4-Hydroxybenzyl Alcohol Confers Neuroprotection Through Up-Regulation of Antioxidant Protein Expression

Unveiling the Significance of Peroxiredoxin 6 in Central Nervous System Disorders

Peroxiredoxin 6 (Prdx6), a unique 1-Cys member of the peroxiredoxin family, exhibits peroxidase activity, phospholipase activity, and lysophosphatidylcholine acyltransferase (LPCAT) activity. Prdx6 has been known to be an important enzyme for the maintenance of lipid peroxidation repair, cellular metabolism, inflammatory signaling, and antioxidant damage. Growing research has demonstrated that the altered activity of this enzyme is linked with various pathological processes including central nervous system (CNS) disorders. This review discusses the distinctive structure, enzyme activity, and function of Prdx6 in different CNS disorders, as well as emphasizing the significance of Prdx6 in neurological disorders.

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.

The gut metabolite 3-hydroxyphenylacetic acid rejuvenates spermatogenic dysfunction in aged mice through GPX4-mediated ferroptosis

BACKGROUND

Aging-related fertility decline is a prevalent concern globally. Male reproductive system aging is mainly characterized by a decrease in sperm quality and fertility. While it is known that intestinal physiology changes with age and that microbiota is shaped by physiology, the underlying mechanism of how the microbiota affects male reproductive aging is still largely unexplored.

RESULTS

Here, we utilized fecal microbiota transplantation (FMT) to exchange the fecal microbiota between young and old mice. Cecal shotgun metagenomics and metabolomics were used to identify differences in gut microbiota composition and metabolic regulation during aging. Our results demonstrated that FMT from young to old mice alleviated aging-associated spermatogenic dysfunction through an unexpected mechanism mediated by a gut bacteria-derived metabolite, 3-hydroxyphenylacetic acid (3-HPAA). 3-HPAA treatment resulted in an improvement of spermatogenesis in old mice. RNA sequencing analysis, qRT-PCR and Western blot revealed that 3-HPAA induced an upregulation of GPX4, thereby restraining ferroptosis and restoring spermatogenesis. These findings were further confirmed by in vitro induction of ferroptosis and inhibition of GPX4 expression.

CONCLUSIONS

Our results demonstrate that the microbiome-derived metabolite, 3-HPAA, facilitates spermatogenesis of old mice through a ferroptosis-mediated mechanism. Overall, these findings provide a novel mechanism of dysregulated spermatogenesis of old mice, and suggest that 3-HPAA could be a potential therapy for fertility decline of aging males in clinical practice. Video Abstract.

Identification of Novel Parishin Compounds from the Twig of Maclura tricuspidata and Comparative Analysis of Parishin Derivatives in Different Parts

Parishin compounds are rare polyphenolic glucosides mainly found in the rhizome of the traditional Chinese medicinal plant, Gastrodia elata. These constituents are reported to have several biological and pharmacological activities. In the present study, two novel parishin derivatives not previously reported as plant-based phytochemicals were identified from a twig of Maclura tricuspidata (MT) and two new compounds were elucidated as 1-(4-(β-d-glucopyranosyloxy)benzyl)-3-hydroxy-3-methylpentane-1,5-dioate (named macluraparishin E) and 1,3-bis(4-(β-d-glucopyranosyloxy)benzyl)-3-hydroxy-3-methylpentane- 1,5-dioate (macluraparishin C), based on the experimental data obtained by UV-Visible (UV-Vis) spectroscopy, high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (HPLC-QTOF-MS) and nuclear magnetic resonance (NMR) spectroscopy. Additionally, gastrodin, parishin A and parishin B were positively identified by spectroscopic evidence and the comparison of HPLC retention time with the corresponding authentic standards. Gastrodin, parishin A and parishin B, macluraparishin E and macluraparishin C were found to be the most abundant constituents in the MT twig. The compositions and contents of these constituents were found to vary depending on the different parts of the MT plant. In particular, the contents of parishin A, parishin B, macluraparishin C and macluraparishin E were higher in the twig, bark and root than in the leaves, xylem and fruit.

p-Hydroxybenzyl Alcohol Antagonized the ROS-Dependent JNK/Jun/Caspase-3 Pathway to Produce Neuroprotection in a Cellular Model of Parkinson's Disease

Parkinson's disease (PD) is a progressive disorder that affects brain nerve cells responsible for body motion and remains incurable. p-Hydroxybenzyl alcohol (HBA) is the primary phenolic compound in Gastrodiae Rhizoma, known for its therapeutic benefits against neurodegeneration. However, the protective effect of HBA against Parkinson's disease (PD) remains unclear. The objective of this study was to evaluate the neuroprotective effects of HBA in vitro 6-hydroxydopamine (6-OHDA)-induced PD model in SH-SY5Y cells. SH-SY5Y cells were pretreated with various concentrations of HBA for 1 h and incubated with 100 μmol/L 6-OHDA for 24 h to induce cellular lesions. 2,5-Diphenyl-2H-tetrazolium bromide was used to detect cellular viability. 2',7'-dichlorofluorescin oxidation detects reactive oxygen species (ROS). The enzyme-linked immunosorbent assay was used to determine the activities of superoxide dismutase, catalase, and glutathione peroxidase. The cellular mitochondrial function was identified through the collapse of the mitochondrial membrane potential, the release of cytochrome c, and the synthesis of mitochondrial ATP. Expression of pro-and anti-apoptotic factors was measured by Western blot. HBA enhanced cell viability, blocked ROS overproduction, and reduced antioxidant activities induced by 6-OHDA. HBA also reduced mitochondrial dysfunction and cell death caused by 6-OHDA. Moreover, HBA reversed the 6-OHDA-mediated activation of c-Jun N-terminal kinase, the downregulation of the Bcl-2/Bax ratio, the Apaf-1 upregulation and the induction of caspase-9, caspase-3, and PARP cleavage. This study shows that the protective effects of HBA against 6-OHDA-induced cell injury provide the potential preventive effects of HBA, making it a promising preventive agent for PD.

Gut microbiome mediates the protective effects of exercise after myocardial infarction

BACKGROUND

Gut microbiota plays important roles in health maintenance and diseases. Physical exercise has been demonstrated to be able to modulate gut microbiota. However, the potential role of gut microbiome in exercise protection to myocardial infarction (MI) remains unclear.

RESULTS

Here, we discovered exercise training ameliorated cardiac dysfunction and changed gut microbial richness and community structure post-MI. Moreover, gut microbiota pre-depletion abolished the protective effects of exercise training in MI mice. Furthermore, mice receiving microbiota transplants from exercised MI mice had better cardiac function compared to mice receiving microbiota transplants from non-exercised MI mice. Mechanistically, we analyzed metabolomics in fecal samples from exercised mice post-MI and identified 3-Hydroxyphenylacetic acid (3-HPA) and 4-Hydroxybenzoic acid (4-HBA), which could be applied individually to protect cardiac dysfunction post-MI and apoptosis through NRF2.

CONCLUSIONS

Together, our study provides new insights into the role of gut microbiome in exercise protection to MI, offers opportunities to modulate cardiovascular diseases by exercise, microbiome and gut microbiota-derived 3-HPA and 4-HBA. Video Abstract.

Characterization by HPLC of p-Hydroxybenzyl Alcohol Biotransformation to Gastrodin In Vivo

Gastrodin (GAS) and its aglycone, p-hydroxybenzyl alcohol (HBA), are both bioactive compounds extracted from Gastrodia elata Blume (GEB). In the current Chinese pharmacopoeia, they are regarded as quality control markers for GEB. In this study, we developed a high-performance liquid chromatography method coupled with a diode array detector to quantify GAS and HBA concentrations in plasma following oral ingestion by rats. For the first time, GAS was detected in vivo after HBA administration. GAS and HBA both had similar pharmacological effects, but the influence of the glucose moiety resulted in different pharmacokinetic characteristics. In this study, the effects of GAS and HBA at different administration durations were investigated in zebrafish larvae. These compounds were found to induce a sedative effect but had different onset times. In conclusion, a biotransformation of HBA to GAS could be observed in the rats. This may be a new insight into the pharmacokinetic characteristics of these bioactive compounds and also relates to the different ways in which they take effect.

The Roles of Peroxiredoxin 6 in Brain Diseases

Peroxiredoxin 6 (PRDX6), the only mammalian 1-Cys member of the peroxiredoxins (PRDXs) family, has multiple functions of glutathione peroxidase (Gpx) activity, acidic calcium-independent phospholipase (aiPLA2) activity, and lysophosphatidylcholine acyl transferase (LPCAT) activity. It has been documented to be involved in redox homeostasis, phospholipid turnover, glycolipid metabolism, and cellular signaling. Here, we reviewed the characteristics of the available Prdx6 genetic mouse models and the research progresses made with regard to PRDX6 in neuropsychiatric disorders, including neurodegenerative diseases, brain aging, stroke, neurotrauma, gliomas, major depressive disorder, drug addiction, post-traumatic stress disorder, and schizophrenia. The present review highlights the important roles of PRDX6 in neuropsychiatric disorders and may provide novel insights for the development of effective pharmacological treatments and genetic therapies.

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.

Dentate Gyrus Peroxiredoxin 6 Levels Discriminate Aged Unimpaired From Impaired Rats in a Spatial Memory Task

Similar to humans, the normal aged rat population is not homogeneous in terms of cognitive function. Two distinct subpopulations of aged Sprague-Dawley rats can be identified on the basis of spatial memory performance in the hole-board paradigm. It was the aim of the study to reveal protein changes relevant to aging and spatial memory performance. Aged impaired (AI) and unimpaired (AU) male rats, 22-24 months old were selected from a large cohort of 160 animals; young animals served as control. Enriched synaptosomal fractions from dentate gyrus from behaviorally characterized old animals were used for isobaric tags labeling based quantitative proteomic analysis. As differences in peroxiredoxin 6 (PRDX6) levels were a pronounced finding, PRDX6 levels were also quantified by immunoblotting. AI showed impaired spatial memory abilities while AU performed comparably to young animals. Our study demonstrates substantial quantitative alteration of proteins involved in energy metabolism, inflammation and synaptic plasticity during aging. Moreover, we identified protein changes specifically coupled to memory performance of aged rats. PRDX6 levels clearly differentiated AI from AU and levels in AU were comparable to those of young animals. In addition, it was observed that stochasticity in protein levels increased with age and discriminate between AI and AU groups. Moreover, there was a significantly higher variability of protein levels in AI. PRDX6 is a member of the PRDX family and well-defined as a cystein-1 PRDX that reduces and detoxifies hydroxyperoxides. It is well-known and documented that the aging brain shows increased active oxygen species but so far no study proposed a potential target with antioxidant activity that would discriminate between impaired and unimpaired memory performers. Current data, representing so far the largest proteomics data set in aging dentate gyrus (DG), provide the first evidence for a probable role of PRDX6 in memory performance.

Sestrin2 overexpression attenuates focal cerebral ischemic injury in rat by increasing Nrf2/HO-1 pathway-mediated angiogenesis

Sestrin2 (Sesn2) is a stress response protein which expresses neuroprotective characteristics in some neurodegenerative disorders. However, the impact of Sesn2 on the clinical outcome of stroke is unclear. The nuclear factor-erythroid 2 related factor 2/heme oxygenase-1 (Nrf2/HO-1) pathway is a key factor in angiogenesis, which aids in attenuating cerebral ischemia damage. In this study the investigators examine the effects of Sesn2 on cerebral ischemia damage by increasing angiogenesis through the Nrf2/HO-1 signaling pathway. Healthy adult Sprague-Dawley (SD) rats were exposed to photochemical cerebral ischemia while AAV injection was used to overexpress Sesn2. At 5 days after photochemical embolization, the investigators observed a reduction in neurological problems, decreased infarct volume, and diminished neuronal injury in the Sesn2 overexpression samples compared to the controls. To further explore these defensive mechanisms, the investigators also silenced Nrf2. While Sesn2, Nrf2, HO-1, and VEGF were significantly increased following cerebral ischemia, overexpression of Sesn2 further increased their expression. After silencing Nrf2, the opposite effect was observed. These results imply that Sestrin2 may activate the Nrf2 / HO-1 pathway, leading to enhanced angiogenesis following photothrombotic cerebral ischemia.

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.

Magnesium sulphate can alleviate oxidative stress and reduce inflammatory cytokines in rat placenta of intrahepatic cholestasis of pregnancy model

PURPOSE

In our study, we try to investigate whether magnesium sulphate (MgSO₄) could provide protection against oxidative damage and inflammatory response in rat placenta of intrahepatic cholestasis of pregnancy (ICP) model.

METHODS

The rat model of ICP was established by injecting s.c. 17α-ethinyl estradiol (EE) daily for 5 days. MgSO₄, as an therapeutic drug for ICP, was injected i.p. daily for 3 days. Age-matched pregnant rats served as controls. The level of serum total bile acid (TBA) was measured. The data including the number and weight of offsprings on day 20 of pregnancy were collected. We observed ultrastructural changes of mitochondria and endoplasmic reticulum (ER) in placenta by transmission electron microscope. The antioxidant proteins peroxiredoxin-6 (Prdx6) and nuclear factor erythroid 2-related factor-2 (Nrf2) were analyzed by Western Blot. The inflammatory cytokines including IL-1β, TNF-α and IFN-γ were investigated by real-time PCR (RT-PCR) and enzyme-linked immune-sorbent assay (ELISA).

RESULTS

The weight of offsprings on day 20 of pregnancy increased in ICP rats treated with MgSO₄ (ICP + MG group) compared with that in ICP rats (ICP group). However, the level of TBA was not reduced. The damage of mitochondria and ER was observed in placenta, which was much more slighter in ICP + MgSO₄ group as compared with that in ICP group. Prdx6 and Nrf2 were increased, while the inflammatory cytokines including IL-1β, TNF-α and IFN-γ were decreased in ICP + MgSO₄ group compared with that in ICP group.

CONCLUSIONS

MgSO₄ had beneficial effect on improving growth of offsprings in rat model of ICP. The protective effect of MgSO₄ on alleviating oxidative damage and inflammatory response in placenta may play an important role in the process. MgSO₄ may improve the function of placenta.

Anti-Zn2+-Toxicity of 4-Hydroxybenzyl Alcohol in Astrocytes and Neurons Contribute to a Robust Neuroprotective Effects in the Postischemic Brain

4-Hydroxybenzyl alcohol (4-HBA) is an important phenolic constituent of Gastrodia elata (GE) Blume, which is used as a traditional herbal medicine in East Asia. Many activities have been reported to underlie the beneficial effects of 4-HBA in brain, such as, anti-oxidative, anti-inflammatory, anti-excitotoxic, and anti-apoptotic effects in neurons and microglia. Here, the authors demonstrate the robust neuroprotective effects of 4-HBA in rat middle cerebral artery occlusion (MCAO) model of stroke, and showed anti-Zn²⁺ toxicity in neurons and astrocytes as a molecular mechanism contributing to these effects. Intraperitoneal administration of 4-HBA (20 mg/kg) in Sprague-Dawley rats 1 h after MCAO reduced infarct volumes to 27.1 ± 9.2% of that of MCAO controls and significantly ameliorated motor impairments and neurological deficits. Significant suppressions of Zn²⁺-induced cell death, ROS generation, and PARP-1 induction by 4-HBA were observed in primary cortical cultures. 4-HBA also protected astrocytes from Zn²⁺-induced toxicity and suppressing ROS generation by employing slightly different molecular mechanisms, i.e., suppressing PARP-1 induction and NAD depletion under acute Zn²⁺-treatment and suppressing p67 NADPH oxidase subunit induction under chronic Zn²⁺-treatment. Results indicate that the protective effects of 4-HBA against Zn²⁺-toxicity in neurons and astrocytes contribute to its robust neuroprotective effects in the postischemic brain. Considering the pleiotropic effects of 4-HBA, which have been reported in previous reports and added in the present study, it has therapeutic potential for the amelioration of ischemic brain damage.

Neuroprotective effects of sulfiredoxin-1 during cerebral ischemia/reperfusion oxidative stress injury in rats

As an endogenous antioxidant protein, Sulfiredoxin1 (Srxn1) can prevent cell oxidative stress damage. However, its role in cerebral ischemia/reperfusion (I/R) injury and the underlying signaling mechanisms remain largely unknown. Here, we explored effects of Srxn1 knockdown on oxidative stress using in vitro and in vivo I/R models and investigated related neuroprotective mechanisms. For in vitro studies, primary cortical neuronal cultures were transfected with an interfering lentivirus targeting Srxn1. Oxygen-glucose deprivation (OGD) was conducted after Srxn1 knockdown. MTS and lactate dehydrogenase assays indicated that knockdown of Srxn1 increased cell death and reduced cell viability. Similarly, superoxide dismutase (SOD) and reduced glutathionekits assays showed that knockdown of Srxn1 worsened oxidative stress injury. For in vivo studies, siRNA for Srxn1 or negative control siRNA was injected intracerebroventricularly 24h before middle cerebral artery occlusion (MCAO). Data shows silencing Srxn1 resulted in a significant increase in cerebral infarction, neurological deficits, histological injury, and oxidative stress injury 24h after ischemic stroke. Moreover, immunoblot analysis assessed the relationship between Srxn1 levels and Prdx1-4 as well as Prdx-SO3 activity both in vitro and in vivo models. We found that decreased Srxn1 reduced Prdx1-4 and enhanced Prdx-SO3 protein levels. In addition, knockdown of Nrf2 was performed; immunoblot analysis was used to measure Srxn1 and NQO1 protein levels. We further found that interference of Nrf2 reduced Srxn1 and NQO1 protein levels. In summary, Srxn1 can protect neurons from I/R oxidative stress injury and the mechanism involves Prdx activity. Srxn1, which might be downstream of Nrf2, can prevent cerebral ischemia reperfusion by reversing overoxidized Prdx and restoring antioxidant activity of Prdx.

Prdx6 Upregulation by Curcumin Attenuates Ischemic Oxidative Damage via SP1 in Rats after Stroke

Background

The role of Peroxiredoxin 6 (Prdx6) in brain ischemia remains unclear. Curcumin (Cur) treatment elicits neuroprotective effects against cerebral ischemic injury, and the associated mechanisms may involve Prdx6. In this study, we investigated whether Prdx6 and the transcription factor specific protein 1 (SP1) were involved in the antioxidant effect of Cur after stoke.

Methods

Focal cerebral ischemic injury was induced by transient middle cerebral artery occlusion for 2 hours in male Sprague-Dawley rats treated with or without Prdx6 siRNA. Expression of Prdx6 in the penumbra was assessed by Real-Time PCR (RT-PCR), Western blot analysis, and immunoflourescent staining. In addition, infarct volume, neurological deficit score, and oxidative stress were evaluated. Prdx6 levels were also determined in the presence and absence of SP1 antagonist mithramycin A (MTM-A).

Results

Cur treatment upregulated Prdx6 protein expression and the number of Prdx6-positive neuronal cells 24 hours after reperfusion. Cur treatment also attenuated oxidative stress and induced neuroprotective effects against ischemic damage, whereas the beneficial effects of Cur treatment were lost in animals treated with Prdx6-siRNA. Prdx6 upregulation by Cur treatment was abolished by SP1 antagonists MTM.

Conclusions

Prdx6 upregulation by Cur treatment attenuates ischemic oxidative damage through SP1 induction in rats after stroke. This represents a novel mechanism of Cur-induced neuroprotection against cerebral ischemia.

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.

The aqueous extract of rhizome of Gastrodia elata Blume attenuates locomotor defect and inflammation after traumatic brain injury in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Traumatic brain injury (TBI) has an incident rate of 200-300 people per 100,000 annually in the developed countries. TBI has relatively high incidence at an early age and may cause long-term physical disability. Patients suffered from severe TBI would have motor and neuropsychological malfunctions, affecting their daily activities. Traditionally, Gastrodia elata Blume is a Chinese Medicines which was used for the head diseases, while their efficiency on reducing brain damage was still largely unknown. In the present study, we aimed to examine the effect of water extract of G. elata Blume (GE) against TBI and elucidate its underlying mechanism.

MATERIALS AND METHODS

Sprague-Dawley rats were treated with GE for 7 days, immediately after controlled cortical impact-induced TBI. Impaired neurobehavioral functioning was measured on day 3 and 6 after TBI. Histology of TBI was examined to assess the extent of inflammation, and the expressions of pro-inflammatory cytokines were examined by immunofluorescence study on day 7.

RESULTS

GE treatment significantly improved the impaired locomotor functions induced by TBI. GE treatment reduced inflammation and gliosis in the penumbral area. The increase in brain levels of pro-inflammatory cytokines interleukin-6 and tumor necrosis factor-alpha observed in non-GE treated TBI rats were also reversed.

CONCLUSIONS

GE treatment attenuated the locomotor deficit caused by TBI. The anti-inflammatory activity might be mediated by inhibition of pro-inflammatory cytokines responses in the TBI-brain.

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.

Sulfiredoxin-1 protects primary cultured astrocytes from ischemia-induced damage

Astrocytes appear to be important regulators of the inflammatory events that occur in stroke. Sulfiredoxin-1 (Srxn1), an endogenous antioxidant protein, exhibits neuroprotective effects. Although the mechanism by which Srxn1 negatively regulates oxidative and apoptotic pathways has been extensively characterized, the impact of Srxn1 on inflammation has not been well studied. In this study, we used oxygen-glucose deprivation followed by recovery (OGD/R) and hydrogen peroxide (H2O2) to mimic stress from cerebral ischemic damage on primary cultured astrocytes. We found that knockdown of Srxn1 by two shRNAs resulted in decreased cell viability of astrocytes. Decreased level of Srxn1 also correlated with excessive levels of proinflammatory cytokines and chemokines such as TNF-α, MPO, IL-1β, and IL-6. In addition, Srxn1 appeared to influence the strength of TLR4 signaling pathway; the expression of COX-2, IL-6, and NOS2 were strongly induced by OGD/R and H2O2 in astrocyte cultures with Srxn1-shRNAs. Our results suggested that loss of Srxn1 expression in astrocytes may cause excessive activation of inflammatory responses which contribute to OGD/R- and H2O2-induced cell death. Restoring Srxn1 function by gene therapy and/or pharmacology emerges as a promising strategy for the treatment of stroke and other chronic neurodegenerative diseases.

Recovery of brain biomarkers following peroxisome proliferator-activated receptor agonist neuroprotective treatment before ischemic stroke

Background

Lipid lowering agent such as agonists of peroxisome proliferator-activated receptors (PPAR) are suggested as neuroprotective agents and may protect from the sequelae of brain ischemic stroke. Although the demonstration is not clearly established in human, the underlying molecular mechanism may be of interest for future therapeutic purposes. To this end, we have used our well established rodent model of ischemia-reperfusion pre-treated or not with fenofibrate or atorvastatin and performed a differential proteomics analyses of the brain and analysed the protein markers which levels returned to “normal” following pre-treatments with PPARα agonists.

Results

In order to identify potential therapeutic targets positively modulated by pre-treatment with the PPARα agonists, two-dimensional gel electrophoresis proteome profiles between control, ischemia-reperfusion and pre-treated or not, were compared. The polypeptide which expression was altered following ischemia – reperfusion but whose levels remain unchanged after pre-treatment were characterized by mass spectrometry and further investigated by Western-blotting and immunohistochemistry. A series of 28 polypeptides were characterized among which the protein disulfide isomerase reduction – a protein instrumental to the unfolded protein response system - was shown to be reduced following PPARα agonists treatment while it was strongly increased in ischemia-reperfusion.

Conclusions

Pre-treatment with PPARα agonist or atorvastatin show potential neuroprotective effects by inhibiting the PDI overexpression in conjunction with the preservation of other neuronal markers, several of which are associated with the regulation of protein homeostasis, signal transduction and maintenance of synaptic plasticity. This proteomic study therefore suggests that neuroprotective effect of PPARα agonists supposes the preservation of the expression of several proteins essential for the maintenance of protein homeostasis not necessarily directly linked to PPARα known-regulated targets.