Tetramethylpyrazine Reduces Epileptogenesis Progression in Electrical Kindling Models by Modulating Hippocampal Excitatory Neurotransmission

Age-Dependent Phenomena of 6-Hz Corneal Kindling Model in Mice

Although numerous studies have acknowledged disparities in epilepsy-related disease processes between young and aged animals, little is known about how epilepsy changes from young adulthood to middle age. This study investigates the impact of aging on 6-Hz corneal kindling in young-adult mice and middle-aged mice. We found that the kindling acquisition of the 6-Hz corneal kindling model was delayed in middle-aged mice when compared to young-adult mice. While the seizure stage and incidence of generalized seizures (GS) were similar between the two age groups, the duration of GS in the kindled middle-aged mice was shorter than that in the kindled young-adult mice. Besides, all kindled mice, regardless of age, were resistant to phenytoin sodium (PHT), valproate sodium (VPA), and lamotrigine (LGT), whereas middle-aged mice exhibited higher levetiracetam (LEV) resistance compared to young-adult mice. Both age groups of kindled mice displayed hyperactivity and impaired memory, which are common behavioral characteristics associated with epilepsy. Furthermore, middle-aged mice displayed more pronounced astrogliosis in the hippocampus. Additionally, the expression of Brain-Derived Neurotrophic Factor (BDNF) was lower in middle-aged mice than in young-adult mice prior to kindling. These data demonstrate that both the acquisition and expression of 6-Hz corneal kindling are attenuated in middle-aged mice, while hippocampal astrogliosis and pharmacological resistance are more pronounced in this age group. These results underscore the importance of considering age-related factors when utilizing the 6-Hz corneal kindling model in mice of varying age groups.

Harnessing the power of natural alkaloids: the emergent role in epilepsy therapy

The quest for effective epilepsy treatments has spotlighted natural alkaloids due to their broad neuropharmacological effects. This review provides a comprehensive analysis of the antiseizure properties of various natural compounds, with an emphasis on their mechanisms of action and potential therapeutic benefits. Our findings reveal that bioactive substances such as indole, quinoline, terpenoid, and pyridine alkaloids confer medicinal benefits by modulating synaptic interactions, restoring neuronal balance, and mitigating neuroinflammation-key factors in managing epileptic seizures. Notably, these compounds enhance GABAergic neurotransmission, diminish excitatory glutamatergic activities, particularly at NMDA receptors, and suppress proinflammatory pathways. A significant focus is placed on the strategic use of nanoparticle delivery systems to improve the solubility, stability, and bioavailability of these alkaloids, which helps overcome the challenges associated with crossing the blood-brain barrier (BBB). The review concludes with a prospective outlook on integrating these bioactive substances into epilepsy treatment regimes, advocating for extensive research to confirm their efficacy and safety. Advancing the bioavailability of alkaloids and rigorously assessing their toxicological profiles are essential to fully leverage the therapeutic potential of these compounds in clinical settings.

Neuroprotection by tetramethylpyrazine and its synthesized analogues for central nervous system diseases: a review

BACKGROUND

Due to the global increase in aging populations and changes in modern lifestyles, the prevalence of neurodegenerative diseases, cerebrovascular disorders, neuropsychiatrcic conditions, and related ailments is rising, placing an increasing burden on the global public health system.

MATERIALS AND METHODS

All studies on tetramethylpyrazine (TMP) and its derivatives were obtained from reputable sources such as PubMed, Elsevier, Library Genesis, and Google Scholar. Comprehensive data on TMP and its derivatives was meticulously compiled.

RESULTS

This comprehensive analysis explains the neuroprotective effects demonstrated by TMP and its derivatives in diseases of the central nervous system. These compounds exert their influence on various targets and signaling pathways, playing crucial roles in the development of various central nervous system diseases. Their multifaceted mechanisms include inhibiting oxidative damage, inflammation, cell apoptosis, calcium overload, glutamate excitotoxicity, and acetylcholinesterase activity.

CONCLUSION

This review provides a brief summary of the most recent advancements in research on TMP and its derivatives in the context of central nervous system diseases. It involves synthesizing analogs of TMP and evaluating their effectiveness in models of central nervous system diseases. The ultimate goal is to facilitate the practical application of TMP and its derivatives in the future treatment of central nervous system diseases.

An integrated in vitro human iPSCs-derived neuron and in vivo animal approach for preclinical screening of anti-seizure compounds

INTRODUCTION

One-third of people with epilepsy continue to experience seizures despite treatment with existing anti-seizure medications (ASMs). The failure of modern ASMs to substantially improve epilepsy prognosis has been partly attributed to overreliance on acute rodent models in preclinical drug development as they do not adequately recapitulate the mechanisms of human epilepsy, are labor-intensive and unsuitable for high-throughput screening (HTS). There is an urgent need to find human-relevant HTS models in preclinical drug development to identify novel anti-seizure compounds.

OBJECTIVES

This paper developed high-throughput preclinical screening models to identify new ASMs.

METHODS

14 natural compounds (α-asarone, curcumin, vinpocetine, magnolol, ligustrazine, osthole, tanshinone IIA, piperine, gastrodin, quercetin, berberine, chrysin, schizandrin A and resveratrol) were assessed for their ability to suppress epileptiform activity as measured by multi-electrode arrays (MEA) in neural cultures derived from human induced pluripotent stem cells (iPSCs). In parallel, they were tested for anti-seizure effects in zebrafish and mouse models, which have been widely used in development of modern ASMs. The effects of the compounds in these models were compared. Two approved ASMs were used as positive controls.

RESULTS

Epileptiform activity could be induced in iPSCs-derived neurons following treatment with 4-aminopyridine (4-AP) and inhibited by standard ASMs, carbamazepine, and phenytoin. Eight of the 14 natural compounds significantly inhibited the epileptiform activity in iPSCs-derived neurons. Among them, piperine, magnolol, α-asarone, and osthole showed significant anti-seizure effects both in zebrafish and mice. Comparative analysis showed that compounds ineffective in the iPSCs-derived neural model also showed no anti-seizure effects in the zebrafish or mouse models.

CONCLUSION

Our findings support the use of iPSCs-derived human neurons for first-line high-throughput screening to identify compounds with anti-seizure properties and exclude ineffective compounds. Effective compounds may then be selected for animal evaluation before clinical testing. This integrated approach may improve the efficiency of developing novel ASMs.

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.

Cadherins and the pathogenesis of epilepsy

Epilepsy is a nervous system disease caused by abnormal discharge of brain neurons, which is characterized by recurrent seizures. The factors that induce epilepsy include genetic and environmental factors. Genetic factors are important pathogenic factors of epilepsy, such as epilepsy caused by protocadherin-19 (PCDH-19) mutation, which is an X-linked genetic disease. It is more common in female heterozygotes, which are caused by mutations in the PCDH-19 gene. Epilepsy caused by environmental factors is mainly caused by brain injury, which is commonly caused by brain tumors, brain surgery, or trauma to the brain. In addition, the pathogenesis of epilepsy is closely related to abnormalities in some signaling pathways. The Wnt/β-catenin signaling pathway is considered a new target for the treatment of epilepsy. This review summarizes these factors inducing epilepsy and the research hypotheses regarding the pathogenesis of epilepsy. The focus of this review centers on cadherins and the pathogenesis of epilepsy. We analyzed the pathogenesis of epilepsy induced by N-cadherin and PCDH-19 in the cadherin family members. Finally, we expect that in the future, new breakthroughs will be made in the study of the pathogenesis and mechanism of epilepsy at the cellular and molecular levels.

The GluN2B-Trp373 NMDA Receptor Variant is Associated with Autism-, Epilepsy-Related Phenotypes and Reduces NMDA Receptor Currents in Rats

Autism spectrum disorder (ASD) is a neurodevelopmental condition with core clinical features of abnormal communication, social interactions, atypical intelligence, and a higher risk of epilepsy. Prior work has suggested that de novo heterozygous mutations in the GRIN2B gene that encodes the GluN2B subunit of N-methyl-D-aspartic acid receptors are likely linked to ASD. However, whether GLuN2B-Trp373 mutation derived from autistic individuals causes ASD-like behavioral aberrations in rats remains to be determined. Here, through in utero electroporation and in vivo studies, we conducted a battery of tests to examine ASD-associated behaviors, cognitive impairments, and susceptibility to pentylenetetrazol-induced seizures. Whole-cell patch recording was utilized to determine whether the GluN2B-Trp373 mutation influences GluN2B-containing NMDA receptor currents in rats. Results show that, behaviorally, GLuN2B-Trp373 mutant rats exhibited core behavioral manifestations of ASD, such as social interaction deficits, increases in stereotyped behaviors and anxiety stereotyped/repetitive, impaired spatial memory, and enhanced risk of pentylenetetrazol-induced seizures, consistent with many of the hallmarks of low-functioning ASD in humans. Functionally, the GluN2B-Trp373 mutation results in reduced GluN2B surface protein expression together with decreased hippocampal NMDA receptor currents. Collectively, our findings highlight that GluN2B-Trp373 mutations can drive the manifestation of ASD-associated symptoms via the suppression of NMDA receptor currents.

Emerging perspectives on mitochondrial dysfunctioning and inflammation in epileptogenesis

INTRODUCTION

Mitochondrial dysfunction is a common denominator of neuroinflammation recognized by neuronal oxidative stress-mediated apoptosis that is well recognized by common intracellular molecular pathway-interlinked neuroinflammation and mitochondrial oxidative stress, a feature of epileptogenesis. In addition, the neuronal damage in the epileptic brain corroborated the concept of brain injury-mediated neuroinflammation, further providing an interlink between inflammation, mitochondrial dysfunction, and oxidative stress in epilepsy.

MATERIALS AND METHODS

A systematic literature review of Bentham, Scopus, PubMed, Medline, and EMBASE (Elsevier) databases was carried out to provide evidence of preclinical and clinically used drugs targeting such nuclear, cytosolic, and mitochondrial proteins suggesting that the correlation of mechanisms linked to neuroinflammation has been elucidated in the current review. Despite that, the evidence of elevated levels of inflammatory mediators and pro-apoptotic protein levels can provide the correlation of inflammatory responses often concerned with hyperexcitability attributing to the fact that mitochondrial redox mechanisms and higher susceptibilities to neuroinflammation result from repetitive recurring epileptic seizures. Therefore, providing an understanding of seizure-induced pathological changes read by activating neuroinflammatory cascades like NF-kB, RIPK, MAPK, ERK, JNK, and JAK-STAT signaling further related to mitochondrial damage promoting hyperexcitability.

CONCLUSION

The current review highlights the further opportunity for establishing therapeutic interventions underlying the apparent correlation of neuroinflammation mediated mitochondrial oxidative stress might contribute to common intracellular mechanisms underlying a future prospective of drug treatment targeting mitochondrial dysfunction linked to the neuroinflammation in epilepsy.

Inconsistent Time-Dependent Effects of Tetramethylpyrazine on Primary Neurological Disorders and Psychiatric Comorbidities

The aim of this study was to investigate the time dependent effects of tetramethylpyrazine (TMP, main activity compound of Ligusticum chuanxiong Hort) on two neurological disorders and their neuropsychiatric comorbidities. 6 Hz corneal rapid kindling was used to induce epileptogenesis and the inflammatory pain was induced by intra-articular Complete Freund's adjuvant (CFA) injection. The mechanical pain thresholds were measured using von Frey hair (D4, D11, D18, D25 after CFA first injection), and the vertical rearings of the mice was observed. To test the neuropsychiatric comorbidities, anxiety-like behaviors of mice were examined by open field and elevated plus maze tests. Two behavioral despair models, tail suspension test and forced swimming test were also used to evaluate the depressive like behaviors. The results showed that TMP administered from the initial day (D1-D35 in kindling model, D0-D14 and D0-D28 in CFA model) of modeling retarded both the developments of 6 Hz corneal rapid kindling epileptogenesis and the CFA induced inflammatory pain. In comparison, late periods administration of TMP (D21-D35 in kindling and D14-D28 in CFA model) showed no effect on the epileptogenesis and the generalized seizures (GS) of kindling, but alleviated maintenance of CFA induced inflammatory pain. Furthermore, we also found all TMP treatments from the initial day of modeling alleviated the co-morbid depressive and anxiety-like behaviors in both models; however, late periods treatments did not, either in kindling or the CFA induced inflammatory pain. BDNF/ERK signaling impairment was also tested by western blot, and the results showed that TMP administered from the initial day of modeling increased the hippocampal BDNF/ERK expression, whereas late period administration showed no effects. Overall, our findings reveal the inconsistent time dependent effects of Tetramethylpyrazine on neurological disorders and their relative neuropsychiatric comorbidities, and provide novel insight into the early application of TMP that might enhance hippocampal BDNF/ERK signaling to alleviate neuropsychiatric comorbidities in neurological diseases.

Natural Medicines for the Treatment of Epilepsy: Bioactive Components, Pharmacology and Mechanism

Epilepsy is a chronic disease that can cause temporary brain dysfunction as a result of sudden abnormal discharge of the brain neurons. The seizure mechanism of epilepsy is closely related to the neurotransmitter imbalance, synaptic recombination, and glial cell proliferation. In addition, epileptic seizures can lead to mitochondrial damage, oxidative stress, and the disorder of sugar degradation. Although the mechanism of epilepsy research has reached up to the genetic level, the presently available treatment and recovery records of epilepsy does not seem promising. Recently, natural medicines have attracted more researches owing to their low toxicity and side-effects as well as the excellent efficacy, especially in chronic diseases. In this study, the antiepileptic mechanism of the bioactive components of natural drugs was reviewed so as to provide a reference for the development of potential antiepileptic drugs. Based on the different treatment mechanisms of natural drugs considered in this review, it is possible to select drugs clinically. Improving the accuracy of medication and the cure rate is expected to compensate for the shortage of the conventional epilepsy treatment drugs.

The Tetramethylpyrazine Analogue T-006 Alleviates Cognitive Deficits by Inhibition of Tau Expression and Phosphorylation in Transgenic Mice Modeling Alzheimer's Disease

T-006, a small-molecule compound derived from tetramethylpyrazine (TMP), has potential for the treatment of neurological diseases. In order to investigate the effect of T-006 prophylactic treatment on an Alzheimer's disease (AD) model and identify the target of T-006, we intragastrically administered T-006 (3 mg/kg) to Alzheimer's disease (AD) transgenic mice (APP/PS1-2xTg and APP/PS1/Tau-3xTg) for 6 and 8 months, respectively. T-006 improved cognitive ability after long-term administration in two AD mouse models and targeted mitochondrial-related protein alpha-F1-ATP synthase (ATP5A). T-006 significantly reduced the expression of phosphorylated-tau, total tau, and APP while increasing the expression of synapse-associated proteins in 3xTg mice. In addition, T-006 modulated the JNK and mTOR-ULK1 pathways to reduce both p-tau and total tau levels. Our data suggested that T-006 mitigated cognitive decline primarily by reducing the p-tau and total tau levels in 3xTg mice, supporting further investigation into its development as a candidate drug for AD treatment.