Glycine attenuates cerebral ischemia/reperfusion injury by inhibiting neuronal apoptosis in mice

Proteomic analysis discovers potential biomarkers of early traumatic axonal injury in the brainstem

OBJECTIVE

Application of Tandem Mass Tags (TMT)-based LC-MS/MS analysis to screen for differentially expressed proteins (DEPs) in traumatic axonal injury (TAI) of the brainstem and to predict potential biomarkers and key molecular mechanisms of brainstem TAI.

METHODS

A modified impact acceleration injury model was used to establish a brainstem TAI model in Sprague-Dawley rats, and the model was evaluated in terms of both functional changes (vital sign measurements) andstructural changes (HE staining, silver-plating staining and β-APP immunohistochemical staining). TMT combined with LC-MS/MS was used to analyse the DEPs in brainstem tissues from TAI and Sham groups. The biological functions of DEPs and potential molecular mechanisms in the hyperacute phase of TAI were analysed by bioinformatics techniques, and candidate biomarkers were validated using western blotting and immunohistochemistry on brainstem tissues from animal models and humans.

RESULTS

Based on the successful establishment of the brainstem TAI model in rats, TMT-based proteomics identified 65 DEPs, and bioinformatics analysis indicated that the hyperacute phase of TAI involves multiple stages of biological processes including inflammation, oxidative stress, energy metabolism, neuronal excitotoxicity and apoptosis. Three DEPs, CBR1, EPHX2 and CYP2U1, were selected as candidate biomarkers and all three proteins were found to be significantly expressed in brainstem tissue 30 min-7 days after TAI in both animal models and humans.

CONCLUSION

Using TMT combined with LC-MS/MS analysis for proteomic study of early TAI in rat brainstem, we report for the first time that CBR1, EPHX2 and CYP2U1 can be used as biomarkers of early TAI in brainstem by means of western blotting and immunohistochemical staining, compensating for the limitations of silver-plating staining and β-APP immunohistochemical staining, especially in the case of very short survival time after TAI (shorter than 30 min). A number of other proteins that also have a potential marker role are also presented, providing new insights into the molecular mechanisms, therapeutic targets and forensic identification of early TAI in brainstem.

The NR2B-targeted intervention alleviates the neuronal injuries at the sub-acute stage of cerebral ischemia: an exploration of stage-dependent strategy against ischemic insults

Stroke is reported to be the second leading cause of death worldwide, among which ischemic stroke has fourfold greater incidence than intracerebral hemorrhage. Excitotoxicity induced by NMDAR plays a central role in ischemic stroke-induced neuronal death. However, intervention targeted NMDARs against ischemic stroke has failed, which may result from the complex composition of NMDARs and the dynamic changes of their subunits. In this current study, the levels of NR1, NR2A and NR2B subunits of NMDARs were observed upon different time points during the reperfusion after 1 h ischemia with the western blot assay. It was found that the changes of NR1 subunit were only detected after ischemia 1 h/reperfusion 1 day (1 d). While, the changes of NR2A and NR2B subunits may last to ischemia 1 h/reperfusion 7 day(7 d), indicating that NR2subunits may be a potential target for ischemia-reperfusion injuries at the sub-acute stage of ischemic stroke. Simultaneously, mitochondrial injuries in neurons were investigated with transmission electron microscopy (TEM), and mitochondrial dysfunction was evaluated with mitochondrial membrane proteins oxidative respiratory chain complex and OCR. When the antagonist of NMDARs was used before ischemic exposure, the neuronal mitochondrial dysfunction was alleviated, suggesting that these aberrant deviations of NMDARs from basal levels led to mitochondrial dysfunction. Furthermore, when the antagonist of NR2B was administrated intracerebroventricularly at the sub-acute cerebral ischemia, the volume of cerebral infarct region was decreased and the neural functions were improved. To sum up, the ratio of NR2B-containing NMDARs is vital for mitochondrial homeostasis and then neuronal survival. NR2B-targeted intervention should be chosen at the sub-acute stage of cerebral ischemia.

Accurately quantified plasma free glycine concentration as a biomarker in patients with acute ischemic stroke

We developed a hollow fiber centrifugal ultrafiltration (HFCF-UF) method to study the change of plasma levels of free glycine (Gly) in patients with acute ischemic stroke (AIS). Twenty-four patients with AIS confirmed by diffusion-weighted imaging (DWI) were enrolled. During the study period, the patients did not receive any supplemental amino acids therapy that could affect the obtained results. Our results showed that although AIS patients adopted different methods of treatment (thrombolytic and non-thrombolytic), the clinical NIHSS score of AIS showed a downward trend whereas Gly concentration showed increased trend. Moreover, plasma free Gly concentration was positively correlated with ASPECTS score. The correlation between Gly levels and infarct volume showed a statistical significance. That is to say, higher Gly level predicted smaller infarct size. Thus, the change of free Gly level in plasma could be considered as a potential biomarker of AIS.

Super-Assembled Periodic Mesoporous Organosilica Frameworks for Real-Time Hypoxia-Triggered Drug Release and Monitoring

Hypoxia, induced by inadequate oxygen supply, is a key indication of various major illnesses, which necessitates the need to develop new nanoprobes capable of sensing hypoxia environments for the targeted system monitoring and drug delivery. Herein, we report a hypoxia-responsive, periodic mesoporous organosilica (PMO) nanocarrier for repairing hypoxia damage. β-cyclodextrin (β-CD) capped azobenzene functionalization on the PMO surface could be effectively cleaved by azoreductase under a hypoxia environment. Moreover, the nanosystem is equipped with fluorescence resonance energy transfer (FRET) pair (tetrastyrene derivative (TPE) covalently attached to the PMO framework as the donor and Rhodamine B (RhB) in the mesopores as the receptor) for intracellular visualization and tracking of drug release in real-time. The design of intelligent nanocarriers capable of simultaneous reporting and treating of hypoxia conditions highlights a great potential in the biomedical domain.

Analysis of Metabolite and Lipid Association Networks Reveals Molecular Mechanisms Associated with 3-Month Mortality and Poor Functional Outcomes in Patients with Acute Ischemic Stroke after Thrombolytic Treatment with Recombinant Tissue Plasminogen Activator

Here, we present an integrated multivariate, univariate, network reconstruction and differential analysis of metabolite–metabolite and metabolite–lipid association networks built from an array of 18 serum metabolites and 110 lipids identified and quantified through nuclear magnetic resonance spectroscopy in a cohort of 248 patients, of which 22 died and 82 developed a poor functional outcome within 3 months from acute ischemic stroke (AIS) treated with intravenous recombinant tissue plasminogen activator. We explored differences in metabolite and lipid connectivity of patients who did not develop a poor outcome and who survived the ischemic stroke from the related opposite conditions. We report statistically significant differences in the connectivity patterns of both low- and high-molecular-weight metabolites, implying underlying variations in the metabolic pathway involving leucine, glycine, glutamine, tyrosine, phenylalanine, citric, lactic, and acetic acids, ketone bodies, and different lipids, thus characterizing patients’ outcomes. Our results evidence the promising and powerful role of the metabolite–metabolite and metabolite–lipid association networks in investigating molecular mechanisms underlying AIS patient’s outcome.

Melatonin and Glycine Reduce Uterus Ischemia/Reperfusion Injury in a Rat Model of Warm Ischemia

Ischemia/reperfusion injury (IRI) remains a significant problem to be solved in uterus transplantation (UTx). Melatonin and glycine have been shown to possess direct cytoprotective activities, mainly due to their antioxidative and anti-inflammatory properties. The aim of this study was to investigate the protective effects of melatonin and glycine and their combination on IRI in a rat model of warm ischemia. In this study, Sprague-Dawley rats were assigned to eight groups, including sham and IRI (n = 80). Melatonin and glycine alone or their combination were administered prior to 1 h of uterus ischemia followed by 1 h of reperfusion. Melatonin (50 mg/kg) was administered via gavage 2 h before IRI and glycine in an enriched diet for 5 days prior to intervention. Uterus IRI was estimated by histology, including immunohistochemistry, and biochemical tissue analyses. Histology revealed that uterus IRI was significantly attenuated by pretreatment with melatonin (p = 0.019) and glycine (p = 0.044) alone as well as their combination (p = 0.003). Uterus IRI led to increased myeloperoxidase expression, which was significantly reduced by melatonin (p = 0.004), glycine (p < 0.001) or their combination (p < 0.001). The decline in superoxide dismutase activity was significantly reduced in the melatonin (p = 0.027), glycine (p = 0.038) and combined treatment groups (p = 0.015) when compared to the IRI control group. In conclusion, melatonin, glycine and their combination significantly reduced oxidative stress-induced cell damage after IRI in a small animal warm ischemia model, and, therefore, clinical studies are required to evaluate the protective effects of these well-characterized substances in uterus IRI.

10-O-(N N-Dimethylaminoethyl)-Ginkgolide B Methane-Sulfonate (XQ-1H) Ameliorates Cerebral Ischemia Via Suppressing Neuronal Apoptosis

OBJECTIVES

The 10-O-(N N-dimethylaminoethyl)-ginkgolide B methane-sulfonate (XQ-1H) is an effective novel drug for the treatment of ischemic cerebrovascular disease derived from Ginkgolide B, a traditional Chinese medicine, has been widely used in the treatment of cardiovascular and cerebrovascular diseases. However, whether XQ-1H exerts neuroprotective effect via regulating neuronal apoptosis and the underlying mechanism remain to be elucidated.

MATERIALS AND METHODS

This study was aimed to investigate the neuroprotective effect of XQ-1H in rats subjected to middle cerebral artery occlusion/reperfusion (MCAO/R) and the oxygen glucose deprivation/reoxygenation (OGD/R) induced neuronal apoptosis on pheochromocytoma (PC-12) cells.

RESULTS

The results showed that administration of XQ-1H at different dosage (7.8, 15.6, 31.2 mg/kg) reduced the brain infarct and edema, attenuated the neuro-behavioral dysfunction, and improved cell morphology in brain tissue after MCAO/R in rats. Moreover, incubation with XQ-1H (1 µM, 3 µM, 10 µM, 50 µM, 100 µM) could increase the cell viability, and showed no toxic effect to PC-12 cells. XQ-1H at following 1 µM, 10 µM, 100 µM decreased the lactate dehydrogenase (LDH) activity and suppressed the cell apoptosis in PC-12 cells exposed to OGD/R. In addition, XQ-1H treatment could significantly inhibit caspase-3 activation both in vivo and in vitro, reciprocally modulate the expression of apoptosis related proteins, bcl-2, and bax via activating PI3K/Akt signaling pathway. For mechanism verification, LY294002, the inhibitor of PI3K/Akt pathway was introduced the expressions of bcl-2 and phosphorylated Akt were down-regulated, the expression of bax was up-regulated, indicating that XQ-1H could alleviate the cell apoptosis through activating the PI3K/Akt pathway.

CONCLUSIONS

Our findings demonstrated that XQ-1H treatment could provide a neuroprotective effect against ischemic stroke induced by cerebral ischemia/reperfusion injury in vivo and in vitro through regulating neuronal survival and inhibiting apoptosis. The findings of the study confirmed that XQ-1H could be develop as a potential drug for treatment of cerebral ischemic stroke.

Transient receptor potential vanilloid four channels modulate inhibitory inputs through differential regulation of GABA and glycine receptors in rat retinal ganglion cells

The transient receptor potential vanilloid 4 (TRPV4) channel is widely distributed in the retina. Activation of the TRPV4 channel enhances excitatory signaling from bipolar cells to retinal ganglion cells (RGCs), thereby increasing RGC firing rate and membrane excitability. In this study, we investigated the effect of TRPV4 channel activation on the miniature inhibitory postsynaptic current (mIPSC) in rat RGCs. Our results showed that perfusion with HC-067047, a TRPV4-channel antagonist, significantly reduced the amplitude of RGC mIPSCs. Extracellular application of the TRPV4 channel agonist GSK1016790A (GSK101) enhanced the frequency and amplitude of mIPSCs in ON- and OFF-type RGCs; pre-application of HC-067047 blocked the effect of GSK101 on mIPSCs. Furthermore, TRPV4 channels were able to enhance the frequency and amplitude of glycine receptor (GlyR)-mediated mIPSCs and inhibit the frequency of type A γ-aminobutyric acid receptor (GABA_A R)-mediated mIPSCs. Upon intracellular administration or intravitreal injection of GSK101, TRPV4 channel activation reduced the release of presynaptic glycine and enhanced the function and expression of postsynaptic GlyRs; however, it inhibited presynaptic release of GABA, but did not affect postsynaptic GABA_A Rs. Our study results provide insight regarding the effect of TRPV4 channel activation on RGCs and offer a potential interventional target for retinal diseases involving TRPV4 channels.

Predicting metabolite-disease associations based on KATZ model

BACKGROUND

Increasing numbers of evidences have illuminated that metabolites can respond to pathological changes. However, identifying the diseases-related metabolites is a magnificent challenge in the field of biology and medicine. Traditional medical equipment not only has the limitation of its accuracy but also is expensive and time-consuming. Therefore, it's necessary to take advantage of computational methods for predicting potential associations between metabolites and diseases.

RESULTS

In this study, we develop a computational method based on KATZ algorithm to predict metabolite-disease associations (KATZMDA). Firstly, we extract data about metabolite-disease pairs from the latest version of HMDB database for the materials of prediction. Then we take advantage of disease semantic similarity and the improved disease Gaussian Interaction Profile (GIP) kernel similarity to obtain more reliable disease similarity and enhance the predictive performance of our proposed computational method. Simultaneously, KATZ algorithm is applied in the domains of metabolomics for the first time.

CONCLUSIONS

According to three kinds of cross validations and case studies of three common diseases, KATZMDA is worth serving as an impactful measuring tool for predicting the potential associations between metabolites and diseases.

Antioxidative Property and Molecular Mechanisms Underlying Geniposide-Mediated Therapeutic Effects in Diabetes Mellitus and Cardiovascular Disease

Geniposide, an iridoid glucoside, is a major component in the fruit of Gardenia jasminoides Ellis (Gardenia fruits). Geniposide has been experimentally proved to possess multiple pharmacological actions involving antioxidative stress, anti-inflammatory, antiapoptosis, antiangiogenesis, antiendoplasmic reticulum stress (ERS), etc. In vitro and in vivo studies have further identified the value of geniposide in a spectrum of preclinical models of diabetes mellitus (DM) and cardiovascular disorders. The antioxidative property of geniposide should be attributed to the result of either the inhibition of numerous pathological processes or the activation of various proteins associated with cell survival or a combination of both. In this review, we will summarize the available knowledge on the antioxidative property and protective effects of geniposide in DM and cardiovascular disease in the literature and discuss antioxidant mechanisms as well as its potential applications in clinic.

Glycine receptors are involved in hippocampal neuronal damage caused by oxygen-glucose deficiency

Glycine receptors (GlyRs) belong to the family of ligand-gated cys-loop receptors and effectuate fast inhibitory neurotransmission in central nervous system (CNS). They are involved in numerous physiological processes, such as movement, respiration, and processing of sensory information, as well as in regulation of neuronal excitability in different brain regions. GlyRs play important role in the maintenance of excitatory/inhibitory balance in the hippocampus and participate in the development of various brain pathologies. In the present study, we have examined a surface expression of GlyRs by pyramidal neurons and astrocytes in control and after 30 min of oxygen-glucose deprivation (OGD) in the organotypic culture of hippocampal slices. Our investigation has demonstrated a decrease in GlyR-positive staining associated with pyramidal neurons and relative stability of GlyRs expression at the surface of astrocytes 4 hs after OGD. These data indicate that GlyRs dysfunction may represent a significant additional factor leading to enhanced neuronal damage induced by OGD. Pharmacological modulation of GlyRs is a promising venue of research for the correction of negative consequences of oxygen-glucose deficiency.

Dose-dependent target diversion of Danhong injection on the Glu-GLT-1/Gly-GlyRα dynamic balance module of cerebral ischemia

Function-oriented modular structure analysis is a great challenge in module-based pharmacological studies. A strategy to uncover target-target interaction (TTI) and dynamic balance regularity (DBR) was established to discover the structural factors influencing modular functions and explore the mechanism of Danhong injection (DHI) in treating cerebral ischemia. The dose-related metabolic features of DHI intervention were investigated using metabolomics and modular pharmacology. The findings indicated that Glu/Gly was a biomarker and Glu-GLT-1/Gly-GlyRα was the core unit regulated by DHI. Gly and Glu displayed opposite patterns and functional roles, representing intra-modular balance. GlyRα was identified as the upstream target and GLT-1 as the downstream target by inhibiting or activating GlyRα, indicating that DHI has two dose-dependent regulatory modes. GlyRα was the major target at low doses, while GLT-1 was activated as the dominant target as doses accumulated. Our study reveals that target-target interaction and dynamic balance regularity are the key factors influencing modular functions, which is a promising breakthrough for module-based pharmacological studies.

Gelatin versus its two major degradation products, prolyl-hydroxyproline and glycine, as supportive therapy in experimental colitis in mice

Gelatin is an anti-inflammatory dietary component, and its predominant metabolites entering circulation are prolyl-hydroxyproline (Pro-Hyp) and glycine. We evaluated the protective effects of orally administered gelatin, glycine, and Pro-Hyp 10:3:0.8 (w/w/w) against dextran sodium sulfate (DSS)-induced colitis in mice. According to clinical, histological, and biochemical parameters, they exhibited significant activities in the order of gelatin < glycine < Pro-Hyp. Gelatin prevented the DSS-induced increase in interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) in the colon, rather than in peripheral blood. Glycine and Pro-Hyp attenuated the DSS-induced rise in colonic IL-6 and TNF-α, as well as peripheral IL-1β, IL-6, and TNF-α. Hematologic results show the attenuation of DSS-induced leukocytosis and lymphocytosis by glycine and Pro-Hyp, rather than gelatin. These findings suggest that glycine and Pro-Hyp constitute the material basis for gelatin's anticolitis efficacy, and they have better anticolitis activities and distinct mechanisms of action when ingested as free compounds than as part of gelatin.

Metabolomics and Lipidomics of Ischemic Stroke

Ischemic stroke is a sudden loss of brain function due to the reduction of blood flow. Brain tissues cease to function with subsequent activation of the ischemic cascade. Metabolomics and lipidomics are modern disciplines that characterize the metabolites and lipid components of a biological system, respectively. Because the pathogenesis of ischemic stroke is heterogeneous and multifactorial, it is crucial to establish comprehensive metabolomic and lipidomic approaches to elucidate these alterations in this disease. Fortunately, metabolomic and lipidomic studies have the distinct advantages of identifying tissue/mechanism-specific biomarkers, predicting treatment and clinical outcome, and improving our understanding of the pathophysiologic basis of disease states. Therefore, recent applications of these analytical approaches in the early diagnosis of ischemic stroke were discussed. In addition, the emerging roles of metabolomics and lipidomics on ischemic stroke were summarized, in order to gain new insights into the mechanisms underlying ischemic stroke and in the search for novel metabolite biomarkers and their related pathways.

Glycine Protects H9C2 Cardiomyocytes from High Glucose- and Hypoxia/Reoxygenation-Induced Injury via Inhibiting PKCβ2 Activation and Improving Mitochondrial Quality

BACKGROUND

Patients with diabetes are more vulnerable to myocardial ischemia reperfusion injury (IRI), which is involved in PKCβ2 activation and mitochondrial dysfunction. Glycine has been documented as a cytoprotective agent to attenuate diabetes-related abnormalities and reduce myocardial IRI, but the underlying mechanisms are still unclear. We determined whether glycine could attenuate high glucose- (HG-) and hypoxia/reoxygenation- (H/R-) induced injury by inhibiting PKCβ2 activation and improving mitochondrial quality in cultured H9C2 cells.

METHODS

H9C2 cells were either exposed to low glucose (LG) or HG conditions with or without treatment of glycine or CGP53353 (a selective inhibitor of PKCβ2) for 48 h, then subjected to 4 h of hypoxia followed by 2 h of reoxygenation (H/R). Cell viability, lactate dehydrogenase (LDH) release, mitochondrial membrane potential (MMP), superoxide dismutase (SOD) activity, and malondialdehyde (MDA) concentration were detected using corresponding commercial kits. Mitochondrial quality control-related proteins (LC-3II, Mfn-2, and Cyt-C) and PKCβ2 activation were detected by Western blot.

RESULTS

HG stimulation significantly decreased cell viability and SOD activity and increased LDH release, MDA production, and PKCβ2 activation as compared to LG group, all of which changes were further increased by H/R insult. Glycine or CGP53353 treatment significantly reduced the increase of LDH release, MDA production, PKCβ2 activation, and Cyt-C expression and the decrease of cell viability, SOD activity, MMP, Mfn-2 expression, and LC-3II/LC-3I ratio induced by HG and H/R stimulation.

CONCLUSIONS

Supplementary glycine protects H9C2 cells from HG- and H/R-induced cellular injury by suppressing PKCβ2 activation and improving mitochondria quality.

Identification of risk genes associated with myocardial infarction based on the recursive feature elimination algorithm and support vector machine classifier

The aim of the present study was to identify risk genes in myocardial infarction. Microarray data GSE34198, containing data from the peripheral blood of 49 myocardial infarction samples and 48 corresponding control samples, were downloaded from the Gene Expression Omnibus database to screen the differentially expressed genes (DEGs). The DEGs were used to construct a protein-protein interaction (PPI) network of patient samples, from which the feature genes were identified using the neighboring score method. The recursive feature elimination (RFE) algorithm was employed to select the risk genes among feature genes, which were subsequently applied to perform a support vector machine (SVM) classifier to identify the specific signature in myocardial infarction samples. Another dataset, GSE61144, was also downloaded to verify the efficacy of the classifier. A total of 724 downregulated and 483 upregulated DEGs were screened in patient samples compared with control samples in the GSE34198 dataset. The PPI network of myocardial infarction was comprised of 1,083 nodes (genes) and 46,363 lines (connections). Using the neighborhood scoring method, the top 100 feature genes in myocardial infarction samples were identified as the disease feature genes, which distinguish the myocardial infarction samples from the control samples. The RFE algorithm screened 15 risk genes, which were employed to construct a SVM classifier with an average precision of 88% to the patient sample following visualization by a confusion matrix. The predictive precision of the classifier on another microarray dataset, GSE61144, was 0.92, with an average true positive of 0.9278 and an average false positive of 0.2361. A-kinase-anchoring protein 12 (AKAP12) and glycine receptor α2 (GLRA2) were two risk genes in the SVM classifier. Therefore, AKAP12 and GLRA2 exert potential roles in the development of myocardial infarction, potentially by influencing cardiac contractility and protecting against ischemia-reperfusion injury, which may provide clues in developing potential diagnostic biomarkers or therapeutic targets for myocardial infarction.

Sesamol attenuates oxidative stress, apoptosis and inflammation in focal cerebral ischemia/reperfusion injury

The aim of the present study was to evaluate the therapeutic potential of sesamol treatment on focal ischemia/reperfusion (I/R) injury in the rat brain. The results demonstrated that pretreatment with sesamol seven days prior to focal cerebral I/R injury had significant positive effects, including improvements in neurological deficits (P<0.05), and a reduction in malondialdehyde content and elevation of antioxidant levels (superoxide dismutase, glutathione and glutatione peroxidase; both P<0.05). Furthermore, levels of B cell lymphoma-2 (Bcl-2)-associated X protein and caspase-3 were significantly downregulated, whereas the level of Bcl-2 was effectively increased. Conversely, the mRNA expression of proinflammatory cytokines were significantly reduced in focal cerebral I/R injury rats upon sesamol intervention. Therefore, the beneficial effects of sesamol on cerebral I/R injury may be due to the reduction of oxidative stress, inhibition of apoptosis and inflammation. The findings of the present study suggest that sesamol supplementation may serve as potent adjuvant in the treatment of focal cerebral ischemia/reperfusion injury due to its neuroprotective effects.

N-stearoyltyrosine protects primary cortical neurons against oxygen-glucose deprivation-induced apoptosis through inhibiting anandamide inactivation system

N-stearoylthrosine (NST), a synthesized anandamide (AEA) analogue, plays a neuroprotective role in neurodegenerative diseases and cerebrovascular diseases. Several studies have demonstrated that the endocannabinoids systems (ECS) are involved in the neuroprotective effects against cerebral ischemic injury. Oxygen-glucose deprivation (OGD)-induced neuronal injury elevated the levels of endocannabinoids and activated ECS. This research was conducted to investigate the neuroprotective effect of NST against OGD-induced neuronal injury in cultured primary cortical neurons and the potential mechanism involved. Cortical neurons were treated with NST at indicate concentrations for 30min prior to injury and OGD injured neurons were incubated with normal conditions for 0-24h. The best neuroprotective effect of NST against OGD-induced injury occurred at 10μM. All data indicated that the neuroprotective effect of NST against OGD-induced injury resulted from blocking anandamide membrane transporter (AMT) (IC₅₀=11.74nM) and inhibiting fatty acid amide hydrolase activity (FAAH) (IC₅₀=16.54nM). Our findings demonstrated that NST has an important role in cerebral ischemic injury pathological progression through activating cannabinoid receptors by inhibiting AEA inactivation system. These data suggested a potential role for NST in the therapeutic consideration of cerebral ischemic injury. However, inhibition of AEA inactivation system may provide a neuroprotective effect during cerebral ischemic injury.

MORIN MITIGATES OXIDATIVE STRESS, APOPTOSIS AND INFLAMMATION IN CEREBRAL ISCHEMIC RATS

Background:

Morin is a flavanoid which exhibits potent antioxidant activity in various oxidative stress related diseases. The current study was attempted to scrutinize the preclinical bio-efficacy of morin on focal ischemia.

Methods:

The animal model of focal cerebral ischemic injury was done by midbrain carotid artery occlusion (MCAO) method, followed by Morin (30mg/kg) administration for seven days.

Results:

The outcome of the study showed that treatment with morin displayed positive effects in reducing the focal cerebral ischemia. This effect was evident with the improvements in neurological deficits, reduction in MDA content and elevation of antioxidant levels (SOD, GSH and Gpx). Furthermore, protein expression of Bax and caspase-3 were effectively down-regulated, whilst the expression of Bcl-2 was significantly elevated. On the other hand, the mRNA expression of proinflammatory cytokines was significantly reduced in focal cerebral ischemic rats upon morin intervention.

Conclusion:

Thus, the beneficial effects of morin on cerebral ischemia assault may result from the reduction of oxidative stress, inhibition of apoptosis and inflammation. The neuroprotective effects of morin supplement may serve as potent adjuvant in the amelioration of ischemic stroke.

Glycine increases preimplantation development of mouse oocytes following vitrification at the germinal vesicle stage

Ice-free cryopreservation, referred to as vitrification, is receiving increased attention in the human and animal assisted reproduction. However, it introduces the detrimental osmotic stress by adding and removing high contents of cryoprotectants. In this study, we evaluated the effects of normalizing cell volume regulation by adding glycine, an organic osmolyte, during vitrification of mouse germinal vesicle stage oocyte and/or subsequent maturation on its development. The data showed that glycine supplementation in either vitrification/thawing or maturation medium significantly improved the cytoplasmic maturation of MII oocytes manifested by spindle assembly, chromosomal alignment, mitochondrial distribution, euploidy rate, and blastocyst development following fertilization in vitro, compared to the control without glycine treatment. Furthermore, glycine addition during both vitrification/thawing and maturation further enhanced the oocyte quality demonstrated by various markers, including ATP contents and embryo development. Lastly, the effect of anti-apoptosis was also observed when glycine was added during vitrification. Our result suggests that reducing osmotic stress induced by vitrification could improve the development of vitrified mouse oocyte.

Panax notoginseng saponins provide neuroprotection by regulating NgR1/RhoA/ROCK2 pathway expression, in vitro and in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Panax notoginseng saponins (PNS) extracted from a traditional Chinese herbal medicine, Panax notoginseng (Burkill) F.H. Chen (Araliaceae), which has been extensively used in treating coronary heart disease, ischemic cerebrovascular disease and hemorrhagic disorders in China over hundreds of years.

AIMS OF THE STUDY

This study explored whether panax notoginseng saponins (PNS) provided neuroprotective effects by inhibiting the expressions of NgR1, RhoA, and ROCK2 following middle cerebral artery occlusion in rats and oxygen-glucose deprivation/reoxygenation (OGD/R) injury in SH-SY5Y cells.

MATERIALS AND METHODS

2,3,5-Triphenyltetrazolium chloride staining was used to determine successful middle cerebral artery occlusion establishment in sham-operated and operated Sprague-Dawley rats 1 day after injury. The rats were randomly separated into sham, model, NEP1-40, PNS, and NEP1-40 plus PNS (N+P) groups. After 7 days of treatment, body mass and neurological deficit scores were analyzed. Tissues were harvested and analyzed by hematoxylin-eosin staining and immunohistochemical analysis, western blotting, and quantitative real-time PCR (qRT-PCR). The optimal drug concentration of NEP1-40 and PNS on SH-SY5Y cells exposed to OGD/R injury was determined by CCK8 analysis. qRT-PCR was used to measure mRNA expression profiles of NgR1, RhoA, and ROCK2 in SH-SY5Y cells subjected to OGD/R.

RESULTS

The results showed that MCAO surgery successfully produced an infarct, and the PNS, NEP1-40, and N+P groups exhibited increased body mass and ameliorated neurological deficits compared with the model group. NEP1-40 treatment markedly reduced NgR1 and RhoA overexpression when compared to the model group, although there was no significant difference in ROCK2 expression. PNS and N+P treatment significantly decreased NgR1, RhoA, and ROCK2 overexpression compared with the model group. However, N+P treatment did not result in a synergistic effect, as assessed by immunohistochemistry, western blotting, and qRT-PCR. Following optimal administration of PNS (160μg/ml) and NEP1-40 (10ng/ml) on SH-SY5Y cells exposed to OGD/R injury, cell viability in the NEP1-40, PNS, and N+P groups significantly increased compared with the model group, as assessed by CCK8 analysis. Additionally, NgR1, RhoA, and ROCK2 mRNA expression profiles were significantly less in the NEP1-40, PNS, and N+P groups compared with the model group.

CONCLUSION

PNS provided neuroprotective effects in a rat model of cerebral ischemia and SH-SY5Y cells exposed to oxygen/glucose deprivation injury by inhibiting the overexpression of NgR1, RhoA, and ROCK2.

The role of glycine in regulated cell death

The cytoprotective effects of glycine against cell death have been recognized for over 28 years. They are expressed in multiple cell types and injury settings that lead to necrosis, but are still not widely appreciated or considered in the conceptualization of cell death pathways. In this paper, we review the available data on the expression of this phenomenon, its relationship to major pathophysiologic pathways that lead to cell death and immunomodulatory effects, the hypothesis that it involves suppression by glycine of the development of a hydrophilic death channel of molecular dimensions in the plasma membrane, and evidence for its impact on disease processes in vivo.

Neuroprotection by triptolide against cerebral ischemia/reperfusion injury through the inhibition of NF-κB/PUMA signal in rats

Triptolide, an active compound extracted from the Chinese herb thunder god vine (Tripterygium wilfordii Hook F.), has potent antitumor activity. Recently, triptolide was found to have protective effects against acute cerebral ischemia/reperfusion (I/R) injury through inhibition of cell apoptosis. However, the regulatory mechanism of the effect remains unclear. We hypothesize that the regulatory mechanisms of triptolide are mediated by nuclear factor κB (NF-κB) and p53-upregulated-modulator-of-apoptosis signal inhibition. To verify this hypothesis, we occluded the middle cerebral artery in male rats to establish focal cerebral I/R model. The rats received triptolide or vehicle at the onset of reperfusion following middle cerebral artery occlusion. At 24 hours after reperfusion, neurological deficits, infarct volume, and cell apoptosis were evaluated. The expression levels of NF-κBp65, PUMA, and caspase-3 were determined by Western blot. Real-time polymerase chain reaction was used to determine the levels of NF-κBp65 mRNA, PUMA mRNA, and caspase-3 mRNA. NF-κB activity was determined by electrophoretic mobility shift assay. Apoptotic cells were detected using terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining. In I/R group, neurological deficit scores, cerebral infarct volume, expression of NF-κBp65, PUMA, caspase-3, NF-κB activity, and TUNEL-positive cells were found to be increased at 24 hours after I/R injury. The I/R/triptolide rats showed significantly better neurological deficit scores, decreased neural apoptosis, and reduced cerebral infarct volume. In addition, the expression of NF-κBp65, PUMA, caspase-3, and NF-κB activity was suppressed in the I/R/triptolide rats. These results indicate that the neuroprotective effects of triptolide during acute cerebral I/R injury are possibly related to the inhibition of apoptosis through suppression of NF-κB/PUMA signaling pathway.

PI3K/Akt pathway contributes to neuroprotective effect of Tongxinluo against focal cerebral ischemia and reperfusion injury in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Tongxinluo (TXL), a compound prescription, is formulated according to the collateral disease doctrine of traditional Chinese medicine, and is widely used for the treatment of cardio-cerebrovascular diseases in China.

AIM OF THE STUDY

We aimed to investigate the neuroprotective effect of TXL on focal cerebral ischemia and reperfusion injury in rats by attenuating its brain damage and neuronal apoptosis, and to assess the potential role of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway in this protection.

MATERIALS AND METHODS

Adult Male Sprague-Dawley rats (n=120) were randomly divided into 5 groups: sham, cerebral ischemia and reperfusion (I/R), cerebral ischemia and reperfusion plus TXL (1.6g/kg/day) (TXL1.6), TXL1.6 plus LY294002 and dimethyl sulfoxide (DMSO) (TXL1.6+LY294002), TXL1.6 plus DMSO (TXL1.6+vehicle). Prior to the grouping, TXL1.6 was selected to be the optimal dose of TXL by evaluating the neurological deficits score of five group rats (Sham, I/R, TXL0.4, TXL0.8 and TXL1.6, n=30) at 0, 1, 3, 5, and 7 days after reperfusion. Rats, being subjected to middle cerebral artery occlusion (MCAO) for 90min followed by 24h reperfusion, were the cerebral ischemia/reperfusion models. At 24h after reperfusion, cerebral infarct area was measured via tetrazolium staining and neuronal damage was showed by Nissl staining. The double staining of Terminal deoxynucleotidyl transferase-mediated deoxyuridine 5-triphosphate nick end labeling (TUNEL) staining and immunofluorescence labeling with NeuN, was performed to evaluate neuronal apoptosis. Proteins involved in PI3K/Akt pathway were detected by Western blot.

RESULTS

The results showed that TXL markedly improved neurological function, reduced cerebral infarct area, decreased neuronal damage, and significantly attenuated neuronal apoptosis, while these effects were eliminated by inhibition of PI3K/Akt with LY294002. We also found that TXL up-regulated the expression levels of p-PDK1, p-Akt, p-c-Raf, p-BAD and down-regulated Cleaved caspase 3 expression notably, which were partially reversed by LY294002. Additionally, the increment of p-PTEN level on which LY294002 had little effect was also detected in response to TXL treatment.

CONCLUSIONS

These findings demonstrated that TXL provided neuroprotection against cerebral ischemia/reperfusion injury and neuronal apoptosis, and this effect was mediated partly by activation of the PI3K/Akt pathway.

Clematichinenoside Serves as a Neuroprotective Agent Against Ischemic Stroke: The Synergistic Action of ERK1/2 and cPKC Pathways

There are numerous evidences suggesting that inhibition of apoptosis of neurons play a critical role in preventing the damage and even death of neurons after brain ischemia/reperfusion, which shows therapeutic potential for clinical treatment of brain injury induced by stroke. In this study, we aimed to investigate the neuroprotective effect of Clematichinenoside (AR) and its underlying mechanisms. MCAO mode was performed in rats and OGD/R model in primary cortical neurons to investigate the neuroprotective effect of AR. The rate of apoptotic cells was measured using TUNEL assay in cerebral cortex and flow cytometric assay in cortical neurons. Apoptosis-related proteins such as bcl-2, bcl-xl, and bax and the phosphorylation of ERK1/2, cPKC, p90RSK, and CREB in ischemic penumbra were assayed by western blot. Furthermore, we made a thorough inquiry about how these proteins play roles in the anti-apoptotic mechanism using targets-associated inhibitors step by step. The results revealed that AR could activate both ERK1/2 and cPKC which resulted in p90RSK phosphorylation and translocation into the nucleus. Moreover, CREB, a downstream target of p90RSK, was phosphorylated and then bound to cAMP-regulated enhancer (CRE) to activate apoptosis-related genes, and finally ameliorate ischemic stroke through preventing neuron death. In conclusion, these data strongly suggest that AR could be used as an effective neuroprotective agent to protect against ischemic stroke after cerebral I/R injury through regulating both ERK1/2 and cPKC mediated p90RSK/CREB apoptotic pathways.

In Vivo Detection of Perinatal Brain Metabolite Changes in a Rabbit Model of Intrauterine Growth Restriction (IUGR)

Background

Intrauterine growth restriction (IUGR) is a risk factor for abnormal neurodevelopment. We studied a rabbit model of IUGR by magnetic resonance imaging (MRI) and spectroscopy (MRS), to assess in vivo brain structural and metabolic consequences, and identify potential metabolic biomarkers for clinical translation.

Methods

IUGR was induced in 3 pregnant rabbits at gestational day 25, by 40–50% uteroplacental vessel ligation in one horn; the contralateral horn was used as control. Fetuses were delivered at day 30 and weighted. A total of 6 controls and 5 IUGR pups underwent T2-w MRI and localized proton MRS within the first 8 hours of life, at 7T. Changes in brain tissue volumes and respective contributions to each MRS voxel were estimated by semi-automated registration of MRI images with a digital atlas of the rabbit brain. MRS data were used for: (i) absolute metabolite quantifications, using linear fitting; (ii) local temperature estimations, based on the water chemical shift; and (iii) classification, using spectral pattern analysis.

Results

Lower birth weight was associated with (i) smaller brain sizes, (ii) slightly lower brain temperatures, and (iii) differential metabolite profile changes in specific regions of the brain parenchyma. Specifically, we found estimated lower levels of aspartate and N-acetylaspartate (NAA) in the cerebral cortex and hippocampus (suggesting neuronal impairment), and higher glycine levels in the striatum (possible marker of brain injury). Our results also suggest that the metabolic changes in cortical regions are more prevalent than those detected in hippocampus and striatum.

Conclusions

IUGR was associated with brain metabolic changes in vivo, which correlate well with the neurostructural changes and neurodevelopment problems described in IUGR. Metabolic parameters could constitute non invasive biomarkers for the diagnosis and abnormal neurodevelopment of perinatal origin.

The neuroprotective effect of a novel agent N2 on rat cerebral ischemia associated with the activation of PI3K/Akt signaling pathway

Ischemic stroke is the third leading cause of death and the main reason for severe disabilities in the world today. N2, 4 - (2 - (1H - imidazol - 1 - yl) ethoxy) - 3 - methoxybenzoic acid is considered as a novel potent agent for cerebral ischemia due to its effect in preventing neuronal cell death after ischemic stroke. In the present study, we investigated the post-ischemic neuroprotective effect of N2 and its underlying mechanisms. Using a MCAO rat model, we found that N2 reversed brain infarct size, reduced cerebral edema and decreased the neurological deficit score significantly. Moreover, N2 diminished TUNEL positive cells, down-regulated bax expression and up-regulated bcl-2 expression notably. In addition, we evaluated the oxygen glucose deprivation/reoxygenation (OGD/R) injury induced neuron cell death in rat primary cortical neuron and assessed the neuroprotective effect of our drug. N2 increased cell viability, ameliorated neuron cell injury by decreasing LDH activity, and inhibited cell apoptotic rate while suppressed apoptotic signaling via inhibiting the bax expression, and elevating the bcl-2 expression. Furthermore, the neuroprotective effect of N2 was associated with the PI3K/Akt pathway which was proved by the use of PI3K inhibitor LY294002. The combination of our findings disclosed that N2 can be used as an effective neuroprotective agent for ischemic stroke due to its significant effect on preventing neuronal cell death after cerebral ischemia both in vivo and in vitro and the effectiveness was dose dependent.

Inhibition of inflammatory mediator release from microglia can treat ischemic/hypoxic brain injury

Interleukin-1α and interleukin-1β aggravate neuronal injury by mediating the inflammatory reaction following ischemic/hypoxic brain injury. It remains unclear whether interleukin-1α and interleukin-1β are released by microglia or astrocytes. This study prepared hippocampal slices that were subsequently subjected to oxygen and glucose deprivation. Hematoxylin-eosin staining verified that neurons exhibited hypoxic changes. Results of enzyme-linked immunosorbent assay found that interleukin-1α and interleukin-1β participated in this hypoxic process. Moreover, when hypoxic injury occurred in the hippocampus, the release of interleukin-1α and interleukin-1β was mediated by the P2X4 receptor and P2X7 receptor. Immunofluorescence staining revealed that during ischemia/hypoxia, the P2X4 receptor, P2X7 receptor, interleukin-1α and interleukin-1β expression was detectable in rat hippocampal microglia, but only P2X4 receptor and P2X7 receptor expression was detected in astrocytes. Results suggested that the P2X4 receptor and P2X7 receptor, respectively, mediated interleukin-1α and interleukin-1β released by microglia, resulting in hippocampal ischemic/hypoxic injury. Astrocytes were activated, but did not synthesize or release interleukin-1α and interleukin-1β.

Acetylpuerarin increases cell viability and reduces apoptosis in rat hippocampal neurons following oxygen‑glucose deprivation/reperfusion

The effects of acetylpuerarin treatment following oxygen-glucose deprivation/reperfusion (OGD/R) were examined in rat hippocampal neurons in vitro and compared with the effects of acetylpuerarin in normoxic cells to confirm acetylpuerarin's potential neuroprotective effects, including apoptosis inhibition. Wistar rat embryo hippocampal cells (day 18, E18) cultured for 8 days were subjected to 3 h OGD treatment, followed by reperfusion for 12, 24 or 36 h. For each time interval, a group of cells was left untreated (OGD/R-only groups) and treated with 0.1, 0.4 and 1.6 µM acetylpuerarin (OGD/R+acetylpuerarin). Neuron viability, apoptosis and caspase-8 and -3 activities were assessed by the reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), 4',6-diamidino-2-phenylindole (DAPI) and terminal deoxynucleotidyl-transferase-mediated dUTP nick end labeling (TUNEL) and spectrophotometric assays, respectively. Fas-ligand (Fas-L), Fas-associated death domain (FADD) and tumor necrosis factor-α (TNF-α) were determined by western blot analysis. Compared with control cells, OCD/R+acetylpuerarin cells treated with 0.1, 0.4 and 1.6 µM doses showed a concentration-dependent increase in hippocampal cell survival and viability by 69.93 ± 2.28%, 81.49 ± 2.13% and 85.28 ± 2.38% at 12 h, 68.59 ± 3.02%, 77.85 ± 2.84% and 85.64 ± 4.39% at 24 h and 69.70 ± 1.70%, 77.21 ± 3.21% and 83.90 ± 2.12% at 36 h (P<0.05). Furthermore, OCD/R+acetylpuerarin cells exhibited a dose-dependent decrease in caspase-8 and -3 activation, TUNEL and DAPI-positive neurons and Fas-L, FADD and TNF-α expression. In conclusion, acetylpuerarin protects against OGD/R-induced neuronal apoptosis predominantly in the first 24 h following ischemia, which may be useful in mediating neuronal apoptosis in ischemic stroke patients.

Hydrogen sulfide prevents OGD/R-induced apoptosis via improving mitochondrial dysfunction and suppressing an ROS-mediated caspase-3 pathway in cortical neurons

Hydrogen sulfide (H2S), an endogenous gaseous mediator, has been shown to have protective effects against neuronal damage caused by brain ischemia. In this study, we explored the potential effects of H2S on oxygen-glucose deprivation/reoxygenation (OGD/R)-induced neuronal apoptosis and the possible mechanisms. We find that sodium hydrosulfide (NaHS, a donator of H2S) prevents OGD/R-induced intracellular reactive oxygen species (ROS) elevation and activation of caspase-3 in cultured mouse cortical neurons. The pretreatment of N-acetyl-l-cysteine (NAC, an ROS scavenger) also prevents OGD/R-induced activation of caspase-3. Both NaHS and NAC counteract OGD/R-induced decline in mitochondria membrane potential (MMP). Additionally, NaHS, NAC or N-Acetyl-Asp-Glu-Val-Asp-CHO (DEVD-CHO, a caspase-3 inhibitor), is shown to significantly inhibit OGD/R-induced neuronal apoptosis. These data suggest that H2S can protect against OGD/R-induced neuronal apoptosis through improving mitochondria dysfunction and suppressing an ROS-activated caspase-3 signaling pathway.