Therapeutic neuroprotective effects of ginkgolide B on cortex and basal ganglia in a rat model of transient focal ischemia

The Janus face of HIF-1α in ischemic stroke and the possible associated pathways

Stroke is the most devastating disease, causing paralysis and eventually death. Many clinical and experimental trials have been done in search of a new safe and efficient medicine; nevertheless, scientists have yet to discover successful remedies that are also free of adverse effects. This is owing to the variability in intensity, localization, medication routes, and each patient's immune system reaction. HIF-1α represents the modern tool employed to treat stroke diseases due to its functions: downstream genes such as glucose metabolism, angiogenesis, erythropoiesis, and cell survival. Its role can be achieved via two downstream EPO and VEGF strongly related to apoptosis and antioxidant processes. Recently, scientists paid more attention to drugs dealing with the HIF-1 pathway. This review focuses on medicines used for ischemia treatment and their potential HIF-1α pathways. Furthermore, we discussed the interaction between HIF-1α and other biological pathways such as oxidative stress; however, a spotlight has been focused on certain potential signalling contributed to the HIF-1α pathway. HIF-1α is an essential regulator of oxygen balance within cells which affects and controls the expression of thousands of genes related to sustaining homeostasis as oxygen levels fluctuate. HIF-1α's role in ischemic stroke strongly depends on the duration and severity of brain damage after onset. HIF-1α remains difficult to investigate, particularly in ischemic stroke, due to alterations in the acute and chronic phases of the disease, as well as discrepancies between the penumbra and ischemic core. This review emphasizes these contrasts and analyzes the future of this intriguing and demanding field.

CB1 as a novel target for Ginkgo biloba's terpene trilactone for controlling chemotherapy-induced peripheral neuropathy (CIPN)

The application of antineoplastic chemotherapeutic agents causes a common side effect known as chemotherapy-induced peripheral neuropathy (CIPN) that leads to reducing the quality of patient's life. This research involves the performance of molecular docking and molecular dynamic (MD) simulation studies to explore the impact of terpenoids of Ginkgo biloba on the targets (CB-1, TLR4, FAAH-1, COX-1, COX-2) that can significantly affect the controlling of CIPN's symptoms. According to the in-vitro and in-vivo investigations, terpenoids, particularly ginkgolides B, A, and bilobalide, can cause significant effects on neuropathic pain. The molecular docking results disclosed the tendency of our ligands to interact with mainly CB1 and FAAH-1, as well as partly with TLR4, throughout their interactions with targets. Terpene trilactone can exhibit a lower rate of binding energy than CB1's inhibitor (7dy), while being precisely located in the CB1's active site and capable of inducing stable interactions by forming hydrogen bonds. The analyses of MD simulation proved that ginkgolide B was a more suitable activator and inhibitor for CB1 and TLR4, respectively, when compared to bilobalide and ginkgolide A. Moreover, bilobalide is capable of inhibiting FAAH-1 more effectively than the two other ligands. According to the analyses of ADME, every three ligands followed the Lipinski's rule of five. Considering these facts, the exertion of three ligands is recommended for their anti-inflammatory, neuroprotective, and anti-nociception influences caused by primarily activating CB1 and inhibiting FAAH-1 and TLR4; in this regard, these compounds can stand as potential candidates for the control and treatment of CIPN's symptoms.

Local Administration of Ginkgolide B Using a Hyaluronan-Based Hydrogel Improves Wound Healing in Diabetic Mice

The delayed and incomplete healing of diabetic wounds remains a major concern of global healthcare. The complex biological processes within the diabetic wound, such as chronic inflammation, impaired blood vessel growth and immature collagen remodeling, dramatically cause the failure of current treatments. Thus, emerging therapeutic strategies are highly desirable. Ginkgolide B (GB, a natural product extracted from the leaves of Ginkgo biloba L.) has been applied in the treatment of cerebrovascular and cardiovascular disorders, which is mainly due to the anti-oxidative, anti-inflammatory and proliferative effects. In this study, the role of GB in facilitating the anti-inflammatory and pro-healing effects on diabetic wounds was for the first time confirmed using in vitro, ex vivo and in vivo experimental methods. As a consequence, GB was able to significantly achieve the activities of anti-inflammation, re-epithelialization, and pro-angiogenesis. Previously, a hydrogel has been developed using the high molecular weight hyaluronan (hyaluronic acid, HA) in our laboratory. In this study, this hydrogel was utilized in vivo for local administration of GB to the full-thickness wounds of diabetic mice. The resultant hydrogel formulation (HA-GB) resulted in the reduction of inflammation, the enhancement of re-epithelialization and angiogenesis, and the modulation of collagens from type III to type I, significantly promoting the healing outcome as compared with a commercially available wound dressing product (INTRASITE Gel). This study confirms a great therapeutic promise of HA-GB for the chronic wounds of diabetic patients.

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.

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

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

Ginkgolide B Maintains Calcium Homeostasis in Hypoxic Hippocampal Neurons by Inhibiting Calcium Influx and Intracellular Calcium Release

Ginkgolide B (GB), a terpene lactone and active ingredient of Ginkgo biloba, shows protective effects in neuronal cells subjected to hypoxia. We investigated whether GB might protect neurons from hypoxic injury through regulation of neuronal Ca²⁺ homeostasis. Primary hippocampal neurons subjected to chemical hypoxia (0.7 mM CoCl₂) in vitro exhibited an increase in cytoplasmic Ca²⁺ (measured from the fluorescence of fluo-4), but this effect was significantly diminished by pre-treatment with 0.4 mM GB. Electrophysiological recordings from the brain slices of rats exposed to hypoxia in vivo revealed increases in spontaneous discharge frequency, action potential frequency and calcium current magnitude, and all these effects of hypoxia were suppressed by pre-treatment with 12 mg/kg GB. Western blot analysis demonstrated that hypoxia was associated with enhanced mRNA and protein expressions of Ca_v1.2 (a voltage-gated Ca²⁺ channel), STIM1 (a regulator of store-operated Ca²⁺ entry) and RyR2 (isoforms of Ryanodine Receptor which mediates sarcoplasmic reticulum Ca²⁺ release), and these actions of hypoxia were suppressed by GB. Taken together, our in vitro and in vivo data suggest that GB might protect neurons from hypoxia, in part, by regulating Ca²⁺ influx and intracellular Ca²⁺ release to maintain Ca²⁺ homeostasis.

Emerging neuroprotective strategies for the treatment of ischemic stroke: An overview of clinical and preclinical studies

Stroke is the leading cause of disability and thesecond leading cause of death worldwide. With the global population aged 65 and over growing faster than all other age groups, the incidence of stroke is also increasing. In addition, there is a shift in the overall stroke burden towards younger age groups, particularly in low and middle-income countries. Stroke in most cases is caused due to an abrupt blockage of an artery (ischemic stroke), but in some instances stroke may be caused due to bleeding into brain tissue when a blood vessel ruptures (hemorrhagic stroke). Although treatment options for stroke are still limited, with the advancement in recanalization therapy using both pharmacological and mechanical thrombolysis some progress has been made in helping patients recover from ischemic stroke. However, there is still a substantial need for the development of therapeutic agents for neuroprotection in acute ischemic stroke to protect the brain from damage prior to and during recanalization, extend the therapeutic time window for intervention and further improve functional outcome. The current review has assessed the past challenges in developing neuroprotective strategies, evaluated the recent advances in clinical trials, discussed the recent initiative by the National Institute of Neurological Disorders and Stroke in USA for the search of novel neuroprotectants (Stroke Preclinical Assessment Network, SPAN) and identified emerging neuroprotectants being currently evaluated in preclinical studies. The underlying molecular mechanism of each of the neuroprotective strategies have also been summarized, which could assist in the development of future strategies for combinational therapy in stroke treatment.

The effect of intravenous ginkgolide on clinical improvement of patients with acute ischemic stroke

Aims: To compare the efficacy of ginkgolide in the treatment of Chinese patients with ischemic stroke between pre-marketing and post-marketing studies.Methods: This is a re-analysis of a pre-marketing (phase II/III, multicenter, double-blind, parallel-controlled; February 2005 to September 2005) and post-marketing (phase IV, multicenter, open, single-arm registration; April 2013 to June 2014) studies. The intervention groups received intravenous ginkgolide (10 mL daily, 14 days). Primary outcome was an improvement of National Institute of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) scores after 14 days.Results: In pre- and post-marketing studies, NIHSS and mRS scores all improved, compared to that of baseline (P < 0.001) in acute phase. Those factors significantly associated with △NIHSS after 14 days of therapy with ginkgolide were grouping (pre-marketing vs. post-marketing; OR 2.169, 95%CI = 1.462-3.216, P < 0.001), male (OR = 1.532, 95%CI = 1.152-2.037, P = 0.003), enrollment within 30 days after onset (OR = 1.915, 95%CI = 1.452-2.526, P < 0.001) and NIHSS score more than 8 points at baseline (OR = 15.140, 95%CI = 11.436-20.045, P < 0.001) after adjustment. Ginkgolide had a greater effect on patients in a relatively acute phase (time of onset to enrollment ≤30 days) and moderate-severe stroke (baseline NIHSS>8 points). Incidences of adverse reactions in the pre-marketing and post-marketing studies were 0.46% and 5.28%, respectively (P < 0.001).Conclusion: Intravenous ginkgolide may improve the outcome of acute ischemic stroke. Differences in effect between pre-marketing and post-marketing studies may be associated with gender, time of onset to enrollment and severity of stroke.

Pharmacokinetics and pharmacodynamics analysis of XQ-1H and its combination therapy with clopidogrel on cerebral ischemic reperfusion injury in rats

Ischemic stroke is the main cause of disability and mortality worldwide. 10-O-(N N-dimethylaminoethyl)-ginkgolide B methane-sulfonate (XQ-1 H) is a novel drug based on the remedial approach for ischemic stroke. Clopidogrel, a widely used anti-platelet drug, is often co-prescribed in the clinic. In this study, we established an UPLC-MS/MS spectrometry method for the determination of XQ-1H and investigated the pharmacokinetic effect of clopidogrel on XQ-1H in rats subjected to middle cerebral artery occlusion (MCAO). Meanwhile, the anti-apoptotic and neuroprotective effects of XQ-1H and its combination with clopidogrel were also studied. The results revealed that XQ-1H and its combination with clopidogrel abridged brain infarct volume, cerebral edema and alleviated neurological dysfunction caused by cerebral ischemic reperfusion injury. Further study demonstrated that XQ-1H combined with clopidogrel lessened TUNEL positive cells, up-regulated bcl-2 expression notably and down-regulated bax expression as compared to both XQ-1H and clopidogrel individually. In addition, a rapid, sensitive UPLC-MS/MS method was developed to quantify the concentration of XQ-1H in MCAO/R rats. Our pharmacokinetic results showed that clopidogrel significantly increased the exposure of XQ-1H, increased the peak plasma concentration (C_max), area under the curve (AUC) and slowed elimination of XQ-1H in the co-administered group. Besides, for further exploring which CYP450 isoforms are involved in the XQ-1H metabolism, XQ-1H was incubated in human liver microsomes (HLMs) system with or without P450 isoform-selective inhibitors. Our results revealed that clopidogrel altered pharmacokinetics of XQ-1H potentially and subsequently enhanced the pharmacological effect of XQ-1H. Moreover, XQ-1H could be applied as an efficacious neuroprotective agent for ischemic stroke because of its considerable effect on averting neuronal apoptosis.

LncRNA KCNQ1OT1 contributes to oxygen-glucose-deprivation/reoxygenation-induced injury via sponging miR-9 in cultured neurons to regulate MMP8

Our study proposed to investigate the function of potassium voltage-gated channel sub-family Q member 1 opposite strand 1 (KCNQ1OT1) in cerebral ischemia-reperfusion (I/R) injury and the underlying mechanism. We constructed an oxygen-glucose-deprivation/reoxygenation (OGD/R) model using the primary cortical neurons to mimic the cerebral I/R injury in vitro. Small inference RNA (siRNA) was used to silencing KCNQ1OT1. Dual luciferase assay was conducted to verify the interaction between KCNQ1OT1 and miR-9 and interaction between miR-9 and MMP8. CCK8 assay and flow cytometry analysis were applied for determing the viability and apoptosis of neurons, accordingly. QPCR and Western blot were performed to determine the RNA and protein expression. Our outcomes revealed that the expression of KCNQ1OT1 in cultured neurons was notably enhanced after suffered to OGD/R. Knockdown of KCNQ1OT1 weakened OGD/R-induced injury in neurons. Moreover, depletion of KCNQ1OT1 lead to the up-regulation of miR-9 and down-regulation of MMP8. Dual luciferase target validation assays demonstrated that KCNQ1OT1 directly interact with miR-9 and MMP8 is a direct target of miR-9, suggesting that KCNQ1OT1/miR-9/MMP8 might constitute the competing endogenous RNA (ceRNA) mechanism. Knockdown of MMP8 or up-regulation of miR-9 also could weaken OGD/R-induced injury. Furthermore, cells co-transfected with si-KCNQ1OT1, miR-9 mimic and si-MMP8 could significantly abolish the injury on neurons caused by OGD/R. Taken together, our data manifested that KCNQ1OT1 possibly acts as a facilitator in cerebral I/R injury through modulating miR-9/MMP8 axis as a ceRNA.

Ginkgolide B ameliorates myocardial ischemia reperfusion injury in rats via inhibiting endoplasmic reticulum stress

Purpose

Ginkgolide B (GB) is a terpene lactone component found in Ginkgo biloba, which has a protective role on ischemia reperfusion (I/R) injury. This study was aimed at exploring the protective mechanism of GB on the myocardial I/R.

Patients and methods

Myocardial I/R model was established on Sprague Dawley rats. The levels of cardiac troponin I, cardiac troponin T, lactic dehydrogenase, and myoglobin were determined by a 200FR NEO automatic biochemical analyzer. Histological examination was performed through HE and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling staining. The expression levels of p-PERK, p-IRE1α, ATF6, p-AKT, and mTOR were detected by Western blot.

Results

The results exhibited that GB treatment suppressed the high levels of cardiac troponin I, cardiac troponin T, lactic dehydrogenase, and myoglobin and ameliorated the damaged and irregularly arranged myocardial cells induced by I/R injury significantly, indicating that GB could ameliorate myocardial I/R injury. Moreover, the high expression levels of endoplasmic reticulum (ER) stress key proteins caused by I/R injury were suppressed significantly by GB treatment, including p-PERK, p-IRE1α, and ATF6. GB treatment also decreased the number of apoptotic cells compared with I/R group. In addition, activation of ER stress by Tunicamycin treatment could counteract the protective effects of GB on I/R injury, suggesting that GB ameliorated myocardial I/R injury through inhibition of ER stress-induced apoptosis. Finally, the decreased p-AKT and p-mTOR expressions caused by I/R injury were upregulated by GB and inhibition of PI3K/AKT/mTOR pathway by LY294002 abolished the protective effects of GB on I/R injury, indicating that GB activated PI3K/AKT/mTOR pathway during I/R injury.

Conclusion

GB protected against myocardial I/R injury through inhibiting ER stress-induced apoptosis via PI3K/AKT/mTOR signaling pathway.

Ginkgolide B ameliorates NLRP3 inflammasome activation after hypoxic-ischemic brain injury in the neonatal male rat

INTRODUCTION

Perinatal hypoxic-ischemic (HI) insult is an important cause of brain injury in neonates. The development of novel treatment strategies for neonates with HI brain injury is urgently needed. Ginkgolide B (GB) is a main component of Ginkgo biloba extracts with a long history of use in traditional Chinese medicine. However, it is unknown whether GB could play a protective role in hypoxic stress in immature animals.

METHODS

Using neonatal hypoxic-ischemic (HI) brain injury model of rat pups, neurological score, infarct size, and brain edema were evaluated after HI injury. The activation of microglia and the production of IL-1β and IL-18 were detected by immunohistochemistry and ELISA, respectively. A priming signal (NF-κB P65) and an activation signal (Caspase-1) of NLRP3 inflammasome activation were detected by western blot analyses.

RESULTS

GB administrated 30 min prior to ischemia induction can improve neurological disorder, reduce infarct volume and alleviate cerebral edema. Compared with the HI groups, GB inhibited the activation of microglia and decreased the production of IL-1β and IL-18 in neocortex. Furthermore, GB reduced NLRP3 expression mainly in microglia, and significantly inhibited the expression of Caspase-1 and the nuclear translocation of NF-κB P65, preventing NLRP3 inflammasome activation.

CONCLUSIONS

GB ameliorates hypoxic-ischemic brain injury in the neonatal male rat via inhibiting NLRP3 inflammasome activation.

Pharmacokinetic and metabolomic analyses of the neuroprotective effects of salvianolic acid A in a rat ischemic stroke model

Salvianolic acid A (SAA), a water-soluble phenolic acid isolated from the root of Dan Shen, displays distinct antioxidant activity and effectiveness in protection against cerebral ischemia/reperfusion (I/R) damage. However, whether SAA can enter the central nervous system and exert its protective effects by directly targeting brain tissue remains unclear. In this study, we evaluated the cerebral protection of SAA in rats subjected to transient middle cerebral artery occlusion (tMCAO) followed by reperfusion. The rats were treated with SAA (5, 10 mg/kg, iv) when the reperfusion was performed. SAA administration significantly decreased cerebral infarct area and the brain water content, attenuated the neurological deficit and pathology, and enhanced the anti-inflammatory and antioxidant capacity in tMCAO rats. The concentration of SAA in the plasma and brain was detected using LC-MS/MS. A pharmacokinetic study revealed that the circulatory system exposure to SAA was equivalent in the sham controls and I/R rats, but the brain exposure to SAA was significantly higher in the I/R rats than in the sham controls (fold change of 9.17), suggesting that the enhanced exposure to SAA contributed to its cerebral protective effect. Using a GC/MS-based metabolomic platform, metabolites in the serum and brain tissue were extracted and profiled. According to the metabolomic pattern of the tissue data, SAA administration significantly modulated the I/R-caused perturbation of metabolism in the brain to a greater extent than that in the serum, demonstrating that SAA worked at the brain tissue level rather than the whole circulation system. In conclusion, a larger amount of SAA enters the central nervous system in ischemia/reperfusion rats to facilitate its protective and regulatory effects on the perturbed metabolism.

Neuroprotective effects of Ginkgo biloba extract and Ginkgolide B against oxygen-glucose deprivation/reoxygenation and glucose injury in a new in vitro multicellular network model

Acute ischemic stroke (AIS), as the third leading cause of death worldwide, is characterized by its high incidence, mortality rate, high incurred disability rate, and frequent reoccurrence. The neuroprotective effects of Ginkgo biloba extract (GBE) against several cerebral diseases have been reported in previous studies, but the underlying mechanisms of action are still unclear. Using a novel in vitro rat cortical capillary endothelial cell-astrocyte-neuron network model, we investigated the neuroprotective effects of GBE and one of its important constituents, Ginkgolide B (GB), against oxygen-glucose deprivation/reoxygenation and glucose (OGD/R) injury. In this model, rat cortical capillary endothelial cells, astrocytes, and neurons were cocultured so that they could be synchronously observed in the same system. Pretreatment with GBE or GB increased the neuron cell viability, ameliorated cell injury, and inhibited the cell apoptotic rate through Bax and Bcl-2 expression regulation after OGD/R injury. Furthermore, GBE or GB pretreatment enhanced the transendothelial electrical resistance of capillary endothelial monolayers, reduced the endothelial permeability coefficients for sodium fluorescein (Na-F), and increased the expression levels of tight junction proteins, namely, ZO-1 and occludin, in endothelial cells. Results demonstrated the preventive effects of GBE on neuronal cell death and enhancement of the function of brain capillary endothelial monolayers after OGD/R injury in vitro; thus, GBE could be used as an effective neuroprotective agent for AIS/reperfusion, with GB as one of its significant constituents.

Neuroprotective Effect of Oxysophocarpine by Modulation of MAPK Pathway in Rat Hippocampal Neurons Subject to Oxygen-Glucose Deprivation and Reperfusion

Oxysophocarpine (OSC), an alkaloid isolated from Sophora flavescens Ait, has been traditionally used as a medicinal agent based on the observed pharmacological effects. In this study, the direct effect of OSC against neuronal injuries induced by oxygen and glucose deprivation (OGD) in neonatal rat primary-cultured hippocampal neurons and its mechanisms were investigated. Cultured hippocampal neurons, which were exposed to OGD for 2 h followed by a 24 h reoxygenation, were used as an in vitro model of ischemia and reperfusion. 2-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and lactate dehydrogenase (LDH) assay were used to confirm neural damage and to further evaluate the protective effects of OSC. The concentration of intracellular-free calcium [Ca²⁺]_i and mitochondrial membrane potential (MMP) were measured to determine the intracellular mechanisms and to further estimate the degree of neuronal damage. Changes in expression of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, p-ERK1/2, p-JNK1/2, and p-p38 MAPK were also observed in the in vitro model. It was shown that OSC (0.8, 2, or 5 µmol/L) significantly attenuated the increased absorbance of MTT, and the release of LDH manifests the neuronal damage by the OGD/R. Meanwhile, the pretreatment of the neurons during the reoxygenation period with OSC significantly increased MMP; it also inhibited [Ca²⁺]_i the elevation in a dose-dependent manner. Furthermore, the pretreatment with OSC (0.8, 2, or 5 µmol/L) significantly down-regulated expressions of IL-1β, TNF-α, p-ERK1/2, p-JNK1/2, and p-p38 MAPK in neonatal rat primary-cultured hippocampal neurons induced by OGD/R injury. In conclusion, OSC displays a protective effect on OGD-injured hippocampal neurons by attenuating expression of inflammatory factors via down-regulated the MAPK signaling pathway.

Ginkgolides and bilobalide protect BV2 microglia cells against OGD/reoxygenation injury by inhibiting TLR2/4 signaling pathways

Ginkgolide and bilobalide are major trilactone constituent of Ginkgo biloba leaves and have been shown to exert powerful neuroprotective properties. The aims of this study were to observe the inhibitory effects of ginkgolide and bilobalide on the activation of microglial cells induced by oxygen-glucose deprivation and reoxygenation (OGD/R) and the specific mechanisms by which these effects are mediated. For detecting whether ginkgolide and bilobalide increased cell viability in a dose-dependent manner, BV2 cells were subjected to oxygen-glucose deprivation for 4 h followed by 3 h reoxygenation with various concentrations of drugs (6.25, 12.5, 25, 50, and 100 μg/ml). The extent of apoptosis effect of OGD/R with or without ginkgolide and bilobalide treatment were also measured by Annexin V-FITC/PI staining. Similarly, the levels of pro-inflammatory cytokines TNF-α, IL-1β, IL-6, IL-8, and IL-10 were detected using a specific Bio-Plex Pro™ Reagent Kit. The effects of ginkgolide and bilobalide on protein levels of TLR2/4, MyD88, p-TAK1, p-IKKβ, p-IkBα, NF-κB p65, Bcl-2, Bax, Bak, RIP3, cleaved-Caspase-3, cleaved PARP-1 and cellular localization of NF-κB p65 were evaluated by Western blot and double-labeled immunofluorescence staining, respectively. OGD/R significantly decreased the cell viability and increased the release of IL-1β, IL-6, IL-8, IL-10, TNF-α in BV2 microglia cells; these effects were suppressed by ginkgolide and bilobalide. Meanwhile, ginkgolide and bilobalide also attenuated the OGD/R-induced increases in TLR2, TLR4, MyD88, Bak, RIP3 levels and reversed cleaved caspase-3/caspase-3, Bax/Bcl-2 and cleaved PARP-1/PARP-1 ratio. Furthermore, ginkgolide and bilobalide also downregulated p-TAK1, p-IkBα, and p-IKKβ and inhibited the OGD/R-induced transfer of NF-κB p65 from cytoplasm to nucleus in BV2 microglia cells. The results showed that ginkgolide and bilobalide can inhibit OGD/R-induced production of inflammatory factors in BV2 microglia cells by regulating the TLRs/MyD88/NF-κB signaling pathways and attenuating inflammatory response. The possible mechanism of anti-inflammatory and neuroprotective effects of ginkgolides results from the synergistic reaction among each monomer constituents.

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.

Clematichinenoside protects blood brain barrier against ischemic stroke superimposed on systemic inflammatory challenges through up-regulating A20

Suppression of excessive inflammation can ameliorate blood brain barrier (BBB) injury, which shows therapeutic potential for clinical treatment of brain injury induced by stroke superimposed on systemic inflammatory diseases. In this study, we investigated whether and how clematichinenoside (AR), an anti-inflammatory triterpene saponin, protects brain injury from stroke superimposed on systemic inflammation. Lipopolysaccharide (LPS) was intraperitoneally injected immediately after middle cerebral artery occlusion (MCAO) in rats. Rat microvessel endothelial cells (rBMECs) were exposed to hypoxia/reoxygenation (H/R) coexisting with LPS. The results revealed that AR suppressed the excessive inflammation, restored BBB dysfunction, alleviated brain edema, decreased neutrophil infiltration, lessened neurological dysfunction, and decreased infarct rate. Further study demonstrated that the expression of nucleus nuclear factor kappa B (NF-κB), inducible nitric oxide synthase (iNOS), intercellular adhesion molecule-1 (ICAM-1), tumor necrosis factor-α (TNF-α) and interlukin-1β (IL-1β) were suppressed by AR via zinc finger protein A20. Besides, AR increased in vitro BBB integrity through A20. In conclusion, AR alleviated cerebral inflammatory injury through A20-NF-κB signal pathway, offering an alternative medication for stroke associated with systemic inflammatory diseases.

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.

Ginkgolide B prevents cathepsin-mediated cell death following cerebral ischemia/reperfusion injury

Ginkgolide B (GB) has been shown to exert neuroprotective effects against cerebral ischemia/reperfusion (I/R) injury. However, the underlying mechanism by which GB prevents ischemic cell death remains unclear. Lysosomal proteases, including cathepsins B and L, have been implicated in ischemic cell death following reperfusion. Therefore, in the present study, we investigated the role of GB with respect to cathepsin-mediated cell death following I/R. Both the expression and enzymatic activity of cathepsins B and L were significantly increased in the ischemic cortex following cerebral I/R injury. We found that GB treatment markedly decreased the activity and expression of cathepsins B and L following I/R. Moreover, GB reduced necrotic and apoptotic cell death following I/R. These data strongly suggest that GB prevents cathepsin-mediated cell death following focal cerebral I/R injury, and they might provide new insights into the mechanism of the neuroprotective effects of GB.

Vascular calcification in diabetes: mechanisms and implications

Cardiovascular disease (CVD) remains the leading cause of death among adults with diabetes, and CVD prevention remains a major challenge. Coronary artery calcium (CAC) score measured by electron beam tomography (EBT) or multi-slice detector computed tomography correlates closely with plaque burden and coronary angiography, and predicts coronary events independently of other risk factors. Further, progression of CAC over several years has been shown to predict increased mortality. Coronary calcification is an active process strongly associated with atherosclerotic plaque evolution and is an accepted surrogate endpoint in studies of patients with diabetes older than 30. In this review, recent findings regarding the mechanisms and implications of vascular calcification in diabetes will be discussed.