Gastrodin Reduces the Severity of Status Epilepticus in the Rat Pilocarpine Model of Temporal Lobe Epilepsy by Inhibiting Nav1.6 Sodium Currents

Analysis of the action mechanisms and targets of herbal anticonvulsants highlights opportunities for therapeutic engagement with refractory epilepsy

Epilepsy is a neurological disorder characterized by spontaneous and recurring seizures. It poses significant therapeutic challenges due to diverse etiology, pathobiology, and pharmacotherapy-resistant variants. The anticonvulsive effects of herbal leads with biocompatibility and toxicity considerations have attracted much interest, inspiring mechanistic analysis with the view of their use for engagement of new targets and combination with antiseizure pharmacotherapies. This article presents a comprehensive overview of the key molecular players and putative action mechanisms of the most common antiepileptic herbals demonstrated in tissue culture and preclinical models. From the review of the literature, it emerges that their effects are mediated via five distinct mechanisms: (1) reduction of membrane excitability through inhibition of cation channels, (2) improvement of mitochondrial functions with antioxidant effects, (3) enhancement in synaptic transmission mediated by GABAA receptors, (4) improvement of immune response with anti-inflammatory action, and (5) suppression of protein synthesis and metabolism. While some of the primary targets and action mechanisms of herbal anticonvulsants (1, 3) are shared with antiseizure pharmacotherapies, herbal leads also engage with distinct mechanisms (2, 4, and 5), suggesting new drug targets and opportunities for their integration with antiseizure medications. Addressing outstanding questions through research and in silico modeling should facilitate the future use of herbals as auxiliary therapy in epilepsy and guide the development of treatment of pharmacoresistant seizures through rigorous trials and regulatory approval.

Gastrodin: a comprehensive pharmacological review

Tianma is the dried tuber of Gastrodia elata Blume (G. elata), which is frequently utilized in clinical practice as a traditional Chinese medicine. Gastrodin (GAS) is the main active ingredient of Tianma, which has good pharmacological activity. Therefore, for the first time, this review focused on the extraction, synthesis, pharmacological effects, and derivatives of GAS and to investigate additional development options for GAS. The use of microorganisms to create GAS is a promising method. GAS has good efficacy in the treatment of neurological diseases, cardiovascular diseases, endocrine diseases, and liver diseases. GAS has significant anti-inflammatory, antioxidant, neuroprotective, vascular protective, blood sugar lowering, lipid-regulating, analgesic, anticancer, and antiviral effects. The mechanism involves various signaling pathways such as Nrf2, NF-κB, PI3K/AKT, and AMPK. In addition, the derivatives of GAS and biomaterials synthesized by GAS and PU suggested a broader application of GAS. The research on GAS is thoroughly summarized in this paper, which has useful applications for tackling a variety of disorders and exhibits good development value.

Anti-PD-1 treatment protects against seizure by suppressing sodium channel function

AIMS

Although programmed cell death protein 1 (PD-1) typically serves as a target for immunotherapies, a few recent studies have found that PD-1 is expressed in the nervous system and that neuronal PD-1 might play a crucial role in regulating neuronal excitability. However, whether brain-localized PD-1 is involved in seizures and epileptogenesis is still unknown and worthy of in-depth exploration.

METHODS

The existence of PD-1 in human neurons was confirmed by immunohistochemistry, and PD-1 expression levels were measured by real-time quantitative PCR (RT-qPCR) and western blotting. Chemoconvulsants, pentylenetetrazol (PTZ) and cyclothiazide (CTZ), were applied for the establishment of in vivo (rodents) and in vitro (primary hippocampal neurons) models of seizure, respectively. SHR-1210 (a PD-1 monoclonal antibody) and sodium stibogluconate (SSG, a validated inhibitor of SH2-containing protein tyrosine phosphatase-1 [SHP-1]) were administrated to investigate the impact of PD-1 pathway blockade on epileptic behaviors of rodents and epileptiform discharges of neurons. A miRNA strategy was applied to determine the impact of PD-1 knockdown on neuronal excitability. The electrical activities and sodium channel function of neurons were determined by whole-cell patch-clamp recordings. The interaction between PD-1 and α-6 subunit of human voltage-gated sodium channel (Nav1.6) was validated by performing co-immunostaining and co-immunoprecipitation (co-IP) experiments.

RESULTS

Our results reveal that PD-1 protein and mRNA levels were upregulated in lesion cores compared with perifocal tissues of surgically resected specimens from patients with intractable epilepsy. Furthermore, we show that anti-PD-1 treatment has anti-seizure effects both in vivo and in vitro. Then, we reveal that PD-1 blockade can alter the electrophysiological properties of sodium channels. Moreover, we reveal that PD-1 acts together with downstream SHP-1 to regulate sodium channel function and hence neuronal excitability. Further investigation suggests that there is a direct interaction between neuronal PD-1 and Nav1.6.

CONCLUSION

Our study reveals that neuronal PD-1 plays an important role in epilepsy and that anti-PD-1 treatment protects against seizures by suppressing sodium channel function, identifying anti-PD-1 treatment as a novel therapeutic strategy for epilepsy.

Traditional uses, phytochemistry, pharmacology, applications, and quality control of Gastrodia elata Blume: A comprehensive review

ETHNOPHARMACOLOGICAL RELEVANCE

Gastrodia elata Blume (G. elata) has a long historical application in Asian countries and its tubers, seeds, and stalks are capable of being utilized for medicine, food, or health care products.

AIM OF THE REVIEW

This study aimed to offer a systematic and up-to-date analysis of the current review of the G. elata research advances in traditional uses, phytochemistry, pharmacology, applications, and quality control, as well as a scientific reference for the development and utilization of this plant.

MATERIALS AND METHODS

Electronic databases including PubMed, Web of Science, Google Scholar, ScienceDirect, SciFinder, and CNKI were used for the collection of publications on G. elata. The following keywords of G. elata were used truncated with other relevant topic terms, such as phenolic compounds, polysaccharides, glycosides, neuroprotection, learning and memory improvement effects, cardioprotection, applications, and quality control.

RESULTS AND CONCLUSIONS

Approximately 134 chemical components mainly categorizing as phenolic compounds, polysaccharides, glycosides, organic acids, and sterols were reported from this plant. Moreover, preclinical studies indicated that G. elata performs several functions, including neuroprotection, learning and memory improvement effects, cardioprotection, vaso-modulatory effect, anti-depression, anti-cancer, and other effects. Currently, G. elata has been widely applied to clinics and foods. The available literature shows that the quality of G. elata might be affected by factors such as origin, fungus, and harvest time, which will have an impact on the drug efficacy. According to past research, G. elata is a potential medicinal and edible plant with several active components and pharmacological activity that has a high application value in medicine and the food business. Nevertheless, few studies have concentrated on characterization of polysaccharides structure and study of non-medicinal parts, implying that further comprehensive research on its polysaccharides structure and non-medicinal parts is critical for full utilization of resources of G. elata.

Review on pharmacological effects of gastrodin

Gastrodia elata Blume is a well-known traditional Chinese medicine that is mainly used to treat diseases related to the nervous system, such as stroke, epilepsy, and headache. Gastrodin is the main bioactive component of Gastrodia elata Blume, and studies have shown that it has extensive pharmacological activity. This narrative review aims to systematically review relevant studies on the pharmacological effects of gastrodin to provide researchers with the latest and most useful information. Studies have shown that gastrodin has prominent neuroprotective effects and can treat or improve epilepsy, Tourette syndrome, Alzheimer's disease, Parkinson's disease, emotional disorders, cerebral ischemia-reperfusion injury, cognitive impairment, and neuropathic pain. Gastrodin can also improve myocardial hypertrophy, hypertension, and myocardial ischemia-reperfusion injury. In addition, gastrodin can mitigate liver, kidney, and bone tissue damage caused by oxidative stress and inflammation. In short, gastrodin is expected to treat many diseases, and it is worth investing more effort in research on this compound.

The processing methods, phytochemistry and pharmacology of Gastrodia elata Bl.: A comprehensive review

ETHNOPHARMACOLOGICAL RELEVANCE

Gastrodia elata Bl. (GE) is one of the rare Chinese medicinal materials with a long history of medicine and cooking. It consists of a variety of chemical components, including aromatic compounds, organic acids and esters, steroids, saccharides and their glycosides, etc., which has medicinal and edible value, and is widely used in various diseases, such as infantile convulsions, epilepsy, tetanus, headache, dizziness, limb numbness, rheumatism and arthralgia. It is also commonly used in health care products and cosmetics. Thus, its chemical composition and pharmacological activity have attracted more and more attention from the scientific community.

AIM

In this review, the processing methods, phytochemistry and pharmacological activities of GE were comprehensively and systematically summarized, which provides a valuable reference for researchers the rational of GE.

MATERIALS AND METHODS

A comprehensive search of published literature and classic books from 1958 to 2023 was conducted using online bibliographic databases PubMed, Google Scholar, ACS, Science Direct Database, CNKI and others to identify original research related to GE, its processing methods, active ingredients and pharmacological activities.

RESULTS

GE is traditionally used to treat infantile convulsion, epilepsy, tetanus, headache, dizziness, limb numbness, rheumatism and arthralgia. To date, more than 435 chemical constituents were identified from GE including 276 chemical constituents, 72 volatile components and 87 synthetic compounds, which are the primary bioactive compounds. In addition, there are other biological components, such as organic acids and esters, steroids and adenosines. These extracts have nervous system and cardiovascular and cerebrovascular system activities such as sedative-hypnotic, anticonvulsant, antiepileptic, neuron protection and regeneration, analgesia, antidepressant, antihypertensive, antidiabetic, antiplatelet aggregation, anti-inflammatory, etc. CONCLUSION: This review summarizes the processing methods, chemical composition, pharmacological activities, and molecular mechanism of GE over the last 66 years, which provides a valuable reference for researchers to understand its research status and applications.

Complementary and alternative medicine for treating epilepsy in China: A systematic review

There are about 10 million people with epilepsy (PWE) in China. In addition to therapies approved by the National Medical Products Administration, the use of complementary and alternative medicine (CAM) is prevalent in Chines PWE. These CAM therapies mainly comprise traditional Chinese medicine herbs (TCMHs), acupuncture, and music. A retrospective literature search was performed to summarize the updates of CAM in China in the past ten years, and sixty-two papers were finally included. In this following review, we listed the animal and clinical studies to summarize the antiepileptic mechanisms and clinical efficacy of CAM in Chines PWE. The main mechanisms of TCMHs and acupuncture included regulation of neurotransmitters and receptors, voltage-gated ion channels modulation, expression of apoptosis-related genes, antioxidant response, and anti-inflammation. Although there were enormous clinical studies on them, the current available clinical trials were small, short-term, heterogeneous, and had a high risk of bias. With regard to music, a few studies conducted by Chinese scholars suggested that it was beneficial for PWE as an add-on therapy, which was consistent with the results of foreign studies. Further randomized clinical trials in large populations are required to prove the effectiveness and safety of CAM.

Analysis of Medication Rule of Primary Epilepsy Based on Xiaocheng Yan’s Clinical Experience Collection of Epilepsy

Objective

To explore and analyze the medication rule of Professor Xiaocheng Yan in the treatment of primary epilepsy, hoping to provide reference for the clinical treatment of primary epilepsy.

Methods

Mining and analysis of Professor Xiaocheng Yan sorted out the medical cases of primary epilepsy in Xiaocheng Yan's clinical experience collection of epilepsy, extracted the traditional Chinese medicine (TCM) prescription data in the medical cases, standardized the obtained TCM prescription data, and used the data mining function integrated by the ancient and modern medical case cloud platform V2.3.5 to carry out frequency statistics, cluster analysis, association analysis, and complex network analysis on the TCM data, and the common herbs used by Professor Xiaocheng Yan in the treatment of primary epilepsy, properties and classifications of commonly used herbs, pairs of commonly used herbs, and core prescriptions were obtained.

Results

A total of 39 cases, 228 medical records, and 230 prescriptions data of TCM were included. A total of 96 Chinese medicinal herbs were involved, and the total frequency of medication was 3,828. High-frequency herbs include Rhizoma Gastrodiae (Tianma) (222 times), Ramulus Uncariae cum Uncis (Gouteng) (220 times), Rhizoma Acori Tatarinowii (Shichangpu) (216 times), Rhizoma Pinelliae Praeparatum (Fabanxia) (207 times), Bombyx Batryticatus (Jiangcan) (206 times), and Periostracum Cicadae (Chantui) (181 times). The main properties and flavors of commonly used Chinese medicinal herbs were sweet, bitter, and pungent, which were mainly attributed to the four meridians of liver, lung, heart, and spleen. Commonly used couplet herbs were {Periostracum Cicadae (Chantui)} ≥ {Bombyx Batryticatus (Jiangcan)}, {Rhizoma Acori Tatarinowii (Shichangpu)} ≥{ Bombyx Batryticatus (Jiangcan)}, {Radix Bupleuri (Chaihu)} ≥ {Radix Scutellariae (Huangqin)}, {Rhizoma Gastrodiae (Tianma)} ≥ {Ramulus Uncariae cum Uncis (Gouteng)}, {Rhizoma Acori Tatarinowii (Shichangpu)} ≥ {Periostracum Cicadae (Chantui)}, {Ramulus Uncariae cum Uncis (Gouteng)} ≥ {Bombyx Batryticatus (Jiangcan)}, {Bombyx Batryticatus (Jiangcan)} ≥ {Rhizoma Gastrodiae (Tianma)}, {Rhizoma Acori Tatarinowii (Shichangpu)} ≥ {Ramulus Uncariae cum Uncis (Gouteng)}, etc. The core prescription composition was based on the addition and subtraction of Tianma Gouteng decoction and Erchen decoction. The main pharmacological mechanisms of core prescriptions are mainly reflected in antioxidation, enhancing GABA efficacy, and regulating NMDA channel and sodium channel, neuroprotection, and so on.

Conclusion

Professor Xiaocheng Yan's medication for the treatment of primary epilepsy was based on the principle of relieving wind and spasm, drying dampness and resolving phlegm, giving consideration to both Qi and blood, and harmonizing liver, lung, heart, and spleen.

Mechanisms Underlying Gastrodin Alleviating Vincristine-Induced Peripheral Neuropathic Pain

Gastrodin (GAS) is the main bioactive ingredient of Gastrodia, a famous Chinese herbal medicine widely used as an analgesic, but the underlying analgesic mechanism is still unclear. In this study, we first observed the effects of GAS on the vincristine-induced peripheral neuropathic pain by alleviating the mechanical and thermal hyperalgesia. Further studies showed that GAS could inhibit the current density of Na_V1.7 and Na_V1.8 channels and accelerate the inactivation process of Na_V1.7 and Na_V1.8 channel, thereby inhibiting the hyperexcitability of neurons. Additionally, GAS could significantly reduce the over-expression of Na_V1.7 and Na_V1.8 on DRG neurons from vincristine-treated rats according to the analysis of Western blot and immunofluorescence results. Moreover, based on the molecular docking and molecular dynamic simulation, the binding free energies of the constructed systems were calculated, and the binding sites of GAS on the sodium channels (Na_V1.7 and Na_V1.8) were preliminarily determined. This study has shown that modulation of Na_V1.7 and Na_V1.8 sodium channels by GAS contributing to the alleviation of vincristine-induced peripheral neuropathic pain, thus expanding the understanding of complex action of GAS as a neuromodulator.

Loop Diuretics Inhibit Ischemia-Induced Intracellular Ca2+ Overload in Neurons via the Inhibition of Voltage-Gated Ca2+ and Na+ Channels

One consequence of ischemic stroke is disruption of intracellular ionic homeostasis. Intracellular overload of both Na⁺ and Ca²⁺ has been linked to neuronal death in this pathophysiological state. The etiology of ionic imbalances resulting from stroke-induced ischemia and acidosis includes the dysregulation of multiple plasma membrane transport proteins, such as increased activity of sodium-potassium-chloride cotransporter-1 (NKCC-1). Experiments using NKCC1 antagonists, bumetanide (BMN) and ethacrynic acid (EA), were carried out to determine if inhibition of this cotransporter affects Na⁺ and Ca²⁺ overload observed following in vitro ischemia-acidosis. Fluorometric Ca²⁺ and Na⁺ measurements were performed using cultured cortical neurons, and measurements of whole-cell membrane currents were used to determine target(s) of BMN and EA, other than the electroneutral NKCC-1. Both BMN and EA depressed ischemia-acidosis induced [Ca²⁺]_i overload without appreciably reducing [Na⁺]_i increases. Voltage-gated Ca²⁺ channels were inhibited by both BMN and EA with half-maximal inhibitory concentration (IC₅₀) values of 4 and 36 μM, respectively. Similarly, voltage-gated Na⁺ channels were blocked by BMN and EA with IC₅₀ values of 13 and 30 μM, respectively. However, neither BMN nor EA affected currents mediated by acid-sensing ion channels or ionotropic glutamatergic receptors, both of which are known to produce [Ca²⁺]_i overload following ischemia. Data suggest that loop diuretics effectively inhibit voltage-gated Ca²⁺ and Na⁺ channels at clinically relevant concentrations, and block of these channels by these compounds likely contributes to their clinical effects. Importantly, inhibition of these channels, and not NKCC1, by loop diuretics reduces [Ca²⁺]_i overload in neurons during ischemia-acidosis, and thus BMN and EA could potentially be used therapeutically to lessen injury following ischemic stroke.

Chinese Herbal Medicine for Treating Epilepsy

Chinese herbal medicine has a long history of use for treating epilepsy. Because of the side effects of Western antiepileptic therapy and the quest for more accessible treatment, complementary and alternative medicines have become popular. Traditional Chinese medical diet therapy appears to be safe and effective. We searched PubMed and the Cochrane Library through November 2020 for the use of traditional Chinese medicine in clinical settings, including plants, fungi, and animals. Combinations of keywords included “epilepsy,” “seizure,” “antiepileptic,” “anticonvulsive,” “Chinese herbal medicine,” “Chinese herb,” and each of the Latin names, English names, and scientific names of herbs. We also summarized the sources and functions of these herbs in Chinese medicine. Different herbs can be combined to increase antiepileptic effects through various mechanisms, including anti-inflammation, antioxidation, GABAergic effect enhancement, modulation of NMDA channels and sodium channel, and neuroprotection. Despite reports of their anticonvulsive effects, adequate experimental evidence and randomized controlled clinical trials are required to confirm their antiepileptic effects.

Gastrodin alleviates seizure severity and neuronal excitotoxicities in the rat lithium-pilocarpine model of temporal lobe epilepsy via enhancing GABAergic transmission

ETHNOPHARMACOLOGICAL RELEVANCE

Temporal lobe epilepsy remains one of the most drug-resistant focal epilepsy, leading to enormous healthcare burden. Among traditional herb medicine, some ingredients have the potential to treat seizure and alleviate the neuronal excitoxicity. The dried rhizome of Gastrodia elata Blume has been used to treat convulsive disorder, dizziness, dementia and migraine in eastern Asia.

AIM OF THE STUDY

To determine whether gastrodin, an active ingredient of Gastrodia elata Blume, can reduce lithium-pilocarpine induced seizure severity and neuronal excitotoxicity and explore the underlying mechanism.

MATERIALS AND METHODS

We divided the Sprague-Dawley rats into an experimental group (gastrodin group) and a control group (Dimethyl sulfoxide, vehicle group) and performed the behavioral analysis and electroencephalography to determine the effect of gastrodin on the seizure severity induced by lithium-pilocarpine injection. Nissl-stained histopathology elucidated the degree of rat hippocampal neuronal damage as markers of acute and subacute neuronal excitotoxicity. Besides, the Western blotting of dissected hippocampus was carried out to demonstrate the protein expression involving GABAergic transmission and metabolic pathway.

RESULTS

Gastrodin reduced the acute seizure severity in lithium-pilocarpine-induced seizure model. In electroencephalography recording, gastrodin exerted inhibitory action on epileptiform discharge. Compared with control group, gastrodin exhibited neuroprotective effect against seizure related hippocampal neuronal damage at acute and subacute stages. The Western blotting showed that gastrodin reversed the degradation of GABAA receptor after pilocarpine-induced seizures.

CONCLUSIONS

In the experimental seizure model, gastrodin showed anti-seizure and neuroprotective abilities. Enhancing the expression of GABAA receptor plays an important role in its antiepileptic mechanism. The results offer a new insight of developing new antiepileptic drugs from traditional Chinese medicine.

Response of Voltage-Gated Sodium and Calcium Channels Subtypes on Dehydroepiandrosterone Treatment in Iron-Induced Epilepsy

Epilepsy is a neurological disorder characterized by the occurrence of spontaneous and recurrent seizures. In post-traumatic epilepsy (PTE), the mechanism of epileptogenesis is very complex and seems to be linked with voltage-gated ion channels. Dehydroepiandrosterone (DHEA), a neurosteroid have shown beneficial effect against various neurological disorders. We investigated antiepileptic effect of DHEA with respect to expression of voltage-gated ion channels subtypes in iron-induced epilepsy. Iron (FeCl3) solution was intracartically injected to induce epilepsy in rats and DHEA was intraperitoneally administered for 21 days. Results showed markedly increased epileptiform seizures activity along with up-regulation of Nav1.1 and Nav1.6, and down-regulation of Cav2.1α at the mRNA and protein level in the cortex and hippocampus of epileptic rats. Moreover, the study demonstrated that these channels subtypes were predominantly expressed in the neurons. DHEA treatment has countered the epileptic seizures, down-regulated Nav1.1 and Nav1.6, and up-regulated Cav2.1α without affecting their cellular localization. In conclusion, the present study demonstrates antiepileptic potential of DHEA, escorted by regulation of Nav1.1, Nav1.6, and Cav2.1α subtypes in the neurons of iron-induced epileptic rats.

Differential Inhibition of Human Nav1.2 Resurgent and Persistent Sodium Currents by Cannabidiol and GS967

Many epilepsy patients are refractory to conventional antiepileptic drugs. Resurgent and persistent currents can be enhanced by epilepsy mutations in the Nav1.2 channel, but conventional antiepileptic drugs inhibit normal transient currents through these channels, along with aberrant resurgent and persistent currents that are enhanced by Nav1.2 epilepsy mutations. Pharmacotherapies that specifically target aberrant resurgent and/or persistent currents would likely have fewer unwanted side effects and be effective in many patients with refractory epilepsy. This study investigated the effects of cannbidiol (CBD) and GS967 (each at 1 μM) on transient, resurgent, and persistent currents in human embryonic kidney (HEK) cells stably expressing wild-type hNav1.2 channels. We found that CBD preferentially inhibits resurgent currents over transient currents in this paradigm; and that GS967 preferentially inhibits persistent currents over transient currents. Therefore, CBD and GS967 may represent a new class of more targeted and effective antiepileptic drugs.

The antiepileptic effect of Gastrodiae Rhizoma through modulating overexpression of mTOR and attenuating astrogliosis in pilocarpine mice model

Objective

To investigate the effect of water extract of Gastrodiae Rhizoma (GR) on the development of acquired temporal lobe epilepsy (TLE) and on regulating the expression of the mammalian target of rapamycin (mTOR) and semaphorin 3F (SEMA3F).

Methods

A pilocarpine‐induced status epilepticus (SE) model was adopted to precipitate injury in the limbic systems. GR and carbamazepine (CBZ) treatments were given to mice for 14 days prior to SE induction to demonstrate the antiepileptic effects and continued for 5 more days to illustrate the effects on histologic studies.

Results

Our results consolidated that GR treatment (92.1 minutes) could delay the SE onset in comparison with the control group (61.5 minutes, P = .041). Fewer mice had reached SE with GR treatment (41.7%) when compared with the control group (83.3%, P = .044). GR treatment (2.1 hours/mouse) could suppress the number of acute seizures in post‐SE survival mice when compared with the control group (4.5 hours/mouse, P < .001). The effects of GR treatment were elucidated with the mechanism of actions. GR treatment reduced the overexpression of mTOR (0.27 vs 0.67 AU/mg protein, P = .047). GR treatment increased the underexpression of SEMA3F (0.51 vs 0.16 µg/mg protein, P = .034). In the histochemical study of microtubule‐associated protein 2 (MAP2) staining, our results showed that GR prevented neuronal loss in the GR treatment group (64.8% positively stained pixel area) as compared with the control group (59%, P = .014) in the hippocampus. In glial fibrillary acidic protein (GFAP) staining, the severity of astrogliosis was mitigated by the GR treatment (4.1% positively stained pixel area) when compared to the control group (5.6%, P = .047) in the hippocampus.

Significance

These results provide preclinical evidence to support the use of GR, which could suppress acute seizures and relieve pathological changes in pilocarpine‐induced TLE mice. We demonstrated that the antiepileptic effects of GR could be accompanied by mTOR reduction and astrogliosis attenuation.

Resurgent and Gating Pore Currents Induced by De Novo SCN2A Epilepsy Mutations

Over 150 mutations in the SCN2A gene, which encodes the neuronal Nav1.2 protein, have been implicated in human epilepsy cases. Of these, R1882Q and R853Q are two of the most commonly reported mutations. This study utilized voltage-clamp electrophysiology to characterize the biophysical effects of the R1882Q and R853Q mutations on the hNav1.2 channel, including their effects on resurgent current and gating pore current, which are not typically investigated in the study of Nav1.2 channel mutations. HEK cells transiently transfected with DNA encoding either wild-type (WT) or mutant hNav1.2 revealed that the R1882Q mutation induced a gain-of-function phenotype, including slowed fast inactivation, depolarization of the voltage dependence of inactivation, and increased persistent current. In this model system, the R853Q mutation primarily produced loss-of-function effects, including reduced transient current amplitude and density, hyperpolarization of the voltage dependence of inactivation, and decreased persistent current. The presence of a Navβ4 peptide (KKLITFILKKTREK-OH) in the pipette solution induced resurgent currents, which were increased by the R1882Q mutation and decreased by the R853Q mutation. Further study of the R853Q mutation in Xenopus oocytes indicated a reduced surface expression and revealed a robust gating pore current at negative membrane potentials, a function absent in the WT channel. This not only shows that different epileptogenic point mutations in hNav1.2 have distinct biophysical effects on the channel, but also illustrates that individual mutations can have complex consequences that are difficult to identify using conventional analyses. Distinct mutations may, therefore, require tailored pharmacotherapies in order to eliminate seizures.

Anticonvulsant Effects of Dingxian Pill in Pentylenetetrazol-Kindled Rats

Dingxian pill has been used as an antiepilepsy agent in China from ancient to modern times, of which the concrete pharmacological characterization and the underlying molecular mechanism remain unclear. The present study was undertaken to investigate them by animal behavior, electroencephalogram (EEG), Morris water maze, immunohistochemistry, transcriptomics, and real-time PCR. In our results, the treatment of Dingxian pill dose-dependently inhibited PTZ-induced seizure-like behavior and reduced the seizure grades, LFP power spectral density, and brain wave of the epileptiform EEG component induced by PTZ. In Morris water maze tests, the learning and memory ability of kindled epileptic rats could be attenuated more efficiently by Dingxian pill. For the immediate early gene c-fos, the expression was reduced after Dingxian pill treatment, and the difference was significant between the treatment and the model group. Through the transcriptome analysis of the gene expression in hippocampus, Egr3, Nrg, Arc, and Ptgs2, closely related to epilepsy, had been proved to be downregulated by application of Dingxian pill. All of the results not only highlight the antiepileptic effects of Dingxian pill and its molecular mechanism, but also provide a modern validity theory for the clinical application of traditional Chinese medicine (TCM).

A Review on Central Nervous System Effects of Gastrodin

Rhizoma Gastrodiae (also known as Tian ma), the dried rhizome of Gastrodia elata Blume, is a famous Chinese herb that has been traditionally used for the treatment of headache, dizziness, spasm, epilepsy, stoke, amnesia and other disorders for centuries. Gastrodin, a phenolic glycoside, is the main bioactive constituent of Rhizoma Gastrodiae. Since identified in 1978, gastrodin has been extensively investigated on its pharmacological properties. In this article, we reviewed the central nervous system (CNS) effects of gastrodin in preclinical models of CNS disorders including epilepsy, Alzheimer's disease, Parkinson's disease, affective disorders, cerebral ischemia/reperfusion, cognitive impairment as well as the underlying mechanisms involved and, where possible, clinical data that support the pharmacological activities. The sources and pharmacokinetics of gastrodin were also reviewed here. As a result, gastrodin possesses a broad range of beneficial effects on the above-mentioned CNS diseases, and the mechanisms of actions include modulating neurotransmitters, antioxidative, anti-inflammatory, suppressing microglial activation, regulating mitochondrial cascades, up-regulating neurotrophins, etc. However, more detailed clinical trials are still in need for positioning it in the treatment of neurological disorders.