Basic pharmacology of valproate: a review after 35 years of clinical use for the treatment of epilepsy

Review of pharmacogenetics of antiseizure medications: focusing on genetic variants of mechanistic targets

Antiseizure medications (ASMs) play a central role in seizure management, however, unpredictability in the response to treatment persists, even among patients with similar seizure manifestations and clinical backgrounds. An objective biomarker capable of reliably predicting the response to ASMs would profoundly impact epilepsy treatment. Presently, clinicians rely on a trial-and-error approach when selecting ASMs, a time-consuming process that can result in delays in receiving alternative non-pharmacological therapies such as a ketogenetic diet, epilepsy surgery, and neuromodulation therapies. Pharmacogenetic studies investigating the correlation between ASMs and genetic variants regarding their mechanistic targets offer promise in predicting the response to treatment. Sodium channel subunit genes have been extensively studied along with other ion channels and receptors as targets, however, the results have been conflicting, possibly due to methodological disparities including inconsistent definitions of drug response, variations in ASM combinations, and diversity of genetic variants/genes studied. Nonetheless, these studies underscore the potential effect of genetic variants on the mechanism of ASMs and consequently the prediction of treatment response. Recent advances in sequencing technology have led to the generation of large genetic datasets, which may be able to enhance the predictive accuracy of the response to ASMs.

Medication-induced central sleep apnea: a unifying concept

Medication-induced central sleep apnea (CSA) is one of the eight categories of causes of CSA but in the absence of awareness and careful history may be misclassified as primary CSA. While opioids are a well-known cause of respiratory depression and CSA, non-opioid medications including sodium oxybate, baclofen, valproic acid, gabapentin, and ticagrelor are less well-recognized. Opioids-induced respiratory depression and CSA are mediated primarily by µ-opioid receptors, which are abundant in the pontomedullary centers involved in breathing. The non-opioid medications, sodium oxybate, baclofen, valproic acid, and gabapentin, act upon brainstem gamma-aminobutyric acid (GABA) receptors, which co-colonize with µ-opioid receptors and mediate CSA. The pattern of ataxic breathing associated with these medications is like that induced by opioids on polysomnogram. Finally, ticagrelor also causes periodic breathing and CSA by increasing central chemosensitivity and ventilatory response to carbon dioxide. Given the potential consequences of CSA and the association between some of these medications with mortality, it is critical to recognize these adverse drug reactions, particularly because discontinuation of the offending agents has been shown to eliminate CSA.

Low intensity transcranial ultrasound stimulation induces hemodynamic responses through neurovascular coupling

Collective studies have demonstrated that transcranial ultrasound stimulation (TUS) can elicit activation in hemodynamics, implying its potential in treating cerebral or peripheral vessel-related malfunction. The theory for hemodynamic response to TUS is neurovascular coupling (NVC) following the ultrasound-induced cellular (de)polarization. However, it was not conclusive due to the co-existence of the pathway of direct ultrasound-vessel interactions. This study thus aims to investigate and provide direct evidence for NVC pathway in a rodent model of TUS by inhibiting neural activity with sodium valproate (VPA), a GABAergic agent. Twenty Sprague-Dawley rats were randomly assigned to VPA and Saline groups. Microelectrode and optical imaging were utilized to record local field potential and relative cerebral blood flow (rCBF) during baseline, before, and after TUS periods. We found the attenuated neural activity was associated with reduced rCBF responses. These results provided direct evidence for the presence of NVC pathway in hemodynamic modulation by TUS.

Gestational valproic acid exposure enhances facial stimulation-evoked cerebellar mossy fiber-granule cell transmission via GluN2A subunit-containing NMDA receptor in offspring mice

Valproic acid (VPA) is one of the most effective antiepileptic drugs, and exposing animals to VPA during gestation has been used as a model for autism spectrum disorder (ASD). Numerous studies have shown that impaired synaptic transmission in the cerebellar cortical circuits is one of the reasons for the social deficits and repetitive behavior seen in ASD. In this study, we investigated the effect of VPA exposure during pregnancy on tactile stimulation-evoked cerebellar mossy fiber-granule cell (MF-GC) synaptic transmission in mice anesthetized with urethane. Three-chamber testing showed that mice exposed to VPA mice exhibited a significant reduction in social interaction compared with the control group. In vivo electrophysiological recordings revealed that a pair of air-puff stimulation on ipsilateral whisker pad evoked MF-GC synaptic transmission, N1, and N2. The evoked MF-GC synaptic responses in VPA-exposed mice exhibited a significant increase in the area under the curve (AUC) of N1 and the amplitude and AUC of N2 compared with untreated mice. Cerebellar surface application of the selective N-methyl-D-aspartate (NMDA) receptor blocker D-APV significantly inhibited facial stimulation-evoked MF-GC synaptic transmission. In the presence of D-APV, there were no significant differences between the AUC of N1 and the amplitude and AUC of N2 in the VPA-exposed mice and those of the untreated mice. Notably, blockade of the GluN2A subunit-containing, but not the GluN2B subunit-containing, NMDA receptor, significantly inhibited MF-GC synaptic transmission and decreased the AUC of N1 and the amplitude and AUC of N2 in VPA-exposed mice to levels similar to those seen in untreated mice. In addition, the GluN2A subunit-containing NMDA receptor was expressed at higher levels in the GC layer of VPA-treated mice than in control mice. These results indicate that gestational VPA exposure in mice produces ASD-like behaviors, accompanied by increased cerebellar MF-GC synaptic transmission and an increase in GluN2A subunit-containing NMDA receptor expression in the offspring.

Role of hippocampal and prefrontal cortical cholinergic transmission in combination therapy valproate and cannabidiol in memory consolidation in rats: involvement of CREB- BDNF signaling pathways

PURPOSE

Cognitive disorders are associated with valproate and drugs used to treat neuropsychological diseases. Cannabidiol (CBD) has beneficial effects on cognitive function. This study examined the effects of co-administration of CBD and valproate on memory consolidation, cholinergic transmission, and cyclic AMP response element-binding protein (CREB)-brain-derived neurotrophic factor (BDNF) signaling pathway in the prefrontal cortex (PFC) and hippocampus (HPC).

METHODS

One-trial, step-through inhibitory test was used to evaluate memory consolidation in rats. The intra-CA1 injection of physostigmine and atropine was performed to assess the role of cholinergic transmission in this co-administration. Phosphorylated CREB (p-CREB)/CREB ratio and BDNF levels in the PFC and HPC were evaluated.

RESULTS

Post-training intraperitoneal (i.p.) valproate injection reduced memory consolidation; however, post-training co-administration of CBD with valproate ameliorated memory impairment induced by valproate. Post-training intra-CA1 injection of physostigmine at the ineffective doses in memory consolidation (0.5 and 1 µg/rat), plus injection of 10 mg/kg of CBD as an ineffective dose, improved memory loss induced by valproate, which was associated with BDNF and p-CREB level enhancement in the PFC and HPC. Conversely, post-training intra-CA1 injection of ineffective doses of atropine (1 and 2 µg/rat) reduced the positive effects of injection of CBD at a dose of 20 mg/kg on valproate-induced memory loss associated with BDNF and p-CREB level reduction in the PFC and HPC.

CONCLUSION

The results indicated a beneficial interplay between valproate and CBD in the process of memory consolidation, which probably creates this interaction through the BDNF-CREB signaling pathways in the cholinergic transmission of the PFC and HPC regions.

Unusual Voltage-Gated Sodium and Potassium Channelopathies Related to Epilepsy

BACKGROUND AND PURPOSE

There is extensive literature on monogenic epilepsies caused by mutations in familiar channelopathy genes such as SCN1A. However, information on other less-common channelopathy genes is scarce. This study aimed to explore the genetic and clinical characteristics of patients diagnosed with unusual voltage-gated sodium and potassium channelopathies related to epilepsy.

METHODS

This observational, retrospective study analyzed pediatric patients with epilepsy who carried pathogenic variants of unusual voltage-gated sodium and potassium channelopathy genes responsible for seizure-associated phenotypes. Targeted next-generation sequencing (NGS) panel tests were performed between November 2016 and June 2022 at Severance Children's Hospital, Seoul, South Korea. Clinical characteristics and the treatment responses to different types of antiseizure medications were further analyzed according to different types of gene mutation.

RESULTS

This study included 15 patients with the following unusual voltage-gated sodium and potassium channelopathy genes: SCN3A (n=1), SCN4A (n=1), KCNA1 (n=1), KCNA2 (n=4), KCNB1 (n=6), KCNC1 (n=1), and KCNMA1 (n=1). NGS-based genetic testing identified 13 missense mutations (87%), 1 splice-site variant (7%), and 1 copy-number variant (7%). Developmental and epileptic encephalopathy was diagnosed in nine (60%) patients. Seizure freedom was eventually achieved in eight (53%) patients, whereas seizures persisted in seven (47%) patients.

CONCLUSIONS

Our findings broaden the genotypic and phenotypic spectra of less-common voltage-gated sodium and potassium channelopathies associated with epilepsy.

Effect of intrahippocampal microinjection of VU0155041, a positive allosteric modulator of mGluR4, on long term potentiation in a valproic acid-induced autistic male rat model

The precise cause of autism spectrum disorder (ASD) is not fully understood. Despite the involvement of glutamatergic dysregulation in autism, the specific contribution of mGlu4 receptors to synaptic plasticity remains unclear. Using the positive allosteric modulator VU0155041, we aimed to restore long-term potentiation (LTP) in the perforant path-dentate gyrus (PP-DG) pathway in VPA-induced autistic rat model. High-frequency stimulation was applied to the PP-DG synapse to induce LTP, while the VU0155041 was administered into the DG. Unexpectedly, VU0155041 failed to alleviate the observed LTP reduction in VPA-exposed rats, further resulting in a significant decrease in population spike LTP. This unexpected outcome prompts discussion on the complex nature of mGlu4 receptor modulation, highlighting potential interference with physiological processes underlying synaptic plasticity.

Addressing neurodegeneration in glaucoma: Mechanisms, challenges, and treatments

Glaucoma is the leading cause of irreversible blindness globally. The disease causes vision loss due to neurodegeneration of the retinal ganglion cell (RGC) projection to the brain through the optic nerve. Glaucoma is associated with sensitivity to intraocular pressure (IOP). Thus, mainstay treatments seek to manage IOP, though many patients continue to lose vision. To address neurodegeneration directly, numerous preclinical studies seek to develop protective or reparative therapies that act independently of IOP. These include growth factors, compounds targeting metabolism, anti-inflammatory and antioxidant agents, and neuromodulators. Despite success in experimental models, many of these approaches fail to translate into clinical benefits. Several factors contribute to this challenge. Firstly, the anatomic structure of the optic nerve head differs between rodents, nonhuman primates, and humans. Additionally, animal models do not replicate the complex glaucoma pathophysiology in humans. Therefore, to enhance the success of translating these findings, we propose two approaches. First, thorough evaluation of experimental targets in multiple animal models, including nonhuman primates, should precede clinical trials. Second, we advocate for combination therapy, which involves using multiple agents simultaneously, especially in the early and potentially reversible stages of the disease. These strategies aim to increase the chances of successful neuroprotective treatment for glaucoma.

A Zebrafish-Based Platform for High-Throughput Epilepsy Modeling and Drug Screening in F0

The zebrafish model has emerged as a reference tool for phenotypic drug screening. An increasing number of molecules have been brought from bench to bedside thanks to zebrafish-based assays over the last decade. The high homology between the zebrafish and the human genomes facilitates the generation of zebrafish lines carrying loss-of-function mutations in disease-relevant genes; nonetheless, even using this alternative model, the establishment of isogenic mutant lines requires a long generation time and an elevated number of animals. In this study, we developed a zebrafish-based high-throughput platform for the generation of F0 knock-out (KO) models and the screening of neuroactive compounds. We show that the simultaneous inactivation of a reporter gene (tyrosinase) and a second gene of interest allows the phenotypic selection of F0 somatic mutants (crispants) carrying the highest rates of mutations in both loci. As a proof of principle, we targeted genes associated with neurodevelopmental disorders and we efficiently generated de facto F0 mutants in seven genes involved in childhood epilepsy. We employed a high-throughput multiparametric behavioral analysis to characterize the response of these KO models to an epileptogenic stimulus, making it possible to employ kinematic parameters to identify seizure-like events. The combination of these co-injection, screening and phenotyping methods allowed us to generate crispants recapitulating epilepsy features and to test the efficacy of compounds already during the first days post fertilization. Since the strategy can be applied to a wide range of indications, this study paves the ground for high-throughput drug discovery and promotes the use of zebrafish in personalized medicine and neurotoxicity assessment.

Puerarin attenuates valproate-induced features of ASD in male mice via regulating Slc7a11-dependent ferroptosis

Autism spectrum disorder (ASD) is a complicated, neurodevelopmental disorder characterized by social deficits and stereotyped behaviors. Accumulating evidence suggests that ferroptosis is involved in the development of ASD, but the underlying mechanism remains elusive. Puerarin has an anti-ferroptosis function. Here, we found that the administration of puerarin from P12 to P15 ameliorated the autism-associated behaviors in the VPA-exposed male mouse model of autism by inhibiting ferroptosis in neural stem cells of the hippocampus. We highlight the role of ferroptosis in the hippocampus neurogenesis and confirm that puerarin treatment inhibited iron overload, lipid peroxidation accumulation, and mitochondrial dysfunction, as well as enhanced the expression of ferroptosis inhibitory proteins, including Nrf2, GPX4, Slc7a11, and FTH1 in the hippocampus of VPA mouse model of autism. In addition, we confirmed that inhibition of xCT/Slc7a11-mediated ferroptosis occurring in the hippocampus is closely related to puerarin-exerted therapeutic effects. In conclusion, our study suggests that puerarin targets core symptoms and hippocampal neurogenesis reduction through ferroptosis inhibition, which might be a potential drug for autism intervention.

Distribution pattern of UGT1A6 and UGT2B7 gene polymorphism and its impact on the pharmacokinetics of valproic acid and carbamazepine: Prospective genetic association study conducted in Pakistani patients with epilepsy

BACKGROUND

Ethnic variation is one of the important factors in clinical practice that may affect the pharmacokinetics of drugs. The present study aims to determine the distribution pattern of UGT1A6 and UGT2B7 gene polymorphism and its possible impact on the metabolism of valproic acid (VPA) and carbamazepine (CBZ) in patients with epilepsy from Khyber Pakhtunkhwa region of Pakistan.

METHODS

After the enrollment of targeted patients, blood was collected for genotype analysis through Sanger sequencing. Plasma concentrations of VPA and CBZ were determined by reversed-phase high-performance liquid chromatography (HPLC) at the follow-up visit of third month from the initiation of therapy. The drug plasma levels were correlated with different genotypes of UGT1A6 and UGT2B7 to determine the impact of genetic polymorphism on the drug metabolism.

RESULTS

Of the total 178 epileptic patients, 120 subjects were prescribed VPA monotherapy while 58 subjects were given CBZ monotherapy. The mean age of the subjects was recorded as 26.1 ± 13.5 years with a predominance of the male gender. Generalized tonic-clonic (GTC) was the most prevalent type of seizure (82%) followed by partial seizure. Genotype analysis revealed that the frequency of homozygous and heterozygous variants of the targeted UGT genes were exceptionally high in the Khyber Pakhtunkhwa population compared to the ethnic groups of other countries. In UGT1A6-A552C and UGT1A6-A541G, AC and AG were the most prevalent genotypes with respective frequencies of 43.2% and 41.1% whereas, in UGT2B7-T161C and UGT2B7-G211T, TC and GG were the most prevalent genotypes with respective frequencies of 42.7% and 99.4%. In the VPA-treated group, the homozygous and heterozygous variants of UGT1A6-A552C and UGT1A6-A541G were significantly associated with lower drug plasma concentrations (p < 0.05). However, none of the genotypes of UGT2B7-T161C revealed any significant association with VPA plasma concentration (p greater than 0.05). In the CBZ-treated group, UGT gene polymorphisms were not recognized to cause alteration in the drug plasma concentrations (p greater than 0.05).

CONCLUSION

The genetic polymorphisms of UGT1A6, but not UGT2B7 significantly affected the plasma levels of valproic acid. The chosen SNPs did not reveal a role in determining the plasma levels of carbamazepine.

Clinical and Genetic Features of Dravet Syndrome: A Prime Example of the Role of Precision Medicine in Genetic Epilepsy

Dravet syndrome (DS), also known as severe myoclonic epilepsy of infancy, is a rare and drug-resistant form of developmental and epileptic encephalopathies, which is both debilitating and challenging to manage, typically arising during the first year of life, with seizures often triggered by fever, infections, or vaccinations. It is characterized by frequent and prolonged seizures, developmental delays, and various other neurological and behavioral impairments. Most cases result from pathogenic mutations in the sodium voltage-gated channel alpha subunit 1 (SCN1A) gene, which encodes a critical voltage-gated sodium channel subunit involved in neuronal excitability. Precision medicine offers significant potential for improving DS diagnosis and treatment. Early genetic testing enables timely and accurate diagnosis. Advances in our understanding of DS's underlying genetic mechanisms and neurobiology have enabled the development of targeted therapies, such as gene therapy, offering more effective and less invasive treatment options for patients with DS. Targeted and gene therapies provide hope for more effective and personalized treatments. However, research into novel approaches remains in its early stages, and their clinical application remains to be seen. This review addresses the current understanding of clinical DS features, genetic involvement in DS development, and outcomes of novel DS therapies.

The role of NMDA receptors in bipolar disorder: A systematic review

OBJECTIVES

Glutamatergic transmission and N-methyl-D-aspartate receptors (NMDARs) have been implicated in the pathophysiology schizophrenic spectrum and major depressive disorders. Less is known about the role of NMDARs in bipolar disorder (BD). The present systematic review aimed to investigate the role of NMDARs in BD, along with its possible neurobiological and clinical implications.

METHODS

We performed a computerized literature research on PubMed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement, using the following string: (("Bipolar Disorder"[Mesh]) OR (manic-depressive disorder[Mesh]) OR ("BD") OR ("MDD")) AND ((NMDA [Mesh]) OR (N-methyl-D-aspartate) OR (NMDAR[Mesh]) OR (N-methyl-D-aspartate receptor)).

RESULTS

Genetic studies yield conflicting results, and the most studied candidate for an association with BD is the GRIN2B gene. Postmortem expression studies (in situ hybridization and autoradiographic and immunological studies) are also contradictory but suggest a reduced activity of NMDARs in the prefrontal, superior temporal cortex, anterior cingulate cortex, and hippocampus.

CONCLUSIONS

Glutamatergic transmission and NMDARs do not appear to be primarily involved in the pathophysiology of BD, but they might be linked to the severity and chronicity of the disorder. Disease progression could be associated with a long phase of enhanced glutamatergic transmission, with ensuing excitotoxicity and neuronal damage, resulting into a reduced density of functional NMDARs.

Group I and group II metabotropic glutamate receptors are upregulated in the synapses of infant rats prenatally exposed to valproic acid

RATIONALE

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impaired social interaction and restricted/stereotyped behavior. Prenatal exposure to valproic acid (VPA) is associated with an increased risk of developing ASD in humans and autistic-like behaviors in rodents. Increasing evidence indicates that dysfunctions of glutamate receptors at synapses are associated with ASD. In the VPA rat model, an involvement of glutamate receptors in autism-like phenotypes has been suggested; however, few studies were carried out on metabotropic glutamate (mGlu) receptors.

OBJECTIVES

We examined the protein expression levels of group I (mGlu1 and mGlu5) and group II (mGlu2/3) mGlu receptors in rats prenatally exposed to VPA and evaluated the effect of mGlu receptor modulation on an early autism-like phenotype in these animals.

METHODS

We used western blotting analysis on synaptosomes obtained from forebrain of control and VPA rats at different ages (postnatal day P13, 35, 90) and carried out ultrasonic vocalization (USV) emission test in infant control and VPA rats.

RESULTS

The expression levels of all these receptors were significantly increased in infant VPA rats. No changes were detected in adolescent and adult rats. An acute treatment with the preferential mGlu2/3 antagonist, LY341495, attenuated the impairment in the USV emission in VPA rats. No effect was observed after a treatment with the mGlu5 selective antagonist, MTEP.

CONCLUSIONS

Our findings demonstrate that the expression of group I and group II mGlu receptors is upregulated at synapses of infant VPA rats and suggest that mGlu2/3 receptor modulation may have a therapeutic potential in ASD.

Physiologically based mechanistic insight into differential risk of valproate hepatotoxicity between children and adults: A focus on ontogeny impact

The anticonvulsant valproic acid (VPA) despite complex pharmacokinetics has been in clinical use for nearly 6 decades. Previous reports indicated neonates, infants, and toddlers/preschoolers had higher risk of valproate hepatotoxicity than adults. However, dosing recommendations for those less than 10 years of age are lacking. To decipher clinical puzzles, physiologically-based pharmacokinetic (PBPK) models of VPA and its hepatotoxic metabolite 4-ene-VPA were constructed and simulated with particularly integrated information of drug-metabolizing enzyme ontogeny. Adult and pediatric PK data of VPA (n = 143 subjects) and 4-ene-VPA (n = 8 subjects) collected from previous reports were used for model development and validation. Sensitivity analyses were performed to characterize ontogeny impacts of CYP2C9 and UGT2B7 on dispositions of VPA and 4-ene-VPA across age groups. Optimal VPA dosing for each pediatric age group was also predicted and objectively judged by ensuring VPA efficacy and avoiding 4-ene-VPA hepatotoxicity. The study revealed UGT2B7 ontogeny was quite influential on VPA clearance even in neonates and small children. Intrinsic clearance of CYP2C9 was the most prominent determinant for areas under the concentration-time curve of VPA and 4-ene-VPA in infants, and toddlers/preschoolers, reflecting higher hepatotoxicity risk due to noxious 4-ene-VPA accumulation in these groups. The ontogeny-based PBPK approach complements conventional allometric methods in dosing estimation for the young by providing more mechanistic insight of the processes changing with age. The established ontogeny-based PBPK approach for VPA therapy deserves further corroboration by real-world therapeutic data to affirm its clinical applicability.

Research progress on the treatment of epilepsy with traditional Chinese medicine

BACKGROUND

Traditional Chinese Medicine (TCM) system is a medical system that has been expanding for thousands of years that was formed by the extensive clinical practice experience of many physicians and the accumulation of personal medication habits in China. In TCM, there is a history of long-term medication for epilepsy, the main treatment for epilepsy is TCM drugs and its prescription, supplemented by TCM modalities such as acupuncture therapy, moxibustion therapy, tuina, emotion adjustment therapy, etc. PURPOSE: With the modernization of TCM, the active ingredients and molecular mechanisms of TCM for epilepsy treatment have been gradually revealed. This review aimed to comprehensively summarize the TCM treatment of epilepsy, focusing on the current TCM drugs and some TCM formulae for the treatment of epilepsy, and to discuss the research progress of TCM for the treatment of epilepsy, and to provide a reference to develop future related studies in this field.

MATERIALS AND METHODS

The mechanism of action of antiepileptic drugs (AEDs) was interpreted from different perspectives by searching online databases and querying various materials identify drugs used in both modern medicine and TCM systems for the treatment of epilepsy. We collected all relevant TCM for epilepsy literature published in the last 30 years up to December 2022 from electronic databases such as PubMed, CNKI and Web of Science, and statistically analyzed the literature for the following keyword information. The search terms comprise the keywords "TCM", "phytochemistry", "pharmacological activity", "epilepsy" and "traditional application" as a combination. Scientific plant names were provided by "The Plant List" (www.theplantlist.org).

RESULTS

Epilepsy is a complex and serious disease of the brain and nervous system. At present, the treatment of epilepsy in modern medicine is mainly surgery and chemotherapy, but there are many serious side effects. By summarizing the treatment of epilepsy in TCM, it is found that there are various methods to treat epilepsy in TCM, mainly TCM drugs and its formulae. Many TCM drugs have antiepileptic effects. Now found that the main effective TCM drugs for the treatment of epilepsy are Curcumae Longae Rhizoma, Scorpio, Acori Tatarinowii Rhizoma, Uncariae Ramulus Cum Uncis and Ganoderma, etc. And the main compounds that play a role in the treatment of epilepsy are curcumin, gastrodin, ligustrazine, baicalin and rhynchophylline, etc. These TCM drugs have played an important role in the treatment of epilepsy in TCM clinic. However, the chemically active components of these TCM drugs are diverse and their mechanisms of action are complex, which are not fully understood and need to be further explored.

CONCLUSIONS

TCM treats epilepsy in a variety of ways, and with the discovery of a variety of potential bioactive substances for treatment of epilepsy. With the new progress in the research of other TCM treatment methods for epilepsy, TCM will have greater potential in the clinical application of epilepsy.

Long-lasting antiseizure effects of chronic intrasubthalamic convection-enhanced delivery of valproate

Intracerebral drug delivery is an experimental approach for the treatment of drug-resistant epilepsies that allows for pharmacological intervention in targeted brain regions. Previous studies have shown that targeted pharmacological inhibition of the subthalamic nucleus (STN) via modulators of the GABAergic system produces antiseizure effects. However, with chronic treatment, antiseizure effects are lost as tolerance develops. Here, we report that chronic intrasubthalamic microinfusion of valproate (VPA), an antiseizure medication known for its wide range of mechanisms of action, can produce long-lasting antiseizure effects over three weeks in rats. In the intravenous pentylenetetrazole seizure-threshold test, seizure thresholds were determined before and during chronic VPA application (480 μg/d, 720 μg/d, 960 μg/d) to the bilateral STN. Results indicate a dose-dependent variation in VPA-induced antiseizure effects with mean increases in seizure threshold of up to 33%, and individual increases of up to 150%. The lowest VPA dose showed a complete lack of tolerance development with long-lasting antiseizure effects. Behavioral testing with all doses revealed few, acceptable adverse effects. VPA concentrations were high in STN and low in plasma and liver. In vitro electrophysiology with bath applied VPA revealed a reduction in spontaneous firing rate, increased background membrane potential, decreased input resistance and a significant reduction in peak NMDA, but not AMPA, receptor currents in STN neurons. Our results suggest an advantage of VPA over purely GABAergic modulators in preventing tolerance development with chronic intrasubthalamic drug delivery and provide first mechanistic insights in intracerebral pharmacotherapy targeting the STN.

Gad1 knock-out rats exhibit abundant spike-wave discharges in EEG, exacerbated with valproate treatment

Objective

To elucidate the functional role of gamma-aminobutyric acid (GABA)-ergic inhibition in suppressing epileptic brain activities such as spike-wave discharge (SWD), we recorded electroencephalogram (EEG) in knockout rats for Glutamate decarboxylase 1 (Gad1), which encodes one of the two GABA-synthesizing enzymes in mammals. We also examined how anti-epileptic drug valproate (VPA) acts on the SWDs present in Gad1 rats and affects GABA synthesis in the reticular thalamic nucleus (RTN), which is known to play an essential role in suppressing SWD.

Methods

Chronic EEG recordings were performed in freely moving control rats and homozygous knockout Gad1 (-/-) rats. Buzzer tones (82 dB) were delivered to the rats during EEG monitoring to test whether acoustic stimulation could interrupt ongoing SWDs. VPA was administered orally to the rats, and the change in the number of SWDs was examined. The distribution of GABA in the RTN was examined immunohistochemically.

Results

SWDs were abundant in EEG from Gad1 (-/-) rats as young as 2 months old. Although SWDs were universally detected in older rats irrespective of their Gad1 genotype, SWD symptom was most severe in Gad1 (-/-) rats. Acoustic stimulation readily interrupted ongoing SWDs irrespective of the Gad1 genotype, whereas SWDs were more resistant to interruption in Gad1 (-/-) rats. VPA treatment alleviated SWD symptoms in control rats, however, counterintuitively exacerbated the symptoms in Gad1 (-/-) rats. The immunohistochemistry results indicated that GABA immunoreactivity was significantly reduced in the somata of RTN neurons in Gad1 (-/-) rats but not in their axons targeting the thalamus. VPA treatment greatly increased GABA immunoreactivity in the RTN neurons of Gad1 (-/-) rats, which is likely due to the intact GAD2, another GAD isozyme, in these neurons.

Discussion

Our results revealed two opposing roles of GABA in SWD generation: suppression and enhancement of SWD. To account for these contradictory roles, we propose a model in which GABA produced by GAD1 in the RTN neuronal somata is released extrasynaptically and mediates intra-RTN inhibition.

In situbiosensing technologies for an organ-on-a-chip

Thein vitrosimulation of organs resolves the accuracy, ethical, and cost challenges accompanyingin vivoexperiments. Organoids and organs-on-chips have been developed to model thein vitro, real-time biological and physiological features of organs. Numerous studies have deployed these systems to assess thein vitro, real-time responses of an organ to external stimuli. Particularly, organs-on-chips can be most efficiently employed in pharmaceutical drug development to predict the responses of organs before approving such drugs. Furthermore, multi-organ-on-a-chip systems facilitate the close representations of thein vivoenvironment. In this review, we discuss the biosensing technology that facilitates thein situ, real-time measurements of organ responses as readouts on organ-on-a-chip systems, including multi-organ models. Notably, a human-on-a-chip system integrated with automated multi-sensing will be established by further advancing the development of chips, as well as their assessment techniques.

Evaluation of ganglion cell complex and retinal nerve fiber layer thinning in epilepsy patients

Purpose

This study aimed to compare the perimacular ganglion cell complex (GCC) and peripapillary retinal nerve fiber layer (RNFL) thickness measurements of epileptic and healthy individuals.

Methods

The right eyes of 38 epileptic and 38 healthy individuals who had been using antiepileptic drugs (AEDs) for at least 1 year were included in the study. Central macular thickness, perimacular GCC thickness and volume, and peripapillary retinal nerve fiber layers were measured by optical coherence tomography (OCT) device. Perimacular 1, 3, and 6 mm circle diameters of Early Treatment of Diabetic Retinopathy Study (ETDRS.

)

were selected for GCC measurements.

Results

In epilepsy patients, GCC was significantly lower in the 3 mm superior quadrant and 6 mm in all quadrants compared to the control group (P < 0.05). RNFL was significantly thinner in epilepsy patients only in the temporal-inferior quadrant (P < 0.05). There was no significant difference between the patients who received AEDs as monotherapy and polytherapy (P > 0.05).

Conclusion

We found that epilepsy patients had significant thinning in the GCC layers and temporal-inferior quadrant of RNFL compared to the control group. Our findings from the study show that early retinal changes in epilepsy patients, especially perimacular GCC layers, can be followed up with OCT.

KCNC2 variants of uncertain significance are also associated to various forms of epilepsy

Recently, de novo variants in KCNC2, coding for the potassium channel subunit K_V3.2, have been described as causative for various forms of epilepsy including genetic generalized epilepsy (GGE) and developmental and epileptic encephalopathy (DEE). Here, we report the functional characteristics of three additional KCNC2 variants of uncertain significance and one variant classified as pathogenic. Electrophysiological studies were performed in Xenopus laevis oocytes. The data presented here support that KCNC2 variants with uncertain significance may also be causative for various forms of epilepsy, as they show changes in the current amplitude and activation and deactivation kinetics of the channel, depending on the variant. In addition, we investigated the effect of valproic acid on K_V3.2, as several patients carrying pathogenic variants in the KCNC2 gene achieved significant seizure reduction or seizure freedom with this drug. However, in our electrophysiological investigations, no change on the behavior of K_V3.2 channels could be observed, suggesting that the therapeutic effect of VPA may be explained by other mechanisms.

Effects of Deacetylase Inhibition on the Activation of the Antioxidant Response and Aerobic Metabolism in Cellular Models of Fanconi Anemia

Fanconi anemia (FA) is a rare genetic disease characterized by a dysfunctional DNA repair and an oxidative stress accumulation due to defective mitochondrial energy metabolism, not counteracted by endogenous antioxidant defenses, which appear down-expressed compared to the control. Since the antioxidant response lack could depend on the hypoacetylation of genes coding for detoxifying enzymes, we treated lymphoblasts and fibroblasts mutated for the FANC-A gene with some histone deacetylase inhibitors (HDACi), namely, valproic acid (VPA), beta-hydroxybutyrate (OHB), and EX527 (a Sirt1 inhibitor), under basal conditions and after hydrogen peroxide addition. The results show that VPA increased catalase and glutathione reductase expression and activity, corrected the metabolic defect, lowered lipid peroxidation, restored the mitochondrial fusion and fission balance, and improved mitomycin survival. In contrast, OHB, despite a slight increase in antioxidant enzyme expressions, exacerbated the metabolic defect, increasing oxidative stress production, probably because it also acts as an oxidative phosphorylation metabolite, while EX527 showed no effect. In conclusion, the data suggest that VPA could be a promising drug to modulate the gene expression in FA cells, confirming that the antioxidant response modulation plays a pivotal in FA pathogenesis as it acts on both oxidative stress levels and the mitochondrial metabolism and dynamics quality.

Valproic Acid-Associated Hyperammonemia: A Systematic Review

BACKGROUND

Hyperammonemia is an adverse effect that poses clinical uncertainty around valproic acid (VPA) use. The prevalence of symptomatic and asymptomatic hyperammonemia and its relationship to VPA concentration is not well established. There is also no clear guidance regarding its management. This results in variability in the monitoring and treatment of VPA-induced hyperammonemia. To inform clinical practice, this systematic review aims to summarize evidence available around VPA-associated hyperammonemia and its prevalence, clinical outcomes, and management.

METHODS

An electronic search was performed through Ovid MEDLINE, Ovid Embase, Web of Science, and PsycINFO using search terms that identified hyperammonemia in patients receiving VPA. Two reviewers independently performed primary title and abstract screening with a third reviewer resolving conflicting screening results. This process was repeated during the full-text review process.

RESULTS

A total of 240 articles were included. Prevalence of asymptomatic hyperammonemia (5%-73%) was higher than symptomatic hyperammonemia (0.7%-22.2%) and occurred within the therapeutic range of VPA serum concentration. Various risk factors were identified, including concomitant medications, liver injury, and defects in carnitine metabolism. With VPA discontinued, most symptomatic patients returned to baseline mental status with normalized ammonia level. There was insufficient data to support routine monitoring of ammonia level for VPA-associated hyperammonemia.

CONCLUSIONS

Valproic acid-associated hyperammonemia is a common adverse effect that may occur within therapeutic range of VPA. Further studies are required to determine the benefit of routine ammonia level monitoring and to guide the management of VPA-associated hyperammonemia.

Population pharmacokinetics of oxcarbazepine 10-monohydroxy derivative in Chinese adult epileptic patients

OBJECTIVE

Oxcarbazepine (OXC) is metabolised to active 10-monohydroxy derivative (MHD) after oral administration. Using this fact we aimed to develop an MHD population pharmacokinetic (PPK) model in Chinese adult epileptic patients to facilitate the clinical implementation of model-guided individualised drug therapy.

METHODS

We collected blood samples from Chinese adult epileptic patients taking OXC at the Second Affiliated Hospital of Zhejiang University School of Medicine. We used high performance liquid chromatography (HPLC-MS/MS) with tandem mass spectrometry to detect MHD concentrations in the blood samples. We collected various data from patients including their demographic, pathological, and physiological information. MassARRAY method was used to detect ABCC2, ABCB1, SCN8A, SCN1A, SCN2A, SCN3A, UGT1A9, and UGT2B7 gene polymorphisms. We used a nonlinear mixed-effects modelling method to develop the PPK model and we predicted dosing regimens through simulation.

RESULT

In total we collected 164 blood samples from 118 patients. We found that a one-compartment model with first-order absorption better described the in vivo MHD pharmacokinetics. UGT2B7 gene (rs7439366) site mutation and the combined use of valproic acid enhanced the MHD clearance rate. We divided patients into groups based on the UGT2B7 genotype and whether they were also using valproic acid at the same time. Individualised OXC dosing regimens were proposed for different subgroups of patients.

CONCLUSION

In Chinese adult epileptic patients, individualised drug administration can be facilitated using a PPK model of OXC.

TRIAL REGISTRATION NUMBER

ChiCTR-OOC-17012141.

A comprehensive review on pharmacological applications and drug-induced toxicity of valproic acid

Valproic acid, a branching short chain fatty acid, is a popular drug to treat epilepsy and acts as a mood-stabilizing drug. The obstruction of ion channels and Gamma Amino Butyrate transamino butyrate GABA has been linked to antiepileptic effects. Valproic acid has been characterized as a Histone deacetylase inhibitor, functioning directly transcription of gene levels by blocking the deacetylation of histones and increasing the accessibility of transcription sites. Study has been extensively focused on pharmaceutical activity of valproic acid through various pharmacodynamics activity from absorption, distribution and excretion particularly in patients who are resistant to or intolerant of lithium or carbamazepine, as well as those with mixed mania or rapid cycling.

Impact of valproic acid on busulfan pharmacokinetics: In vitro assessment of potential drug-drug interaction

Busulfan (Bu) is an alkylating agent commonly used at high doses in the preparative regimens of hematopoietic stem cell transplantation (HSCT). It has been shown that such high doses of Bu are associated with generalized seizures which are usually managed by prophylactic antiepileptic drugs (AEDs) such as valproic acid (VPA). Being a strong enzyme inhibitor, VPA may inhibit Bu metabolism and thus increase its potential toxicity. Despite its clinical relevance, the potential interaction between Bu and VPA has not yet been evaluated. The aim of the present study was to assess and evaluate the potential drug-drug interaction (DDI) between Bu and VPA. This study was carried out by incubating Bu in laboratory-prepared rat liver-subcellular fractions including S9, microsomes, and cytosol, alone or in combination with VPA. The liver fractions were prepared by differential centrifugation of the liver homogenate. Analysis of Bu was employed using a fully validated LC-MS/MS method. The validation parameters were within the proposed limits of the international standards guidelines. Bu metabolic stability was assessed by incubating Bu at a concentration of 8 μg/ml in liver fractions at 37°C. There were significant reductions in Bu levels in S9 and cytosolic fractions, whereas these levels were not significantly (P ˃ 0.05) changed in microsomes. However, in presence of VPA, Bu levels in S9 fraction remained unchanged. These results indicated, for the first time, the potential metabolic interaction of Bu and VPA being in S9 only. This could be explained by inhibiting Bu cytosolic metabolism by the interaction with VPA either by sharing the same metabolic enzyme or the required co-factor. In conclusion, the present findings suggest, for the first time, a potential DDI between Bu and VPA in vitro using rat liver fractions. Further investigations are warranted in human-derived liver fractions to confirm such an interaction.

Valproate-coenzyme A conjugate blocks opening of receptor binding domains in the spike trimer of SARS-CoV-2 through an allosteric mechanism

The receptor-binding domains (RBDs) of the SARS-CoV-2 spike trimer exhibit "up" and "down" conformations often targeted by neutralizing antibodies. Only in the "up" configuration can RBDs bind to the ACE2 receptor of the host cell and initiate the process of viral multiplication. Here, we identify a lead compound (3-oxo-valproate-coenzyme A conjugate or Val-CoA) that stabilizes the spike trimer with RBDs in the down conformation. Val-CoA interacts with three R408 residues, one from each RBD, which significantly reduces the inter-subunit R408-R408 distance by ∼ 13 Å and closes the central pore formed by the three RBDs. Experimental evidence is presented that R408 is part of a triggering mechanism that controls the prefusion to postfusion state transition of the spike trimer. By stabilizing the RBDs in the down configuration, this and other related compounds can likely attenuate viral transmission. The reported findings for binding of Val-CoA to the spike trimer suggest a new approach for the design of allosteric antiviral drugs that do not have to compete for specific virus-receptor interactions but instead hinder the conformational motion of viral membrane proteins essential for interaction with the host cell. Here, we introduce an approach to target the spike protein by identifying lead compounds that stabilize the RBDs in the trimeric "down" configuration. When these compounds trimerize monomeric RBD immunogens as co-immunogens, they could also induce new types of non-ACE2 blocking antibodies that prevent local cell-to-cell transmission of the virus, providing a novel approach for inhibition of SARS-CoV-2.

Anti-hydatidosis Potential of Sodium Valproate: Evaluating New Therapeutic Potential for Sodium Valproate

Background: Larval stage of Echinococcus granulosus is the main cause of the hydatid cyst. Surgery, which is both aggressive and high-risk, is the most common treatment for this type of cyst. Some medicines, such as mebendazole, are also used as a complementary approach to preventing the recurrence of hydatid cysts. Objectives: Considering the approved antiparasitic effects of sodium valproate (VPA) on some parasites, this research intended to examine the potential of VPA against protoscolices and hydatid walls. Methods: Liver hydatid cysts caused by E. granulosus were collected from a slaughterhouse. Protoscolices and hydatid cysts were exposed to RPMI and dimethyl sulfoxide (DMSO) media (control groups) or different concentrations of VPA and mebendazole in vitro. The viability of protoscolices was evaluated via light microscopy. Also, tissue changes and expression of apoptotic caspase-3 were examined in hydatid cyst walls (HCWs) using histological and immunohistochemical methods, respectively. Results: The mortality rates of VPA-treated and mebendazole-treated protoscolices were dose- and time-dependent. There was a significant difference between the intervention and control groups (P < 0.05). Tissue changes and apoptosis were observed in VPA-treated and mebendazole-treated HCWs. Conclusions: Valproate and mebendazole had significant effects on protoscolices and HCWs, although VPA exerted its effects more rapidly. It seems that VPA can be a new promising protoscolicidal agent and anti-hydatid medicine.

Anti-seizure mechanisms of midazolam and valproate at the β2(L51M) variant of the GABAA receptor

Genetic sequencing is identifying an expanding number of variants of GABAA receptors associated with human epilepsies. We identified a new de novo variant of the β2 subunit (β2L51M) of the inhibitory GABAA receptor associated with seizures. Our analysis determined the pathogenicity of the variant and the effects of anti-seizure medications. Our data demonstrates that the variant reduced cell surface trafficking and peak GABA-gated currents. Synaptic currents mediated by variant-containing receptors decayed faster than wild-type and single receptor currents showed that the variant shortened the duration of receptor activity by decreasing receptor open times. We tested the effects of the anti-seizure medications, midazolam, carbamazepine and valproate and found that all three enhance variant receptor surface expression. Additionally, midazolam restored receptor function by increasing single receptor active periods and synaptic current decay times towards wild-type levels. By contrast, valproate increased synaptic peak currents, event frequency and promoted synaptic bursting. Our study identifies a new disease-causing variant to the GABAA receptor, profiles its pathogenic effects and demonstrates how anti-seizure drugs correct its functional deficits.

Targeting the epigenome in malignant melanoma: Facts, challenges and therapeutic promises

Malignant melanoma is the most lethal type of skin cancer with high rates of mortality. Although current treatment options provide a short-clinical benefit, acquired-drug resistance highlights the low 5-year survival rate among patients with advanced stage of the disease. In parallel, the involvement of an aberrant epigenetic landscape, (e.g., alterations in DNA methylation patterns, histone modifications marks and expression of non-coding RNAs), in addition to the genetic background, has been also associated with the onset and progression of melanoma. In this review article, we report on current therapeutic options in melanoma treatment with a focus on distinct epigenetic alterations and how their reversal, by specific drug compounds, can restore a normal phenotype. In particular, we concentrate on how single and/or combinatorial therapeutic approaches have utilized epigenetic drug compounds in being effective against malignant melanoma. Finally, the role of deregulated epigenetic mechanisms in promoting drug resistance to targeted therapies and immune checkpoint inhibitors is presented leading to the development of newly synthesized and/or improved drug compounds capable of targeting the epigenome of malignant melanoma.

Pharmacogenetics-based population pharmacokinetic analysis and dose optimization of valproic acid in Chinese southern children with epilepsy: Effect of ABCB1 gene polymorphism

Objective: The aim of this study was to establish a population pharmacokinetic (PPK) model of valproic acid (VPA) in pediatric patients with epilepsy in southern China, and provide guidance for individualized medication of VPA therapy. Methods: A total of 376 VPA steady-state trough concentrations were collected from 103 epileptic pediatric patients. The PPK parameter values for VPA were calculated by using the nonlinear mixed-effects modeling (NONMEM) method, and a one-compartment model with first-order absorption and elimination processes was applied. Covariates included demographic information, concomitant medications and selected gene polymorphisms. Goodness-of-fit (GOF), bootstrap analysis, and visual predictive check (VPC) were used for model evaluation. In addition, we used Monte Carlo simulations to propose dose recommendations for different subgroup patients. Results: A significant effect of the patient age and ABCB1 genotypes was observed on the VPA oral clearance (CL/F) in the final PPK model. Compared with patients with the ABCB1 rs3789243 AA genotype, CL/F in patients with GG and AG genotypes was increased by 8% and reduced by 4.7%, respectively. The GOF plots indicated the satisfactory predictive performance of the final model, and the evaluation by bootstrap and VPC showed that a stable model had been developed. A table of individualized dosing regimens involving age and ABCB1 genotype was constructed based on the final PPK model. Conclusion: This study quantitatively investigated the effects of patient age and ABCB1 rs3789243 variants on the pharmacokinetic variability of VPA. The PPK models could be beneficial to individual dose optimization in epileptic children on VPA therapy.

Probiotics and prebiotics alleviate behavioral deficits, inflammatory response, and gut dysbiosis in prenatal VPA-induced rodent model of autism

Autism spectrum disorders are neuropsychiatric conditions characterized by social interaction and communication disorders and repetitive stereotypical behaviors. These disorders are also accompanied by an inflammatory status. Bidirectional communication between microbiome, gut, and brain has been discovered as a major mechanism influencing core symptoms and biomarkers of autism. Therefore, the modulation of the gut microbiota in autism has recently attracted interest. In this study, probiotic- and prebiotic-mediated modulation of the gut microbiota was compared in terms of different symptoms and findings in an experimental autism model. Valproic acid (VPA) (500 mg/kg) was administered to Wistar rats (on prenatal day 12.5) to induce autistic-like behaviors. Based on the supply of probiotics and prebiotics, animals were grouped as control (saline), autistic-like (prenatal VPA), probiotic (prenatal VPA + 22.5 × 10⁹ cfu/day probiotic), prebiotic (prenatal VPA + 100 mg/day prebiotic), and combined treatment (prenatal VPA + 22.5 × 10⁹ cfu/day probiotic + 100 mg/day prebiotic). After the treatment process, behavioral tests (social behaviors, anxiety, stereotypical behavior, sensorimotor gating, and behavioral despair) and biochemical analyses (serum and brain tissue) were conducted, and the quantities of some phyla and genera were determined in stool samples. Significant positive effects of probiotic and combined treatments were observed on the sociability, social interaction, and anxiety parameters. In addition, all three treatments had positive effects on stereotypical behavior. However, the treatments did not affect sensorimotor gating deficits and behavioral despair. Further, probiotic treatment reversed the VPA-induced increase and decrease in serum IL-6 and IL-10 levels, respectively. Combined treatment also significantly increased the IL-10 levels. Prenatal VPA exposure decreased 5-hydroxytryptamine (5-HT) levels in the prefrontal cortex of the brain; however, combined treatment reversed this decrease. Prenatal VPA exposure also caused a decrease in Bacteroidetes/Firmicutes ratio in the gut microbiota, while the probiotic treatment significantly increased this ratio. These findings indicate that probiotic- and prebiotic-mediated microbial modulation may represent a new therapeutic approach to alleviate autistic-like symptoms.

Valproic Acid Overdose: Case Report and Literature Review

BACKGROUND

Valproic acid (VPA) is a common antiepileptic drug that is also used routinely for various psychiatric disorders. VPA toxicity typically manifests as central nervous system depression, while hyperammonemic encephalopathy and hepatotoxicity are potentially life-threatening complications.

CASE REPORT

We describe the case of a 56-year-old man who presented to the emergency department after an intentional VPA overdose, was found to have hyperammonemia, and was treated with L-carnitine exclusively. He was subsequently admitted to the hospital for monitoring and serial laboratory testing. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Although VPA toxicity has conventionally been managed by gastric decontamination, L-carnitine, and, in severe and refractory cases, extracorporeal removal, recent literature supports the use of carbapenem antibiotics, particularly meropenem. Thus, we report the details of current treatment modalities for VPA toxicity by reviewing current literature.

Thyroid hormones regulate reelin expression in neuropsychiatric disorders

The incidence and prevalence of hypothyroidism in pregnancy have increased over the past two decades, leading to the occurrence of neuropsychiatric disorders. However, the underlying mechanisms of thyroid hormone (TH)-regulated gene expression and neuropsychiatric development during the postnatal period remain unknown. Recent achievements have shown that reelin, a large extracellular glycoprotein, plays a crucial role in neuronal migration and localization during the development of neocortex and cerebellar cortex, thereby participating in the development of neuropsychiatric diseases. Reelin-induced neuronal migration requires triiodothyronine (T3) from the deiodination of thyroxine (T4) by fetal brain deiodinases. Previous studies have reported decreased reelin levels and abnormal gene expression, which are the same as the pathological alternations in reelin-induced neuropsychiatric disorders including schizophrenia and autism. Low T3 in the fetal brain due to hypothyroxinemia during pregnancy may be detrimental to neuronal migration, leading to neuropsychiatric disorders. In this review, we focus on the reelin expression between hypothyroidism and neuropsychiatric disorders.

Low-intensity exercise combined with sodium valproate attenuates kainic acid-induced seizures and associated co-morbidities by inhibiting NF-κB signaling in mice

Sodium valproate (VPA) is a broad-spectrum anticonvulsant that is effective both in adults and children suffering from epilepsy, but it causes psychiatric and behavioral side effects in patients with epilepsy. In addition, 30% of patients with epilepsy develop resistance to VPA. At present, regular physical exercise has shown many benefits and has become an effective complementary therapy for various brain diseases, including epilepsy. Therefore, we wondered whether VPA combined with exercise would be more effective in the treatment of seizures and associated co-morbidities. Here, we used a mouse model with kainic acid (KA)-induced epilepsy to compare the seizure status and the levels of related co-morbidities, such as cognition, depression, anxiety, and movement disorders, in each group using animal behavioral experiment and local field potential recordings. Subsequently, we investigated the mechanism behind this phenomenon by immunological means. Our results showed that low-intensity exercise combined with VPA reduced seizures and associated co-morbidities. This phenomenon seems to be related to the Toll-like receptor 4, activation of the nuclear factor kappa B (NF-κB), and release of interleukin 1β (IL-1β), tumor necrosis factor α (TNF-α), and IL-6. In brief, low-intensity exercise combined with VPA enhanced the downregulation of NF-κB-related inflammatory response, thereby alleviating the seizures, and associated co-morbidities.

Effectiveness of Antiseizure Medication Duotherapies in Patients With Glioma: A Multicenter Observational Cohort Study

BACKGROUND AND OBJECTIVES

About 30% of patients with glioma need an add-on antiseizure medication (ASM) due to uncontrolled seizures on ASM monotherapy. This study aimed to determine whether levetiracetam combined with valproic acid (LEV + VPA), a commonly prescribed duotherapy, is more effective than other duotherapy combinations including either LEV or VPA in patients with glioma.

METHODS

In this multicenter retrospective observational cohort study, treatment failure (i.e., replacement by, addition of, or withdrawal of an ASM) for any reason was the primary outcome. Secondary outcomes included (1) treatment failure due to uncontrolled seizures and (2) treatment failure due to adverse effects. Time to treatment failure was estimated from the moment of ASM duotherapy initiation. Multivariable cause-specific Cox proportional hazard models were estimated to study the association between risk factors and treatment failure. The maximum duration of follow-up was 36 months.

RESULTS

A total of 1,435 patients were treated with first-line monotherapy LEV or VPA, of which 355 patients received ASM duotherapy after they had treatment failure due to uncontrolled seizures on monotherapy. LEV + VPA was prescribed in 66% (236/355) and other ASM duotherapy combinations including LEV or VPA in 34% (119/355) of patients. Patients using other duotherapy vs LEV + VPA had a higher risk of treatment failure for any reason (cause-specific adjusted hazard ratio [aHR] 1.50 [95% CI 1.07-2.12], p = 0.020), due to uncontrolled seizures (cause-specific aHR 1.73 [95% CI 1.10-2.73], p = 0.018), but not due to adverse effects (cause-specific aHR 0.88 [95% CI 0.47-1.67], p = 0.703).

DISCUSSION

This observational cohort study suggests that LEV + VPA has better efficacy than other ASM combinations. Similar toxicities were experienced in the 2 groups.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that for patients with glioma with uncontrolled seizures on ASM monotherapy, LEV + VPA has better efficacy than other ASM combinations.

Seratrodast, a thromboxane A2 receptor antagonist, inhibits neuronal ferroptosis by promoting GPX4 expression and suppressing JNK phosphorylation

More than 30 % of individuals with epilepsy are refractory to currently available drugs, highlighting the urgent need to develop novel candidate drugs. Accumulating evidence implicates the key role of ferroptosis in the pathophysiology of epileptic seizuresand its potential as a new drug target. Drug repurposing is a promising strategy for the rapid generation of new candidate drugs from the market drugs with new therapeutic indications, such as the best-selling drug thalidomide. Herein, we reported the discovery of Seratrodast, a market drug of thromboxane A2 receptor antagonist as a new ferroptosis inhibitor (IC₅₀: 4.5 μmol·L^-1). Seratrodast could reduce lipid ROS production, regulate the system x_c^-/glutathione (GSH)/glutathione peroxidase 4 (GPX4) axis, and inhibit JNK phosphorylation and p53 expression. In addition, Seratrodast elevated GPX4 expression and decreased JNK phosphorylation in pentylenetetrazole-induced seizures in mice. Seratrodast increased the latency of seizures and reduced seizure duration in pentylenetetrazole-induced seizures. Our results suggest Seratrodast might be either a ferroptosis inhibitor or a novel lead compound for further optimization of novel drug discovery.

Clinical Pharmacokinetic Monitoring of Free Valproic Acid Levels: A Systematic Review

BACKGROUND

Current guidelines recommend therapeutic drug monitoring as a critical component of valproic acid (VPA) therapy. Due to high protein binding, the active unbound (free) portion of VPA can be misrepresented by total VPA serum levels in certain clinical scenarios. Monitoring free VPA serum levels may be warranted when assessing the clinical response to VPA therapy.

OBJECTIVES

The aims were to conduct a systematic review to identify a therapeutic range for free VPA serum levels; to explore the correlation of free VPA serum levels with clinical toxicity and therapeutic benefit; and to examine predictors of discordance between free and total VPA levels.

METHODS

Medline, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), PsycINFO, BIOSIS Previews, and Cumulative Index to Nursing and Allied Health Literature (CINAHL) were searched from the time of database inception to June 20, 2021. Randomized controlled trials and observational studies that evaluated any patient receiving VPA with free VPA level monitoring were included.

RESULTS

Of 189 citations, we identified 27 relevant studies, which included 14 observational studies, two case series, and 11 case reports. Three studies provided a therapeutic range for free VPA levels between 20 and 410 μmol/L. Two studies suggested the occurrence of hyperammonemia and thrombocytopenia at free VPA serum levels above 60 µmol/L and 103.3 µmol/L, respectively. Two studies suggested an upper limit for neurotoxicity at free VPA serum levels of 70 µmol/L and 207.9 µmol/L. Hypoalbuminemia was identified as a predictor of therapeutic discordance.

CONCLUSIONS

This review demonstrates a paucity of data informing the clinical utility of free VPA serum levels. Further high-quality trials are needed to validate an optimal therapeutic range for free VPA levels.

A Double-Blind Placebo-Controlled, Randomized Trial of Divalproex Sodium for Posttraumatic Irritability Greater Than 1 Year After Mild to Moderate Traumatic Brain Injury

OBJECTIVE

Posttraumatic irritability after traumatic brain injury (TBI) may become a chronic problem and contribute to impaired everyday function, either alone or in combination with alcohol use disorder. The authors hypothesized that divalproex sodium (VPA) would improve posttraumatic irritability and result in lessened alcohol use.

METHODS

This randomized, placebo-controlled double-blind clinical trial recruited participants with an index TBI occurring 1 or more years prior to enrollment, a history of alcohol use disorder, and posttraumatic irritability corroborated by a knowledgeable informant. An 8-item subset of the Agitated Behavior Scale served as the primary outcome measure of VPA efficacy. Doses of VPA were titrated to standard serum concentrations of 50 µg/ml to 100 µg/ml.

RESULTS

Forty-eight persons completed this clinical trial (VPA, N=22; placebo, N=26). At baseline, participants rated their posttraumatic irritability as less severe than did their informants (p<0.05). During the trial, informants reported significant and sustained reduction of posttraumatic irritability (p=0.03) in the study participants. Biweekly averages during drug exposure confirmed this (p<0.03, Cohen's d=0.44). Treatment efficacy was not related to measures of anxiety, posttraumatic stress disorder, sedation, or veteran versus nonveteran status. Alcohol use did not change as a result of treatment. There were no serious adverse events.

CONCLUSIONS

This study demonstrated an effect of VPA on posttraumatic irritability, and VPA was well tolerated. Further definition of treatment efficacy and safety requires a large-scale multisite trial, using a randomized, double-blind placebo-controlled design.

Emerging Promise of Phytochemicals in Ameliorating Neurological Disorders

BACKGROUND

The field of medicine and synthetic drug development have advanced rapidly over the past few decades. However, research on alternative medicine such as phytochemicals cannot be ignored. The main reason for prominent curiosity about phytochemicals stems from the belief that usage of natural compounds is safer and has lesser detrimental side effects.

OBJECTIVE

The aim of the present review was to discuss in detail with several phytochemicals that have been studied or are being studied in the context of various neurological disorders including depression, Alzheimer's disease, Huntington's disease and even neuroinflammatory disorders such as encephalitis.

METHODS

The potential role of phytochemicals in the treatment or management of symptoms associated with neurological disorders have been included in this article. All data included in this paper has been pooled from various databases including Google Scholar, PubMed, Science Direct, Springer and Wiley Online Library.

RESULTS

Phytochemicals have been widely studied for their therapeutic properties associated with neurological disorders. Using various experimental techniques for both in vivo and in vitro experiments, studies have shown that phytochemicals do have antioxidant, anti-inflammatory and neuroprotective activities which play major roles in the treatment of neurological diseases.

CONCLUSION

Even though there has been compelling evidence of the therapeutic role of phytochemicals, further research is still required to evaluate the safety and efficacy of these medicines. Using previously published papers as foundation for additional research such as preclinical studies and clinical trials, phytochemicals can become a safer alternative to synthetic drugs for treating a spectrum of neurological diseases.

Transcriptome meta-analysis of valproic acid exposure in human embryonic stem cells

Valproic acid (VPA) is a widely used antiepileptic drug not recommended in pregnancy because it is teratogenic. Many assays have assessed the impact of the VPA exposure on the transcriptome of human embryonic stem-cells (hESC), but the molecular perturbations that VPA exerts in neurodevelopment are not completely understood. This study aimed to perform a transcriptome meta-analysis of VPA-exposed hESC to elucidate the main biological mechanisms altered by VPA effects on the gene expression. Publicly available microarray and RNA-seq transcriptomes were selected in the Gene Expression Omnibus (GEO) repository. Samples were processed according to the standard pipelines for each technology in the Galaxy server and R. Meta-analysis was performed using the Fisher-P method. Overrepresented genes were obtained by evaluating ontologies, pathways, and phenotypes' databases. The meta-analysis performed in seven datasets resulted in 61 perturbed genes, 54 upregulated. Ontology and pathway enrichments suggested neurodevelopment and neuroinflammatory effects; phenotype overrepresentation included epilepsy-related genes, such as SCN1A and GABRB2. The NDNF gene upregulation was also identified; this gene is involved in neuron migration and survival during development. Sub-network analysis proposed TGFβ and BMP pathways activation. These results suggest VPA exerts effects in epilepsy-related genes even in embryonic cells. Neurodevelopmental genes, such as NDNF were upregulated and VPA might also disturb several development pathways. These mechanisms might help to explain the spectrum of VPA-induced congenital anomalies and the molecular effects on neurodevelopment.

Dogs as a Natural Animal Model of Epilepsy

Epilepsy is a common neurological disease in both humans and domestic dogs, making dogs an ideal translational model of epilepsy. In both species, epilepsy is a complex brain disease characterized by an enduring predisposition to generate spontaneous recurrent epileptic seizures. Furthermore, as in humans, status epilepticus is one of the more common neurological emergencies in dogs with epilepsy. In both species, epilepsy is not a single disease but a group of disorders characterized by a broad array of clinical signs, age of onset, and underlying causes. Brain imaging suggests that the limbic system, including the hippocampus and cingulate gyrus, is often affected in canine epilepsy, which could explain the high incidence of comorbid behavioral problems such as anxiety and cognitive alterations. Resistance to antiseizure medications is a significant problem in both canine and human epilepsy, so dogs can be used to study mechanisms of drug resistance and develop novel therapeutic strategies to benefit both species. Importantly, dogs are large enough to accommodate intracranial EEG and responsive neurostimulation devices designed for humans. Studies in epileptic dogs with such devices have reported ictal and interictal events that are remarkably similar to those occurring in human epilepsy. Continuous (24/7) EEG recordings in a select group of epileptic dogs for >1 year have provided a rich dataset of unprecedented length for studying seizure periodicities and developing new methods for seizure forecasting. The data presented in this review substantiate that canine epilepsy is an excellent translational model for several facets of epilepsy research. Furthermore, several techniques of inducing seizures in laboratory dogs are discussed as related to therapeutic advances. Importantly, the development of vagus nerve stimulation as a novel therapy for drug-resistant epilepsy in people was based on a series of studies in dogs with induced seizures. Dogs with naturally occurring or induced seizures provide excellent large-animal models to bridge the translational gap between rodents and humans in the development of novel therapies. Furthermore, because the dog is not only a preclinical species for human medicine but also a potential patient and pet, research on this species serves both veterinary and human medicine.

Valproic acid modulates collagen architecture in the postoperative conjunctival scar

Valproic acid (VPA), widely used for the treatment of neurological disorders, has anti-fibrotic activity by reducing collagen production in the postoperative conjunctiva. In this study, we investigated the capacity of VPA to modulate the postoperative collagen architecture. Histochemical examination revealed that VPA treatment was associated with the formation of thinner collagen fibers in the postoperative days 7 and 14 scars. At the micrometer scale, measurements by quantitative multiphoton microscopy indicated that VPA reduced mean collagen fiber thickness by 1.25-fold. At the nanometer scale, collagen fibril thickness and diameter measured by transmission electron microscopy were decreased by 1.08- and 1.20-fold, respectively. Moreover, delicate filamentous structures in random aggregates or closely associated with collagen fibrils were frequently observed in VPA-treated tissue. At the molecular level, VPA reduced Col1a1 but induced Matn2, Matn3, and Matn4 in the postoperative day 7 conjunctival tissue. Elevation of matrilin protein expression induced by VPA was sustained till at least postoperative day 14. In primary conjunctival fibroblasts, Matn2 expression was resistant to both VPA and TGF-β2, Matn3 was sensitive to both VPA and TGF-β2 individually and synergistically, while Matn4 was modulable by VPA but not TGF-β2. MATN2, MATN3, and MATN4 localized in close association with COL1A1 in the postoperative conjunctiva. These data indicate that VPA has the capacity to reduce collagen fiber thickness and potentially collagen assembly, in association with matrilin upregulation. These properties suggest potential VPA application for the prevention of fibrotic progression in the postoperative conjunctiva. KEY MESSAGES: VPA reduces collagen fiber and fibril thickness in the postoperative scar. VPA disrupts collagen fiber assembly in conjunctival wound healing. VPA induces MATN2, MATN3, and MATN4 in the postoperative scar.

Pharmacological activation of ATF6 remodels the proteostasis network to rescue pathogenic GABAA receptors

BACKGROUND

Genetic variants in the subunits of the gamma-aminobutyric acid type A (GABAA) receptors are implicated in the onset of multiple pathologic conditions including genetic epilepsy. Previous work showed that pathogenic GABAA subunits promote misfolding and inefficient assembly of the GABAA receptors, limiting receptor expression and activity at the plasma membrane. However, GABAA receptors containing variant subunits can retain activity, indicating that enhancing the folding, assembly, and trafficking of these variant receptors offers a potential opportunity to mitigate pathology associated with genetic epilepsy.

RESULTS

Here, we demonstrate that pharmacologically enhancing endoplasmic reticulum (ER) proteostasis using small molecule activators of the ATF6 (Activating Transcription Factor 6) signaling arm of the unfolded protein response (UPR) increases the assembly, trafficking, and surface expression of variant GABAA receptors. These improvements are attributed to ATF6-dependent remodeling of the ER proteostasis environment, which increases protein levels of pro-folding ER proteostasis factors including the ER chaperone BiP (Immunoglobulin Binding Protein) and trafficking receptors, such as LMAN1 (Lectin Mannose-Binding 1) and enhances their interactions with GABAA receptors. Importantly, we further show that pharmacologic ATF6 activators increase the activity of GABAA receptors at the cell surface, revealing the potential for this strategy to restore receptor activity to levels that could mitigate disease pathogenesis.

CONCLUSIONS

These results indicate that pharmacologic ATF6 activators offer an opportunity to restore GABAA receptor activity in diseases including genetic epilepsy and point to the potential for similar pharmacologic enhancement of ER proteostasis to improve trafficking of other disease-associated variant ion channels implicated in etiologically-diverse diseases.

Influence of Umbelliferone on the Anticonvulsant and Neuroprotective Activity of Selected Antiepileptic Drugs: An In Vivo and In Vitro Study

Umbelliferone (7-hydroxycoumarin; UMB) is a coumarin with many biological properties, including antiepileptic activity. This study evaluated the effect of UMB on the ability of classical and novel antiepileptic drugs (e.g., lacosamide (LCM), levetiracetam (LEV), phenobarbital (PB) and valproate (VPA)) to prevent seizures evoked by the 6-Hz corneal-stimulation-induced seizure model. The study also evaluated the influence of this coumarin on the neuroprotective properties of these drugs in two in vitro models of neurodegeneration, including trophic stress and excitotoxicity. The results indicate that UMB (100 mg/kg, i.p.) significantly enhanced the anticonvulsant action of PB (p < 0.01) and VPA (p < 0.05), but not that of LCM orLEV, in the 6-Hz test. Whether alone or in combination with other anticonvulsant drugs (at their ED50 values from the 6-Hz test), UMB (100 mg/kg) did not affect motor coordination; skeletal muscular strength and long-term memory, as determined in the chimney; grip strength; or passive avoidance tests, respectively. Pharmacokinetic characterization revealed that UMB had no impact on total brain concentrations of PB or VPA in mice. The in vitro study indicated that UMB has neuroprotective properties. Administration of UMB (1 µg/mL), together with antiepileptic drugs, mitigated their negative impact on neuronal viability. Under trophic stress (serum deprivation) conditions, UMB enhanced the neurotrophic abilities of all the drugs used. Moreover, this coumarin statistically enhanced the neuroprotective effects of PB (p < 0.05) and VPA (p < 0.001) in the excitotoxicity model of neurodegeneration. The obtained results clearly indicate a positive effect of UMB on the anticonvulsant and neuroprotective properties of the selected drugs.

DFT analysis of valproic acid adsorption onto Al12/B12-N12/P12 nanocages with solvent effects

Using density functional theory, the adsorption of valproic acid onto the surface of fullerene-like nanocages was investigated. Valproic acid interacts with the nanocages through the carboxylic group with energies of - 144.14, - 109.71, - 105.22, and - 84.96 kcal/mol. The frontier molecular orbital (FMO) energy levels were considerably altered upon adsorption, resulting in a reduction in energy gap and increase in electrical conductivity. This suggests that nanocages could be used as sensors as well as options for drug administration in biological systems. Solvation effects in water are also reported.

Valproic acid decreases vascular smooth muscle cell proliferation via protein phosphatase 2A-mediated p70 S6 kinase inhibition

Valproic acid (VPA) has been used to treat epilepsy and bipolar disorder. Although the abnormal proliferation of vascular smooth muscle cells (VSMCs) is a well-established contributor to the development of various vascular diseases including atherosclerosis, the effect of VPA on VSMC proliferation and its mechanism of action have not been fully revealed. Herein, we investigated the molecular mechanism by which VPA inhibits rat VSMC proliferation. VPA dose-dependently decreased VSMC proliferation, which was accompanied by the dose-dependent decrease in phosphorylation of p70 S6 kinase (p70S6K) at Thr389 (p-p70S6K-Thr³⁸⁹), and overexpression of the p70S6K-T389E mutant gene significantly reversed VPA-inhibited VSMC proliferation. Co-treatment with okadaic acid, a specific protein phosphatase 2A (PP2A) inhibitor, significantly restored p-p70S6K-Thr³⁸⁹. Furthermore, knockdown of PP2Ac gene expression by siRNA significantly reversed VPA-inhibited p-p70S6K-Thr³⁸⁹ and VSMC proliferation. Confocal microscopic analyses and co-immunoprecipitation results clearly showed that the physical binding of p70S6K and PP2Ac was promoted by VPA. Valpromide, a VPA's structural derivative with no histone deacetylase (HDAC) inhibition activity, as well as VPA and sodium butyrate, an HDAC inhibitor similar to VPA, decreased VSMC proliferation and p-p70S6K-Thr³⁸⁹, indicating that HDAC is not involved in VPA-inhibited VSMC proliferation. Finally, the inhibitory effects of VPA on p-p70S6K-Thr³⁸⁹ and VSMC proliferation were reiterated in a platelet-derived growth factor (PDGF)-induced in vitro atherosclerosis model. In conclusion, our results demonstrate that VPA decreased cell proliferation via PP2A-mediated inhibition of p-p70S6K-Thr³⁸⁹ in basal and PDGF-stimulated VSMCs. The results suggest that VPA could be used in the treatment and prevention of atherosclerosis and in-stent restenosis.