Neuroprotective effect of ginkgolide K against acute ischemic stroke on middle cerebral ischemia occlusion in rats

Ginkgolide injections in meglumine, combined with edaravone, significantly increases the efficacy in acute ischemic stroke: A meta-analysis

Objective

This study aimed to evaluate the efficacy of combining diterpene ginkgolide meglumine injection (DGMI) with edaravone for the treatment of acute ischemic stroke. This is particularly relevant because Western drugs, excluding intravenous thrombolysis, have shown limited success.

Methods

A comprehensive search was conducted using multiple databases, including PubMed, Cochrane Library, Web of Science, China National Knowledge Infrastructure WanFang, VIP, and Chinese Biomedical Database (CBM) until June 2023. The data were analyzed using fixed-effects and random-effects models in Review Manager. The mean difference with 95% confidence interval was calculated for each outcome.

Results

Eighteen studies involving 1,636 participants were included in the analysis. The DGMI group showed significant reductions in the National Institutes of Health Stroke Scale (NIHSS) score, modified Rankin Scale (mRS) score, and C-reactive protein (CRP) level, compared to the control group. Furthermore, the DGMI group showed a significant improvement in superoxide dismutase (SOD) levels and a reduction in malondialdehyde (MDA) levels. The combination of DGMI and edaravone was more effective in reducing neuron-specific enolase (NSE) levels following brain tissue injury than edaravone alone. Additionally, DGMI complemented edaravone in reducing rheological parameters associated with ischemic stroke, including hematocrit, plasma viscosity, platelet adhesion rate, and erythrocyte deformation index.

Conclusion

The combination of DGMI and edaravone significantly improved the therapeutic efficacy in patients with acute ischemic stroke. However, more extensive and high-quality clinical trials are required to validate these underlying mechanisms.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=260215, identifier: PROSPERO (CRD42021260215).

Natural Fatty Acid Guards against Brain Endothelial Cell Death and Microvascular Pathology following Ischemic Insult in the Presence of Acute Hyperglycemia

Ischemic stroke is worsened by the presence of sudden high blood sugar levels, even in individuals without pre-existing diabetes. This elevated glucose concentration hampers the ability of energy-starved brain cells to efficiently use it as a source of energy. Consequently, this leads to the production of abundant amounts of toxic glucose metabolites, which trigger oxidative stress in the brain milieu, particularly in the microvasculature of the brain. A prominent feature of this oxidative stress is the demise of endothelial cells, causing detrimental changes in blood vessels, including a reduction in their vascular diameter, a decreased efficiency of vessel proliferation, and the impaired integrity of tight junctions. These vascular pathologies contributed to an increase in the volume of damaged tissues (infarct), an exacerbation of brain swelling (edema), and a decline in cognitive and motor functions. In a mouse model of ischemic stroke with induced acute hyperglycemia, a naturally occurring saturated fatty acid provides protective cover to the microvasculature by preventing damage related to oxidative stress. Our current research revealed that lauric acid (LA) attenuated infarct volume and reduced brain edema by reducing endothelial cell death, enhancing vessels' diameter, promoting vascular angiogenesis, and stabilizing barrier functions. Animals administered with this natural compound showed a significant reduction in 4-HNE-positive vessels. In conclusion, natural saturated fatty acids help to preserve brain microvascular functions following ischemic insults in the presence of acute hyperglycemia.

Ginkgolide A improves the pleiotropic function and reinforces the neuroprotective effects by mesenchymal stem cell-derived exosomes in 6-OHDA-induced cell model of Parkinson's disease

Parkinson's disease (PD) is a common disorder attributed to the loss of midbrain dopamine (mDA) neurons and reduced dopamine secretion. Currently, the treatment regimes for PD comprise deep brain stimulations, however, it attenuates the PD progression marginally and does not improve neuronal cell death. We investigated the function of Ginkgolide A (GA) to reinforce Wharton's Jelly-derived mesenchymal stem cells (WJMSCs) for treating the in vitro model of PD. GA enhanced the self-renewal, proliferation, and cell homing function of WJMSCs as assessed by MTT and transwell co-culture assay with a neuroblastoma cell line. GA pre-treated WJMSCs can restore 6-hydroxydopamine (6-OHDA)-induced cell death in a co-culture assay. Furthermore, exosomes isolated from GA pre-treated WJMSCs significantly rescued 6-OHDA-induced cell death as determined by MTT assay, flow cytometry, and TUNEL assay. Western blotting showed that apoptosis-related proteins were decreased following GA-WJMSCs exosomal treatment which further improved mitochondrial dysfunction. We further demonstrated that exosomes isolated from GA-WJMSCs could restore autophagy using immunofluorescence staining and immunoblotting assay. Finally, we used the alpha-synuclein recombinant protein and found that exosomes derived from GA-WJMSCs led to the reduced aggregation of alpha-synuclein compared to that in control. Our results suggested that GA could be a potential candidate for strengthening stem cell and exosome therapy for PD.

Neuroprotective efficacy of N-t-butylhydroxylamine (NtBHA) in transient focal ischemia in rats

The pharmacological or toxicological activities of the degradation products of drug candidates have been unaddressed during the drug development process. Ischemic stroke accounts for 80% of all strokes and is responsible for considerable mortality and disability worldwide. Despite decades of research on neuroprotective agents, tissue plasminogen activators (t-PA), a thrombolytic agent, remains the only approved acute stroke pharmacological therapy. NXY-059, a free radical scavenger, exhibited striking neuroprotective properties in preclinical models and met all the criteria established by the Stroke Academic Industry Roundtable (STAIR) for a neuroprotective agent. In phase 3 clinical trials, NXY-059 exhibited significant neuroprotective effects in one trial (SAINT-I), but not in the second (SAINT-II). Some have hypothesized that N-t-butyl hydroxylamine (NtBHA), a breakdown product of NXY-059 was the actual neuroprotective agent in SAINT-I and that changes to the formulation of NXY-059 to prevent its breakdown to NtBHA in SAINT -II was the reason for the lack of efficacy. We evaluated the neuroprotective effect of NtBHA in N-methyl-D-aspartate (NMDA)-treated primary neurons and in rat focal cerebral ischemia. NtBHA significantly attenuated infarct volume in rat transient focal ischemia, and attenuated NMDA-induced cytotoxicity in primary cortical neurons. NtBHA also reduced free radical generation and exhibited mitochondrial protection.

Challenges and Improvements of Novel Therapies for Ischemic Stroke

Stroke is the third most common disease all over the world, which is regarded as a hotspot in medical research because of its high mortality and morbidity. Stroke, especially ischemic stroke, causes severe neural cell death, and no effective therapy is currently available for neuroregeneration after stroke. Although many therapies have been shown to be effective in preclinical studies of ischemic stroke, almost none of them passed clinical trials, and the reasons for most failures have not been well identified. In this review, we focus on several novel methods, such as traditional Chinese medicine, stem cell therapy, and exosomes that have not been used for ischemic stroke till recent decades. We summarize the proposed basic mechanisms underlying these therapies and related clinical results, discussing advantages and current limitations for each therapy emphatically. Based on the limitations such as side effects, narrow therapeutic window, and less accumulation at the injury region, structure transformation and drug combination are subsequently applied, providing a deep understanding to develop effective treatment strategies for ischemic stroke in the near future.

Medicinal herbs and nutritional supplements for dementia therapy: potential therapeutic targets and clinical evidence

Spices and herbs have been used for medicinal purposes for centuries. Also, in the last decades, the use of different nutritional supplements has been implemented to treat all kinds of diseases, including those that present an alteration in cognitive functioning. Dementia is a clinical syndrome in which a person's mental and cognitive capacities gradually decline. As the disease progresses, the person's autonomy diminishes. As there is not an effective treatment to prevent progressive deterioration in many of these pathologies, nutritional interventions have been, and still are, one of the most widely explored therapeutic possibilities. In this review, we have discussed a great number of potentially interesting plants, nutritional derivatives and probiotics for the treatment of dementia around the world. Their action mechanisms generally involve neuroprotective effects via anti-inflammatory, antioxidant, anti-apoptotic, b-amyloid and tau anti-aggregate actions; brain blood flow improvement, and effects on synaptic cholinergic and dopaminergic neurotransmission, which may optimize cognitive performance in patients with cognitive impairment. As for their efficacy in patients with cognitive impairment and/or dementias, evidence is still scarce and/or their outcomes are controversial. We consider that many of these substances have promising therapeutic properties. Therefore, the scientific community has to continue with a more complete research focused on both identifying possible action mechanisms and carrying out clinical trials, preferably randomized double-blind ones, with a greater number of patients, a long-term follow-up, dose standardization and the use of current diagnosis criteria.

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.

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.

Nose to brain drug delivery - A promising strategy for active components from herbal medicine for treating cerebral ischemia reperfusion

Cerebral ischemia reperfusion injury (CIRI), one of the major causes of death from stroke in the world, not only causes tremendous damage to human health, but also brings heavy economic burden to society. Current available treatments for CIRI, including mechanical therapies and drug therapies, are often accompanied by significant side-effects. Therefore, it is necessary to discovery new strategies for treating CIRI. Many studies have confirmed that the herbal medicine has the advantages of abundant resources, good curative effect and little side effects, which can be used as potential drug for treatment of CIRI through multiple targets. It's known that oral administration commonly has low bioavailability, and injection administration is inconvenient and unsafe. Many drugs can't delivery to brain through routine pathways due to the blood-brain-barrier (BBB). Interestingly, increasing evidences have suggested the nasal administration is a potential direct route to transport drug into brain avoiding the BBB and has the characteristics of high bioavailability for treating brain diseases. Therefore, intranasal administration can be treated as an alternative way to treat brain diseases. In the present review, effective methods to treat CIRI by using active ingredients derived from herbal medicine through nose to brain drug delivery (NBDD) are updated and discussed, and some related pharmacological mechanisms have also been emphasized. Our present study would be beneficial for the further drug development of natural agents from herbal medicines via NBDD.

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.

The neuroprotective mechanisms of ginkgolides and bilobalide in cerebral ischemic injury: a literature review

The incidence and mortality of strokes have increased over the past three decades in China. Ischemic strokes can cause a sequence of detrimental events in patients, including increased permeability and dysfunction of the blood-brain barrier, brain edema, metabolic disturbance, endoplasmic reticulum stress, autophagy, oxidative stress, inflammation, neuron death and apoptosis, and cognitive impairment. Thrombolysis using recombinant tissue plasminogen activator (rtPA) and mechanical embolectomy with a retrievable stent are two recognized strategies to achieve reperfusion after a stroke. Nevertheless, rtPA has a narrow therapeutic timeframe, and mechanical embolectomy has limited rates of good neurological outcomes. EGb761 is a standardized and extensively studied extract of Ginkgo biloba leaves. The ginkgolides and bilobalide that constitute a critical part of EGb761 have demonstrated protective properties towards cerebral injury. Ginkgolides include Ginkgolide A (GA), Ginkgolide B (GB), Ginkgolide C (GC), Ginkgolide J (GJ), Ginkgolide K (GK), Ginkgolide L (GL), and Ginkgolide M (GM). This review seeks to elucidate the neuroprotective effects and mechanisms of ginkgolides, especially GA and GB, and bilobalide in cerebral injury following ischemic strokes.

Ginkgolide K supports remyelination via induction of astrocytic IGF/PI3K/Nrf2 axis

Although several therapies are approved, none promote re-myelination in multiple sclerosis (MS) patients, limiting their ability for sustained recovery. Thus, treatment development in MS has the opportunity to tackle the challenges, including experimental therapies targeting neuroprotection and re-myelination. Here, we provide a novel therapeutic target for Ginkgolide K (GK) that is now becoming a very critical natural compound to treat demyelination and neurodegeneration. GK improves behavioral dysfunction and demyelination in cuprizone (CPZ) model, followed by the migration and enrichment of astrocytes in the corpus callosum. Both in vitro and in vivo experiments demonstrates that GK triggers the upregulation of Nrf2/HO-1 in astrocytes and inhibition of p-NF-kB/p65, which is associated with the outcome of anti-inflammation and anti-oxidation by suppressing the production of IL-6 and TNFα as well as nitric oxide and iNOS in astrocytes. Further findings suggest that IGF/PI3K, but not BDNF, was induced in the corpus callosum after GK treatment, revealing that Nrf2 activation inhibited caspase-3 and apoptosis in O4+ oligodendrocytes possibly through IGF/PI3K signaling molecules. Since the current immunomodulatory therapies for MS have failed to prevent patients from entering the progressive phase of the disease, thus targeting Nrf2 in astrocytes with GK would be an ideal strategy for myelin protection and regeneration.

The therapeutic potential of ginkgolide K in experimental autoimmune encephalomyelitis via peripheral immunomodulation

Multiple sclerosis is a T cell-mediated inflammatory, demyelinating disease of the central nervous system, accompanied by neuronal degeneration. Based on the anti-inflammatory effects of Ginkgolide K (GK), a platelet activating factor antagonist, we explored the possible application of GK in the treatment of MS. The results showed that GK effectively ameliorated the severity of experimental autoimmune encephalomyelitis. The intervention of GK inhibited the infiltration of inflammatory cells and demyelination in the spinal cord. At the same time, the expression of the inflammation-related molecules TLR4, NF-κB, and COX2 in the spinal cord was significantly lower in the GK-treated mice, indicating that GK intervention can inhibit the inflammatory microenvironment of the spinal cord in EAE mice. In mouse spleen lymphocytes, GK increased the proportion of regulatory T cells (Treg) and reduced the proportion of T helper 17 cells (Th17), modifying the imbalance between Th17/Treg cells. Additionally, GK shifted macrophage/microglia polarization from M1 to M2 cell type. Importantly, GK inhibited the expression of chemotactic molecules CCL-2, CCL-3 and CCL-5, thereby limiting the migration of inflammatory cells to the spinal cord. Our results provide the possibility that GK may be a promising naturally small molecule compound for the future treatment of MS.

Comparing the role of Ginkgolide B and Ginkgolide K on cultured astrocytes exposed to oxygen‑glucose deprivation

Ginkgolide B (GB) and ginkgolide K (GK) are two main active monomers of ginkgolides that present a unique group of diterpenes found naturally in the leaves of the Ginkgo biloba tree. Astrocytes are the most abundant cell type within the central nervous system (CNS) and serve essential roles in maintaining healthy brain function. The present study compared the biological effects of GB and GK on astrocytes exposed to oxygen-glucose deprivation (OGD). The results demonstrated that GB and GK exhibit many different actions. The level of the platelet-activating factor (PAF) was elevated on astrocytes exposed to OGD, and inhibited by GB and GK treatment. Although GB and GK inhibited the expression of p-NF-κB/p65, GK exerted stronger anti-inflammatory and antioxidant effects on astrocytes exposed to OGD than GB by inhibiting interleukin (IL)-6 and tumor necrosis factor-α, and inducing IL-10 and the nuclear factor-erythroid 2-related factor 2/HO-1 signaling pathway. When compared with GB treatment, GK treatment maintained high levels of phosphoinositide 3-kinase/phosphorylated-protein kinase B expression, and induced a marked upregulation of Wnt family member 1 and brain derived neurotrophic factor, indicating that GK, as a natural plant compound, may have more attractive prospects for clinical application in the treatment of neurological disorders than GB.

A Possible Role for Platelet-Activating Factor Receptor in Amyotrophic Lateral Sclerosis Treatment

Amyotrophic lateral sclerosis (ALS) is the third most prevalent neurodegenerative disease affecting upper and lower motor neurons. An important pathway that may lead to motor neuron degeneration is neuroinflammation. Cerebrospinal Fluids of ALS patients have increased levels of the inflammatory cytokine IL-18. Because IL-18 is produced by dendritic cells stimulated by the platelet-activating factor (PAF), a major neuroinflammatory mediator, it is expected that PAF is involved in ALS. Here we show pilot experimental data on amplification of PAF receptor (PAFR) mRNA by RT-PCR. PAFR is overexpressed, as compared to age matched controls, in the spinal cords of transgenic ALS SOD1-G93A mice, suggesting PAF mediation. Although anti-inflammatory drugs have been tested for ALS before, no clinical trial has been conducted using PAFR specific inhibitors. Therefore, we hypothesize that administration of PAFR inhibitors, such as Ginkgolide B, PCA 4248 and WEB 2086, have potential to function as a novel therapy for ALS, particularly in SOD1 familial ALS forms. Because currently there are only two approved drugs with modest effectiveness for ALS therapy, a search for novel drugs and targets is essential.

Ginkgolide K promotes the clearance of A53T mutation alpha-synuclein in SH-SY5Y cells

Alpha-synuclein (α-syn) is associated to Parkinson's disease (PD). The aggregated form of α-syn has potential neurotoxicity. Thus, the clearance of α-syn aggregation is a plausible strategy to delay disease progression of PD. In our study, we found that the treatment of Ginkgolide B (GB) and Ginkgolide K (GK) reduced cell death, and enhanced cell proliferation in SH-SY5Y cells, which overexpressed A53T mutant α-syn. Surprisingly, GK, but not GB, promoted the clearance of A53T α-syn, which can be abolished by autophagy inhibitor 3-methyladenine, indicating that GK-induced autophagy intervened in the clearance of A53T α-syn. However, GK did not affect the NEDD4 that belongs to the ubiquitin ligase in the endosomal-lysosomal pathway. Furthermore, GK treatment inhibited the p-NF-kB/p65 and induced the PI3K, BDNF, and PSD-95. Taken together, GK increased the clearance of α-syn, reduced cell death, and triggered complex crosstalk between different signaling pathways. Although our results show a potentially new therapeutic candidate for PD, the details of this mechanism need to be further identified.

Plants-Derived Neuroprotective Agents: Cutting the Cycle of Cell Death through Multiple Mechanisms

Neuroprotection is the preservation of the structure and function of neurons from insults arising from cellular injuries induced by a variety of agents or neurodegenerative diseases (NDs). The various NDs including Alzheimer's, Parkinson's, and Huntington's diseases as well as amyotropic lateral sclerosis affect millions of people around the world with the main risk factor being advancing age. Each of these diseases affects specific neurons and/or regions in the brain and involves characteristic pathological and molecular features. Hence, several in vitro and in vivo study models specific to each disease have been employed to study NDs with the aim of understanding their underlying mechanisms and identifying new therapeutic strategies. Of the most prevalent drug development efforts employed in the past few decades, mechanisms implicated in the accumulation of protein-based deposits, oxidative stress, neuroinflammation, and certain neurotransmitter deficits such as acetylcholine and dopamine have been scrutinized in great detail. In this review, we presented classical examples of plant-derived neuroprotective agents by highlighting their structural class and specific mechanisms of action. Many of these natural products that have shown therapeutic efficacies appear to be working through the above-mentioned key multiple mechanisms of action.

The protective effects of hydrogen on HO-1 expression in the brainafter focal cerebral ischemia reperfusion in rats

BACKGROUND/AIM

The aim of this study was to investigate whether a hydrogen administration can produce neuroprotective effects after brain ischemia reperfusion in rats.

MATERIALS AND METHODS

A brain ischemia reperfusion injury was induced by a 2-h left middle cerebral artery occlusion (MCAO) using an intraluminal filament, followed by 46 h of reperfusion. A hydrogen-rich saline (1 mL/kg body weight i.p.) was administered at the beginning of reperfusion. Saline (1 mL/kg)-treated animals were used as the control. Sham-operated animals were also used. Subsequently, 48 h after the MCAO, histological alternations, heme oxygenase-1 (HO-1) expression, and levels of malondialdehyde (MDA) and superoxide dismutase (SOD) in the cerebral cortex and the hippocampus were examined.

RESULTS

Hydrogen significantly alleviated brain tissue histological damage, promoted HO-1 expression, upregulated levels of SOD, and decreased the levels of MDA in brain tissue after the ischemia reperfusion injury.

CONCLUSION

The results suggest that the neuroprotective effects of hydrogen may be mediated by promoting HO-1 expression and attenuated the oxidative injury.

Current Understanding of Platelet-Activating Factor Signaling in Central Nervous System Diseases

Platelet-activating factor (PAF) is a bioactive lipid mediator which serves as a reciprocal messenger between the immune and nervous systems. PAF, a pluripotent inflammatory mediator, is extensively expressed in many cells and tissues and has either beneficial or detrimental effects on the progress of inflammation-related neuropathology. Its wide distribution and various biological functions initiate a cascade of physiological or pathophysiological responses during development or diseases. Current evidence indicates that excess PAF accumulation in CNS diseases exacerbates the inflammatory response and pathological consequences, while application of PAF inhibitors or PAFR antagonists by blocking this signaling pathway significantly reduces inflammation, protects cells, and improves the recovery of neural functions. In this review, we integrate the current findings of PAF signaling in CNS diseases and elucidate topics less appreciated but important on the role of PAF signaling in neurological diseases. We propose that the precise use of PAF inhibitors or PAFR antagonists that target the specific neural cells during the appropriate temporal window may constitute a potential therapy for CNS diseases.

Ginkgolide K protects the heart against endoplasmic reticulum stress injury by activating the inositol-requiring enzyme 1α/X box-binding protein-1 pathway

BACKGROUND AND PURPOSE

Endoplasmic reticulum (ER) stress is increasingly recognized as an important causal factor of many diseases. Targeting ER stress has now emerged as a new therapeutic strategy for treating cardiovascular diseases. Here, we investigated the effects and underlying mechanism of ginkgolide K (1,10-dihydroxy-3,14-didehydroginkgolide, GK) on cardiac ER stress.

EXPERIMENTAL APPROACH

Cell death, apoptosis and ER stress-related signalling pathways were measured in cultured neonatal rat cardiomyocytes, treated with the ER stress inducers tunicamycin, hydrogen peroxide and thapsigargin. Acute myocardial infarction was established using left coronary artery occlusion in mice, and infarct size was measured by triphenyltetrazolium chloride staining. Echocardiography was used to assess heart function and transmission electron microscopy for evaluating ER expansion.

KEY RESULTS

Ginkgolide K (GK) significantly decreased ER stress-induced cell death in both in vitro and in vivo models. In ischaemic injured mice, GK treatment reduced infarct size, rescued heart dysfunction and ameliorated ER dilation. Mechanistic studies revealed that the beneficial effects of GK occurred through enhancement of inositol-requiring enzyme 1α (IRE1α)/X box-binding protein-1 (XBP1) activity, which in turn led to increased ER-associated degradation-mediated clearance of misfolded proteins and autophagy. In addition, GK was also able to partly repress the pro-apoptotic action of regulated IRE1-dependent decay and JNK pathway.

CONCLUSIONS AND IMPLICATIONS

In conclusion, GK acts through selective activation of the IRE1α/XBP1 pathway to limit ER stress injury. GK is revealed as a promising therapeutic agent to ameliorate ER stress for treating cardiovascular diseases.

Treatment of acute cerebral ischemia using animal models: a meta-analysis

BACKGROUND

There are numerous potential treatments assessed for acute cerebral ischemia using animal models. This study aimed to assess the effect of these treatments in terms of infarct size and neurobehavioral change. This meta-analysis was conducted to determine if any of these treatments provide a superior benefit so that they might be used on humans.

METHODS

A systematic search was conducted using several electronic databases for controlled animal studies using only nonsurgical interventions for acute cerebral ischemia. A random-effects model was used.

RESULTS

After an extensive literature search, 145 studies were included in the analysis. These studies included 1408 treated animals and 1362 control animals. Treatments that had the most significant effect on neurobehavioral scales included insulin, various antagonists, including N-methyl-D-aspartate (NMDA) receptor antagonist ACEA1021, calmodulin antagonist DY-9760e, and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist YM872, and antiviral agents. Treatments providing the greatest effect on infarct size included statins, sphingosine-1-phosphate agonist (fingolimod), alcohol, angiotensin, and leukotrienes. Treatments offering the greatest reduction in brain water content included various agonists, including sphingosine-1-phosphate agonist fingolimod, statins, and peroxisome proliferator-activated receptor gamma (PPAR-γ). Treatment groups with more than one study all had high heterogeneity (I² > 80%), however, using meta-regression we determined several sources of heterogeneity including sample size of the treatment and control groups, the occlusion time, but not the year when the study was conducted.

CONCLUSIONS

Some treatments stand out when compared to others for acute cerebral ischemia in animals. Greater replication of treatment studies is required before any treatments are selected for future human trials.

Advances in Herbal Medicine for Treatment of Ischemic Brain Injury

Ischemic brain injury is one of the leading causes of death worldwide and has attracted a lot of attention in the field of drug discovery. Cerebral ischemia is a complex pathological process involving a series of mechanisms, including generation of free radicals, oxidative stress, disruption of the membrane function, release of neurotransmitters and apoptosis. Thrombolytic therapy is the most effective therapeutic strategy, but the benefits are far from being absolute. Increased attention in the field of drug discovery has been focused on using natural compounds from traditional medicinal herbs for neuroprotection, which appears to be a promising therapeutic option for cerebral ischemia with minimal systemic adverse effects that could limit their long term use. The scenario calls for extensive investigations which can result in the development of lead molecules for neuroprotection in the future. In this context, the present review focuses on possible mechanisms underlying the beneficial effects of herbal drugs in patients with cerebral ischemic injury. Natural compounds have been demonstrated to have neurofunctional regulatory actions with antioxidative, anti-inflammatory, calcium antagonizing and anti-apoptotic activities. Among the several leads obtained from plant sources as potential neuroprotective agents, resveratrol, EGb761, curcumin and epigallocatechin-3-gallate have shown significant therapeutic benefits in cerebral ischemic conditions. However, ligustilide, tanshinone, scutellarin and shikonin are the few lead molecules which are under investigation for treatment of cerebral ischemia.

Screening of radical-scavenging natural neuroprotective antioxidants from Swertia chirayita

To detect and identify natural antioxidants in Swertia chirayita with protective effect against cerebral infarction, a screening method, using column chromatography and cerebral ischemia-reperfusion injury in rat, was developed. Seventeen compounds were purposefully separated and identified by Nuclear Magnetic Resonance, Fourier Transform Infrared Spectroscopy, Ultraviolet Spectrum, and Mass Spectrometry. The purified compounds were further screened by radical scavenging activity and cerebral ischemia-reperfusion injury in rats. Two compounds showed apparent radical scavenging activity and neuroprotective activity. The two compounds were identified as 1-hydroxy-2,3,4,6-tetramethoxyxanthone and 1,5,8-trihydroxy-3-methoxy xanthone, and were preliminarily considered as primary natural neuroprotective antioxidants in Swertia chirayita. These two compounds (20 mg kg-1) markedly decreased infarct size to below 5%, and also caused a significant improvement of activities of superoxide dismutase (SOD) (92.90 ± 11.19 U ml-1), glutathione peroxidase (GSH-Px) (122.58 ± 12.31 μmol mg-1) and a decrease in the content of malondialdehyde (MDA) (3.98 ± 2.00 nmol ml-1) in serum. The two compounds showed strong capability for protective effects against cerebral damages induced by ischemia-reperfusion, and the protective effect may be related to the inhibition of lipid peroxidation. The use of the screening method based on tracing separation and ischemia reperfusion would provide a new way for detection of radical-scavenging and natural neuroprotective compounds from Swertia chirayita or complex matrices.

The effect of Ginkgo biloba on functional outcome of patients with acute ischemic stroke: a double-blind, placebo-controlled, randomized clinical trial

BACKGROUND

Acute ischemic stroke is a major cerebrovascular disease with potential morbidity and mortality. Despite the availability of thrombolytic therapy in some centers, risk factor modification and rehabilitation therapy are the mainstays of stroke management. There is supporting evidence that Ginkgo biloba may afford neuroprotection and improve the outcomes of patients with acute ischemic stroke.

METHODS

In a double-blind, placebo-controlled, randomized controlled trial, we assessed the efficacy of G biloba on functional outcome in patients with acute stroke. The National Institutes of Heath Stroke Scale (NIHSS) was used to measure functional outcome. A total of 102 patients with acute ischemic stroke were studied. All patients received either G biloba or placebo tablets for 4 months. This trial was registered to the Iranian Registry of Clinical Trials (www.irct.ir; trial IRCT138804212150N1).

RESULTS

There were 52 patients who received G biloba and 50 patients who were in the placebo group. Age, sex distribution, previous medical condition, and laboratory data did not have any significant difference between the 2 groups (P>.05). The mean difference of 4-month follow-up NIHSS scores and NIHSS scores at admission was 4.7±2.7 and 4.1±3.0 in the G biloba and placebo groups, respectively (P>.05). The primary outcome-a 50% reduction in the 4-month follow-up NIHSS score compared to the baseline NIHSS score-was reached in 17 patients (58.6%) and 5 patients (18.5%) in the G biloba and placebo groups, respectively (P<.05). The risk ratio and number needed to treat were 3.16 (confidence interval 1.35-7.39) and 2.50 (confidence interval 1.58-5.90), respectively. In addition, multivariate regression adjusted for age and sex revealed a significant NIHSS decline in the G biloba group compared to the placebo group (P<.05).

CONCLUSIONS

Our data suggest that G biloba may have protective effects in ischemic stroke. Therefore, the administration of G biloba is recommended after acute ischemic stroke.

Method parameters' impact on mortality and variability in rat stroke experiments: a meta-analysis

Background

Even though more than 600 stroke treatments have been shown effective in preclinical studies, clinically proven treatment alternatives for cerebral infarction remain scarce. Amongst the reasons for the discrepancy may be methodological shortcomings, such as high mortality and outcome variability, in the preclinical studies. A common approach in animal stroke experiments is that A) focal cerebral ischemia is inflicted, B) some type of treatment is administered and C) the infarct sizes are assessed. However, within this paradigm, the researcher has to make numerous methodological decisions, including choosing rat strain and type of surgical procedure. Even though a few studies have attempted to address the questions experimentally, a lack of consensus regarding the optimal methodology remains.

Methods

We therefore meta-analyzed data from 502 control groups described in 346 articles to find out how rat strain, procedure for causing focal cerebral ischemia and the type of filament coating affected mortality and infarct size variability.

Results

The Wistar strain and intraluminal filament procedure using a silicone coated filament was found optimal in lowering infarct size variability. The direct and endothelin methods rendered lower mortality rate, whereas the embolus method increased it compared to the filament method.

Conclusions

The current article provides means for researchers to adjust their middle cerebral artery occlusion (MCAo) protocols to minimize infarct size variability and mortality.

Novel multiple agents loaded PLGA nanoparticles for brain delivery via inner ear administration: in vitro and in vivo evaluation

The aim of this study was to develop novel multiple agents loaded poly (D,L-lactide-co-glycolide acid) (PLGA) nanoparticles (NPs) and evaluate their potential for brain delivery via inner ear administration. PLGA NPs loaded with salvianolic acid B (Sal B), tanshinone IIA (TS IIA) and panax notoginsenoside (PNS) were prepared by double emulsion/solvent evaporation method. It was observed that optimized NPs displayed satisfactory encapsulation efficiency and desired sustained-release characteristics. NPs following intratympanic administration (IT) in guinea pigs greatly improved drug distribution within the inner ear, cerebrospinal fluid (CSF) and brain tissues compared with intravenous administration (IV). Pharmacodynamic studies demonstrated that NPs following IT markedly inhibited oxidizing reactions and protected the brain from cerebral ischemia reperfusion (I/R) injury by upregulating superoxide dismutase (SOD) activity both in serum and brain tissues, simultaneously significantly reducing the levels of malondialdehyde (MDA) and nitric oxide synthase (NOS). Moreover intratympanic delivery did not cause injury of cochlear function by preliminary study on the toxicity. These findings suggested that PLGA NPs-based delivery system via inner ear administration was a promising candidate to brain delivery for the treatment of brain diseases.