Tetramethylpyrazine suppresses HIF-1alpha, TNF-alpha, and activated caspase-3 expression in middle cerebral artery occlusion-induced brain ischemia in rats

Microneedle-mediated drug delivery for neurological diseases

Neurological disorders, including brain injury, brain tumors, and neurodegenerative diseases, rank as the second leading cause of death worldwide. Exploring effective new treatments for neurological disorders has long been a hot research issue in clinical practice. Recently, microneedles (MNs) have attracted much attention due to their designation as a "painless and non-invasive" novel transdermal delivery method, characterized by their biocompatibility and sustainability. The advantages of MNs open an avenue for potential therapeutic interventions targeting neurological disorders. This review presents a concise overview of progress in the field of MNs, with highlights on the application in the treatment of neurological disorders. Notably, trends in the development of MNs and future challenges are also discussed.

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.

Traditional Chinese medicines treat ischemic stroke and their main bioactive constituents and mechanisms

Ischemic stroke (IS) remains one of the leading causes of death and disability in humans. Unfortunately, none of the treatments effectively provide functional benefits to patients with IS, although many do so by targeting different aspects of the ischemic cascade response. The advantages of traditional Chinese medicine (TCM) in preventing and treating IS are obvious in terms of early treatment and global coordination. The efficacy of TCM and its bioactive constituents has been scientifically proven over the past decades. Based on clinical trials, this article provides a review of commonly used TCM patent medicines and herbal decoctions indicated for IS. In addition, this paper also reviews the mechanisms of bioactive constituents in TCM for the treatment of IS in recent years, both domestically and internationally. A comprehensive review of preclinical and clinical studies will hopefully provide new ideas to address the threat of IS.

A series of ligustrazine platinum(IV) complexes with potent anti-proliferative and anti-metastatic properties that exert chemotherapeutic and immunotherapeutic effects

The development of novel anticancer drugs with antiproliferative and antimetastatic activities is of great importance in the pharmaceutical field. Herein, a series of ligustrazine (LSZ) platinum(IV) complexes with chemotherapeutic and immunotherapeutic effects were designed, prepared and evaluated as antitumor agents for the first time. Complex 4 with potent antitumor activities both in vitro and in vivo was screened out as a candidate. Notably, it displays significantly more effective anti-metastatic activities than the platinum(II) drugs cisplatin and oxaliplatin. Mechanism detection discloses that it causes serious DNA damage and increases the expression of γ-H2AX and P53. Then, the apoptosis of tumor cells is promoted by activating the mitochondrial apoptotic pathway Bcl-2/Bax/caspase-3 and causing autophagy via modulating LC3-I/II and P62 expression. Furthermore, the immune therapeutic responses are significantly elevated by blocking HIF-1α, ERK 1/2 and COX-2 pathways to reduce PD-L1 expression, and further increasing CD3+ and CD8+ T cells to elevate T cell immunity in tumors. Tumor metastasis is blocked by the synergistic functions of DNA damage, hypoxia modulation and immune activation.

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.

Tetramethylpyrazine Attenuates Oxygen-glucose Deprivation-induced Neuronal Damage through Inhibition of the HIF-1α/BNIP3 Pathway: From Network Pharmacological Finding to Experimental Validation

AIMS

A network pharmacological analysis combined with experimental validation was used to investigate the neuroprotective mechanism of the natural product Tetramethylpyrazine(TMP).

BACKGROUND

Protecting neurons is critical for acute ischemic stroke treatment. Tetramethylpyrazine is a bioactive component extracted from Chuanxiong. The neuroprotective potential of TMP has been reported, but a systematic analysis of its mechanism has not been performed.

OBJECTIVE

Based on the hints of network pharmacology and bioinformatics analysis, the mechanism by which TMP alleviates oxygen-glucose deprivation-induced neuronal damage through inhibition of the HIF-1α/BNIP3 pathway was verified.

METHOD

In this study, we initially used network pharmacology and bioinformatics analyses to elucidate the mechanisms involved in TMP's predictive targets on a system level. The HIF-1α/BNIP3 pathway mediating the cellular response to hypoxia and apoptosis was considered worthy of focus in the bioinformatic analysis. An oxygen-glucose deprivation (OGD)-induced PC12 cell injury model was established for functional and mechanical validation. Cell viability, lactate dehydrogenase leakage, intracellular reactive oxygen species, percentage of apoptotic cells, and Caspase-3 activity were determined to assess the TMP's protective effects. Transfection with siRNA/HIF-1α or pcDNA/HIF-1α plasmids to silence or overexpress hypoxia-inducible factor 1α(HIF-1α). The role of HIF-1α in OGD-injured cells was observed first. After that, TMP's regulation of the HIF-1α/BNIP3 pathway was investigated. The pcDNA3.1/HIF-1α-positive plasmids were applied in rescue experiments.

RESULT

The results showed that TMP dose-dependently attenuated OGD-induced cell injury. The expression levels of HIF-1α, BNIP3, and the Bax/Bcl-2 increased significantly with increasing OGD duration. Overexpression of HIF-1α decreased cell viability, increased BNIP3 expression, and Bax/Bcl-2 ratio; siRNA-HIF-1α showed the opposite effect. TMP treatment suppressed HIF-1α, BNIP3 expression, and the Bax/Bcl-2 ratio and was reversed by HIF-1α overexpression.

CONCLUSION

Our study shows that TMP protects OGD-damaged PC12 cells by inhibiting the HIF-1α/BNIP3 pathway, which provides new insights into the mechanism of TMP and its neuroprotective potential.

Neuroprotective Strategies for Stroke by Natural Products: Advances and Perspectives

Cerebral ischemic stroke is a disease with high prevalence and incidence. Its management focuses on rapid reperfusion with intravenous thrombolysis and endovascular thrombectomy. Both therapeutic strategies reduce disability, but the therapy time window is short, and the risk of bleeding is high. Natural products (NPs) have played a key role in drug discovery, especially for cancer and infectious diseases. However, they have made little progress in clinical translation and pose challenges to the treatment of stroke. Recently, with the investigation of precise mechanisms in cerebral ischemic stroke and the technological development of NP-based drug discovery, NPs are addressing these challenges and opening up new opportunities in cerebral stroke. Thus, in this review, we first summarize the structure and function of diverse NPs, including flavonoids, phenols, terpenes, lactones, quinones, alkaloids, and glycosides. Then we propose the comprehensive neuroprotective mechanism of NPs in cerebral ischemic stroke, which involves complex cascade processes of oxidative stress, mitochondrial damage, apoptosis or ferroptosis-related cell death, inflammatory response, and disruption of the blood-brain barrier (BBB). Overall, we stress the neuroprotective effect of NPs and their mechanism on cerebral ischemic stroke for a better understanding of the advances and perspective in NPs application that may provide a rationale for the development of innovative therapeutic regimens in ischemic stroke.

Natural products regulate mitochondrial function in cognitive dysfunction-A scoping review

Medicines from natural products can not only treat neurodegenerative diseases but also improve the cognitive dysfunction caused by treatments with western medicines. This study reviews the literature related to the regulation of mitochondrial participation in cognitive function by natural products. In this study, we focused on English articles in PubMed, Web of Science, and Google Scholar, from 15 October 2017, to 15 October 2022. Fourteen studies that followed the inclusion criteria were integrated, analyzed, and summarized. Several studies have shown that natural products can improve or reduce cognitive dysfunction by ameliorating mitochondrial dysfunction. These results suggest that natural products may serve as new therapeutic targets for neurodegenerative diseases.

Traditional Chinese Medicine for Post-Stroke Cognitive Impairment: A Systematic Review and Meta-Analysis

Background: Post-stroke cognitive impairment (PSCI) affects more than one-third of stroke patients, and causes much greater harm to long-term function than the initial brain damage. No conventional Western medications have shown convincing clinical effectiveness for treating PSCI. Research shows that Traditional Chinese medicine (TCM) can improve cognitive function in patients. However, the clinical efficacy and safety remain controversial. The aim of this study was to examine the effectiveness and harmful effects of TCMs in the treatment of PSCI. Method: We searched seven databases and two clinical registration websites for randomized controlled trials (RCTs). The revised Cochrane risk of bias tool (RoB 2.0) was used to evaluate the methodological quality and RevMan 5.4 was used for data analysis. This study has been submitted to PROSPERO with registration number is CRD42020149299. Results: We included 34 studies in this review. The results of this study showed that TCM adjuvant therapy improved scores on the MoCA [MD = 2.55, 95% CI (1.56, 3.53), p < 0.00001; MD = 3.07, 95% CI (1.98, 4.17), p < 0.00001 at treatment duration of <3 and 3 months, respectively], MMSE [MD = 2.55, 95% CI (1.99, 3.10), p < 0.00001; MD = 2.53, 95% CI (1.59, 3.47), p < 0.00001; MD = 2.91, 95% CI (1.26, 4.56), p = 0.0006; MD = 3.11, 95% CI (-0.04, 6.27), p = 0.05 at treatment duration of <3, 3, 4, and 6 months, respectively], and BI [MD = 7.34, 95% CI (3.83, 10.85), p < 0.0001; MD = 8.98, 95% CI (4.76, 13.21), p < 0.0001 at treatment duration of <3 and 3 months, respectively] and reduced scores on the ADL (MD = -8.64, 95% CI (-9.83, -7.45), p < 0.00001; MD = -2.00, 95% CI (-2.94, -1.06), p < 0.0001 at treatment duration of 3 and 4 months, respectively], NIHSS [MD = -2.48, 95% CI (-4.97, 0.00), p = 0.05; MD = -3.81, 95% CI (-6.21, -1.40), p = 0.002 at treatment duration of <3 and 3 months, respectively], and CSS [MD = -2.47, 95% CI (-3.49, -1.45), p < 0.00001 at a treatment duration of 3 months]. No serious adverse reactions were observed. Conclusion: Despite the significant positive results, the present evidence supports, to a limited extent because of the methodological flaws and herbal heterogeneity, that TCM adjuvant therapy can be used for patients with PSCI. While, further rigorous RCTs are warranted to confirm the efficacy and safety of TCM. Systematic Review Registration: https://www.crd.york.ac.uk/prospero, identifier CRD42020149299.

Vortioxetine mitigates neuronal damage by restricting PERK/eIF2α/ATF4/CHOP signaling pathway in rats subjected to focal cerebral ischemia-reperfusion

AIMS

Stroke has risen to the fifth and third most common causes of death in the United States and the rest of the world, respectively. Vortioxetine (VTX) is a multimodal antidepressant agent that balances 5-HT receptors and represses the serotonin transporter. Our study aimed to examine the neuroprotective impacts of VTX against cerebral ischemia caused by occluding the middle cerebral artery (MCA).

MAIN METHODS

Until the middle cerebral artery occlusion (MCAO) induction, VTX (10 mg/kg/day) was taken orally for 14 days. Behavioral assessments were carried out 24 h after the MCAO technique. The hippocampal and cortical tissues of the brain were isolated to assess the histological changes and the levels of the biochemical parameters.

KEY FINDINGS

MCAO damage led to severe neurological deficits and histopathological damage. However, VTX improved MCAO-induced neurological deficits and ameliorated histopathological changes in both hippocampal and cortical tissues of MCAO rats. Western blot analysis showed increments of p-PERK, CHOP, ASK-1, NICD, HES-1, HES-5, and p-eIF2α expression levels in MCAO rats. Moreover, ELISA revealed an increase in the levels of ATF4, IRE1, Apaf-1, and HIF-1α, while VTX administration ameliorated most of these perturbations induced after MCAO injury.

SIGNIFICANCE

This research suggests that VTX could be a potent neuroprotective agent against ischemic stroke by inhibiting a variety of oxidative, apoptotic, inflammatory, and endoplasmic reticulum stress pathways.

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.

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.

Tetramethylpyrazine Improves Cognitive Impairment and Modifies the Hippocampal Proteome in Two Mouse Models of Alzheimer's Disease

Alzheimer's disease (AD), one of the most common neurodegenerative diseases, has no effective treatment. We studied the potential effects of tetramethylpyrazine (TMP), an alkaloid in the rhizome of Ligusticum chuanxiong Hort. used in Traditional Chinese Medicine (chuānxiong) to treat ischemic stroke, on AD progression in two AD mouse models. Eight-month-old 3xTg-AD mice received TMP treatment (10 mg/kg/d) for 1 month, and 4-month-old APP/PS1-AD mice received TMP treatment (10 mg/kg/d) for 2 months. Behavioral tests, including step-down passive avoidance (SDA), new object recognition (NOR), Morris water maze (MWM), and Contextual fear conditioning test showed that TMP significantly improved the learning and memory of the two AD-transgenic mice. In addition, TMP reduced beta-amyloid (Aß) levels and tau phosphorylation (p-tau). Venny map pointed out that 116 proteins were commonly changed in 3xTg mice vs. wild type (WT) mice and TMP-treated mice vs. -untreated mice. The same 130 proteins were commonly changed in APP/PS1 mice vs. WT mice and TMP-treated mice vs. -untreated mice. The functions of the common proteins modified by TMP in the two models were mainly involved in mitochondrial, synaptic, cytoskeleton, ATP binding, and GTP binding. Mitochondrial omics analysis revealed 21 and 20 differentially expressed mitochondrial proteins modified by TMP in 3xTg-AD mice and APP/PS1 mice, respectively. These differential proteins were located in the mitochondrial inner membrane, mitochondrial outer membrane, mitochondrial gap, and mitochondrial matrix, and the function of some proteins is closely related to oxidative phosphorylation (OXPHOS). Western-blot analysis confirmed that TMP changed the expression of OXPHOS complex proteins (sdhb, ndufa10, uqcrfs1, cox5b, atp5a) in the hippocampus of the two AD mice. Taken together, we demonstrated that TMP treatment changed the hippocampal proteome, reduced AD pathology, and reduced cognitive impairment in the two AD models. The changes might be associated with modification of the mitochondrial protein profile by TMP. The results of the study suggest that TMP can improve the symptoms of AD.

Empagliflozin alleviates neuronal apoptosis induced by cerebral ischemia/reperfusion injury through HIF-1α/VEGF signaling pathway

Ischemic stroke is a serious condition associated with severe functional disability and high mortality, however; effective therapy remains elusive. Empagliflozin, a sodium-glucose cotransporter 2 inhibitor, has been shown to exert additional non-glycemic benefits including anti-apoptotic effects in different disease settings. Thereby, this study was designed to investigate the ameliorative effect of empagliflozin on the neuronal apoptosis exhibited in cerebral ischemia/reperfusion (I/R) in a rat model targeting HIF-1α/VEGF signaling which is involved in this insult. Global cerebral I/R injury was induced in male Wistar rats through occlusion of the bilateral common carotid arteries for 30 min followed by one-hour reperfusion. Empagliflozin doses of 1 and 10 mg/kg were administered 1 and 24 h after reperfusion. In I/R-injured rats, empagliflozin treatments significantly reduced infarct size and enhanced neurobehavioral functions in a dose-dependent manner. The drug alleviated neuronal death and cerebral injury inflicted by global ischemia as it suppressed neuronal caspase-3 protein expression. In parallel, protein expressions of HIF-1α and its downstream mediator VEGF were upregulated in the ischemic brain following empagliflozin treatment. The results indicated that empagliflozin attenuates cerebral I/R-induced neuronal death via the HIF-1α/VEGF cascade.

The impact of single and combined PPAR-α and PPAR-γ activation on the neurological outcomes following cerebral ischemia reperfusion

AIM

The neuronal damage and accompanied functional deficits induced by cerebral ischemia are among the most common causes of disabilities in adults. Activation of subtypes of peroxisome proliferator-activated receptors (PPARs); PPAR-α and PPAR-γ have shown neuroprotective effects in different neurodegenerative diseases including stroke. Thus, this study aimed to compare the effects of two different agonists: PPAR-α (fenofibrate) and PPAR-γ (pioglitazone) as well as the effect of their combination in ameliorating post-ischemia behavioral deficits.

METHODS

Male Wistar rats were either pretreated with vehicle, fenofibrate (100 mg/kg/day p.o), pioglitazone (10 mg/kg/day p.o) or their combination for 14 days prior to bilateral common carotid artery occlusion followed by reperfusion for 24 hoursh. The sensory motor functions of rats were assessed, then rats were sacrificed to determine infarct volume and histopathological changes as well as oxidative stress, inflammatory and apoptotic markers in the brain tissue.

KEY FINDINGS

Pre-treatment with fenofibrate and pioglitazone in addition to their combination improved neurobehavioral dysfunction, reduced cerebral infarct volume, attenuated inflammatory and apoptotic markers and ameliorated histopathological changes in I/R injured rats. The effect of pioglitazone in cerebral cortex was higher than its corresponding effect in fenofibrate while the combined administration of both drugs had additive neuroprotective effect and normalized inflammatory and apoptotic mediators in ischemic rats.

SIGNIFICANCE

The study compared the neuroprotective effects of PPAR-α and PPAR-γ agonists, and tested the impact of their combination. We concluded that no additional benefits on the functional outcomes might be gained upon their combination.

RETRACTED: Tetramethylpyrazine alleviates lipopolysaccharide-induced damage in ATDC5 cells via down-regulating MyD88

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor-in-Chief and the authors. Following the concerns raised about the background pattern of the Western Blots from Figures 7A and 7C, the authors have contacted the journal to request the retraction of the article as they were reportedly not confident of the accuracy of the data and the conclusions of the article. Given the comments of Dr Elisabeth Bik regarding this article “This paper belongs to a set of over 400 papers (as per February 2020) that share very similar Western blots with tadpole-like shaped bands, the same background pattern, and striking similarities in title structures, paper layout, bar graph design, and - in a subset - flow cytometry panels”, the journal requested the authors to provide the raw data. However, the authors were not able to fulfil this request and therefore the Editor-in-Chief decided to retract the article.

Ligustrazine Protects Homocysteine-Induced Apoptosis in Human Umbilical Vein Endothelial Cells by Modulating Mitochondrial Dysfunction

Ligustrazine is one of the alkaloid compounds isolated from the traditional Chinese herb, which shows protective effects on cardiovascular disorders. High homocysteine (Hcy) level can predict cardiovascular-related events including death. In this study, we used Hcy to stimulate the human umbilical vein endothelial cells (HUVECs) and investigated the protective effect of ligustrazine on endothelial dysfunction by assessing the cell apoptosis, oxidative damage, mitochondrial dysfunction, and the potential molecular pathways. Our results clearly showed that ligustrazine increased HUVEC cell viability, decreased the dehydrogenase (LDH) level, and inhibited HUVEC apoptosis, which was associated with the attenuation of attenuated oxidative damage. The mitochondrial-dependent pathway was closely related in the regulation of ligustrazine, reflected by the attenuated mitochondrial membrane potential change and decreased cytochrome c release from the mitochondria to the cytosol. Ligustrazine may protect Hcy-induced apoptosis in HUVECs by attenuating oxidative damage and modulating mitochondrial dysfunction.

Proteomic analysis reveals the potential neuroprotective effects of tetramethylpyrazine dimer in neuro2a/APPswe cells

Alzheimer's disease (AD) is a common neurodegenerative disease characterized by pathological processes, including abnormal amyloid deposits and filament tangles, oxidative stress, neuroinflammation, and neurotrophic insufficiency, leading to chronic and prolonged neuronal loss and cognitive deficits. Tetramethylpyrazine (TMP) is one of the main active components of Ligusticum wallichii, a traditional Chinese medicine widely used for brain related disease. Here, we synthesized the TMP derivative tetramethylpyrazine dimer (DTMP), and evaluated the potential mechanisms underlying its potential neuroprotective effects using the murine neuron-like cells (N2a) transfected with the human "Swedish" mutant amyloid precursor protein (N2aAPP). ELISA results indicated that DTMP reduced the levels of Aβ1-40 and Aβ1-42 in N2aAPP. Then through proteomic analysis we identified a total of 208 differentially expressed proteins in N2aAPP cells compared to the wild-type N2a cells (N2aWT), including 144 increased and 64 decreased proteins. 449 differentially expressed proteins were revealed in N2aAPP cells on DTMP treatment with 69 increased and 380 decreased proteins. Bioinformatic analysis suggested that these proteins are enriched in mitochondrial function, the electronic transmission chain, ATP binding, oxidative phosphorylation, GTPase function, the transcriptional translation process, amino acid metabolism, nucleotide binding and others. Given the vital role of mitochondria in the pathogenesis of AD, we selected the electron transport chain pathway-related molecules to further validate these findings. Western-blot analysis demonstrated that DTMP significantly increased the levels of complex I (NDUAA), complex II (SDHB), complex III (UCRI), complex IV (COX5A) and complex V (ATP5A) in N2aAPP cells. The modulation of dysregulated proteins implicated in AD pathogenesis implies the pharmacological mechanisms of DTMP and its potential as a novel therapeutic choice in AD.

Role and mechanism of nursing cooperation and tetramethylpyrazine application in post-operative pain in patients undergoing total knee arthroplasty

The aim of the present study was to investigate the effect of nursing cooperation on the post-operative complication of pain following total knee arthroplasty (TKA) and to explore the effects of tetramethylpyrazine (TMP) application on post-TKA pain. A total of 26 patients who received TKA between June 2014 and March 2016 were enrolled in this study. Nursing cooperation was provided to the patients during the TKA surgery, and pain was evaluated based on the visual analog scale (VAS). In addition, 40 male Sprague Dawley rats were used for the TKA model construction. The rats were randomly separated into 4 groups (sham, TKA, TKA+TMP and TKA+TMP+Interferon γ). Pain tolerance in rats was evaluated by mechanical stimulation. Inflammatory cytokine levels in TKA rat tissue were detected using ELISA. mRNA and protein expression of Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) was detected using reverse transcription-polymerase chain reaction and western blot analysis, respectively. The results indicated that nursing cooperation serves a critical function during TKA and was associated with a lower level of pain compared with the control (P<0.05). Furthermore, TMP treatment reduced the level of inflammatory cytokines in the rat tissues, including interleukin (IL)-6, IL-10 and tumor necrosis factor-α in post-TKA (P<0.01). TMP was indicated to alleviate pain in post-TKA through suppressing the JAK/STAT3 signaling pathway. The results of the present study suggest that nursing cooperation is critical to TKA, and TMP may alleviate post-TKA pain through inhibiting the JAK/STAT3 signaling pathway.

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.

Tetramethylpyrazine reverses intracerebroventricular streptozotocin-induced memory deficits by inhibiting GSK-3β

Brain dysfunction, especially cognitive impairment, is one of the main complications in Alzheimer's disease (AD), which threatens the health of 46.8 million people worldwide. At present, the pathogenesis of cognitive dysfunction is only partially understood, and effective therapies for memory loss in AD remain elusive. Tetramethylpyrazine (TMP) is one of the major bioactive compounds purified from Chuanxiong, a Chinese herb used for the treatment of neurovascular and cardiovascular diseases. The neuroprotective properties of TMP are evident in some neurodegenerative diseases, including Parkinson's disease. However, whether TMP plays a neuroprotective role in AD is still unknown. Here, we report that 2-week treatment with TMP rescued both short-term and long-term fear memory impairment induced by intracerebroventricular injection of streptozotocin in a well-known AD rat model. Administration of TMP also restored spatial learning and memory retention abilities in streptozotocin-injected rats. Furthermore, TMP inhibited the activity of GSK-3β, an important kinase that mediates hippocampal synaptic and memory disorders in diabetes mellitus. Finally, we found that TMP treatment restored the function of cholinergic neurons. Our data suggest that dietary uptake of TMP can provide protection against memory loss in AD, and the inhibition of GSK-3β may play an important role in this protective effect.

Tetramethylpyrazine-Loaded Hydrogels: Preparation, Penetration Through a Subcutaneous-Mucous-Membrane Model, and a Molecular Dynamics Simulation

Tetramethylpyrazine (TMP) was extracted from Ligusticum chuanxiong hort. The compound is known to have a variety of medicinal functions; in particular, it is used for the treatment of cerebral ischemic diseases. TMP-loaded hydrogels offer an excellent preparation with the capacity to bypass the blood-brain barrier, allowing treatment of the brain through intranasal administration. We prepared TMP-loaded hydrogels using carbomer 940 and evaluated the release of TMP from the hydrogel. We determined the release rate using Franz-type diffusion cell experiments with a subcutaneous-mucous-membrane model and also by a molecular dynamics (MD) simulation. In general, the former method was more complicated than the latter was. The dynamic behavior of TMP release from the hydrogel was revealed by analysis of the mean square displacement of the trajectory in the MD simulation. The coefficient of TMP diffusion from the hydrogel was calculated at different temperatures (277, 298, and 310 K) by using MD software. The results showed that the coefficient of diffusion increased with an increase in temperature. This trend was observed both experimentally and in the MD simulation. Therefore, the MD simulation was a complementary method to verify the experimental data.

Protective Role of Fucoidan in Cerebral Ischemia-Reperfusion Injury through Inhibition of MAPK Signaling Pathway

Fucoidan has been reported to exhibit various beneficial activities ranging from to antivirus and anticancer properties. However, little information is available about the effects of fucoidan on cerebral ischemia-reperfusion injury (IRI). Our study aimed to explore the effects of fucoidan on cerebral IRI, as well as the underlying mechanisms. Sprague-Dawley (SD) rats were randomly subjected to four groups: Sham, IRI+saline (IRI+S), IRI+80 mg/kg fucoidan (IRI+F80), and IRI+160 mg/kg fucoidan (IRI+F160). Fucoidan (80 mg/kg or 160 mg/kg) was intraperitoneally injected from 7 days before the rats were induced to cerebral IRI model with middle cerebral artery occlusion (MCAO) method. At 24 h after reperfusion, neurological deficits and the total infarct volume were determined. The levels of inflammation-associated cytokines (interleukin (IL)-1β, IL-6, myeloperoxidase (MPO), and tumor necrosis factor (TNF)-α), oxidative stress-related proteins (malondialdehyde (MDA) and superoxide dismutase (SOD)) in the ischemic brain were measured by enzyme-linked immunosorbent assay (ELISA). Besides, the levels of apoptosis-related proteins (p-53, Bax, and B-cell lymphoma (Bcl)-2) and mitogen-activated protein kinase (MAPK) pathway (phosphorylation-extracellular signalregulated kinase (p-ERK), p-c-Jun N-terminal kinase (JNK), and p-p38) were measured. Results showed that administration of fucoidan significantly reduced the neurological deficits and infarct volume compared to the IRI+S group in a dose-dependent manner. Also, fucoidan statistically decreased the levels of inflammation-associated cytokines, and oxidative stress-related proteins, inhibited apoptosis, and suppressed the MAPK pathway. So, Fucoidan plays a protective role in cerebral IRI might be by inhibition of MAPK pathway.

Tetramethylpyrazine Protects against Early Brain Injury after Experimental Subarachnoid Hemorrhage by Affecting Mitochondrial-Dependent Caspase-3 Apoptotic Pathway

This study was to test the hypothesis that tetramethylpyrazine (TMP) protected against early brain injury after subarachnoid hemorrhage (SAH) by affecting the mitochondrial-dependent caspase-3 apoptotic pathway. TMP was administrated after the rats' prechiasmatic SAH mode. Animal neurobehavioral functions were assessed and the mitochondrial morphology, mitochondrial and cytoplasmic calcium, and mitochondrial membrane potential changes (Δψm) of the brain tissues were measured. The expressions of cytoplasmic cytochrome c (cyt c), second mitochondria-derived activator of caspases (Smac), and cleaved caspase-3 B-cell lymphoma 2 (bcl-2) in cells were determined and cellular apoptosis was detected. The treatment of TMP resulted in less apoptotic cells and milder mitochondrial injury and potentially performed better in the neurobehavioral outcome compared to those with saline. Also, TMP ameliorated calcium overload in mitochondria and cytoplasm and alleviated the decrease of Δψm. In addition, TMP inhibited the expression of cytoplasmic cyt c, Smac, and cleaved caspase-3, yet it upregulated the expression of bcl-2. These findings suggest that TMP exerts an antiapoptosis property in the SAH rat model and this is probably mediated by the caspase-3 apoptotic pathway triggered by mitochondrial calcium overload. The finding offers a new therapeutic candidate for early brain injury after SAH.

Regulation of mRNA following brain ischemia and reperfusion

There is growing appreciation that mRNA regulation plays important roles in disease and injury. mRNA regulation and ribonomics occur in brain ischemia and reperfusion (I/R) following stroke and cardiac arrest and resuscitation. It was recognized over 40 years ago that translation arrest (TA) accompanies brain I/R and is now recognized as part of the intrinsic stress responses triggered in neurons. However, neuron death correlates to a prolonged TA in cells fated to undergo delayed neuronal death (DND). Dysfunction of mRNA regulatory processes in cells fated to DND prevents them from translating stress-induced mRNAs such as heat shock proteins. The morphological and biochemical studies of mRNA regulation in postischemic neurons are discussed in the context of the large variety of molecular damage induced by ischemic injury. Open issues and areas of future investigation are highlighted. A sober look at the molecular complexity of ischemia-induced neuronal injury suggests that a network framework will assist in making sense of this complexity. The ribonomic network sits between the gene network and the various protein and metabolic networks. Thus, targeting the ribonomic network may prove more effective at neuroprotection than targeting specific molecular pathways, for which all efforts have failed to the present time to stop DND in stroke and after cardiac arrest. WIREs RNA 2017, 8:e1415. doi: 10.1002/wrna.1415 For further resources related to this article, please visit the WIREs website.

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).

The effects of ozone therapy on caspase pathways, TNF-α, and HIF-1α in diabetic nephropathy

BACKGROUND

Accelerated apoptosis plays a vital role in the development of diabetic vascular complications. Ozone may attenuate diabetic nephropathy by means of decreased apoptosis-related genes. The aim of our study was to investigate the effect of ozone therapy on streptozotocin-induced diabetic nephropathy in rats. Also the histopathological changes in diabetic kidney tissue with ozone treatment were evaluated.

METHODS

The rats were randomly divided into six groups (n = 7): control (C), ozone (O), diabetic (D), ozone-treated diabetic (DO), insulin-treated diabetic (DI), and ozone- and insulin-treated diabetic (DOI). D, DI, and DOI groups were induced by a single intraperitoneal injection of streptozotocin. Ozone was given to the O, DO, and DOI groups. Group DI and DOI received subcutaneous (SC) insulin (3 IU). All animals received daily treatment for 6 weeks.

RESULTS

Expressions of caspase-1-3-9, HIF-1α, and TNF-α genes were significantly higher in D group compared to C group (p < 0.05 for all). Ozone treatment resulted in significant decrease in the expressions of these genes in diabetic kidney tissue compared to both C and D group (p < 0.05 for all). Caspase-1-3-9, HIF-1α, and TNF-α gene expressions were found to be lower in DOI group compared to C group (p < 0.05 for all). Also adding ozone treatment to insulin therapy resulted in more significantly decrease in the expressions of these genes in diabetic tissue compared to only insulin-treated diabetic group (p < 0.05 for all). Regarding histological changes, ozone treatment resulted in decrease in the renal corpuscular inflammation and normal kidney morphology was observed. Both insulin and ozone therapies apparently improved kidney histological findings with less degenerated tubules and less inflammation of renal corpuscle compared to D, DO, and DI groups.

CONCLUSION

Ozone therapy decreases the expressions of apoptotic genes in diabetic kidney tissue and improves the histopathological changes.

Effects of Tetramethylpyrazine on Functional Recovery and Neuronal Dendritic Plasticity after Experimental Stroke

The 2,3,5,6-tetramethylpyrazine (TMP) has been widely used in the treatment of ischemic stroke by Chinese doctors. Here, we report the effects of TMP on functional recovery and dendritic plasticity after ischemic stroke. A classical model of middle cerebral artery occlusion (MCAO) was established in this study. The rats were assigned into 3 groups: sham group (sham operated rats treated with saline), model group (MCAO rats treated with saline) and TMP group (MCAO rats treated with 20 mg/kg/d TMP). The neurological function test of animals was evaluated using the modified neurological severity score (mNSS) at 3 d, 7 d, and 14 d after MCAO. Animals were euthanized for immunohistochemical labeling to measure MAP-2 levels in the peri-infarct area. Golgi-Cox staining was performed to test effect of TMP on dendritic plasticity at 14 d after MCAO. TMP significantly improved neurological function at 7 d and 14 d after ischemia, increased MAP-2 level at 14 d after ischemia, and enhanced spine density of basilar dendrites. TMP failed to affect the spine density of apical dendrites and the total dendritic length. Data analyses indicate that there was significant negative correlation between mNSS and plasticity measured at 14 d after MCAO. Thus, enhanced dendritic plasticity contributes to TMP-elicited functional recovery after ischemic stroke.

Neuroprotective effects of viral overexpression of microRNA-22 in rat and cell models of cerebral ischemia-reperfusion injury

Several studies have reported that microRNA (MIR) is involved in the pathogenesis and progression of ischemic diseases, including cerebral ischemia, and that MIR-22 may inhibit the inflammatory response and cell apoptosis, which contribute to ischemia/reperfusion (I/R) injury. However, the specific function of MIR-22 in cerebral I/R injury remains far from clear. This study aimed to examine the potential protective effect of MIR-22 against cerebral I/R injury and its mechanism. As predicted, adenovirus-mediated MIR-22 overexpression markedly reduced the neurological score and infarct size (P < 0.05). We demonstrated that MIR-22 overexpression resulted in a reduction in inflammatory cytokines TNF-α, IL-6, COX-2, and iNOS, whereas the level of IL-10 was enhanced. MIR-22 overexpression significantly inhibited NF-κB activity by decreasing NF-κB coactivator NCOA1 expression. Furthermore, we found that MIR-22 could reduce the apoptotic rate of cortical neurons. Caspase-3 activity was inhibited by MIR-22, and the expression of the anti-apoptosis gene Bcl-2 in neurons was increased and that of the pro-apoptosis gene Bax decreased following MIR-22 overexpression. Our results suggest that MIR-22 could be used to treat cerebral I/R injury and that its neuroprotective effect may be attributed to a reduction in inflammation and apoptosis.

Ligustrazine monomer against cerebral ischemia/reperfusion injury

Ligustrazine (2,3,5,6-tetramethylpyrazine) is a major active ingredient of the Szechwan lovage rhizome and is extensively used in treatment of ischemic cerebrovascular disease. The mechanism of action of ligustrazine use against ischemic cerebrovascular diseases remains unclear at present. This study summarizes its protective effect, the optimum time window of administration, and the most effective mode of administration for clinical treatment of cerebral ischemia/reperfusion injury. We examine the effects of ligustrazine on suppressing excitatory amino acid release, promoting migration, differentiation and proliferation of endogenous neural stem cells. We also looked at its effects on angiogenesis and how it inhibits thrombosis, the inflammatory response, and apoptosis after cerebral ischemia. We consider that ligustrazine gives noticeable protection from cerebral ischemia/reperfusion injury. The time window of ligustrazine administration is limited. The protective effect and time window of a series of derivative monomers of ligustrazine such as 2-[(1,1-dimethylethyl)oxidoimino]methyl]-3,5,6-trimethylpyrazine, CXC137 and CXC195 after cerebral ischemia were better than ligustrazine.

Ligustrazine reduces blood-brain barrier permeability in a rat model of focal cerebral ischemia and reperfusion

Ligustrazine, also known as 2,3,5,6-tetramethylpyrazine (TMP), one of the major active compounds of Ligusticum wallichii Franchat., has been shown to reduce neuroinflammation and protect neurons during cerebral ischemia/reperfusion injury. However, whether it reduces blood-brain barrier (BBB) permeability during ischemic stroke is unclear. The aim of the present study was to investigate the role that TMP plays in protecting the BBB integrity in ischemia/reperfusion injury and to investigate the relevant mechanisms involved. Rats received an intraperitoneal injection of 20 mg/kg TMP 15 min before the onset of ischemia, which was induced by middle cerebral artery occlusion. Infarct volume, neurological score, brain edema, BBB permeability and tight junction protein impairment were observed. The results showed that TMP reduced the neurological score and levels of brain infarction and edema. In addition, TMP significantly decreased BBB permeability and prevented the impairment of occludin and claudin-5, two tight junction protein components of the BBB, in rat brains with ischemia/reperfusion injury. In addition, the expression and activity of matrix metalloproteinases, enzymes responsible for the degradation of the extracellular matrix and tight junctions, were reduced in the rat brains by TMP treatment. These results combined suggest that TMP reduces BBB permeability as well as neuronal damage in focal cerebral ischemia/reperfusion injury in rats.

Tetramethylpyrazine protects Schwann cells from ischemia-like injury and increases cell survival in cold ischemic rat nerves

Tetramethylpyrazine (TMP), a major active ingredient of Ligusticum wallichi Franchat extract (a Chinese herb), exhibits neuroprotective properties in ischemia. In this study, we assessed its protective effects on Schwann cells (SCs) by culturing them in the presence of oxygen glucose deprivation (OGD) conditions and measuring cell survival in cold ischemic rat nerves. In the OGD-induced ischemic injury model of SCs, we demonstrated that TMP treatment not only reduced OGD-induced cell viability losses, cell death, and apoptosis of SCs in a dose-dependent manner, and inhibited LDH release, but also suppressed OGD-induced downregulation of Bcl-2 and upregulation of Bax and caspase-3, as well as inhibited the consequent activation of caspase-3. In the cold ischemic nerve model, we found that prolonged cold ischemic exposure for four weeks was markedly associated with the absence of SCs, a decrease in cell viability, and apoptosis in preserved nerve segments incubated in University of Wisconsin solution (UWS) alone. However, TMP attenuated nerve segment damage by preserving SCs and antagonizing the decrease in nerve fiber viability and increase in TUNEL-positive cells in a dose-dependent manner. Collectively, our results indicate that TMP not only provides protective effects in an ischemia-like injury model of cultured rat SCs by regulating Bcl-2, Bax, and caspase-3, but also increases cell survival and suppresses apoptosis in the cold ischemic nerve model after prolonged ischemic exposure for four weeks. Therefore, TMP may be a novel and effective therapeutic strategy for preventing peripheral nervous system ischemic diseases and improving peripheral nerve storage.

Preparation and evaluation of a novel biodegradable long-acting intravitreal implant containing ligustrazine for the treatment of proliferative vitreoretinopathy

OBJECTIVES

It is challenging to deliver the therapeutic drug effectively to the posterior ocular disease location with optimized exposure and long-term effects when treating proliferative vitreoretinopathy (PVR). The objective of this study is to develop a novel biodegradable and long-acting ocular implant for PVR therapy with ligustrazine as the active ingredient.

METHODS

The ligustrazine implants were prepared with poly(DL-lactide-co-glycolide) using a hot-melting extrusion. The physicochemical properties of the implants were characterized. The effectiveness of the selected ligustrazine implants was evaluated in a PVR rabbit model. Furthermore, the in-vitro drug release profile and pharmacokinetics were compared, and in-vitro/in-vivo correlations were evaluated.

KEY FINDINGS

The optimal implants had an ideal zero-order in-vitro drug release profile, which was correlated with the in-vivo drug absorption fraction in the vitreous bodies of the rabbits. The sustained-release ligustrazine implants significantly reduced the development of PVR in the animal model.

CONCLUSIONS

Ligustrazine implants can be used to treat posterior ocular disease in rabbit animal models, and it provides more choices for medical research on posterior ocular disease.

The novel tetramethylpyrazine bis-nitrone (TN-2) protects against MPTP/MPP+-induced neurotoxicity via inhibition of mitochondrial-dependent apoptosis

Mitochondrial-dependent apoptosis plays an important role in the degeneration of dopaminergic neurons in Parkinson's disease (PD). Methyl-4-phenyl-1,2,3,6-tetra- hydropyridine (MPTP), the most widely used neurotoxin to simulate PD, is converted to 1-methyl-4-phenylpyridinium (MPP(+)) in vivo. MPP(+) induces excessive intracellular reactive oxygen species (ROS), leading to mitochondrial-dependent apoptosis via sequentially opening mitochondria permeability transition pore (mPTP) to release cytochrome c from mitochondria into cytoplasm and activate pro-apoptotic caspase proteins. We have previously synthesized 2,5-[[(1,1-dimethylethyl)oxidoimino]methyl]-3,6-trimethylpyrazine (TN-2), a novel derivative of the Chinese herb medicine tetramethylpyrazine (TMP). TN-2 is armed with two powerful free radical-scavenging nitrone moieties. TN-2 significantly reversed the loss of dopaminergic neurons in the substantia nigra and the decrease in dopamine level in the striatum induced by MPTP in mice. TN-2 ameliorated the MPTP-induced decrease of brain superoxide dismutase activity and glutathione concentration and increase of brain malondialdehyde. In addition, TN-2 inhibited MPP(+)-induced neuronal damage/apoptosis in primary cerebellum granular neurons (CGNs) and SH-SY5Y cells. TN-2 decreased excessive intracellular ROS, prevented the loss of mitochondrial membrane potential, blocked the release of mitochondrial cytochrome c and inhibited the activation of caspase-3 and caspase-9. Moreover, TN-2 treatment increased the mRNA expression of mitochondrial biogenesis factors peroxisome proliferator-activated receptor (PPAR)-γ coactivator-1 (PGC- 1α and β) and mitochondrial transcription factor A (Tfam) in SH-SY5Y cells and CGNs. These results suggest that TN-2 protects dopaminergic neurons against MPTP/MPP(+)-induced neurotoxicity via the inhibition of mitochondrial-dependent apoptosis and possibly via the activation of mitochondrial biogenesis, indicating that TN-2 is a potential new treatment for PD.

Intravenous administration of tetramethylpyrazine reduces intestinal ischemia-reperfusion injury in rats

Intestinal ischemia-reperfusion injury (IIRI) is a life-threatening condition requiring prompt medical intervention. Tetramethylpyrazine (TMP) is a biologically active alkaloid isolated from Ligusticum wallichii. Previously, it was shown that TMP causes vasodilatation and inhibition of platelet aggregation as well as exhibits significant antioxidant effects. Therefore, the aim of the present study was to evaluate possible therapeutic effects of TMP in the prevention of IIRI. Wistar rats (n = 80) were randomly divided into eight experimental groups and subjected to a 1 h occlusion of cranial mesenteric artery followed by 0, 1, 12, and 24 h period of reperfusion. Thirty minutes before the IIRI animals received either TMP (30 mg/kg, i.v.) or identical volume of saline. In addition, a control group of 10 animals was not exposed to IIRI. Intestine morphology was evaluated by using histopathological injury index examination (HII), goblet and Paneth cells quantification as well as by applying immunofluorescent methods such as InSitu TUNEL and caspase-3 positivity assessment. Here we showed that preconditioning with TMP prior IIRI decreases the grade of injury. Significant reduction of HII was detected in TMP pretreated groups after 0, 1, and 12 h of reperfusion where injury reduction up to 75% was found. Lower histopathological damage in preconditioned groups was accompanied with increased number of secretory epithelial cells and decreased number of apoptotic cells. These results demonstrate the protective effect of TMP on the small intestine mucosa, suggesting administration of TMP as a molecule for pharmacological intervention against IIRI.

Effects of tetramethylpyrazine on neuronal apoptosis in the superficial dorsal horn in a rat model of neuropathic pain

The Bennett and Xie (1988) model of chronic constriction injury (CCI) investigated the effects of tetramethylpyrazine (TMP) on neuropathic pain-associated behaviors and neuronal apoptosis in the spinal dorsal horn. Fifty-four male rats were randomly divided into sham (group S), CCI (group C) and TMP groups (group T). Each group was divided into subgroups (n = 6 in each group) according the time of sacrifice: 3 d, 7 d and 14 d. Rat sciatic nerves were unligated (group S), or the right sciatic nerve was loosely ligated (groups C and T) to produce CCI. Mechanical withdrawal thresholds (MWTs) and thermal withdrawal latencies (TWLs) were measured, and the rats were sacrificed at different time points post-operation. The L4-L6 sections of the spinal cord were removed. Apoptotic changes were evaluated using the TUNEL method. Immunohistochemistry assessed Bcl-2 and caspase-3 expression. TMP treatment increased MWT and TWL values and Bcl-2 expression, but it reduced neuronal apoptosis and caspase-3 expression in laminae I-II of the spinal dorsal horn. These results suggested that the inhibition of neuronal apoptosis via the modulation of Bcl-2 and caspase-3 proteins in the rat spinal dorsal horn contributed to TMP-induced analgesia.

Neuroprotective properties of Melissa officinalis after hypoxic-ischemic injury both in vitro and in vivo

Background

Brain ischemia initiates several metabolic events leading to neuronal death. These events mediate large amount of damage that arises after some neurodegenerative disorders as well as transient brain ischemia. Melissa officinalis is considered as a helpful herbal plant in the prevention of various neurological diseases like Alzheimer that is related with oxidative stress.

Methods

We examined the effect of Melissa officinalis on hypoxia induced neuronal death in a cortical neuronal culture system as in vitro model and transient hippocampal ischemia as in vivo model. Transient hippocampal ischemia was induced in male rats by tow vessel-occlusion for 20 min. After reperfusion, the histopathological changes and the levels inflammation, oxidative stress status, and caspase-3 activity in hippocampus were measured.

Results

Cytotoxicity assays showed a significant protection of a 10 μg/ml dose of Melissa against hypoxia in cultured neurons which was confirmed by a conventional staining (P<0.05). Melissa treatment decrease caspase3 activity (P<0.05) and TUNEL-positive cells significantly (P<0.01). Melissa oil has also inhibited malon dialdehyde level and attenuated decrease of Antioxidant Capacity in the hippocampus. Pro-inflammatory cytokines TNF-α, IL-1β and HIF-1α mRNA levels were highly increased after ischemia and treatment with Melissa significantly suppressed HIF-1α gene expression (P<0.05).

Discussion

Results showed that Melissa officinalis could be considered as a protective agent in various neurological diseases associated with ischemic brain injury.

Evaluation of antioxidant and immunity function of tetramethylpyrazine phosphate tablets in vivo

The aim of the study was to determine the effect of tetramethylpyrazine phosphate tablets (TPT), a Chinese medicine used for cardiovascular disease, on immunity activity and oxidative injury in rats. Heart failure (HF) was induced by isoproterenol (ISO). After the animal model was established, the rats were administered the TPT by gavage (once a day). The results indicated that TPT improved left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP), ±dP/dt, heart weight/body weight. TPT could decrease the levels of tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6). Furthermore, it also could raise the activities of catalase, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), but reduce malonyldialdehyde (MDA) level. The results indicated that TPT improved cardiac function and myocardial fibrosis from myocardial injury, and this cardioprotection might be attributed to a reduction of oxidative stress and regulation of inflammation mediators.

TMP prevents retinal neovascularization and imparts neuroprotection in an oxygen-induced retinopathy model

PURPOSE

To evaluate the effects of tetramethylpyrazine (TMP) on retinal neovascularization (NV) and neuroprotection in an oxygen-induced retinopathy (OIR) model.

METHODS

Neonatal C57BL/6J mice were subjected to 75% oxygen from postnatal day 7 (P7) to P12 and then returned to room air. TMP (200 mg/kg) or normal saline was given daily from P12 to P17. Immunostaining, HE staining, TUNEL assay, and RT-PCR were used to assess the effects of TMP on retinal neurovascular repair.

RESULTS

TMP effectively prevented pathologic NV and accelerated physiologic revascularization by enhancing the formation of endothelial tip cells at the edges of the repairing capillary networks and preserving the astrocytic template in the avascular retina. TMP also prevented morphologic changes and significantly decreased TUNEL-positive cells in the avascular retina by rescuing neurons such as amacrine, rod bipolar, horizontal, and Müller cells. In TMP-treated mice retinas, there was a less obvious loss of amacrine cell bodies and their distinct bands; the number of both rod bipolar and horizontal cell bodies, as well as the density of their dendrites in the outer plexiform layer, was greater than that in OIR control mice. TMP not only decreased the loss of alignment of Müller cell bodies and distortion of processes but reduced the reactive expression of GFAP in Müller cells. Furthermore, HIF-1α and VEGF mRNA expression were downregulated in TMP-treated mice retinas.

CONCLUSIONS

TMP improved neurovascular recovery by preventing NV and protecting retinal astroglia cells and neurons from ischemia-induced cell death partially due to its downregulation of HIF-1α and VEGF mRNA expression.

Synergistic protective effect of astragaloside IV-tetramethylpyrazine against cerebral ischemic-reperfusion injury induced by transient focal ischemia

ETHNOPHARMACOLOGICAL RELEVANCE

Astragaloside IV and tetramethylpyrazine have been extensively used in the cardio-cerbrovascular diseases of medicine as a chief ingredient of glycoside or alkaloid formulations for the treatment of stroke and myocardial ischemia diseases.

AIM OF THE STUDY

To investigate the effects of astragaloside IV (ASG IV) and tetramethylpyrazine (TMPZ) on cerebral ischemia-reperfusion (IR) injury model in rat model.

MATERIALS AND METHODS

Rats were randomly divided into the following five groups: sham group, IR group and treatment group including ASG IV, ASG IV-TMPZ and nimodipine treatment. The therapeutic effect was evaluated by micro-positron emission tomography (Micro-PET) using (18)F-fluoro-2-deoxy-d-glucose. The neurological examination, infarct volume and the levels of oxidative stress- and cell apoptosis-related molecules were assessed.

RESULTS

Micro-PET imaging showed that glucose metabolism in the right hippocampus was significantly decreased in the IR group compared to the sham group (P<0.01). ASG IV and ASG IV-TMPZ treatments reversed the decreased glucose metabolism in the model group (P<0.05 and P<0.01, respectively). IR induced the increase of Caspase-3 mRNA levels, MDA content and iNOS activity, but it caused the decrease of SOD activity and Bcl-2 expression compared the sham group (P<0.01). ASG IV-TMPZ and ASG IV reversed the IR-induced changes of these parameters, i.e. the down regulation of Caspase-3 mRNA, MDA content and iNOS activity, and the up regulation of SOD activity and Bcl-2 expression (P<0.05).

CONCLUSION

This study showed that ASG IV-TMPZ played a pivotal synergistic protective role against focal cerebral ischemic reperfusion damage in a rat experimental model.