Neuroprotection by tetramethylpyrazine against ischemic brain injury in rats

Neutrophil Targeting Platform Reduces Neutrophil Extracellular Traps for Improved Traumatic Brain Injury and Stroke Theranostics

Traumatic brain injuries (TBI) and stroke are major causes of morbidity and mortality in both developing and developed countries. The complex and heterogeneous pathophysiology of TBI and cerebral ischemia-reperfusion injury (CIRI), in addition to the blood-brain barrier (BBB) resistance, is a major barrier to the advancement of diagnostics and therapeutics. Clinical data showed that the severity of TBI and stroke is positively correlated with the number of neutrophils in peripheral blood and brain injury sites. Furthermore, neutrophil extracellular traps (NETs) released by neutrophils correlate with worse TBI and stroke outcomes by impairing revascularization and vascular remodeling. Therefore, targeting neutrophils to deliver NETs inhibitors to brain injury sites and reduce the formation of NETs can be an optimal strategy for TBI and stroke therapy. Herein, the study designs and synthesizes a reactive oxygen species (ROS)-responsive neutrophil-targeting delivery system loaded with peptidyl arginine deiminase 4 (PAD4) inhibitor, GSK484, to prevent the formation of NETs in brain injury sites, which significantly inhibited neuroinflammation and improved neurological deficits, and improved the survival rate of TBI and CIRI. This strategy may provide a groundwork for the development of targeted theranostics of TBI and stroke.

Bibliometric analysis of research progress on tetramethylpyrazine and its effects on ischemia-reperfusion injury

In recent decades, natural products have attracted worldwide attention and become one of the most important resources for pharmacological industries and medical sciences to identify novel drug candidates for disease treatment. Tetramethylpyrazine (TMP) is an alkaloid extracted from Ligusticum chuanxiong Hort., which has shown great therapeutic potential in cardiovascular and cerebrovascular diseases, liver and renal injury, as well as cancer. In this review, we analyzed 1270 papers published on the Web of Science Core Collection from 2002 to 2022 and found that TMP exerted significant protective effects on ischemia-reperfusion (I/R) injury that is the cause of pathological damages in a variety of conditions, such as ischemic stroke, myocardial infarction, acute kidney injury, and liver transplantation. TMP is limited in clinical applications to some extent due to its rapid metabolism, a short biological half-life and poor bioavailability. Obviously, the structural modification, administration methods and dosage forms of TMP need to be further investigated in order to improve its bioavailability. This review summarizes the clinical applications of TMP, elucidates its potential mechanisms in protecting I/R injury, provides strategies to improve bioavailability, which presents a comprehensive understanding of the important compound. Hopefully, the information and knowledge from this review can help researchers and physicians to better improve the applications of TMP in the clinic.

Cocrystallization improves the tabletability of ligustrazine despite a reduction in plasticity

Cocrystallization is an effective method for altering the tableting performance of crystals by modifying their mechanical properties. In this study, cocrystals of ligustrazine (LIG) with malonic acid (MA) and salicylic acid (SA) were investigated to better understand how modifying crystal structure can affect tableting properties. LIG suffered from overcompression at high pressures despite its high plasticity. Both LIG-MA and LIG-SA displayed lower plasticity than LIG, which was confirmed by both an in-die Heckel and energy framework analyses. The LIG-MA cocrystal displayed slightly worse tabletability than LIG, as expected from its lower plasticity. However, LIG-SA surprisingly showed improved tabletability despite its lower plasticity. This was explained by the higher bonding strength of LIG-SA compared with LIG. This work not only provided new examples of tabletability modulation through crystal engineering but also highlighted the risk of failed tabletability predictions based on plasticity alone. Instead, more reliable tabletability predictions of different crystal forms must consider the bonding area - bonding strength interplay.

A narrative review of potential neural repair poststroke: Decoction of Chinese angelica and peony in regulating microglia polarization through the neurosteroid pathway

Ischemic stroke is a major global health crisis, characterized by high morbidity and mortality rates. Although there have been significant advancements in treating the acute phase of this condition, there remains a pressing need for effective treatments that can facilitate the recovery of neurological functions. Danggui-Shaoyao-San (DSS), also known as the Decoction of Chinese Angelica and Peony, is a traditional Chinese herbal formula. It has demonstrated promising results in the regulation of microglial polarization and modulation of neurosteroid receptor expression, which may make it a potent strategy for promoting the recovery of neurological functions. Microglia, which plays a crucial role in neuroplasticity and functional reconstruction poststroke, is regulated by neurosteroids. This review posits that DSS could facilitate the recovery of neuronal function poststroke by influencing microglial polarization through the neurosteroid receptor pathway. We will further discuss the potential mechanisms by which DSS could enhance neural function in stroke, including the regulation of microglial activation, neurosteroid regulation, and other potential mechanisms.

Tetramethylpyrazine contributes to the neuroprotection in a rodent epileptic model of pentylenetetrazole-induced kindling

OBJECTIVES

In this study, tetramethylpyrazine (TMP) was evaluated for its therapeutic potential as an alternative therapy for epileptogenesis and its associated comorbidities in rats.

METHODS

The sub-convulsant dose of pentylenetetrazole (PTZ) (35 mg/kg, intraperitoneally) was injected on alternative days to produce kindling for 32 days and observed for seizure score percent of kindled animals in each group. After kindling, the animals were evaluated in models of anxiety, memory and predictive of depression. The neuroprotective effect of TMP was assessed by estimating the biochemical parameters in the cortex and hippocampus of the brain. Histopathological alterations were also observed in the cortex and hippocampus (CA1, CA3 and DG).

KEY FINDINGS

The administration of TMP reduced the seizure score and percentage of kindled animals dose-dependently. Furthermore, TMP significantly improved the behavioural parameters measured in the predictive models of depression but not in the anxiety and cognitive performances of the animals. The oxidative-nitrosative stress, excitotoxicity, neuroinflammation and histological alterations in the brain induced by PTZ were significantly mitigated by administering the TMP high dose of 60 mg/kg.

CONCLUSION

In conclusion, the TMP attenuated the depression behaviour in the PTZ-induced kindled rats, and reduced the oxidative-nitrosative stress, excitotoxicity, neuroinflammation and histological alterations of the brain.

Ligustrazine Nanoparticle Hitchhiking on Neutrophils for Enhanced Therapy of Cerebral Ischemia-Reperfusion Injury

Ischemic stroke is a refractory disease that endangers human health and safety owing to cerebral ischemia. Brain ischemia induces a series of inflammatory reactions. Neutrophils migrate from the circulatory system to the site of cerebral ischemia and accumulate in large numbers at the site of inflammation across the blood-brain barrier. Therefore, hitchhiking on neutrophils to deliver drugs to ischemic brain sites could be an optimal strategy. Since the surface of neutrophils has a formyl peptide receptor (FPR), this work modifies a nanoplatform surface by the peptide cinnamyl-F-(D)L-F-(D)L-F (CFLFLF), which can specifically bind to the FPR receptor. After intravenous injection, the fabricated nanoparticles effectively adhered to the surface of neutrophils in peripheral blood mediated by FPR, thereby hitchhiking with neutrophils to achieve higher accumulation at the inflammatory site of cerebral ischemia. In addition, the nanoparticle shell is composed of a polymer with reactive oxygen species (ROS)-responsive bond breaking and is encased in ligustrazine, a natural product with neuroprotective properties. In conclusion, the strategy of hitching the delivered drugs to neutrophils in this study could improve drug enrichment in the brain, thereby providing a general delivery platform for ischemic stroke or other inflammation-related diseases.

Regulatory mechanisms of tetramethylpyrazine on central nervous system diseases: A review

Central nervous system (CNS) diseases can lead to motor, sensory, speech, cognitive dysfunction, and sometimes even death. These diseases are recognized to cause a substantial socio-economic impact on a global scale. Tetramethylpyrazine (TMP) is one of the main active ingredients extracted from the Chinese herbal medicine Ligusticum striatum DC. (Chuan Xiong). Many in vivo and in vitro studies have demonstrated that TMP has a certain role in the treatment of CNS diseases through inhibiting calcium ion overload and glutamate excitotoxicity, anti-oxidative/nitrification stress, mitigating inflammatory response, anti-apoptosis, protecting the integrity of the blood-brain barrier (BBB) and facilitating synaptic plasticity. In this review, we summarize the roles and mechanisms of action of TMP on ischemic cerebrovascular disease, spinal cord injury, Parkinson’s disease, Alzheimer’s disease, cognitive impairments, migraine, and depression. Our review will provide new insights into the clinical applications of TMP and the development of novel therapeutics.

Potential Molecular Mechanism of Guishao Pingchan Recipe in the Treatment of Parkinson’s Disease Based on Network Pharmacology and Molecular Docking

Objective: To investigate the potential mechanism of Guishao Pingchan Recipe (GPR) against Parkinson's disease (PD) based on network pharmacology and molecular docking. Methods: The main components of GPR were collected based on TCMSP database, Batman-TCM database, Chinese Pharmacopoeia, and Literatures. The potential therapeutic targets of PD were predicted by Drug Bank Database and Gene Cards database. Cytoscape 3.8.2 software was used to construct herb–component–target network. Then, String database was used to construct a PPI network, and DAVID database was used for gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway annotation of targets function. Core components of GPR and hub targets were imported into AutoDock Vina for molecular docking verification and results were visualized by Pymol. Results: 13 candidate components were selected and 288 corresponding targets of GPR for treating PD were obtained. The GO enrichment analysis mainly involved 135 cell components, 187 molecular functions, and 1753 biological processes. Moreover, KEGG pathway enrichment analysis mainly involved 200 signaling pathways. Molecular docking simulation indicated a good binding ability of components and targets. Conclusion: Based on network pharmacology and molecular docking, we found that sitosterol, 4-Cholesten-3-one and stigmasterol in GPR could combine with MAPK3, APP, VEGFA, and CXCR4 and involved in the cAMP, PI3K/Akt, Rap1 signaling pathways. It is suggested that GPR may have therapeutic effects on PD through multi-component, multi-target, and multi-pathway and predict the relevant mechanism of the anti-PD effect of GPR.

An Overview of Tetramethylpyrazine (Ligustrazine) and its Derivatives as Potent Anti-Alzheimer’s Disease Agents

Abstract:

Tetramethylpyrazine (TMP), or ligustrazine, is an alkaloid isolated from the Chinese herb Ligusticum wallichii. It is known for its broad-spectrum medicinal properties against several diseases, and various studies have shown that it can modulate diverse biological targets and signaling pathways to produce neuroprotective effects, especially against Alzheimer’s disease (AD). This has attracted significant research attention evaluating TMP as a potent multitarget anti-AD agent. This review compiles the results of studies assessing the neuroprotective mechanisms exerted by TMP as well as its derivatives prepared using a multi-target-directed ligand strategy to explore its multitarget modulating properties. The present review also highlights the work done on the design, synthesis, structure-activity relationships, and mechanisms of some potent TMP derivatives that have shown promising anti-AD activities. These derivatives were designed, synthesized, and evaluated to develop anti-AD molecules with enhanced biological and pharmacokinetic activities compared to TMP. This review article paves the way for the exploration and development of TMP and TMP derivatives as an effective treatment for AD.

Association between blood caspase-8 levels and mortality of patients with malignant middle cerebral artery infarction

OBJECTIVE

High concentrations of caspase-8 (main initiator caspase of apoptosis extrinsic pathway) have been found in brain tissue from traumatic brain injury patients and in blood of patients with different diseases. However, there are not data on blood caspase-8 concentrations in ischemic stroke patients. Therefore, the objective of this study was to determine whether there is an association between blood caspase-8 concentrations and the probability and speed of mortality at 30 days in patients with malignant middle cerebral artery infarction (MMCAI).

DESIGN

Observational prospective study.

SETTING

Five Intensive Care Units (ICU).

PATIENTS

Patients with severe malignant middle cerebral artery infarction (MMCAI) defined as acute infarction in more than of 50% of that territory and Glasgow Coma Scale (GCS)<9.

INTERVENTIONS

Determination of serum caspase-8 levels when MMCAI was diagnosed.

MAIN VARIABLES OF INTEREST

Mortality at 30 days and time until this event.

RESULTS

Severe MMCAI patients (n=28) compared to survivor patients (n=28) showed higher serum caspase-8 concentrations (p<0.001), lower platelet count (p=0.01) and lower GCS (p=0.002). We found an area under the curve for mortality prediction of 78% (95% CI=65%-91%; p<0.001) by serum caspase-8 levels. Kaplan-Meier analysis found higher mortality rate in patients with serum caspase-8 levels >62.8ng/mL (hazard ratio=11.2; 95% CI=4.4-28.4; p<0.001).

CONCLUSIONS

The association of high blood caspase-8 concentrations with the rate and the velocity of 30-day mortality in MMCAI patients is the main new finding of our study.

Tetramethylpyrazine Protects Blood-Spinal Cord Barrier Integrity by Modulating Microglia Polarization Through Activation of STAT3/SOCS3 and Inhibition of NF-кB Signaling Pathways in Experimental Autoimmune Encephalomyelitis Mice

We previously reported that tetramethylpyrazine (TMP) alleviates experimental autoimmune encephalomyelitis (EAE) by decreasing glia activation. Activated microglia has been shown to mediate blood-spinal cord barrier (BSCB) disruption, which is a primary and continuous pathological characteristic of multiple sclerosis (MS). Therefore, in this study, we further investigated whether TMP protects the BSCB integrity by inhibition of glia activation to alleviate EAE. Extravasation of evans blue was used to detect the BSCB disruption. Tumor necrosis factor-α (TNF-α)/interlukine-1β (IL-1β) and interlukine-4 (IL-4)/interlukine-10 (IL-10) were determined by enzyme-linked immunosorbent assay. BV2 glial cells stimulated by interferon-γ (IFN-γ) were co-cultured with human brain microvascular endothelial cells to investigate the effect of TMP on the BSCB disruption. Flow cytometry was used to analyze the microglia phenotype. Western blot was performed to reveal the signaling pathways involved in the microglia activation. In this study, most importantly, we found that TMP protects the BSCB integrity by modulating microglia polarization from M1 phenotype to M2 phenotype through activation of STAT3/SOCS3 and inhibition of NF-кB signaling pathways. Moreover, TMP significantly preserves the tight junction proteins, reduces the secretion of pro-inflammatory cytokines (TNF-α, IL-1β) and increases the secretion of anti-inflammatory cytokines (IL-4, IL-10) from IFN-γ-stimulated BV2 microglia cells. Consequently, protection of the BSCB integrity leads to alleviation of clinical symptoms and demyelination in EAE mice. Therefore, TMP might be an effective therapeutic agent for cerebral disorders with BBB or BSCB disruption, such as ischemic stroke, MS, and traumatic brain injury.

Association between blood caspase-8 levels and mortality of patients with malignant middle cerebral artery infarction

OBJECTIVE

High concentrations of caspase-8 (main initiator caspase of apoptosis extrinsic pathway) have been found in brain tissue from traumatic brain injury patients and in blood of patients with different diseases. However, there are not data on blood caspase-8 concentrations in ischemic stroke patients. Therefore, the objective of this study was to determine whether there is an association between blood caspase-8 concentrations and the probability and speed of mortality at 30 days in patients with malignant middle cerebral artery infarction (MMCAI).

DESIGN

Observational prospective study.

SETTING

Five Intensive Care Units (ICU).

PATIENTS

Patients with severe malignant middle cerebral artery infarction (MMCAI) defined as acute infarction in more than of 50% of that territory and Glasgow Coma Scale (GCS)<9.

INTERVENTIONS

Determination of serum caspase-8 levels when MMCAI was diagnosed.

MAIN VARIABLES OF INTEREST

Mortality at 30 days and time until this event.

RESULTS

Severe MMCAI patients (n=28) compared to survivor patients (n=28) showed higher serum caspase-8 concentrations (p<0.001), lower platelet count (p=0.01) and lower GCS (p=0.002). We found an area under the curve for mortality prediction of 78% (95% CI=65%-91%; p<0.001) by serum caspase-8 levels. Kaplan-Meier analysis found higher mortality rate in patients with serum caspase-8 levels >62.8ng/mL (hazard ratio=11.2; 95% CI=4.4-28.4; p<0.001).

CONCLUSIONS

The association of high blood caspase-8 concentrations with the rate and the velocity of 30-day mortality in MMCAI patients is the main new finding of our study.

Neuroprotective Effect for Cerebral Ischemia by Natural Products: A Review

Natural products have a significant role in the prevention of disease and boosting of health in humans and animals. Stroke is a disease with high prevalence and incidence, the pathogenesis is a complex cascade reaction. In recent years, it’s reported that a vast number of natural products have demonstrated beneficial effects on stroke worldwide. Natural products have been discovered to modulate activities with multiple targets and signaling pathways to exert neuroprotection via direct or indirect effects on enzymes, such as kinases, regulatory receptors, and proteins. This review provides a comprehensive summary of the established pharmacological effects and multiple target mechanisms of natural products for cerebral ischemic injury in vitro and in vivo preclinical models, and their potential neuro-therapeutic applications. In addition, the biological activity of natural products is closely related to their structure, and the structure-activity relationship of most natural products in neuroprotection is lacking, which should be further explored in future. Overall, we stress on natural products for their role in neuroprotection, and this wide band of pharmacological or biological activities has made them suitable candidates for the treatment of stroke.

Potential Effects of Nutraceuticals in Retinopathy of Prematurity

Retinopathy of prematurity (ROP), the most common cause of childhood blindness, is a hypoxia-induced eye disease characterized by retinal neovascularization. In the normal retina, a well-organized vascular network provides oxygen and nutrients as energy sources to maintain a normal visual function; however, it is disrupted when pathological angiogenesis is induced in ROP patients. Under hypoxia, inadequate oxygen and energy supply lead to oxidative stress and stimulate neovasculature formation as well as affecting the function of photoreceptors. In order to meet the metabolic needs in the developing retina, protection against abnormal vascular formation is one way to manage ROP. Although current treatments provide beneficial effects in reducing the severity of ROP, these invasive therapies may also induce life-long consequences such as systemic structural and functional complications as well as neurodevelopment disruption in the developing infants. Nutritional supplements for the newborns are a novel concept for restoring energy supply by protecting the retinal vasculature and may lead to better ROP management. Nutraceuticals are provided in a non-invasive manner without the developmental side effects associated with current treatments. These nutraceuticals have been investigated through various in vitro and in vivo methods and are indicated to protect retinal vasculature. Here, we reviewed and discussed how the use of these nutraceuticals may be beneficial in ROP prevention and management.

Structure-Based Design of Acetolactate Synthase From Bacillus licheniformis Improved Protein Stability Under Acidic Conditions

Catabolic acetolactate synthase (cALS) plays a crucial role in the quality of liquor because of its ability to catalyze the synthesis of the endogenous precursor product α-acetolactate of the aromatic compound tetramethylpyrazine (TTMP) and acetoin. However, the vulnerability of cALS to acidic conditions limits its application in the Chinese liquor brewing industry. Here we report the biochemical characterization of cALS from B. licheniformis T2 (BlALS) that was screened from Chinese liquor brewing microorganisms. BlALS showed optimal activity levels at pH 7.0, and the values of K_m and V_max were 27.26 mM and 6.9 mM⋅min^–1, respectively. Through site-directed mutagenesis, we improved the stability of BlALS under acidic conditions. Replacing the two basic residues of BlALS with acidic mutations (N210D and H399D) significantly improved the acid tolerance of the enzyme with a prolonged half-life of 2.2 h (compared with wild-type BlALS of 0.8 h) at pH 4.0. Based on the analysis of homologous modeling, the positive charge area of the electrostatic potential on the protein surface and the number of hydrogen bonds near the active site increased, which helped BlALS^{N210D–H399D} to withstand the acidic environment; this could extend its application in the food fermentation industry.

Quercetin protects against cerebral ischemia/reperfusion and oxygen glucose deprivation/reoxygenation neurotoxicity

Beyond nutrition effect, quercetin is applied as a complement or an alternative for promoting human health and treating diseases. However, its complicated neuroprotective mechanisms have not yet been fully elucidated. This study provides evidence of an alternative target for quercetin, and sheds light on the mechanisms of its neuroprotection against cerebral ischemia/reperfusion (I/R) injury in Sprague-Dawley rats. Oral pretreatment using quercetin has alleviated cerebral I/R-induced neurological deficits, brain infarction, blood-brain barrier disruption, oxidative stress, TNF-α and IL-1β mRNA expression, along with apoptotic caspase 3 activity. The neuroprotective, anti-oxidative, anti-inflammatory, and anti-apoptotic effects of quercetin were replicated in rat hippocampal slice cultures and neuron/glia cultures which suffered from oxygen-glucose deprivation and reoxygenation (OGDR). Biochemical studies revealed a reduction of extracellular signal-regulated kinase (ERK) and Akt phosphorylation, along with an increase in protein tyrosine and serine/threonine phosphatase activity in cerebral I/R rat cortical tissues and OGDR hippocampal slice and neuron/glia cultures. Quercetin alleviated the changes in ERK/Akt phosphorylation and protein phosphatase activities. Inhibition of ERK or Akt alone was enough to cause apoptotic cell death and cytotoxicity in hippocampal slice cultures and neuron/glia cultures, while activators of ERK or Akt alleviated OGDR-induced cytotoxicity. Taken together, our results demonstrate that quercetin alleviated the increment of protein tyrosine and serine/threonine phosphatase activity, along with the reduction of ERK and Akt phosphorylation, which may play pivotal roles in the expansion of brain injury after cerebral I/R.

β-Funaltrexamine Displayed Anti-inflammatory and Neuroprotective Effects in Cells and Rat Model of Stroke

Chronic treatment involving opioids exacerbates both the risk and severity of ischemic stroke. We have provided experimental evidence showing the anti-inflammatory and neuroprotective effects of the μ opioid receptor antagonist β-funaltrexamine for neurodegenerative diseases in rat neuron/glia cultures and a rat model of cerebral Ischemia/Reperfusion (I/R) injury. Independent of in vitro Lipopolysaccharide (LPS)/interferon (IFN-γ)-stimulated neuron/glia cultures and in vivo cerebral I/R injury in Sprague–Dawley rats, β-funaltrexamine downregulated neuroinflammation and ameliorated neuronal degeneration. Alterations in microglia polarization favoring the classical activation state occurred in LPS/IFN-γ-stimulated neuron/glia cultures and cerebral I/R-injured cortical brains. β-funaltrexamine shifted the polarization of microglia towards the anti-inflammatory phenotype, as evidenced by decreased nitric oxide, tumor necrosis factor-α, interleukin-1β, and prostaglandin E2, along with increased CD163 and arginase 1. Mechanistic studies showed that the suppression of microglia pro-inflammatory polarization by β-funaltrexamine was accompanied by the reduction of NF-κB, AP-1, cyclic AMP response element-binding protein, along with signal transducers and activators of transcription transcriptional activities and associated upstream activators. The effects of β-funaltrexamine are closely linked with its action on neuroinflammation by switching microglia polarization from pro-inflammatory towards anti-inflammatory phenotypes. These findings provide new insights into the anti-inflammatory and neuroprotective mechanisms of β-funaltrexamine in combating neurodegenerative diseases, such as stroke.

Comparative Study on Pharmacokinetics of Four Active Compounds in Rat Plasma after Oral Administration of Raw and Wine Processed Chuanxiong Rhizoma

In Chinese medicine, the effect of promoting blood circulation and removing stasis could be enhanced after Chuanxiong Rhizoma is processed by wine. However, the relevant mechanism remains unclear. In this manuscript, a rapid and sensitive quantification method employing ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was established and validated to simultaneously determine butylidenephthalide, ligustilide, senkyunolide A and ferulic acid in rat plasma after oral administration of raw Chuanxiong Rhizoma (RCR) and wine-processed Chuanxiong Rhizoma (WCR) respectively. All analytes were extracted from plasma by proteins precipitation with methanol. Chromatographic separation was carried out on a Hypersil GOLD C₁₈ column by using a gradient mobile phase system of acetonitrile and water with 0.01% formic acid, the flow rate was 0.3 mL/min. For exact mass detecting, quick switching mode was used, positive and negative ions could be detected in one injection. The pharmacokinetic profiles of four components in the two groups were evaluated and compared. The results showed that, compared to the RCR group, the V_d and AUC_0→t values of four active compounds were increased and decreased respectively in WCR group, which revealed the effect of wine processing to Chuanxiong Rhizoma: the stronger the effect, the wider the distribution.

Investigation of the protective effect of heparin pre-treatment on cerebral ischaemia in gerbils

Context: The interruption of cerebral blood circulation may cause stroke characterized by high neurological deficits (NDs) as a result of neuronal dysfunction or destruction. Heparin may exert a neuroprotective effect against cerebral ischaemia/reperfusion injury. Objective: The objective of this study was to investigate the mechanism underlying the effects of heparin pre-treatment on cerebral injury in the gerbil. Materials and methods: A total of 80 healthy Mongolian gerbils were randomly divided into four groups to establish cerebral ischaemia model by bilateral carotid artery occlusion: control (no anaesthesia and surgery), sham (no occlusion), non-anticoagulation (occlusion), and anti-coagulation treatment groups (50 IU/100 g heparin pre-treated, occlusion). Gerbils were anesthetized with 40 mg/kg pentobarbital sodium through intraperitoneal injection before operation except for the control group. Then, the ND and histopathological damage (HD) scores were determined. The percentage of tumour necrosis factor (TNF)-α- and interleukin (IL)-1β-positive cells were calculated based on immunohistochemical results. The mRNA and protein levels of caspase-9, caspase-8, FasL, and calpain were evaluated with real-time polymerase chain reaction (RT-PCR) and western blotting, respectively. Results: Compared with non-anticoagulation group, heparin pre-treatment (50 IU/100 g) delayed the onset of dyspnoea (p < 0.05), and showed a significant decrease in ND (p < 0.01), mortality rate (p < 0.05), HD (p < 0.01) and percentage of positive cells for TNF-α, IL-1β (p < 0.01) in cerebral ischaemia gerbils. Besides, the expression levels of caspase-9, caspase-8, FasL, and calpain were reduced after pre-treatment with 50 IU/100 g heparin. Discussion and conclusions: The damage caused to gerbil brain was reduced upon pre-treatment with heparin, possibly through the amelioration of neuronal cell apoptosis and expression of TNF-α and IL-1β. These findings are expected to provide a new breakthrough in the study and treatment of cerebral ischaemia.

Retracted: Tetramethylpyrazine partially relieves hypoxia-caused damage of cardiomyocytes H9c2 by downregulation of miR-449a

Inadequate oxygen supply is probably one of the most important pathophysiological mechanisms of cardiomyocyte damage in ischemic heart disease. Tetramethylpyrazine (TMP, also known as ligustrazine) is the main active ingredient isolated from the rhizome of Ligusticum chuanxiong Hort. A previous study reported that the TMP could exert cardioprotective activity. This study aimed to explore the molecular mechanism of the protective effects of TMP on cardiomyocyte damage caused by hypoxia. The viability and apoptosis of cardiomyocytes H9c2 were detected using cell counting kit-8 assay and annexin V-FITC/PI staining, respectively. Quantitative reverse transcription polymerase chain reaction was conducted to measure the expression level of microRNA-449a (miR-449a). Cell transfection was performed to upregulate the expression level of miR-449a or downregulate the expression level of sirtuin 1 (Sirt1). The protein expression levels of Sirt1 and key factors involved in cell apoptosis and phosphatidylinositol 3-kinase/protein kinase 3 (PI3K/AKT) pathway were evaluated using western blot analysis. We found that the hypoxia incubation inhibited H9c2 viability, induced cell apoptosis, and inactivated the PI3K/AKT pathway. TMP treatment partially relieved the hypoxia-caused H9c2 cell viability loss and apoptosis, as well as reversed the hypoxia-caused inactivation of the PI3K/AKT pathway. Moreover, TMP partially alleviated the upregulation of miR-449a in H9c2 cells caused by hypoxia. Overexpression of miR-449a weakened the effects of TMP on hypoxia-treated H9c2 cells. Furthermore, Sirt1 was a target gene of miR-449a. Knockdown of Sirt1 also weakened the effects of TMP on hypoxia-treated H9c2 cells. In conclusion, TMP partially relieved hypoxia-caused cardiomyocytes H9c2 viability loss and apoptosis at least through downregulating miR-499a, upregulating Sirt1, and then activating the PI3K/AKT pathway.

Tetramethylpyrazine ameliorates depression by inhibiting TLR4-NLRP3 inflammasome signal pathway in mice

Depression is a common but serious mental illness; meanwhile, it is also an inflammatory disorder. Toll-like receptor 4 (TLR4), as the pattern recognition receptor, has been shown to play a vital role in neuroinflammation. The nucleotide binding and oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome acts as an important signaling molecule downstream of TLR4 and can promote the maturation of inflammatory cytokines, such as interleukin-1β (IL-1β). Tetramethylpyrazine (TMP) is a natural compound with neuroprotective effects but with unknown mechanisms on its antidepressant-like effect. In this study, we hypothesized that TMP ameliorates depression may be through the inhibition of the TLR4-NF-κB-NLRP3 signal pathway. Our results have shown that chronic unpredictable mild stress (CUMS) that induced the decreased sucrose preference and increased immobile time was prominently reversed by TMP and fluoxetine. Additionally, we also found that CUMS induced the upregulation of proinflammatory cytokines; TLR4 and NLRP3-associated proteins were significantly suppressed by TMP in the prefrontal cortex and hippocampus. TMP also exhibited potent antioxidant effects and increased the monoamine levels in the serum and brain, such as increasing the activity of SOD and GSH-Px, and reducing the activity of MDA in the serum, and elevating the 5-HT and NE concentration in the serum and brain. Moreover, treatment with Cli-095 (TLR4 inhibitor) also markedly inhibited CUMS-induced depression-like behaviors. Taken together, our findings suggested that TMP exerted a potential antidepressant-like effect in CUMS mice, and the molecular mechanisms may relate to inhibit the TLR4-NF-κB-NLRP3 signaling pathway in the brain.

A Danshensu-Tetramethylpyrazine Conjugate DT-010 Overcomes Multidrug Resistance in Human Breast Cancer

Background: We previously demonstrated that a Danshensu-Tetramethylpyrazine conjugate DT-010 enhanced anticancer effect of doxorubicin (Dox) in Dox-sensitive human breast cancer cells, and protected against Dox-induced cardiotoxicity. This work was designed to see whether DT-010 overcomes Dox resistance in resistant human breast cancer cells.

Methods: The effects of DT-010, Dox or their combination on cell viability of Dox-resistant human breast cancer MCF-7/ADR cells were conducted using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis was examined by flow cytometry after Annexin V-FITC/PI co-staining. Dox accumulation in MCF-7/ADR cells was detected by flow cytometry and fluorescence microscopy. A fluorometric multidrug resistance (MDR) assay kit was used to evaluate the effect of DT-010 on MDR transporter activity. P-glycoprotein (P-gp) expression and activity were analyzed by Western blot and rhodamine 123 (Rh123) efflux assay, respectively. The effects of DT-010 on glycolysis and mitochondrial stress were detected using an Extracellular Flux Analyzer. A Succinate Dehydrogenase Activity Assay kit was used to measure mitochondrial complex II activity.

Results: At non-cytotoxic concentrations, DT-010 in combination with Dox led to a significant growth inhibition of MCF-7/ADR cells, suggesting a synergy between DT-010 and Dox to reverse Dox resistance. DT-010 restored Dox-mediated apoptosis and p53 induction in MCF-7/ADR cells. DT-010 increased Dox accumulation in MCF-7/ADR cells via inhibiting P-gp activity, but without changing P-gp expression. Further studies showed that DT-010 significantly inhibited glycolysis and mitochondrial function of MCF-7/ADR cells. Mitochondrial complex II activity was inhibited by DT-010 or DT-010/Dox combination, but not by Dox. The DT-010-mediated suppression of metabolic process may render cells more vulnerable to Dox treatment and thus result in enhanced efficacy.

Conclusions: The results indicate that DT-010 overcomes Dox resistance in human breast cancer cells through a dual action via simultaneously inhibiting P-gp-mediated drug efflux and influencing metabolic process.

Tetramethylpyrazine attenuated bupivacaine-induced neurotoxicity in SH-SY5Y cells through regulating apoptosis, autophagy and oxidative damage

Background: Bupivacaine (BUP) acts as a local anesthetic, which is extensively used for clinical patients but could generate neurotoxicity in neurons. Tetramethylpyrazine (TET) exhibits strong neuron protective effects against neurotoxicity. Hence, we investigate the effect of TET on BUP-induced neurotoxicity in SH-SY5Y cells.

Methods: CCK-8 assay was used to detect cell proliferation in SH-SY5Y cells. In addition, Western blotting was used to examine Bax, Bcl-2, active caspase 3, LC3II, Beclin 1 and p-62 protein levels in cells. Moreover, ELISA assay was used to detect the levels of total glutathione (GS), superoxide dismutase (SOD) and malondialdehyde (MDA) in cells.

Results: In this study, we found that TET attenuated the neurotoxicity of BUP on SH-SY5Y cells. Meanwhile, TET alleviated BUP-induced apoptosis in SH-SY5Y cell via decreasing the expressions of active caspase-3 and Bax and increasing the expression of Bcl-2. In addition, monodansylcadaverine staining assay and Western blotting results confirmed that TET induced autophagy in SH-SY5Y cells via increasing the LC3II/I and Beclin 1 levels. Furthermore, TET attenuated BUP-induced oxidative damage in SH-SY5Y cells via upregulation of the levels of total GS and SOD and downregulation of the level of MDA. Interesting, the protective effects of TET against BUP-induced neurotoxicity in SH-SY5Y cells were reversed by autophagy inhibitor 3-methyladenine (3MA).

Conclusion: These data indicated that TET may play a neuroprotective role via inhibiting apoptosis and inducing autophagy in SH-SY5Y cells. Therefore, TET may be a potential agent for the treatment of human neurotoxicity induced by BUP.

The Traditional Chinese Medicine MLC901 inhibits inflammation processes after focal cerebral ischemia

Inflammation is considered as a major contributor to brain injury following cerebral ischemia. The therapeutic potential of both MLC601/MLC901, which are herbal extract preparations derived from Chinese Medicine, has been reported both in advanced stroke clinical trials and also in animal and cellular models. The aim of this study was to investigate the effects of MLC901 on the different steps of post-ischemic inflammation in focal ischemia in mice. In vivo injury was induced by 60 minutes of middle cerebral artery occlusion (MCAO) followed by reperfusion. MLC901 was administered in post-treatment 90 min after the onset of ischemia and once a day during reperfusion. MLC901 treatment resulted in a reduction in infarct volume, a decrease of Blood Brain Barrier leakage and brain swelling, an improvement in neurological scores and a reduction of mortality rate at 24 hours after MCAO. These beneficial effects of MLC901 were accompanied by an inhibition of astrocytes and microglia/macrophage activation, a drastically decreased neutrophil invasion into the ischemic brain as well as by a negative regulation of pro-inflammatory mediator expression (cytokines, chemokines, matrix metalloproteinases). MLC901 significantly inhibited the expression of Prx6 as well as the transcriptional activity of NFκB and the activation of Toll-like receptor 4 (TLR4) signaling, an important pathway in the immune response in the ischemic brain. MLC901 effects on the neuroinflammation cascade induced by cerebral ischemia probably contribute, in a very significant way, in its potential therapeutic value.

High tetramethylpyrazine production by the endophytic bacterial Bacillus subtilis isolated from the traditional medicinal plant Ligusticum chuanxiong Hort

Tetramethylpyrazine (TMP) with significant protective effects on cardiovascular is the active ingredient of traditional Chinese medicine Rhizoma Chuanxiong (RC). However, many studies have reported the low content of TMP in RC. The endophytes of medicinal plants have the biosynthetic potential to produce the same or similar active metabolites as the host, while few reports were conducted to explore the endophytic bacteria of Ligusticum chuanxiong Hort. and its productive capacity for the important ingredient TMP. The present paper focuses on the isolation and identification of TMP producing endophytic bacteria from RC. In this study, the endophytic bacteria were isolated from the rhizome of Ligusticum chuanxiong Hort. (Umbelliferae). Yeast extract peptone glucose medium (YP) was used for fermentation medium (37 °C, 220 rpm agitation, 144 h). GC and GC/MS were performed to determine and verify the product, the fermentation characteristics were investigated. Morphological observation, physiological and biochemical indexes combining with 16S rRNA sequence analysis were carried out to identify the endophytic bacteria. As a result, five strains of endophytic Bacillus subtilis were firstly isolated and identified from RC, named as LB3, LB3-2-1, LB6-2, LB4, LB5 respectively. All five strains of endophytic B. subtilis produced TMP, while LB5 had the highest production of 10.69 g/L at the 144 h fermentation. This work demonstrates the fact that the endophytic B. subtilis of RC can produce a high level of TMP, indicating the endophytic B. subtilis might play a role in the accumulation of TMP during the growth period of RC.

Biomedical applications of microemulsion through dermal and transdermal route

Microemulsions are thermodynamically stable, transparent, colloidal drug carrier system extensively used by the scientists for effective drug delivery across the skin. It is a spontaneous isotropic mixture of lipophilic and hydrophilic substances stabilized by suitable surfactant and co-surfactant. The easy fabrication, long-term stability, enhanced solubilization, biocompatibility, skin-friendly appearance and affinity for both the hydrophilic and lipophilic drug substances make it superior for skin drug delivery over the other carrier systems. The topical administration of most of the active compounds is impaired by limited skin permeability due to the presence of skin barriers. In this sequence, the microemulsion represents a cost-effective and convenient drug carrier system which successfully delivers the drug to and across the skin. In the present review work, we compiled various attempts made in last 20 years, utilizing the microemulsion for dermal and transdermal delivery of various drugs. The review emphasizes the potency of microemulsion for topical and transdermal drug delivery and its effect on drug permeability.

Tetramethylpyrazine‑2'O‑sodium ferulate provides neuroprotection against neuroinflammation and brain injury in MCAO/R rats by suppressing TLR-4/NF-κB signaling pathway

BACKGROUND

Neuroinflammation following cerebral ischemia is a serious risk factor in stroke patients. The purpose of this study was to investigate the neuroprotective effects of tetramethylpyrazine‑2'O‑sodium ferulate (TSF), a structurally modified compound from tetramethylpyrazine and ferulate, on cerebral ischemic injury and the underlying mechanisms.

METHODS

Focal transient cerebral ischemia was induced in rat for 2 h by middle cerebral artery occlusion (MCAO) and the protective effect of TSF was studied using different doses of the drug (10.8, 18, 30 mg/kg, intravenously); Ozagrel (18 mg/kg) was used as the positive control. The drugs were given immediately after MCAO and the efficacy and mechanisms were evaluated at 72 h of reperfusion. The level of pro-inflammatory cytokines such as TNF-α, IL-1β and anti-inflammatory molecules such as IL-10 was measured; other factors such as neurological deficit, brain water content and infarct size and the level of MCP-1, ICAM-1, iNOS, CD11b, TLR-4/NF-κBp65 were also measured.

RESULTS

TSF at the doses of 18, 30 mg/kg significantly improved neurological deficit, reduced brain water content and infarct size, accompanied by a decrease in the concentration of TNF-α, IL-1β, MCP-1, ICAM-1, iNOS and an increase in the concentration of IL-10. The amount of CD11b and ICAM-1 was found largely decreased and the expression of TLR-4 and the nuclear NF-κBp65 was weakened in TSF-treatment group.

CONCLUSIONS

Our study suggests that TSF possesses a neuroprotective effect against ischemic stroke which might be mediated through suppression of the inflammatory pathways in the brain following ischemic stroke.

Ultrasound-Enhanced Protective Effect of Tetramethylpyrazine via the ROS/HIF-1A Signaling Pathway in an in Vitro Cerebral Ischemia/Reperfusion Injury Model

Reactive oxygen species-induced oxidative stress is an important pathophysiological process during cerebral ischemia/reperfusion (I/R) injury. It has been reported that the protective effect of tetramethylpyrazine (TMP) against cerebral I/R injury can be significantly improved by its combination with ultrasound exposure. However, the molecular mechanisms and signaling pathways underlying the synergistic protective effect remain unclear. In the present work, the damage induced by I/R injury was modeled by glutamate-induced toxicity to pheochromocytoma (PC12) cells. The ultrasound-enhanced protective effect of TMP was systemically investigated by measuring variations in cell viability, cell migration and levels of intracellular reactive oxygen species, the oxidative stress-related protein glutathione, apoptosis-related proteins (caspase-8, -9 and -3), as well as expression of related genes (hypoxia-inducible factor-1a, p53, murine double minute2). The results suggest that the ultrasound-enhanced protective effect of TMP against cerebral I/R injury might act via the reactive oxygen species/hypoxia-inducible factor-1a signaling pathway, and an appropriate ultrasound intensity should be selected to achieve an optimal synergistic neuroprotective effect.

Tetramethylpyrazine ameliorates experimental autoimmune encephalomyelitis by modulating the inflammatory response

Multiple sclerosis (MS) is a disabling inflammatory and demyelinating disorder of the central nervous system. Tetramethylpyrazine (TMP) has been demonstrated to ameliorate cerebral ischemic injury and spinal cord injury by inhibiting inflammatory cell activation and pro-inflammatory cytokine production. However, the effects of TMP on MS have not been studied. In this study, we evaluated the effects of TMP on the inflammatory response in experimental autoimmune encephalomyelitis (EAE), which is an animal model of MS. TMP (30 mg/kg) treatment significantly reduced the expression levels of NLR Family, Pyrin Domain-Containing 3 Protein inflammasome and caspase-1and decreased inflammatory infiltration and glial activation. Moreover, TMP (30 mg/kg) suppressed the expression of pro-inflammatory cytokines (interleukin-18 [IL-18] and IL-17) and promoted the expression of an anti-inflammatory cytokine (IL-10). The reduced inflammatory response resulted in improvement in clinical scores and decreased demyelination in EAE mice. Therefore, our results demonstrate that TMP (30 mg/kg) improved functional recovery in part by reducing inflammation in EAE mice. TMP may be a potential therapeutic agent for MS therapy.

Percutaneous absorption and brain distribution facilitation of borneol on tetramethylpyrazine in a microemulsion-based transdermal therapeutic system

In this study, we show that the percutaneous absorption and brain distribution of tetramethylpyrazine (TMP) is enhanced when combined with borneol (BN) in a microemulsion-based transdermal therapeutic system (ME-TTS). The formulation of the TMP and BN microemulsion (TEM-BN-ME) was optimized in skin permeation studies in vitro following a uniform experimental design. Male Sprague-Dawley rats were used for the in vivo pharmacokinetic and tissue distribution studies of TMP-BN-ME-TTS. In the pharmacokinetic study, the TMP-BN-ME-TTS treated rats had significantly higher (P < 0.05) C_max and AUC of TMP than the TMP-ME-TTS treated rats, indicating that BN improves the rate and extent of TMP percutaneous absorption. In the tissue distribution study, the AUC of TMP in brain was significantly higher in the TMP-BN-ME-TTS group (P < 0.05), indicating that BN facilitates the distribution of TMP in brain. In summary, BN enhanced the percutaneous absorption and brain distribution of TMP in a microemulsion-based transdermal therapeutic system.

Neuroprotective activity of tetramethylpyrazine against 3-nitropropionic acid induced Huntington's disease-like symptoms in rats

Huntington's disease (HD) is an autosomal neurodegenerative disease characterized by chorea, dystonia, motor ataxia, cognitive decline and psychiatric disorders with gradual loss of nerve cells and has no existing cure for the disease. In the present study, a mitochondrial toxin, 3-nitropropionic acid (3-NP) is used to induce HD like symptoms in rats. Tetramethylpyrazine is one of the active ingredients of Chuan Xiong which was reported to have neurotrophic and neuroprotective activities. The present study was designed to evaluate the role of TMP on 3-NP induced behavioral, biochemical, neurochemical, and histological alterations in the different regions of the brain. Animals were pretreated with normal saline/TMP for 7 days. From 8th day, the treatment groups were co-administered with 3-NP (10 mg/kg, i.p) and continued to the 21st day of the treatment protocol. At the end of the study, we found that the TMP improved all the behavioral performances of 3-NP induced neurotoxic rats, significantly. Further, oxidative stress parameters (lipid peroxidation, reduced glutathione, catalase, and superoxide dismutase), succinate dehydrogenase enzyme, and neurochemical (GABA and glutamate) estimations were done in the brain homogenate. In our study, the treatment with TMP ameliorated the 3-NP induced alterations, in the biochemical and neurochemical parameter in the brain homogenate, dose-dependently. The protective role of TMP further confirmed by measuring the lesion area with the 2,3,5-triphenyltetrazolium chloride staining of the brain slices and histopathological alteration in the hippocampus (CA1 and CA3) and striatal regions of the brain. Hence, the present findings suggest that the protective role of TMP against 3-NP induced behavioral, biochemical, neurochemical, and histological alterations in rats.

In vivo microdialysis with ultra performance liquid chromatography-mass spectrometry for analysis of tetramethylpyrazine and its interaction with borneol in rat brain and blood

Tetramethylpyrazine (TMP) has been widely used in the treatment of ischemic cerebrovascular disease. However, the mechanism of TMP and how to increase its bioavailability need to be further explored. In our study, an in vivo microdialysis sampling technique coupled with ultra-performance liquid chromatography-mass spectrometry method was developed to investigate the pharmacokinetic properties of TMP and its interaction with different doses of borneol (BO) in rats. Linearity of TMP in brain and blood dialysates exhibited good linear relationships over the concentration range of 0.991-555.14 ng/mL. The specificity, linearity, accuracy, precision, matrix effect and stability were within acceptable ranges. The results demonstrated that BO had a marked impact on the pharmacokinetic properties of TMP. After co-administration, the areas under the concentration-time curve (AUC) of TMP in brain and blood were significantly increased. Meanwhile, the peak concentration of TMP in brain was also enhanced. The AUC_Brain /AUC_Blood of TMP, increased from 44% to 56 and 60.8% after co-administration with BO (15 and 30 mg/kg). The pharmacodynamic results showed that TMP co-administration with BO enhanced the cerebral blood flow during the period of ischemia and reduced the infarct volume. Overall, it might be an effective way to treat stroke to use TMP co-administered with BO.

Synthesis and activity towards Alzheimer's disease in vitro: Tacrine, phenolic acid and ligustrazine hybrids

A series of novel tacrine-phenolic acid dihybrids and tacrine-phenolic acid-ligustrazine trihybrids were synthesized, characterized and screened as novel potential anti-Alzheimer drug candidates. These compounds showed potent inhibition activity towards cholinesterases (ChEs), among of them, 9i was the most potent one towards acetylcholinesterase (eeAChE, IC₅₀ = 3.9 nM; hAChE, IC₅₀ = 65.2 nM). 9i could also effectively block β-amyloid (Aβ) self-aggregation with an inhibition ratio of 47% at 20 μM. In addition, its strong anti-oxidation activity could protect PC12 cells from CoCl₂-damage in the experimental condition while no neurotoxicity. Furthermore, its hepatotoxicity was lower than tacrine in vitro and in vivo. Kinetic and molecular modeling studies revealed that 9i worked in a mixed-type way, could interact simultaneously with catalytic active site (CAS) and peripheral anionic site (PAS) of AChE. Therefore, 9i was a promising multifunctional candidate for the treatment of AD.

Therapeutic Potential of Novel Twin Compounds Containing Tetramethylpyrazine and Carnitine Substructures in Experimental Ischemic Stroke

Although studies have seen dramatic advances in the understanding of the pathogenesis of stroke such as oxidative stress, inflammation, excitotoxicity, calcium overload and apoptosis, the delivery of stroke therapies is still a great challenge. In this study, we designed and synthesized a series of novel twin compounds containing tetramethylpyrazine and carnitine substructures and explored their therapeutic potential and mechanism in stroke-related neuronal injury. We first screened the neuroprotective effects of candidate compounds and found that among the tested compounds, LR134 and LR143 exhibited significant neuroprotection as evidenced by reducing cerebral infarct and edema, improving neurological function as well as blood-brain barrier integrity in rats after cerebral ischemia/reperfusion injury. We further demonstrated that the neuroprotective effects of compounds LR134 and LR143 were associated with the reduced inflammatory responses and NADPH oxidase- (NOX2-) mediated oxidative stress and the protection of mitochondria accompanied by the improvement of energy supply. In summary, this study provides direct evidence showing that the novel twin compounds containing tetramethylpyrazine and carnitine substructures have neuroprotective effects with multiple therapeutic targets, suggesting that modulation of these chemical structures may be an innovative therapeutic strategy for treating patients with stroke.

Tetramethylpyrazine alleviates neural apoptosis in injured spinal cord via the downregulation of miR-214-3p

OBJECTIVE

To evaluate the regulation effect of tetramethylpyrazine on microRNA-214-3p (miR-214-3p) in the spinal cord injury (SCI) rats model and to elucidate the neuroprotective effect and its mechanism of tetramethylpyrazine after SCI.

METHODS

Ten Sprague-Dawley rats were used to establish the SCI rats model, and the expression levels of miR-214-3p and Bcl2l2 were detected by qRT-PCR and Western blotting at 7 days post-SCI. BBB scoring test was performed to evaluate the motor functional recovery at 21 days post-SCI. Twenty-five SCI rats were randomly assigned to five groups: SCI negative control (NC) group, tetramethylpyrazine (TMP) group, miR-214-3p agomir group, TMP/agomir group and the sham group. The rats were given a two-week injection treatment with or without TMP. The expression levels of miR-214-3p, Bcl2l2, Bax and caspase 3 were measured by qRT-PCR and Western blotting at 7 days after injection. Terminal deoxynucleotidyl transferase (TdT) -mediated dUTP Nick-End Labeling (TUNEL) assay was performed to detect cell apoptosis in vivo. Luciferase activity was measured to verify the miR-214-3p target site in the 3'-UTR of Bcl2l2 mRNA. TMP treatment was also performed to injure primary cultured neuron cells and cell apoptosis in vitro was determined by flow cytometry.

RESULTS

MiR-214-3p was up-regulated while anti-apoptotic protein Bcl2l2 was downregulated post-SCI. TMP inhibited the apoptosis in vivo via decreasing the levels of miR-214-3p and increasing the expression level of Bcl2l2. A potential target site of miR-214-3p in the 3'UTR of Bcl2l2 mRNA was identified and validated by luciferase reporter assay. Furthermore, TMP could effectively inhibit neuron cells apoptosis in vitro.

CONCLUSIONS

TMP alleviated neural apoptosis in injured spinal cord via down-regulation of miR-214-3p.

Effect of docosahexaenoic acid on traumatic brain injury in rats

The present study aimed to investigate the protective effects of docosahexaenoic acid (DHA) on traumatic brain injury (TBI) in rats. A model of TBI was induced by lateral fluid percussion injury in adult rats and rats were randomly divided into the TBI-model group, TBI-low DHA group and TBI-high DHA group, while other healthy rats were assigned to the sham-operated group. Motor recovery was tested with beam-walking trials at 2, 7 and 15 days post-TBI. Cognitive recovery was tested with Morris water maze trials at 15 days post-TBI. The expression levels of caspase-3, B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (Bax) were measured by western blotting. DHA protected against motor deficits induced by TBI in beam walking tests. All TBI-model groups had longer escape latency and swimming distances than the sham groups. Compared with the TBI-low DHA group, the TBI-high DHA group demonstrated shorter escape latency and swimming distances. DHA inhibited the expression of caspase-3 and the inhibition effect was more obvious at a high dosage. Furthermore, DHA dose-dependently rescued neurons by upregulating the Bcl-2:Bax ratio. DHA supplementation was a viable strategy to mitigate injury from TBI.

Phosphodiesterase inhibitor ameliorates neuronal injury in spinal cord ischemia/reperfusion injured rat model

This study investigated the mechanisms responsible for the neuroprotective effect of sildenafil citrate (SFC) on ischemia-reperfusion spinal cord (SC) injuries. Balloon occlusion of the thoracic aorta was used to induce SC ischemia. The animals (n=30) were separated into three groups: sham, SC injury with saline, and SC injury with 5mg/kg i.p. SFC treatment (SFC). The Basso, Beattie, and Bresnahan (BBB) score was determined to assess neurological function at different time intervals after reperfusion. After 48h, histopathology of the SC was assessed by triphenyltetrazolium chloride (TTC) and Nissl staining. Myeloperoxidase (MPO) activity was estimated using an MPO assay kit. Western blot and ELISA assays were performed to estimate interleukin 1 & 10 (IL-1 & IL-10), tumour necrosis factor α (TNF-α), and nuclear factor (NF-kB) levels in SC tissue homogenates. The study results suggest that treatment with SFC significantly increased neurological function compared with the SC group. In addition, SFC treatment reduced MPO activity compared with the SC group, which subsequently inhibited the infiltration of neutrophils into the SC. There was a significant (p<0.01) decrease in the expression of IL-1 and TNF-α, and an increase in the expression of IL-10 in SFC tissue homogenates compared with SC tissues. Moreover, SFC treatment inhibited the activation of NF-kB in the SC after injury. This study shows that SFC exerts a neuroprotective effect on the SC after ischemia/reperfusion injury by attenuating inflammatory mediators.

Anti-paralytic medicinal plants - Review

Paralysis is the loss of the ability of one or more muscles to move, due to disruption of signaling between the nervous system and muscles. The most common causes of paralysis are stroke, head injury, spinal cord injury (SCI) and multiple sclerosis. The search for cure of paralysis is yet to be found. Many ethnobotanical surveys have reported the use of medicinal plants by various ethnic communities in treating and curing paralysis. The present review discusses the use of medicinal plants in India for ameliorating and curing paralytic conditions, as well as discuses some of the important developments in future possible applications of medicinal plants in treatment of paralysis. This review reports the use of 37 medicinal plants for their application and cure of ailments related to paralysis. Out of the 37 plants documented, 11 plants have been reported for their ability to cure paralysis. However, the information on the documented plants were mostly found to be inadequate, requiring proper authentication with respect to their specificity, dosage, contradictions etc. It is found that despite the claims presented in many ethnobotanical surveys, the laboratory analysis of these plants remain untouched. It is believed that with deeper intervention on analysis of bioactive compounds present in these plants used by ethic traditional healers for paralysis, many potential therapeutic compounds can be isolated for this particular ailment in the near future.

The effect of additive compounds on glycerol-induced damage to human chondrocytes

High concentrations of cryoprotective agents are required for cryopreservation techniques such as vitrification. Glycerol is a common cryoprotective agent used in cryopreservation protocols but this agent is toxic at high concentrations. This work is an attempt to mitigate the toxic effects of high concentrations of glycerol on intact chondrocytes in human knee articular cartilage from total knee arthroplasty patients by simultaneous exposure to glycerol and a variety of additive compounds. The resulting cell viability in the cartilage samples as measured by membrane integrity staining showed that, in at least one concentration or in combination, all of the tested additive compounds (tetramethylpyrazine, ascorbic acid, chondroitin sulphate, glucosamine sulphate) were able to reduce the deleterious effects of glycerol exposure when examination of membrane integrity took place on a delayed time frame. The use of additive compounds to reduce cryoprotectant toxicity in articular cartilage may help improve cell recovery after cryopreservation.

Design, synthesis and evaluation of new ligustrazine derivatives as potential plasma-stable neuroprotective agents

A series of ligustrazine-phenolic acid esters which exhibited promising neuroprotective activities have previously been reported. Nevertheless, we found that these ester compounds (like T-VA) were not stable in plasma by further in vivo studies. To investigate plasma-stable neuroprotective agents, a series of new ligustrazine derivatives were synthesized by conjoining ligustrazine and phenols with ester, ether and amide bonds. Most of the compounds exhibited higher protective effects against CoCl₂-induced neurotoxicity in differentiated PC12 cells than ligustrazine. Structure-activity relationships were also briefly discussed. We found that compound 2c (2-((2-methoxy-4-(((3,5,6-trimethylpyrazin-2-yl)methoxy) methyl)phenoxy)methyl)-3,5,6-trimethylpyrazine) displayed the highest protective effect on the PC12 cells damaged by CoCl₂ (EC₅₀ = 1.07 μM). Preliminary stability investigation in rat plasma was verified in vitro and better plasma stability was observed with 2c in comparison to T-VA.

Comparing Cerebralcare Granule and aspirin for neurological dysfunction in acute stroke in real-life practice

BACKGROUND

Cerebralcare Granule (CG) is a polyherbal Chinese medicine that has been shown to have neuroprotective effects in experimental models of stroke. We compared the efficacy and safety of CG with aspirin in patients with acute stroke.

METHODS

For this open-label, controlled trial, we recruited patients with angiographically confirmed strokes and US National Institutes of Health Stroke Scale (NIHSS) scores of 4-22 within 2 weeks of symptom onset; recruitment was performed at 55 sites in China. Patients received CG or aspirin. The primary efficacy end-point was neurological function. Analyses were done by intention to treat. Patients were measured for NIHSS, Montreal Cognitive Assessment, and Mini-Mental State Examination scores and Barthel index at baseline and at 4, 8, and 12 weeks after treatment.

RESULTS

Between January 2013 and January 2014, we treated 1963 patients with CG and 1288 patients with aspirin. Baseline NIHSS, Mini-Mental State Examination, and Montreal Cognitive Assessment scores were comparable between the two groups. Patients in the CG group had a greater improvement than the aspirin group in terms of NIHSS (P < 0.01) and Barthel index at 4, 8, and 12 weeks. At 12 weeks, patients in the CG group had a greater improvement than the aspirin group in terms of Mini-Mental State Examination (P < 0.01) and Montreal Cognitive Assessment (P < 0.05). Adverse reactions were similar between the two groups.

CONCLUSIONS

This large-scale, controlled trial indicated that CG may be a useful treatment in the management of post-stroke patients.

Vascular Contributions to Cognitive Impairment and Treatments with Traditional Chinese Medicine

The prevalence of cognitive impairment and dementia caused by cerebrovascular disease is likely to increase with the global aging population. Vascular contributions to cognitive impairment and dementia (VCID) is a wide spectrum term used to include a diverse heterogeneous group of cognitive syndromes with vascular factors regardless of the cause of pathogenesis. VCID ranges from mild cognitive impairment to full-blown dementia with vascular dementia (VaD) as the most severe stage. It is further complexed by the coexistence of other forms of dementia such as Alzheimer's disease (AD). Recent researches in the functions of the neurovascular unit (NVU) suggest that dysfunction of the NVU might be the cause of primary vascular events in the brain that leads to further neurodegeneration. In this review, we have briefly summarized various forms of VCID. There is currently no standard therapy for VCID or dementia. Given the fact that Traditional Chinese Medicine (TCM) has gained popularity worldwide, we also reviewed recent scientific and clinical findings on various antidementia TCM for the treatment of VCID, including Salvia miltiorrhiza, Huperzia serrata, Ligusticum chuanxiong, Ginkgo biloba, Panax ginseng, and also TCM formula Sailuotong capsule (SLT) and Fufangdanshen tablets (FFDS).

Anti-Inflammatory Effects of Traditional Chinese Medicines against Ischemic Injury in In Vivo Models of Cerebral Ischemia

Inflammation plays a crucial role in the pathophysiology of acute ischemic stroke. In the ischemic cascade, resident microglia are rapidly activated in the brain parenchyma and subsequently trigger inflammatory mediator release, which facilitates leukocyte-endothelial cell interactions in inflammation. Activated leukocytes invade the endothelial cell junctions and destroy the blood-brain barrier integrity, leading to brain edema. Toll-like receptors (TLRs) stimulation in microglia/macrophages through the activation of intercellular signaling pathways secretes various proinflammatory cytokines and enzymes and then aggravates cerebral ischemic injury. The secreted cytokines activate the proinflammatory transcription factors, which subsequently regulate cytokine expression, leading to the amplification of the inflammatory response and exacerbation of the secondary brain injury. Traditional Chinese medicines (TCMs), including TCM-derived active compounds, Chinese herbs, and TCM formulations, exert neuroprotective effects against inflammatory responses by downregulating the following: ischemia-induced microglial activation, microglia/macrophage-mediated cytokine production, proinflammatory enzyme production, intercellular adhesion molecule-1, matrix metalloproteinases, TLR expression, and deleterious transcription factor activation. TCMs also aid in upregulating anti-inflammatory cytokine expression and neuroprotective transcription factor activation in the ischemic lesion in the inflammatory cascade during the acute phase of cerebral ischemia. Thus, TCMs exert potent anti-inflammatory properties in ischemic stroke and warrant further investigation.

Micro-CT as a Tool to Investigate the Efficacy of Tetramethylpyrazine in a Rat Spinal Cord Injury Model

STUDY DESIGN

The micro-computed tomography (micro-CT) was applied to assess the effect of tetramethylpyrazine (TMP) on experimental spinal cord injury (SCI).

OBJECTIVE

The aim of the study was to explore the therapeutic effect of TMP on a rat SCI model using micro-CT.

SUMMARY OF BACKGROUND DATA

SCI is a devastating event and always accompanied by severe vascular injury. Promoting angiogenesis after SCI has recently been recognized as a potential way to enhance the neurological function recovery. How the TMP promotes angiogenesis and improved locomotor function recovery after SCI has, however, not been fully clarified. In this study, we used micro-CT to evaluate the effect on the microvasculature changes after TMP treatment.

METHODS

The contusion SCI model was induced in rats by a modified Allen's impact method. In the TMP treatment group, rats were injected intraperitoneally with TMP. The control group was treated with saline. Hindlimb motor function was evaluated using the Basso, Beattie, Bresnahan score. Histology was employed to examine the pathological changes and quantified at 28 days after injury. Spinal cord vessel network and angiogenesis were assessed using micro-CT.

RESULTS

Angiogenesis was increased in groups treated with TMP compared with rat in the control groups (P < 0.05). Micro-CT vividly depicted the three-dimensional morphology changes of the spinal cord microvasculature after injury and demonstrated more vessels number, vessel volume fraction, and vessel connectivity value in the groups treated with TMP than in the control groups (P < 0.05). In addition, the injury-induced lesion area in TMP group was attenuated in comparison with control groups. Similarly, neurological functions were greatly improved in groups treated with TMP compared with rats in the control groups.

CONCLUSION

Micro-CT is useful for detecting angiogenesis after SCI. TMP therapy reduced the neuronal loss, promoted angiogenesis, and exerted a positive effect on neurological function recovery after SCI.

LEVEL OF EVIDENCE

N/A.

Tetramethylpyrazine Ameliorates Rotenone-Induced Parkinson's Disease in Rats: Involvement of Its Anti-Inflammatory and Anti-Apoptotic Actions

Parkinson's disease (PD) is a slowly progressive neurodegenerative movement disorder. Apoptosis, neuroinflammation, and oxidative stress are the current hypothesized mechanisms for PD pathogenesis. Tetramethylpyrazine (TMP), the major bioactive component of Ligusticum wallichii Franchat (ChuanXiong), Family Apiaceae, reportedly has anti-apoptotic, anti-inflammatory and antioxidant effects. This study investigated the role of 'TMP' in preventing rotenone-induced neurobiological and behavioral sequelae. A preliminary dose-response study was conducted where rats received TMP (10, 20, and 40 mg/kg, i.p.) concomitantly with rotenone (2 mg/kg, s.c.) for 4 weeks. Catalepsy, locomotor activity, striatal dopamine content, and tyrosine hydroxylase "TH" and α-synuclein immunoreactivity were evaluated. The selected TMP dose (20 mg/kg) was used for western blot analysis of Bax, Bcl2, and DJ-1, immunohistochemical detection of nuclear factor kappa B (NF-кB), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX2), and glial fibrillary acidic protein (GFAP) expression, in addition to biochemical analysis of caspase-3 activity, nuclear factor erythroid 2-related factor 2 (Nrf2), and heme oxygenase-1 (HO-1) levels. Results showed that TMP (20 mg/kg) significantly improved midbrain and striatal TH expression and striatal dopamine content as well as the motor deficits, compared to rotenone-treated group. These results were correlated with reduction in caspase-3 activity and α-synuclein expression, along with improvement of midbrain and striatal Bax/Bcl2 ratio compared to rotenone-treated group. TMP also attenuated rotenone-induced upregulation of Nrf2/HO-1 pathway. Furthermore, TMP downregulated rotenone-induced neuroinflammation markers: NF-кB, iNOS, COX2, and GFAP expression in both the midbrain and striatum. Taken together, the current study suggests that TMP is entitled to, at least partially, preventing PD neurobiological and behavioral deficits by virtue of its anti-apoptotic, anti-inflammatory, and antioxidant actions.

Tetramethylpyrazine enhances functional recovery after contusion spinal cord injury by modulation of MicroRNA-21, FasL, PDCD4 and PTEN expression

Our previous study showed Tetramethylpyrazine (TMP) has protective effects against SCI. In this study, we aimed to uncover the mechanism underlying the protective effects of TMP in SCI. SCI was induced in Sprague-Dawley rats with a modified weight-drop device. One group was subjected to SCI in combination with TMP administration at a dose of 200mg/kgd, for 3 days. Concurrently, another group received SCI in combination with an equal volume of 0.9% saline. Locomotor functional recovery was assessed during the 4 weeks post-injury by performing the Basso, Beattie, and Bresnahan (BBB) rating procedure. Lesion size and spared tissue were measured by cresyl violet staining. MicroRNA-21 (miR-21) expression was determined by real-time PCR and in situ hybridization. FasL, PDCD4, and PTEN are direct targets of miR-21 in many diseases and cell types; their levels were analyzed by western blot. Immunohistochemistry was performed to observe the expression of PDCD4 and PTEN. Cell apoptosis was assessed by TUNEL staining and DNA laddering. TMP treatment after contusion SCI significantly improved functional recovery, decreased lesion size, and increased tissue sparing and miR-21 levels; expression of FasL, PDCD4, and PTEN was decreased. TMP treatment also reduced apoptosis after SCI. Thus, TMP administration improved functional recovery and reduced cell apoptosis. Its protective effect may partly based on increasing the expression of miR-21 and decreasing the expression of FasL, PDCD4, and PTEN. These could serve as new exploratory targets for SCI treatment.