trimers can be produced through condensation of the co-occurring p-hydroxybenzyl alcohol during processing and decocting of the G. elata rhizomes, demonstrating insights into medicinal chemistry behind application protocols of traditional Chinese medicines.

CDK5 Targeting as a Therapy for Recovering Neurovascular Unit Integrity in Alzheimer's Disease

The neurovascular unit (NVU) is responsible for synchronizing the energetic demand, vasodynamic changes, and neurochemical and electrical function of the brain through a closed and interdependent interaction of cell components conforming to brain tissue. In this review, we will focus on cyclin-dependent kinase 5 (CDK5) as a molecular pivot, which plays a crucial role in the healthy function of neurons, astrocytes, and the endothelium and is implicated in the cross-talk of cellular adhesion signaling, ion transmission, and cytoskeletal remodeling, thus allowing the individual and interconnected homeostasis of cerebral parenchyma. Then, we discuss how CDK5 overactivation affects the integrity of the NVU in Alzheimer's disease (AD) and cognitive impairment; we emphasize how CDK5 is involved in the excitotoxicity spreading of glutamate and Ca2+ imbalance under acute and chronic injury. Additionally, we present pharmacological and gene therapy strategies for producing partial depletion of CDK5 activity on neurons, astrocytes, or endothelium to recover neuroplasticity and neurotransmission, suggesting that the NVU should be the targeted tissue unit in protective strategies. Finally, we conclude that CDK5 could be effective due to its intervention on astrocytes by its end feet on the endothelium and neurons, acting as an intermediary cell between systemic and central communication in the brain. This review provides integrated guidance regarding the pathogenesis of and potential repair strategies for AD.

Treatment with AAV1-Rheb(S16H) provides neuroprotection in a mouse model of photothrombosis-induced ischemic stroke

We recently reported that upregulation of the constitutively active ras homolog enriched in brain [Rheb(S16H)], which induces the activation of the mammalian target of rapamycin complex 1 (mTORC1) signaling pathway, can protect adult neurons, mediated by the induction of neurotrophic factors, such as brain-derived neurotrophic factor (BDNF), in animal models of neurodegenerative diseases. Here we show that neuronal transduction of Rheb(S16H) using adeno-associated virus serotype 1 provides neuroprotection in a mouse model of photothrombosis-induced ischemic stroke. Rheb(S16H)-expressing neurons exhibited neurotrophic effects, such as mTORC1 activation, increases in neuronal size, and BDNF production, in mouse cerebral cortex. Moreover, the upregulation of neuronal Rheb(S16H) significantly attenuated ischemic damage and behavioral impairments as compared to untreated mice, suggesting that Rheb(S16H) upregulation in cortical neurons may be a useful strategy to treat ischemic stroke.

Protein disulfide isomerase in cardiovascular disease

Protein disulfide isomerase (PDI) participates in the pathogenesis of numerous diseases. Increasing evidence indicates that intravascular cell-derived PDI plays an important role in the initiation and progression of cardiovascular diseases, including thrombosis and vascular inflammation. Recent studies with PDI conditional knockout mice have advanced our understanding of the function of cell-specific PDI in disease processes. Furthermore, the identification and development of novel small-molecule PDI inhibitors has led into a new era of PDI research that transitioned from the bench to bedside. In this review, we will discuss recent findings on the regulatory role of PDI in cardiovascular disease.

Efforts to untangle the functions of a large family of enzymes could lead researchers to new therapies for diverse cardiovascular diseases. Members of the protein disulfide isomerase (PDI) family chemically modify other proteins in ways that can alter both their structure and biological activity. Jaehyung Cho of the University of Illinois at Chicago, USA and coworkers have reviewed numerous studies linking PDI with cardiovascular diseases, including thrombosis, heart attack, vascular inflammation, and stroke. The authors also report progress in developing small-molecule PDI inhibitors that could yield the treatment for these conditions.

Differential roles of exogenous protein disulfide isomerase A3 on proliferating cell and neuroblast numbers in the normal and ischemic gerbils

INTRODUCTION

We examined the effects of exogenous protein disulfide isomerase A3 (PDIA3) on hippocampal neurogenesis in gerbils under control and ischemic damage.

METHODS

To facilitate the delivery of PDIA3 to the brain, we constructed Tat-PDIA3 protein and administered vehicle (10% glycerol) or Tat-PDIA3 protein once a day for 28 days. On day 24 of vehicle or Tat-PDIA3 treatment, ischemia was transiently induced by occlusion of both common carotid arteries for 5 min.

RESULTS

Administration of Tat-PDIA3 significantly reduced ischemia-induced spontaneous motor activity, and the number of NeuN-positive nuclei in the Tat-PDIA3-treated ischemic group was significantly increased in the CA1 region compared to that in the vehicle-treated ischemic group. Ki67- and DCX-immunoreactive cells were significantly higher in the Tat-PDIA3-treated group compared to the vehicle-treated control group. In vehicle- and Tat-PDIA3-treated ischemic groups, the number of Ki67- and DCX-immunoreactive cells was significantly higher as compared to those in the vehicle- and Tat-PDIA3-treated control groups, respectively. In the dentate gyrus, the numbers of Ki67-immunoreactive cells were comparable between vehicle- and Tat-PDIA3-treated ischemic groups, while more DCX-immunoreactive cells were observed in the Tat-PDIA3-treated group. Transient forebrain ischemia increased the expression of phosphorylated cAMP-response element-binding protein (pCREB) in the dentate gyrus, but the administration of Tat-PDIA3 robustly increased pCREB-positive nuclei in the normal gerbils, but not in the ischemic gerbils. Brain-derived neurotrophic factor (BDNF) mRNA expression was significantly increased in the Tat-PDIA3-treated group compared to that in the vehicle-treated group. Transient forebrain ischemic increased BDNF mRNA levels in both vehicle- and Tat-PDIA3-treated groups, and there were no significant differences between groups.

CONCLUSIONS

These results suggest that Tat-PDIA3 enhances cell proliferation and neuroblast numbers in the dentate gyrus in normal, but not in ischemic gerbils, by increasing BDNF mRNA and phosphorylation of pCREB.

Characterization of the Inhibitory Effect of Gastrodigenin and Gastrodin on M-type K+ Currents in Pituitary Cells and Hippocampal Neurons

Gastrodigenin (HBA) and gastrodin (GAS) are phenolic ingredients found in Gastrodia elata Blume (GEB), a traditional Chinese herbal medicine. These compounds have been previously used to treat cognitive dysfunction, convulsion, and dizziness. However, at present, there is no available information regarding their potential ionic effects in electrically excitable cells. In the current study, the possible effects of HBA and GAS on different ionic currents in pituitary GH3 cells and hippocampal mHippoE-14 neurons were investigated using the patch-clamp technique. The addition of HBA or GAS resulted in the differential inhibition of the M-type K⁺ current (I_K(M)) density in a concentration-dependent manner in GH₃ cells. HBA resulted in a slowing of the activation time course of I_K(M), while GAS elevated it. HBA also mildly suppressed the density of erg-mediated or the delayed-rectifier K⁺ current in GH₃ cells. Neither GAS nor HBA (10 µM) modified the voltage-gated Na⁺ current density, although they suppressed the L-type Ca²⁺ current density at the same concentration. In hippocampal mHippoE-14 neurons, HBA was effective at inhibiting I_K(M) density as well as slowing the activation time course. Taken together, the present study provided the first evidence that HBA or GAS could act on cellular mechanisms, and could therefore potentially have a functional influence in various neurologic disorders.

Studies of blood-brain barrier permeability of gastrodigenin in vitro and in vivo

According to the basic theories of traditional Chinese medicine, Gastrodia elata (GE) is clinically utilized for the treatment of cephalalgia and migraine. The gastrodigenin (p-hydroxybenzyl alcohol, HBA), one of the effective components of GE, may pass through the blood-brain barrier (BBB) to exert its pharmacological effects. This study aimed to investigate BBB permeability of HBA via in vitro hCMEC/D3 BBB model and in vivo microdialysis in rats. For the establishment of in vitro BBB model, hCMEC/D3 cells were used to construct the monolayer. The integrity of the monolayer was evaluated by TEER measurements, expression analysis of tight junction proteins (claudin-5, zo-1 and occludin) and apparent permeability coefficients (P_app) of fluorescein disodium. During the 6-day incubation of hCMEC/D3 cells, the values of TEER gradually increased and maintained above 100 Ω·cm². Besides, the expression levels of claudin-5 and zo-1 in hCMEC/D3 cells increased over time, and tended to be stable, suggesting that integrity of the monolayer has been completely established. Moreover, the P_app of fluorescein disodium was 3.94 × 10^-7 cm·s^-1 after administration for 180 min, indicating that the monolayer retains the characteristics of BBB and can restrict the diffusion of hydrophilic small-molecule compounds. A sensitive HPLC method was established for HBA detection, and the transport rate of HBA was assessed by a transwell system. HBA crossed the hCMEC/D3 BBB model rapidly, but a plateau was observed when HBA concentrations were relatively similar between the two sides of transwell. Permeability assay revealed that 32.91% of HBA could penetrate the in vitro BBB model after 240 min of administration. In vivo BBB permeability was evaluated by determining the concentrations of HBA in blood and brain simultaneously. Following HBA administration, the samples of microdialysis were collected at 20, 40 and 60 min, and then every 30 min until the procedure ended. Pharmacokinetic parameters of HBA showed that HBA could pass through BBB and reach its maximum concentration at 40 min in blood and brain tissue. Furthermore, AUC_0-t and AUC_0-inf for the brain-to-blood distribution ratio of HBA were 0.1925 and 0.2083, respectively, indicating that approximately 20% of HBA in blood could pass through the BBB and subsequently transported into the brain. Both in vitro and in vivo experiments confirmed that HBA could penetrate the BBB. In summary, the findings of this study highlight that a promising amount of HBA in blood can pass through the BBB and exerts its pharmacological effects on central nervous system (CNS) diseases.

Gastrodin Derivatives from Gastrodia elata

Nine new gastrodin derivatives, including seven p-hydroxybenzyl-modified gastrodin ethers (1-7), 6'-O-acetylgastrodin (8), and 4-[α-D-glucopyranosyl-(1 →6)-β-D-glucopyranosyloxy]benzyl alcohol (9), together with seven known derivatives, were isolated from an aqueous extract of Gastrodia elata ("tian ma") rhizomes. Their structures were determined by spectroscopic and chemical methods as well as single crystal X-ray diffraction. Compounds 1-4, 7, 10, and 11 were also isolated from a reaction mixture by refluxing gastrodin and p-hydroxybenzyl alcohol in H2O. As both gastrodin and p-hydroxybenzyl alcohol exist in the plant, the reaction results provide evidence for the production and increase/decrease of potential effective/toxic components when "tian ma" is decocted solely or together with ingredients in Chinese traditional medicine formulations, though the isolates were inactive in the preliminarily cell-based assays at concentrations of 10 μM. Moreover, using ultra-performance liquid chromatography high-resolution electrospray ionization mass spectrometry (UPLC-HRESIMS), 4, 7, 10, and 11, as well as component variations, were detectable in the freshly prepared extracts of different types of samples, including the freeze-dried fresh G. elata rhizomes.

EPO and TMBIM3/GRINA Promote the Activation of the Adaptive Arm and Counteract the Terminal Arm of the Unfolded Protein Response after Murine Transient Cerebral Ischemia

Ischemic stroke is known to cause the accumulation of misfolded proteins and loss of calcium homeostasis leading to impairment of endoplasmic reticulum (ER) function. The unfolded protein response (UPR) is an ER-located and cytoprotective pathway that aims to resolve ER stress. Transmembrane BAX inhibitor-1 motif-containing (TMBIM) protein family member TMBIM3/GRINA is highly expressed in the brain and mostly located at the ER membrane suppressing ER calcium release by inositol-1,4,5-trisphosphate receptors. GRINA confers neuroprotection and is regulated by erythropoietin (EPO) after murine cerebral ischemia. However, the role of GRINA and the impact of EPO treatment on the post-ischemic UPR have not been elucidated yet. We subjected GRINA-deficient (Grina^−/−) and wildtype mice to transient (30 min) middle cerebral artery occlusion (tMCAo) followed by 6 h or 72 h of reperfusion. We administered EPO or saline 0, 24 and 48 h after tMCAo/sham surgery. Oxygen–glucose deprivation (OGD) and pharmacological stimulation of the UPR using Tunicamycin and Thapsigargin were carried out in primary murine cortical mixed cell cultures. Treatment with the PERK-inhibitor GSK-2606414, IRE1a-RNase-inhibitor STF-083010 and EPO was performed 1 h prior to either 1 h, 2 h or 3 h of OGD. We found earlier and larger infarct demarcations in Grina^−/− mice compared to wildtype mice, which was accompanied by a worse neurological outcome and an abolishment of EPO-mediated neuroprotection after ischemic stroke. In addition, GRINA-deficiency increased apoptosis and the activation of the corresponding PERK arm of the UPR after stroke. EPO enhanced the post-ischemic activation of pro-survival IRE1a and counteracted the pro-apoptotic PERK branch of the UPR. Both EPO and the PERK-inhibitor GSK-2606414 reduced cell death and regulated Grina mRNA levels after OGD. In conclusion, GRINA plays a crucial role in post-ischemic UPR and the use of both GSK-2606414 and EPO might lead to neuroprotection.

The protective effects of Gastrodia elata Blume extracts on middle cerebral artery occlusion in rats

To investigate the effects of Gastrodia elata Blume (GEB) and 4-hydroxybenzyl alcohol (HBA) on brain damage, GEB or HBA was administered orally for 14 days before middle cerebral artery occlusion (MCAO). After 24 h reperfusion, the proportion of circling was significantly reduced in the GEB (79%) or HBA (69%) group compared to the MCAO group (100%) in the corner test, and the removal time in the adhesive removal test was significantly decreased in the GEB (117 ± 21.0 s) and HBA (101 ± 20.9 s) groups compared to the MCAO group (161 ± 12.6 s). GEB treatment significantly reduced infarct volume compared to the MCAO group. In the GEB and HBA group, necrosis of nerve cells in hippocampus and cortex, expressions of TNF-α and TUNEL positive cells were significantly reduced compared to the MCAO group. These results suggest that GEB and HBA prevents brain damage by anti-inflammatory and anti-apoptotic effects.

Critical Role of Nrf2 in Experimental Ischemic Stroke

Ischemic stroke is one of the leading causes of death and long-term disability worldwide; however, effective clinical approaches are still limited. The transcriptional factor Nrf2 is a master regulator in cellular and organismal defense against endogenous and exogenous stressors by coordinating basal and stress-inducible activation of multiple cytoprotective genes. The Nrf2 network not only tightly controls redox homeostasis but also regulates multiple intermediary metabolic processes. Therefore, targeting Nrf2 has emerged as an attractive therapeutic strategy for the prevention and treatment of CNS diseases including stroke. Here, the current understanding of the Nrf2 regulatory network is critically examined to present evidence for the contribution of Nrf2 pathway in rodent ischemic stroke models. This review outlines the literature for Nrf2 studies in preclinical stroke and focuses on the in vivo evidence for the role of Nrf2 in primary and secondary brain injuries. The dynamic change and functional importance of Nrf2 signaling, as well as Nrf2 targeted intervention, are revealed in permanent, transient, and global cerebral ischemia models. In addition, key considerations, pitfalls, and future potentials for Nrf2 studies in preclinical stroke investigation are discussed.

Biliverdin administration regulates the microRNA-mRNA expressional network associated with neuroprotection in cerebral ischemia reperfusion injury in rats

Inflammatory response has an important role in the outcome of cerebral ischemia reperfusion injury (CIR). Biliverdin (BV) administration can relieve CIR in rats, but the mechanism remains unknown. The aim of the present study was to explore the expressional network of microRNA (miRNA)-mRNA in CIR rats following BV administration. A rat middle cerebral artery occlusion model with BV treatment was established. After neurobehavior was evaluated by neurological severity scores (NSS), miRNA and mRNA expressional profiles were analyzed by microarray technology from the cerebral cortex subjected to ischemia and BV administration. Then, bioinformatics prediction was used to screen the correlation between miRNA and mRNA, and 20 candidate miRNAs and 33 candidate mRNAs were verified by reverse transcription-quantitative polymerase chain reaction. Furthermore, the regulation relationship between ETS proto-oncogene 1 (Ets1) and miRNA204-5p was examined by luciferase assay. A total of 86 miRNAs were differentially expressed in the BV group compared with the other groups. A total of 10 miRNAs and 26 candidate genes were identified as a core 'microRNA-mRNA' regulatory network that was linked with the functional improvement of BV administration in CIR rats. Lastly, the luciferase assay results confirmed that miRNA204-5p directly targeted Ets1. The present findings suggest that BV administration may regulate multiple miRNAs and mRNAs to improve neurobehavior in CIR rats, by influencing cell proliferation, apoptosis, maintaining ATP homeostasis, and angiogenesis.

The Phenolic Components of Gastrodia elata improve Prognosis in Rats after Cerebral Ischemia/Reperfusion by Enhancing the Endogenous Antioxidant Mechanisms

Pharmacological or spontaneous thrombolysis in ischemic stroke triggers an outbreak of reactive oxygen species and results in neuron death. Nrf2-mediated antioxidation in cells has been proved as a pivotal target for neuroprotection. This research reports that phenolic components of Gastrodia elata Blume (PCGE), a traditional Chinese medicine, can alleviate the pathological lesions in the penumbra and hippocampus by increasing the survival of neurons and astrocytes and improve neurofunction and cognition after reperfusion in a rat model of middle cerebral artery occlusion. LDH assay indicated that pretreatment of cells with PCGE (25 μg/ml) for 24 h significantly reduced H₂O₂-induced cell death in astrocytes and SH-SY5Y cells. Western blot showed that the nucleus accumulation of Nrf2 and the expression of cellular HO-1 and NQO-1, two of Nrf2 downstream proteins, were increased in both cells. BDNF, an Nrf2-dependent neurotrophic factor, was also upregulated by PCGE in astrocytes. These results illustrated that PCGE can reduce the cerebral ischemia/reperfusion injury and improve prognosis by remedying the cell damage within affected tissues. The protective effects of PCGE seem to be via activation of a Nrf2-mediated cellular defense system. Therefore, PCGE could be a therapeutic candidate for ischemic stroke and other oxidative stress associated neurological disorders.

Anti-oxidative effects of 4-hydroxybenzyl alcohol in astrocytes confer protective effects in autocrine and paracrine manners

4-Hydroxybenzyl alcohol (4-HBA) is an important phenolic constituent of Gastrodia elata Blume (GEB), a traditional herbal medicine used in East Asia. Many activities have been reported to underlie the beneficial effects of 4-HBA in the brain, and in particular, its anti-inflammatory, anti-oxidative, and anti-zinc-toxic effects have been implicated in the postischemic brain. Here, the authors investigated the anti-oxidative effect of 4-HBA on astrocytes and sought to identify the underlying molecular mechanisms involved. 4-HBA dose-dependently suppressed H₂O₂-induced astrocyte cell death. More specifically, pre-incubation of C6 cells (an astrocyte cell line) with 100 μM 4-HBA for 6 hrs increased survival when cells were treated with H₂O₂ (100 μM, 1 hr) from 54.2±0.7% to 85.9±1.5%. In addition, 4-HBA was found to up-regulate and activate Nrf2, and subsequently, to induce the expressions of several anti-oxidative genes, such as, HO-1, NQO1, and GCLM. Notably, HO-1 was induced by 3.4-fold in 4-HBA-treated C6 cells, and siRNA-mediated HO-1 knockdown demonstrated that Nrf2 activation and HO-1 induction were responsible for the observed cytoprotective effect of 4-HBA. ERK and Akt signaling pathways were activated by 4-HBA in C6 cells, suggesting their involvements in protective effect of 4-HBA. In addition, 4-HBA-conditioned astrocyte culture medium was found to have neuroprotective effects on primary neuronal cultures or fresh C6 cells exposed to oxidative stress, and these effects seemed to be mediated by glial cell line-derived neurotrophic factor (GDNF) and vascular endothelial growth factor (VEGF), which both accumulated in 4-HBA-treated astrocyte culture media. Thus, the 4-HBA-mediated activation of Nrf2 and induction of HO-1 in astrocytes were found to act via autocrine and paracrine mechanisms to confer protective effects. Furthermore, given the pleiotropic effects of 4-HBA with respect to its targeting of various brain cell types and functions, it would appear that 4-HBA has therapeutic potential for the prevention and amelioration of various brain diseases.

Unfolded protein response in brain ischemia: A timely update

Folding and processing newly synthesized proteins are vital functions of the endoplasmic reticulum that are sensitive to a variety of stress conditions. The unfolded protein response is activated to restore endoplasmic reticulum function impaired by stress. While we know that brain ischemia impairs endoplasmic reticulum function, the role of unfolded protein response activation in post-ischemic recovery of neurologic function is only beginning to emerge. Here, we summarize what is known about endoplasmic reticulum stress and unfolded protein response in brain ischemia and discuss recent findings from myocardial ischemia studies that could help to advance research on endoplasmic reticulum stress and unfolded protein response in brain ischemia.

Gastrodia elata Blume Extract Modulates Antioxidant Activity and Ultraviolet A-Irradiated Skin Aging in Human Dermal Fibroblast Cells

Gastrodia elata Blume (GEB), a traditional herbal medicine, has been used to treat a wide range of neurological disorders (e.g., paralysis and stroke) and skin problems (e.g., atopic dermatitis and eczema) in oriental medicine. This study was designed to investigate the antioxidant ability of GEB and its antiaging effect on human dermal fibroblast cells (HDF). The total phenolic and flavonoid contents of GEB were 21.8 and 0.43 mg/g dry weight (DW), respectively. The ergothioneine content of GEB was 0.41 mg/mL DW. The DPPH and ABTS radical scavenging activities of GEB at 5 and 10 mg/mL approximately ranged between 31% and 44%. The superoxide dismutase activity of GEB at 10 and 25 mg/mL was 57% and 76%, respectively. GEB increased procollagen type 1 (PC1) production and inhibited matrix metalloproteinase-1 (MMP-1) production and elastase-1 activity in UVA-irradiated HDF. PC1 messenger RNA (mRNA) levels decreased upon UVA irradiation, but recovered in response to high doses of GEB in HDF. On the contrary, GEB significantly decreased MMP-1 and elastase-1 mRNA levels, which were markedly induced in UVA-irradiated HDF. Collectively, these results suggest that GEB has sufficient antioxidant ability to prevent the signs of skin aging in UVA-irradiated human skin cells, suggesting its potential as a natural antiaging product.

The rhizome of Gastrodia elata Blume - An ethnopharmacological review

ETHNOPHARMACOLOGICAL RELEVANCE

Gastrodia elata Blume (Orchidaceae) is commonly called Tian ma in Chinese and mainly distributed in the mountainous areas of eastern Asia, such as China, Korea, Japan and India. It is an extensively used traditional Chinese herbal medicine in the clinical practice of traditional Chinese medicine, to treat headache, migraine, dizziness, epilepsy, infantile convulsion, tetany and so on. The present paper reviews the advancements in investigation of botany and ethnopharmacology, phytochemistry, pharmacology, toxicology and quality control of Gastrodia elata Blume. Finally, the possible tendency and perspective for future investigation of this plant are also put forward.

MATERIALS AND METHODS

The information on Gastrodia elata Blume was collected via piles of resources including classic books about Chinese herbal medicine, and scientific databases including Pubmed, Google Scholar, ACS, Web of science, ScienceDirect databases, CNKI and others. Plant taxonomy was validated by the databases "The Plant List", and "Mansfeld's Encyclopedia".

RESULTS

Over 81 compounds from this plant have been isolated and identified, phenolics and polysaccharides are generally considered as the characteristic and active constituents of Gastrodia elata Blume. Its active compounds possess wide-reaching biological activities, including sedative, hypnotic, antiepileptic, anticonvulsive, antianxietic, antidepressant, neuroprotective, antipsychotic, anti-vertigo, circulatory system modulating, anti-inflammationary, analgesic, antioxidative, memory-improving and antiaging, antivirus and antitumor effects.

CONCLUSION

Despite the publication of various papers on Gastrodia elata Blume, there is still, however, the need for definitive research and clarification of other bioactive compounds using bioactivity-guided isolation strategies, and the possible mechanism of action as well as potential synergistic or antagonistic effects of multi-component mixtures derived from Gastrodia elata Blume need to be evaluated. It is also necessary and important to do more quality control and toxicological study on human subjects in order to maintain its efficacy stable in the body and validate its safety in clinical uses. In addition, more investigations on other parts of this plant beyond the tubers are needed. Further studies on Gastrodia elata Blume will lead to the development of new drugs and therapeutics for various diseases, and how to utilize it better should be paid more attention to.

Anti-depressant effects of Gastrodia elata Blume and its compounds gastrodin and 4-hydroxybenzyl alcohol, via the monoaminergic system and neuronal cytoskeletal remodeling

ETHNOPHARMACOLOGY RELEVANCE

Gastrodia elata Blume is a highly valuable traditional Chinese medicine used in the treatment of depression. However, compounds with antidepressant effects in water extracts of G. elata Bl. (WGE) have not been identified. The aims of this study were to determine the major antidepressant compound in WGE and to evaluate the antidepressant effects of WGE and its active compounds which involved the monoaminergic system and neuronal cytoskeletal remodeling.

MATERIALS AND METHODS

Gastrodin (GAS) and 4-hydroxybenzyl alcohol (HBA) in WGE, were analyzed with high-performance liquid chromatography (HPLC)-ultraviolet detection. The forced swimming test (FST) was used to induce depression-like symptoms in 9 weeks old male Sprague-Dawley rats. The open field test (OFT) was used to measure anxiety after WGE, GAS, and HBA treatments. The levels of monoamine such as serotonin (5-HT), dopamine (DA), and their metabolites 5-hydroxyindoleacetic acid (5-HIAA), 3,4-dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA) were measured using HPLC-electrochemical detection. Western blotting was used to examine the 5-HT1A receptor and the neuronal cytoskeleton remodeling-related proteins, Slit, dihydropyrimidinase-related protein 2 (DPYSL2, also called CRMP2), Ras homologous member A (RhoA), and profilin 1 (PFN1) in vivo. Slit1 expression was evaluated in Hs683 cell line after treated with WGE (0.5mg/mL), GAS (50, 100 and 100μM), and HBA (50, 100 and 100μM).

RESULTS

Oral administration of WGE (500mg/kg bw), GAS (100mg/kg bw), and HBA (100mg/kg bw) exhibited the anti-depressant effect by significantly reducing the immobility time in FST, monoamine metabolism including the 5-HT to 5-HIAA in the hippocampus and DA to DOPAC and HVA ratios in the frontal cortex, amygdala, and hippocampus. In the hippocampus, the expression of the neuronal cytoskeleton remodeling-related negative regulators Slit1 and RhoA were significantly down-regulated. In addition, the positive regulators CRMP2 and PFN1 were significantly up-regulated following GAS, HBA, and WGE treatments. Moreover, WGE, GAS, and HBA were directly down-regulated Slit1 expression in Hs683 cells.

CONCLUSION

WGE, GAS, and HBA exhibited potential anti-depressant effects in rats by decreasing monoamine metabolism and modulated cytoskeleton remodeling-related protein expression in the Slit-Robo pathway. These results suggest that WGE can be used as agent for depressive prevention.

An Analysis of the Combination Frequencies of Constituent Medicinal Herbs in Prescriptions for the Treatment of Stroke in Korean Medicine: Determination of a Group of Candidate Prescriptions for Universal Use

In contrast to Western medicine, which typically prescribes one medicine to treat a specific disease, traditional East Asian medicine uses any one of a large number of different prescriptions (mixtures of medicinal herbs), according to the patient's characteristics. Although this can be considered an advantage, the lack of a universal prescription for a specific disease is considered a drawback of traditional East Asian medicine. The establishment of universally applicable prescriptions for specific diseases is therefore required. As a basic first step in this process, this study aimed to select prescriptions used in the treatment of stroke and, through the analysis of medicinal herb combination frequencies, select a high-frequency medicinal herb combination group for further experimental and clinical research. As a result, we selected some candidates of a medicinal herb combination and 13 candidates of a medicinal herb for the treatment of stroke.

Cell-Permeable Peptide Targeting the Nrf2-Keap1 Interaction: A Potential Novel Therapy for Global Cerebral Ischemia

The current study examined efficacy of a small Tat (trans-activator of transcription)-conjugated peptide activator of the Nrf2 (nuclear factor-E2-related factor-2) antioxidant/cell-defense pathway as a potential injury-specific, novel neuroprotectant against global cerebral ischemia (GCI). A competitive peptide, DEETGE-CAL-Tat, was designed to facilitate Nrf2 activation by disrupting interaction of Nrf2 with Keap1 (kelch-like ECH-associated protein 1), a protein that sequesters Nrf2 in the cytoplasm and thereby inactivates it. The DEETGE-CAL-Tat peptide contained the critical sequence DEETGE for the Nrf2-Keap1 interaction, the cell transduction domain of the HIV-Tat protein, and the cleavage sequence of calpain, which is sensitive to Ca(2+) increase and allows injury-specific activation of Nrf2. Using an animal model of GCI, we demonstrated that pretreatment with the DEETGE-CAL-Tat peptide markedly decreased Nrf2 interaction with Keap1 in the rat hippocampal CA1 region after GCI, and enhanced Nrf2 nuclear translocation and DNA binding. The DEETGE-CAL-Tat peptide also induced Nrf2 antioxidant/cytoprotective target genes, reduced oxidative stress, and induced strong neuroprotection and marked preservation of hippocampal-dependent cognitive function after GCI. These effects were specific as control peptides lacked neuroprotective ability. Intriguingly, the DEETGE-CAL-Tat peptide effects were also injury specific, as it had no effect upon neuronal survival or cognitive performance in sham nonischemic animals. Of significant interest, peripheral, postischemia administration of the DEETGE-CAL-Tat peptide from days 1-9 after GCI also induced robust neuroprotection and strongly preserved hippocampal-dependent cognitive function. Based on its robust neuroprotective and cognitive-preserving effects, and its unique injury-specific activation properties, the DEETGE-CAL-Tat peptide represents a novel, and potentially promising new therapeutic modality for the treatment of GCI.

SIGNIFICANCE STATEMENT

The current study demonstrates that DEETGE-CAL-Tat, a novel peptide activator of a key antioxidant gene transcription pathway in the hippocampus after global cerebral ischemia, can exert robust neuroprotection and preservation of cognitive function. A unique feature of the peptide is that its beneficial effects are injury specific. This feature is attractive as it targets drug activation specifically in the site of injury, and likely would lead to a reduction of undesirable side effects if translatable to the clinic. Due to its injury-specific activation, robust neuroprotection, and cognitive-preserving effects, this novel peptide may represent a much-needed therapeutic advance that could have efficacy in the treatment of global cerebral ischemia.

MicroRNAs: a novel promising therapeutic target for cerebral ischemia/reperfusion injury?

To determine the molecular mechanism of cerebral ischemia/reperfusion injury, we examined the microRNA (miRNA) expression profile in rat cortex after focal cerebral ischemia/reperfusion injury using miRNA microarrays and bioinformatic tools to systematically analyze Gene Ontology (GO) function classifications, as well as the signaling pathways of genes targeted by these differentially expressed miRNAs. Our results show significantly changed miRNA expression profiles in the reperfusion period after focal cerebral ischemia, with a total of 15 miRNAs up-regulated and 44 miRNAs down-regulated. Target genes of these differentially expressed miRNAs were mainly involved in metabolic and cellular processes, which were identified as hub nodes of a miRNA-GO-network. The most correlated pathways included D-glutamine and D-glutamate metabolism, the renin-angiotensin system, peroxisomes, the PPAR signaling pathway, SNARE interactions in vesicular transport, and the calcium signaling pathway. Our study suggests that miRNAs play an important role in the pathological process of cerebral ischemia/reperfusion injury. Understanding miRNA expression and function may shed light on the molecular mechanism of cerebral ischemia/reperfusion injury.

CDK5 knockdown in astrocytes provide neuroprotection as a trophic source via Rac1

Astrocytes perform metabolic and structural support functions in the brain and contribute to the integrity of the blood-brain barrier. Astrocytes influence neuronal survival and prevent gliotoxicity by capturing glutamate (Glu), reactive oxygen species, and nutrients. During these processes, astrocytic morphological changes are supported by actin cytoskeleton remodeling and require the involvement of Rho GTPases, such as Rac1. The protein cyclin-dependent kinase 5 (CDK5) may have a dual effect on astrocytes because it has been shown to be involved in migration, senescence, and the dysfunction of glutamate recapture; however, its role in astrocytes remains unclear. Treating a possible deregulation of CDK5 with RNAi is a strategy that has been proposed as a therapy for neurodegenerative diseases. Models of glutamate gliotoxicity in the C6 astroglioma cell line, primary cultures of astrocytes, and co-cultures with neurons were used to analyze the effects of CDK5 RNAi in astrocytes and the role of Rac1 in neuronal viability. In C6 cells and primary astrocytes, CDK5 RNAi prevented the cell death generated by glutamate-induced gliotoxicity, and this finding was corroborated by pharmacological inhibition with roscovitine. This effect was associated with the appearance of lamellipodia, protrusions, increased cell area, stellation, Rac1 activation, BDNF release, and astrocytic protection in neurons that were exposed to glutamate excitotoxicity. Interestingly, Rac1 inhibition in astrocytes blocked BDNF upregulation and the astrocyte-mediated neuroprotection. Actin cytoskeleton remodeling and stellation may be a functional phenotype for BDNF release that promotes neuroprotection. In summary, our findings suggest that CDK5- knockdown in astrocytes acts as a trophic source for neuronal protection in a Rac1-dependent manner.

4-Hydroxybenzyl-substituted amino acid derivatives from Gastrodia elata

Seven new 4-hydroxybenzyl-substituted amino acid derivatives (1−7), together with 11 known compounds, were isolated from an aqueous extract of the rhizomes of Gastrodia elata Blume. Their structures were determined by spectroscopic and chemical methods. Compounds 1−3 are pyroglutamate derivatives containing 4-hydroxybenzyl units at the N atom and 4−7 are the first examples of natural products with the 4-hydroxybenzyl unit linked via a thioether bond to 2-hydroxy-3-mercaptopropanoic acid (4−6) and 2-hydroxy-4-mercaptobutanoic acid (7), which would be biogenetically derived from cysteine and homocysteine, respectively. The structures of 1 and 2 were verified by synthesis, while the absolute configurations of 4, 5 and 7 were assigned using Mosher’s method based on the MPA determination rule of Δδ_RS values. The known compound 4-(hydroxymethyl)-5-nitrobenzene-1,2-diol (8) exhibited activity against Fe²⁺-cysteine induced rat liver microsomal lipid peroxidation with IC₅₀ values of 9.99×10⁻⁶ mol/L.

Protein disulfide isomerase as a novel target for cyclopentenone prostaglandins: implications for hypoxic ischemic injury

Cyclooxygenase-2 (COX-2) is an important contributor to ischemic brain injury. Identification of the downstream mediators of COX-2 toxicity may allow the development of targeted therapies. Of particular interest is the cyclopentenone family of prostaglandin metabolites. Cyclopentenone prostaglandins (CyPGs) are highly reactive molecules that form covalent bonds with cellular thiols. Protein disulfide isomerase (PDI) is an important molecule for the restoration of denatured proteins following ischemia. Because PDI has several thiols, including thiols within the active thioredoxin-like domain, we hypothesized that PDI is a target of CyPGs and that CyPG binding of PDI is detrimental. CyPG-PDI binding was detected in vitro via immunoprecipitation and MS. CyPG-PDI binding decreased PDI enzymatic activity in recombinant PDI treated with CyPG, and PDI immunoprecipitated from neuronal culture treated with CyPG or anoxia. Toxic effects of binding were demonstrated in experiments showing that: (a) pharmacologic inhibition of PDI increased cell death in anoxic neurons, (b) PDI overexpression protected neurons exposed to anoxia and SH-SY5Y cells exposed to CyPG, and (c) PDI overexpression in SH-SY5Y cells attenuated ubiquitination of proteins and decreased activation of pro-apoptotic caspases. In conclusion, CyPG production and subsequent binding of PDI is a novel and potentially important mechanism of ischemic brain injury. We show that CyPGs bind to PDI, cyclopentenones inhibit PDI activity, and CyPG-PDI binding is associated with increased neuronal susceptibility to anoxia. Additional studies are necessary to determine the relative role of CyPG-dependent inhibition of PDI activity in ischemia and other neurodegenerative disorders.

p-Hydroxybenzyl alcohol-containing biodegradable nanoparticle improves functional blood flow through angiogenesis in a mouse model of hindlimb ischemia

Therapeutic angiogenesis has achieved promising results for ischemic diseases or peripheral artery disease in preclinical and early-phase clinical studies. We examined the therapeutic angiogenic effects of HPOX, which is biodegradable polymer composing the antioxidant p-hydroxybenzyl alcohol (HBA), in a mouse model of hindlimb ischemia. HPOX effectively stimulated blood flow recovery, compared with its degraded compounds HBA and 1,4-cyclohexendimethanol, via promotion of capillary vessel density in the ischemic hindlimb. These effects were highly correlated with levels of angiogenic inducers, vascular endothelial cell growth factor (VEGF), heme oxygenase-1 (HO-1), and Akt/AMPK/endothelial nitric oxide synthase (eNOS) in ischemic mouse hindlimb muscle. Blood perfusion and neovascularization induced by HPOX were reduced in eNOS(-/-) and HO-1(+/-) mice. HPOX also elevated the endothelial cell markers VEGF receptor-2, CD31, and eNOS mRNAs in the ischemic hindlimb, indicating that HPOX increases endothelial cell population and angiogenesis in the ischemic muscle. However, this nanoparticle suppressed expression levels of several inflammatory genes in ischemic tissues. These results suggest that HPOX significantly promotes angiogenesis and blood flow perfusion in the ischemic mouse hindlimb via increased angiogenic inducers, along with suppression of inflammatory gene expression. Thus, HPOX can be used potentially as a noninvasive drug intervention to facilitate therapeutic angiogenesis.

Lipoxin A4 Activates Nrf2 Pathway and Ameliorates Cell Damage in Cultured Cortical Astrocytes Exposed to Oxygen-Glucose Deprivation/Reperfusion Insults

Lipoxin A4 (LXA4), a potent antioxidant and anti-inflammation mediator, protects brains against cerebral ischemia/reperfusion (I/R) injury in vivo. However, few reports concern its function on astrocytes during cerebral I/R injury. The pathogenesis of cerebral I/R injury involves oxidative stress caused by reactive oxygen species (ROS). Upregulation of nuclear factor erythroid 2-related factor 2 (Nrf2) is generally considered to reduce oxidative stress. Nrf2 can induce heme oxygenase-1 (HO-1) expression and glutathione (GSH) release to combat increased oxidative stress. We investigated the effects of LXA4 on astrocytic cell damage, the production of ROS, and Nrf2 pathway, especially on HO-1 expression and GSH release in cultured cortical astrocytes exposed to oxygen-glucose deprivation (OGD)/recovery (OGDR) insults. Primary astrocytes were subjected to a 4-h OGD, followed by 8-h recovery. Cell viability, the production of ROS, and GSH release were measured. Furthermore, Nrf2, HO-1, and p62 expression levels were determined by Western blot. Moreover, Nrf2 location was studied by immunofluorescence staining. Treatment of LXA4 attenuates OGDR-induced cell damage and the production of ROS in a concentration-related manner. LXA4 induced Nrf2 expression and its nuclear translocation, as well as HO-1 expression and GSH release. Moreover, LXA4 induced the excess p62 accumulation. These results indicate that LXA4 can effectively protect against OGDR-induced cell damage in astrocytes, and activation of Nrf2 pathway to reduce oxidative stress may be involved in its protective effects. p62 accumulation induced by LXA4 may be closely related to Nrf2 activation.

Effect of hirulog-like peptide on middle cerebral artery occlusion-induced brain injury in mice

Hirulog-like peptide (HLP) and low-molecular-weight heparin (LMWH) are thrombin inhibitor peptides. Our previous study demonstrated that HLP could reduce vascular neointimal formation or restenosis in animals undergoing balloon catheter injury in the carotid artery. However, the function of HLP during ischemic stroke is largely unknown. The present study investigated the effect of HLP on brain injury, which was induced by suture of middle cerebral artery occlusion in mice. Mice were divided into four groups, which included a sham group and three treatment groups. Ischemia was induced by transient suture insertion into the middle cerebral artery for 90 min, and mice were either treated with saline, HLP or LMWH. Infarct volume, neurologic deficits and apoptotic factors were measured following 1-14 days of ischemia. We demonstrated that HLP intravenous injection alleviated brain infarct volume and improved neurologic outcomes (p<0.05). HLP decreased levels of protease-activated receptor-1 (PAR-1), caspase-3, malondialdehyde (MDA) and Bcl-2-associated X protein (Bax), increased the activities of catalase and B cell lymphoma-2 (Bcl-2), and improved the ratio of Bcl-2/Bax compared with the control (p<0.05). This study indicates that HLP and LMWH reduced infarct volume and improved neurobehavioral outcomes induced by transient middle cerebral artery occlusion (tMCAO). In addition, HLP had a beneficial effect on the regulation of the thrombin receptor and key apoptosis regulators in the mouse brain. These results suggest that HLP may be a potential alternative therapy for arterial occlusion-induced cerebral ischemia.

Gastrodiae Rhizoma (tiān má): a review of biological activity and antidepressant mechanisms

Gastrodiae Rhizoma, also called chì jiàn (赤箭), guǐ dū yóu (鬼督郵), or tiān má (天麻) in Chinese, is considered a top grade (上品 shàng pǐn) medicine described to enter liver channel (肝經 gān jīng) in classic literatures of traditional Chinese medicine and has been used for centuries. Many studies investigating its various bioactivities and active compounds have been conducted worldwide. This article reviews these biological activities and details the antidepressant pharmacology of Gastrodiae Rhizoma. Gastrodiae Rhizoma treatment exerts an effective inhibition of diverse diseases and disorders, including convulsion, oxidative stress, mental disorders, amnesia, cardio-cerebral-vascular diseases, and inflammation, among others. The antidepressant effect of Gastrodiae Rhizoma was evaluated in animal models and several mechanisms of activity were found, including the modulation and regulation of monoamine oxidase activity, monoamine concentration and turnover, antioxidatant activity, GABAergic system induction, BDNF induction, neuroprotection and anti-inflammatory activity.

Potential therapeutic effects of neurotrophins for acute and chronic neurological diseases

The neurotrophins (NTs) nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), NT-3, and NT-4/5 are proteins that regulate cell proliferation, differentiation, and survival in both the developing and mature central nervous system (CNS) by binding to two receptor classes, Trk receptors and p75 NTR. Motivated by the broad growth- and survival-promoting effects of these proteins, numerous studies have attempted to use exogenous NTs to prevent the death of cells that are associated with neurological disease or promote the regeneration of severed axons caused by mechanical injury. Indeed, such neurotrophic effects have been repeatedly demonstrated in animal models of stroke, nerve injury, and neurodegenerative disease. However, limitations, including the short biological half-lives and poor blood-brain permeability of these proteins, prevent routine application from treating human disease. In this report, we reviewed evidence for the neuroprotective efficacy of NTs in animal models, highlighting outstanding technical challenges and discussing more recent attempts to harness the neuroprotective capacity of endogenous NTs using small molecule inducers and cell transplantation.

Pharmacological effects of active compounds on neurodegenerative disease with gastrodia and uncaria decoction, a commonly used poststroke decoction

Neurodegenerative diseases refer to the selective loss of neuronal systems in patients. The diseases cause high morbidity and mortality to approximately 22 million people worldwide and the number is expected to be tripled by 2050. Up to now, there is no effective prevention and treatment for the neurodegenerative diseases. Although some of the clinical therapies target at slowing down the progression of symptoms of the diseases, the general effectiveness of the drugs has been far from satisfactory. Traditional Chinese medicine becomes popular alternative remedies as it has been practiced clinically for more than thousands of years in China. As neurodegenerative diseases are mediated through different pathways, herbal decoction with multiple herbs is used as an effective therapeutic approach to work on multiple targets. Gastrodia and Uncaria Decoction, a popular TCM decoction, has been used to treat stroke in China. The decoction contains compounds including alkaloids, flavonoids, iridoids, carotenoids, and natural phenols, which have been found to possess anti-inflammatory, antioxidative, and antiapoptotic effects. In this review, we will summarize the recent publications of the pharmacological effects of these five groups of compounds. Understanding the mechanisms of action of these compounds may provide new treatment opportunities for the patients with neurodegenerative diseases.

Lipoxin A4 ameliorates cerebral ischaemia/reperfusion injury through upregulation of nuclear factor erythroid 2-related factor 2

OBJECTIVES

Lipoxin A4 (LXA4) is a potent anti-inflammatory mediator that exerts a neuroprotective effect following cerebral ischaemia/reperfusion (I/R) injury. However, little is known about the underlying mechanisms. Upregulation of nuclear factor erythroid 2-related factor 2 (Nrf2) is generally considered to reduce cerebral I/R injury. Nuclear factor erythroid 2-related factor 2 can induce haeme oxygenase-1 (HO-1) and glutathione (GSH) expression to combat increased oxidative stress. The present study aimed to investigate the effects of Nrf2 signalling on LXA4-mediated neuroprotection.

METHODS

Adult male Sprague Dawley rats were subjected to 2-hour middle cerebral artery occlusion followed by 24-hour reperfusion. Rats were randomly divided into four groups: Sham, I/R, LXA4, and LXA4+butoxycarbonyl-Phe-Leu-Phe-Leu-Phe (Boc2) (all n = 24). Brain infarction was detected by 2,3,5-triphenyltetrazolium chloride staining. After 24 hours of reperfusion, Nrf2, HO-1, and p62 expression levels were determined by western blot, and GSH synthesis was assessed.

RESULTS

Lipoxin A4 effectively reduced infarct volumes and improved neurological scores. These effects were partially blocked by Boc2, a specific antagonist of the LXA4 receptor (ALXR). Lipoxin A4 induced Nrf2 expression and its nuclear translocation, as well as HO-1 expression and GSH synthesis; Boc2 did not block these effects. The excess p62 accumulation induced by LXA4 might be closely related to Nrf2 activation.

DISCUSSION

Overall, our data suggest that Nrf2 upregulation is involved in the neuroprotective effects of LXA4 and may be ALXR independent.