Classical neurotransmitters and neuropeptides involved in generalized epilepsy in a multi-neurotransmitter system: How to improve the antiepileptic effect?

Brain activation and connection across resting and motor-task states in patients with generalized tonic-clonic seizures

AIMS

Motor abnormalities have been identified as one common symptom in patients with generalized tonic-clonic seizures (GTCS) inspiring us to explore the disease in a motor execution condition, which might provide novel insight into the pathomechanism.

METHODS

Resting-state and motor-task fMRI data were collected from 50 patients with GTCS, including 18 patients newly diagnosed without antiepileptic drugs (ND_GTCS) and 32 patients receiving antiepileptic drugs (AEDs_GTCS). Motor activation and its association with head motion and cerebral gradients were assessed. Whole-brain network connectivity across resting and motor states was further calculated and compared between groups.

RESULTS

All patients showed over-activation in the postcentral gyrus and the ND_GTCS showed decreased activation in putamen. Specifically, activation maps of ND_GTCS showed an abnormal correlation with head motion and cerebral gradient. Moreover, we detected altered functional network connectivity in patients within states and across resting and motor states by using repeated-measures analysis of variance. Patients did not show abnormal connectivity in the resting state, while distributed abnormal connectivity in the motor-task state. Decreased across-state network connectivity was also found in all patients.

CONCLUSION

Convergent findings suggested the over-response of activation and connection of the brain to motor execution in GTCS, providing new clues to uncover motor susceptibility underlying the disease.

Epilepsy is more than a simple seizure disorder: Causal relationships between epilepsy and its comorbidities

This review draws connections between the pathogenesis of canine epilepsy and its most commonly recognised comorbidities: cognitive impairment (CI), attention deficit hyperactivity disorder (ADHD)-like behaviour, fear and anxiety. Uni/bidirectional causalities and the possibility of a common aetiology triggering both epilepsy and the associated diseases are considered. Research on this topic is sparse in dogs, so information has been gathered and assessed from human and laboratory animal studies. Anatomical structures, functional connections, disrupted neurotransmission and neuroinflammatory processes collectively serve as a common foundation for epilepsy and its comorbidities. Specific anatomical structures, especially parts of the limbic system, such as the amygdala and the hippocampus, are involved in generating seizures, as well as cognitive- and behavioural disorders. Furthermore, disturbances in inhibitory and excitatory neurotransmission influence neuronal excitability and networks, leading to underlying brain dysfunction. Functional magnetic resonance imaging (fMRI), interictal epileptiform discharges (IEDs), and electroencephalography (EEG) have demonstrated functional brain connections that are related to the emergence of both epilepsy and its various comorbidities. Neuroinflammatory processes can either cause or be a consequence of seizures, and inflammatory mediators, oxidative stress and mitochondrial dysfunction, can equally evoke mood disorders. The extensive relationships contributing to the development and progression of seizures and comorbid cognitive and behavioural conditions illustrate the complexity of the disease that is epilepsy.

Delving into the significance of the His289Tyr single-nucleotide polymorphism in the glutamate ionotropic receptor kainate-1 (Grik1) gene of a genetically audiogenic seizure model

Genetic abnormalities affecting glutamate receptors are central to excitatory overload-driven neuronal mechanisms that culminate in seizures, making them pivotal targets in epilepsy research. Increasingly used to advance this field, the genetically audiogenic seizure hamster from Salamanca (GASH/Sal) exhibits generalized seizures triggered by high-intensity acoustic stimulation and harbors significant genetic variants recently identified through whole-exome sequencing. Here, we addressed the influence of the missense single-nucleotide polymorphism (C9586732T, p.His289Tyr) in the glutamate receptor ionotropic kainate-1 (Grik1) gene and its implications for the GASH/Sal seizure susceptibility. Using a protein 3D structure prediction, we showed a potential effect of this sequence variation, located in the amino-terminal domain, on the stability and/or conformation of the kainate receptor subunit-1 protein (GluK1). We further employed a multi-technique approach, encompassing gene expression analysis (RT-qPCR), Western blotting, and immunohistochemistry in bright-field and confocal fluorescence microscopy, to investigate critical seizure-associated brain regions in GASH/Sal animals under seizure-free conditions compared to matched wild-type controls. We detected disruptions in the transcriptional profile of the Grik1 gene within the audiogenic seizure-associated neuronal network. Alterations in GluK1 protein levels were also observed in various brain structures, accompanied by an unexpected lower molecular weight band in the inferior and superior colliculi. This correlated with substantial disparities in GluK1-immunolabeling distribution across multiple brain regions, including the cerebellum, hippocampus, subdivisions of the inferior and superior colliculi, and the prefrontal cortex. Notably, the diffuse immunolabeling accumulated within perikarya, axonal fibers and terminals, exhibiting a prominent concentration in proximity to the cell nucleus. This suggests potential disturbances in the GluK1-trafficking mechanism, which could subsequently affect glutamate synaptic transmission. Overall, our study sheds light on the genetic underpinnings of seizures and underscores the importance of investigating the molecular mechanisms behind synaptic dysfunction in epileptic neural networks, laying a crucial foundation for future research and therapeutic strategies targeting GluK1-containing kainate receptors.

The role of molecular chaperones in the mechanisms of epileptogenesis

Epilepsy is a group of neurological diseases which requires significant economic costs for the treatment and care of patients. The central point of epileptogenesis stems from the failure of synaptic signal transmission mechanisms, leading to excessive synchronous excitation of neurons and characteristic epileptic electroencephalogram activity, in typical cases being manifested as seizures and loss of consciousness. The causes of epilepsy are extremely diverse, which is one of the reasons for the complexity of selecting a treatment regimen for each individual case and the high frequency of pharmacoresistant cases. Therefore, the search for new drugs and methods of epilepsy treatment requires an advanced study of the molecular mechanisms of epileptogenesis. In this regard, the investigation of molecular chaperones as potential mediators of epileptogenesis seems promising because the chaperones are involved in the processing and regulation of the activity of many key proteins directly responsible for the generation of abnormal neuronal excitation in epilepsy. In this review, we try to systematize current data on the role of molecular chaperones in epileptogenesis and discuss the prospects for the use of chemical modulators of various chaperone groups' activity as promising antiepileptic drugs.

Microbiota-gut-brain axis and ketogenic diet: how close are we to tackling epilepsy?

The microbiota-gut-brain axis refers to the intricate bidirectional communication between commensal microorganisms residing in the digestive tract and the central nervous system, along neuroendocrine, metabolic, immune, and inflammatory pathways. This axis has been suggested to play a role in several neurological disorders, such as Parkinson's disease, Alzheimer's disease, multiple sclerosis, and epilepsy, paving the way for microbiome-based intervention strategies for the mitigation and treatment of symptoms. Epilepsy is a multifaceted neurological condition affecting more than 50 million individuals worldwide, 30% of whom do not respond to conventional pharmacological therapies. Among the first-hand microbiota modulation strategies, nutritional interventions represent an easily applicable option in both clinical and home settings. In this narrative review, we summarize the mechanisms underlying the microbiota-gut-brain axis involvement in epilepsy, discuss the impact of antiepileptic drugs on the gut microbiome, and then the impact of a particular dietary pattern, the ketogenic diet, on the microbiota-gut-brain axis in epileptic patients. The investigation of the microbiota response to non-pharmacological therapies is an ever-expanding field with the potential to allow the design of increasingly accessible and successful intervention strategies.

Supplementation of n-3 PUFAs in Adulthood Attenuated Susceptibility to Pentylenetetrazol Induced Epilepsy in Mice Fed with n-3 PUFAs Deficient Diet in Early Life

The growth and development of the fetus and newborn throughout pregnancy and lactation are directly related to the nutritional status of the mother, which has a significant impact on the health of the offspring. The purpose of this experiment was to investigate the susceptibility of n-3 polyunsaturated fatty acid deficiency in early life to seizures in adulthood. The n-3 PUFAs-deficient mice's offspring were established and then fed with α-LNA diet, DHA-enriched ethyl ester, and DHA-enriched phospholipid-containing diets for 17 days at the age of eight weeks. During this period, animals received intraperitoneal injections of 35 mg/kg of pentylenetetrazol (PTZ) every other day for eight days. The results showed that dietary n-3 PUFA-deficiency in early life could aggravate PTZ-induced epileptic seizures and brain disorders. Notably, nutritional supplementation with n-3 PUFAs in adulthood for 17 days could significantly recover the brain n-3 fatty acid and alleviate the epilepsy susceptibility as well as raise seizure threshold to different levels by mediating the neurotransmitter disturbance and mitochondria-dependent apoptosis, demyelination, and neuroinflammation status of the hippocampus. DHA-enriched phospholipid possessed a superior effect on alleviating the seizure compared to α-LNA and DHA-enriched ethyl ester. Dietary n-3 PUFA deficiency in early life increases the susceptibility to PTZ-induced epilepsy in adult offspring, and nutritional supplementation with n-3 PUFAs enhances the tolerance to the epileptic seizure.

Anticonvulsant Activity of trans-Anethole in Mice

Epilepsy is a chronic neurological disorder affecting 1-2% of world population, and one-third of patients are refractory to pharmacological treatment. This fact has stimulated research for new antiepileptic drugs and natural products have been an important source. trans-Anethole (TAN) is a phenylpropanoid, component of some essential oils, extracted from plants, and its effects have been little studied. Therefore, this study is aimed at investigating the TAN effect in classic seizure models and evaluate the electroencephalographic (EEG) profile of animals treated with this substance. For this, Swiss male mice (Mus musculus) were used, and the lethal dose was evaluated and subsequently submitted to the test maximal electroshock (MES), the pentylenetetrazole- (PTZ) induced seizure test, and the EEG profile. Initially, the LD50 for TAN was estimated in 1000 mg/kg (i.p.) dose and there was no sign of acute toxicity or death. In the MES test, TAN 300, i.p. (12.00 ± 2.9 s) and 400 mg/kg, i.p. (9.00 ± 4.4 s) doses was able to decrease tonic seizures duration induced by electric discharge (0.5 mA, 150 pulses/s, for 0.5 s). In the PTZ test (75 mg/kg, i.p.), TAN 400 mg/kg, i.p. increased the latency to myoclonic jerks (80.0 (56.0-134.0)), the latency totonic-clonic seizures (900.0 (861.0-900.0) and decrease seizure duration (0.0 (0.0-10.0)). No deaths were found in this groups compared to vehicle. EEG analysis showed an amplitude decrease of waves (ratio of baseline) in TAN 300 (1.82 ± 0.23) and 400 mg/kg (1.06 ± 0.16) groups. In this way, TAN at 400 mg/kg was able to inhibit and/or attenuate seizures by increasing the time for the onset of spasms and convulsions, as reducing the duration of seizures. The EEG profile corroborate with this results showing a reduction in the amplitude of waves compared to the PTZ group. Thus, TAN showed an anticonvulsant effect in all experimental models performed, behavioral and electroencephalographic.

SYNGAP1 and Methylenetetrahydrofolate in Cerebrospinal Fluid: Cognitive Development after Oral Folate (5-Methyltetrahydrofolate) Supplementation in a 5-Year-Old Girl

Synaptic Ras GTPase-activating protein 1 (SYNGAP1), also called Ras-GAP 1 or RASA5, is a cerebral protein with a role in brain synaptic function. Its expression affects the development, structure, function, and plasticity of neurons. Mutations in the gene cause a neurodevelopment disorder termed mental retardation-type 5, also called SYNGAP1 syndrome. This syndrome can cause many neurological symptoms including pharmaco-resistant epilepsy, intellectual disability, language delay, and autism spectrum disorder. The syndrome naturally evolves as epileptic encephalopathy with handicap and low intellectual level. A treatment to control epilepsy, limit any decrease in social capacities, and improve intellectual development is really a challenging goal for these patients. The etiologic investigation performed in a 5-year-old girl with early epileptic absence seizures (onset at 6 months) and psychomotor delay (language) revealed a low methylenetetrahydrofolate level in cerebrospinal fluid in a lumbar puncture, confirmed by a second one (35 nmol/L and 50 nmol/L vs. 60–100 nmol/L normal), associated with normal blood and erythrocyte folate levels. Hyperhomocysteinemia, de vivo disease, and other metabolic syndromes were excluded by metabolic analysis. No genetic disorders (like methylenetetrahydrofolate reductase and methenyltetrahydrofolate synthetase) with folate metabolism were found. The physical examination showed only a minor kinetic ataxia. An oral folate (5-methyltetrahydrofolate) supplementation was started with oral vitamin therapy. The child showed good progress in language with this new treatment; epilepsy was well balanced with only one antiepileptic drug. The SYNGAP1 mutation was identified in this patient's genetic analysis. Since the start of folate supplementation/vitamin therapy, the patient's neurologic development has improved. To our knowledge, no association between these two pathologies has been linked and no patient with this SYNGAP1 mutation has ever showed much intellectual progress. Low cerebral methylenetetrahydrofolate levels could be associated with SYNGAP1 mutations. One of the hypotheses is the link of folate metabolism with epigenetic changes including methylation process. One inborn metabolic activity in folate metabolism may be associated with SYNGAP1 disease with epigenetic repercussions. Further studies should assess the link of SYNGAP1 and methyltetrahydrofolate and the evolution of SYNGAP1 patients with oral folate supplementation or vitamin therapy.

Rodent Brain Pathology, Audiogenic Epilepsy

The review presents data which provides evidence for the internal relationship between the stages of rodent audiogenic seizures and post-ictal catalepsy with the general pattern of animal reaction to the dangerous stimuli and/or situation. The wild run stage of audiogenic seizure fit could be regarded as an intense panic reaction, and this view found support in numerous experimental data. The phenomenon of audiogenic epilepsy probably attracted the attention of physiologists as rodents are extremely sensitive to dangerous sound stimuli. The seizure proneness in this group shares common physiological characteristics and depends on animal genotype. This concept could be the new platform for the study of epileptogenesis mechanisms.

Microbiota-Gut-Brain Axis and Epilepsy: A Review on Mechanisms and Potential Therapeutics

The gut-brain axis refers to the bidirectional communication between the gut and brain, and regulates intestinal homeostasis and the central nervous system via neural networks and neuroendocrine, immune, and inflammatory pathways. The development of sequencing technology has evidenced the key regulatory role of the gut microbiota in several neurological disorders, including Parkinson's disease, Alzheimer's disease, and multiple sclerosis. Epilepsy is a complex disease with multiple risk factors that affect more than 50 million people worldwide; nearly 30% of patients with epilepsy cannot be controlled with drugs. Interestingly, patients with inflammatory bowel disease are more susceptible to epilepsy, and a ketogenic diet is an effective treatment for patients with intractable epilepsy. Based on these clinical facts, the role of the microbiome and the gut-brain axis in epilepsy cannot be ignored. In this review, we discuss the relationship between the gut microbiota and epilepsy, summarize the possible pathogenic mechanisms of epilepsy from the perspective of the microbiota gut-brain axis, and discuss novel therapies targeting the gut microbiota. A better understanding of the role of the microbiota in the gut-brain axis, especially the intestinal one, would help investigate the mechanism, diagnosis, prognosis evaluation, and treatment of intractable epilepsy.

CB2R induces a protective response against epileptic seizures through ERK and p38 signaling pathways

BACKGROUND AND PURPOSE

Epilepsy is a pivotal neurological disorder characterized by the synchronous discharging of neurons to induce momentary brain dysfunction. Temporal lobe epilepsy is the most common type of epilepsy, with seizures originating from the mesial temporal lobe. The hippocampus forms part of the mesial temporal lobe and plays a significant role in epileptogenesis; it also has a vital influence on the mental development of children. In this study, we aimed to explore the effects of CB2 receptor (CB2R) activation on ERK and p38 signaling in nerve cells of a rat epilepsy model.

MATERIALS AND METHODS

We treated Sprague-Dawley rats with pilocarpine to induce an epilepsy model and treated such animals with a CB2R agonist (JWH133) alone or with a CB2R antagonist (AM630). Nissl's stain showed the neuron conditon in different groups. Western blot analyzed the level of p-ERK and p-p38.

RESULTS

JWH133 can increase the latent period of first seizure attack and decrease the Grades IV-V magnitude ratio after the termination of SE. Nissl's stain showed JWH133 protected neurons in the hippocampus while AM630 inhibited the functioning of CB2R in neurons. Western blot analysis showed that JWH133 decreased levels of p-ERK and p-p38, which is found at increased levels in the hippocampus of our epilepsy model. In contrast, AM630 inhibited the protective function of JWH133 and also enhanced levels of p-ERK and p-p38.

CONCLUSIONS

CB2R activation can induce neurons proliferation and survival through activation of ERK and p38 signaling pathways.

The Promise of the Zebrafish Model for Parkinson's Disease: Today's Science and Tomorrow's Treatment

The second most prevalent neurodegenerative disorder in the elderly is Parkinson's disease (PD). Its etiology is unclear and there are no available disease-modifying medicines. Therefore, more evidence is required concerning its pathogenesis. The use of the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is the basis of most animal models of PD. MPTP is metabolized by monoamine oxidase B (MAO B) to MPP + and induces the loss of dopaminergic neurons in the substantia nigra in mammals. Zebrafish have been commonly used in developmental biology as a model organism, but owing to its perfect mix of properties, it is now emerging as a model for human diseases. Zebrafish (Danio rerio) are cheap and easy to sustain, evolve rapidly, breed transparent embryos in large amounts, and are readily manipulated by different methods, particularly genetic ones. Furthermore, zebrafish are vertebrate species and mammalian findings obtained from zebrafish may be more applicable than those derived from genetic models of invertebrates such as Drosophila melanogaster and Caenorhabditis elegans. The resemblance cannot be taken for granted, however. The goal of the present review article is to highlight the promise of zebrafish as a PD animal model. As its aminergic structures, MPTP mode of action, and PINK1 roles mimic those of mammalians, zebrafish seems to be a viable model for studying PD. The roles of zebrafish MAO, however, vary from those of the two types of MAO present in mammals. The benefits unique to zebrafish, such as the ability to perform large-scale genetic or drug screens, should be exploited in future experiments utilizing zebrafish PD models.

Antiepileptic effects of long-term intracerebroventricular infusion of angiotensin-(1-7) in an animal model of temporal lobe epilepsy

Temporal lobe epilepsy (TLE) is the most frequent type of epilepsy and is often refractory to pharmacological treatment. In this scenario, extensive research has identified components of the renin-angiotensin system (RAS) as potential therapeutic targets. Therefore, the aim of the present study was to evaluate the effects of long-term treatment with angiotensin-(1-7) [Ang-(1-7)] in male Wistar rats with TLE induced by pilocarpine (PILO). Rats with TLE were submitted to intracerebroventricular (icv) infusion of Ang-(1-7) (200 ng/kg/h) for 28 days, starting at the first spontaneous motor seizure (SMS). Body weight, food intake, and SMS were evaluated daily. Behavioral tests and hippocampal protein levels were also evaluated at the end of the treatment. Ang-(1-7) treatment reduced the frequency of SMS and attenuated low anxiety levels, increased locomotion/exploration, and reduced body weight gain that was induced by TLE. Moreover, Ang-(1-7) positively regulated the hippocampal levels of antioxidant protein catalase and antiapoptotic protein B-cell lymphoma 2 (Bcl-2), as well as mammalian target of rapamycin (mTOR) phosphorylation, which were reduced by TLE. The hippocampal up-regulation of angiotensin type 1 receptor induced by TLE was also attenuated by Ang-(1-7), while the Mas receptor (MasR) was down-regulated compared with epilepsy. These data show that Ang-(1-7) presents an antiepileptic effect, increasing neuroprotection markers and reducing SMS frequency, body weight, and behavior impairments found in TLE. Therefore, Ang-(1-7) is a promising coadjutant therapeutic option for the treatment of TLE.

miR-128 regulates epilepsy sensitivity in mice by suppressing SNAP-25 and SYT1 expression in the hippocampus

Epilepsy is accompanied by abnormal neurotransmission, and microRNAs, as versatile players in the modulation of gene expression, are important in epilepsy pathology. Here, we found that miR-128 expression was elevated in the acute seizure phase and decreased during the recurrent seizure phase after status epilepticus in mice. Both SNAP-25 and SYT1 are regulated by miR-128 in vitro and in vivo. Overexpressing miR-128 in cultured neurons decreased neurotransmitter released by suppressing SNAP-25 and SYT1 expression. Anti-miR-128 injection before kainic acid (KA) injection increased the sensitivity of mice to KA-induced seizures, while overexpressing miR-128 at the latent and recurrent phases had a neuroprotective effect in KA-induced seizures. Our study shows for the first time that miR-128, a key regulator of neurotransmission, plays an important role in epilepsy pathology and that miR-128 might be a potential candidate molecular target for epilepsy therapy.

Behavioral and Molecular Effects Induced by Cannabidiol and Valproate Administration in the GASH/Sal Model of Acute Audiogenic Seizures

Despite evidence that supports cannabidiol (CBD) as an anticonvulsant agent, there remains controversy over the antiseizure efficacy, possible adverse effects, and synergistic interactions with classic antiepileptics such as valproate (VPA). The genetic audiogenic seizure hamster from the University of Salamanca (GASH/Sal) is a reliable experimental model of generalized tonic–clonic seizures in response to intense sound stimulation. The present study examines the behavioral and molecular effects of acute and chronic intraperitoneal administrations of VPA (300 mg/kg) and CBD (100 mg/kg) on the GASH/Sal audiogenic seizures, as well as the coadministration of both drugs. The GASH/Sal animals were examined prior to and after the corresponding treatment at 45 min, 7 days, and 14 days for seizure severity and neuroethology, open-field behaviors, body weight variations, and various hematological and biochemical parameters. Furthermore, the brain tissue containing the inferior colliculus (so-called epileptogenic nucleus) was processed for reverse transcription–quantitative polymerase chain reaction analysis to determine the treatment effects on the gene expression of neuronal receptors associated with drug actions and ictogenesis. Our results indicated that single dose of VPA helps prevent the animals from getting convulsions, showing complete elimination of seizures, whereas 7 days of chronic VPA treatment had few effects in seizure behaviors. Acute CBD administration showed subtle attenuation of seizure behaviors, increasing seizure latency and decreasing the duration of the convulsion phase, but without entirely seizure abolition. Chronic CBD treatments had no significant effects on sound-induced seizures, although some animals slightly improved seizure severity. Acute and chronic CBD treatments have no significant adverse effects on body weight, hematological parameters, and liver function, although locomotor activity was reduced. The combination of VPA and CBD did not alter the therapeutic outcome of the VPA monotherapy, showing no apparent synergistic effects. As compared to sham animals, chronic treatments with CBD caused abnormal mRNA expression levels for Trpv1, Adora1, Slc29a1, and Cnr1 genes, whereas no differences in gene expression were found for Htr1a and Sigmar1. Our study shed light on the behavioral and molecular effects of CBD and VPA on the GASH/Sal model and constituted the basis to develop further studies on the pharmacological effects of CBD and its interactions with other anticonvulsants.

Epilepsy in inherited neurotransmitter disorders: Spotlights on pathophysiology and clinical management

Inborn errors of neurotransmitter metabolism are ultrarare disorders affecting neurotransmitter biosynthesis, breakdown or transport or their essential cofactors. Neurotransmitter dysfunctions could also result from the impairment of neuronal receptors, intracellular signaling, vesicle release or other synaptic abnormalities. Epilepsy is the main clinical hallmark in some of these diseases (e.g. disorders of GABA metabolism, glycine encephalopathy) while it is infrequent in others (e.g. all the disorders of monoamine metabolism in exception for dihydropteridine reductase deficiency). This review analyzes the epileptogenic mechanisms, the epilepsy phenotypes and the principle for the clinical management of epilepsy in primary and secondary inherited disorders of neurotransmitter metabolism (disorders of GABA, serine and glycine metabolism, disorders of neurotransmitter receptors and secondary neurotransmitter diseases).

Anti-convulsant effects of cultures bear bile powder in febrile seizure via regulation of neurotransmission and inhibition of neuroinflammation

ETHNOPHARMACOLOGICAL RELEVANCE

Natural bear bile powder (NBBP) has been used to treat seizures for thousands of years, but its application is greatly restricted due to ethical reasons. Cultured bear bile powder (CBBP), which is produced by biotransformation, may be an appropriate substitute for NBBP. However, the anti-convulsant effects of CBBP and its mechanisms remain unclear.

AIM OF THE STUDY

This study aimed to investigate the anti-convulsant effects and possible mechanisms of CBBP in a febrile seizure (FS) rat model.

MATERIALS AND METHODS

FS was induced by placing the rats in a warm water bath (45.5 °C). The incidence rate and latency of FS, and hematoxylin-eosin staining (HE) were conducted for neurological damage. The levels of 4 bile acids and 8 main neurotransmitters in vivo were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The expression of bile acid related transports, neurotransmitter receptors, inflammatory factors, neurotrophic factors and glial fibrillary acidic protein (GFAP) in hippocampal tissues were detected by real-time PCR, western blotting, and immunohistochemistry.

RESULTS

Pre-treatments with CBBP and similarly, NBBP, significantly reduced the incidence rate and prolonged the latency of FS. Additionally, CBBP alleviated the histological injury induced by FS in the rat hippocampus tissue. LC-MS/MS analyses revealed that CBBP markedly increased the levels of tauroursodeoxycholic acid (TUDCA), taurochenodeoxycholic acid (TCDCA), ursodeoxycholic acid (UDCA), and chenodeoxycholic acid (CDCA) in FS rats. Furthermore, the content of gamma-aminobutyric acid (GABA) was up-regulated in rats pre-treated with CBBP whereas GFAP was down-regulated. CBBP also significantly suppressed the expression of interleukin -1β (IL-1β), tumor necrosis factor α (TNF-α), nuclear factor kappa B (NF-κB), and brain-derived neurotrophic factor (BDNF) and its TrkB receptors, and improved the expression of GABA type A receptors (GABA_AR) and farnesoid X receptors (FXR).

CONCLUSIONS

The present study demonstrated that CBBP had anti-convulsant effects in a FS rat model. CBBP may protect rats against FS, probably by up-regulating FXR, which was activated by increasing brain bile acids, up-regulating GABAergic transmission by inhibiting BDNF-TrkB signaling, and suppressing neuroinflammation by inhibiting the NF-κB pathway.

[Gender differences in the pool of free amino acid neurotransmitters in Krushinsky-Molodkina rats]

The study of the role of neurotransmitter systems in the pathogenesis of epilepsy is one of the priorities of epileptology. New data on the functions of free neurotransmitter-like amino acid in the central nervous system are of the greatest importance and determine the prospects for the development of novel effective anticonvulsants. It is widely believed in clinical medicine that epilepsy has distinct gender characteristics. The aim of this study was to investigate the gender peculiarities in the content of neurotransmitter amino acids in the brain of Krushinsky-Molodkina (KM) rats, which were used as model organisms for the study of genetically induced audiogenic epilepsy. The content of Asp, Glu, GABA, Gly, and Tau of the medulla oblongata, hippocampus and cerebral cortex were determined using high-performance liquid chromatography (HPLC) in intact KM rats, KM rats exposed to a series of epileptiform seizures, and Wistar rats (control group). Both the Wistar and KM rats had gender distinctions in the distribution of free amino acids among the investigated brain parts. The audiogenic epilepsy was characterized by smoothing gender differences as well as differences between the concentrations of free amino acids in the cortex and medulla oblongata, specific for Wistar rats. The changes observed in male rats after the set of seizures included the increase in GABA concentration and a decrease in the Gly level in all investigated brain parts, as well as the decrease of the Tau content in the cortex and hippocampus. At the same time, the Glu content in cortex increased, while the Asp level decreased. After 6 days of audiogenic stimulations the female KM rats demonstrated the increase in the Glu level in all investigated brain parts, the increase in Gly and Asp levels in hippocampus, and no changes in the GABA content. Thus, after the set of epileptiform seizures the KM rats achieved a new steady state of the studied amino acids pool, which differed in males and females. In this case, gender differences significantly changed after the seizures.

Morphological and molecular correlates of altered hearing sensitivity in the genetically audiogenic seizure-prone hamster GASH/Sal

Rodent models of audiogenic seizures, in which seizures are precipitated by an abnormal response of the brain to auditory stimuli, are crucial to investigate the neural bases underlying ictogenesis. Despite significant advances in understanding seizure generation in the inferior colliculus, namely the epileptogenic nucleus, little is known about the contribution of lower auditory stations to the seizure-prone network. Here, we examined the cochlea and cochlear nucleus of the genetic audiogenic seizure hamster from Salamanca (GASH/Sal), a model of reflex epilepsy that exhibits generalized tonic-clonic seizures in response to loud sound. GASH/Sal animals under seizure-free conditions were compared with matched control hamsters in a multi-technical approach that includes auditory brainstem responses (ABR) testing, histology, scanning electron microscopy analysis, immunohistochemistry, quantitative morphometry and gene expression analysis (RT-qPCR). The cochlear histopathology of the GASH/Sal showed preservation of the sensory hair cells, but a significant loss of spiral ganglion neurons and mild atrophy of the stria vascularis. At the electron microscopy level, the reticular lamina exhibited disarray of stereociliary tufts with blebs, loss or elongated stereocilia as well as non-parallel rows of outer hair cells due to protrusions of Deiters' cells. At the molecular level, the abnormal gene expression patterns of prestin, cadherin 23, protocadherin 15, vesicular glutamate transporters 1 (Vglut1) and -2 (Vglut2) indicated that the hair-cell mechanotransduction and cochlear amplification were markedly altered. These were manifestations of a cochlear neuropathy that correlated to ABR waveform I alterations and elevated auditory thresholds. In the cochlear nucleus, the distribution of VGLUT2-immunolabeled puncta was differently affected in each subdivision, showing significant increases in magnocellular regions of the ventral cochlear nucleus and drastic reductions in the granule cell domain. This modified inputs lead to disruption of Vglut1 and Vglut2 gene expression in the cochlear nucleus. In sum, our study provides insight into the morphological and molecular traits associated with audiogenic seizure susceptibility in the GASH/Sal, suggesting an upward spread of abnormal glutamatergic transmission throughout the primary acoustic pathway to the epileptogenic region.

Behavioral and neurochemical characterization of the spontaneous mutation tremor, a new mouse model of audiogenic seizures

The tremor mutant phenotype results from an autosomal recessive spontaneous mutation arisen in a Swiss-Webster mouse colony. The mutant mice displayed normal development until three weeks of age when they began to present motor impairment comprised by whole body tremor, ataxia, and decreased exploratory behavior. These features increased in severity with aging suggesting a neurodegenerative profile. In parallel, they showed audiogenic generalized clonic seizures. Results from genetic mapping identified the mutation tremor on chromosome 14, in an interval of 5 cM between D14Mit37 (33.21 cM) and D14Mit115 (38.21 cM), making Early Growth Response 3 (Egr3) the main candidate gene. Comparing with wild type (WT) mice, the tremor mice showed higher hippocampal gene expression of Egr3 and Gabra1 and increased concentrations of noradrenalin (NOR; p = .0012), serotonin (5HT; p = .0083), 5-hydroxyindoleacetic acid (5-HIAA; p = .0032), γ-amino butyric acid (GABA; p = .0123), glutamate (p = .0217) and aspartate (p = .0124). In opposition, the content of glycine (p = .0168) and the vanillylmandelic acid (VMA)/NOR ratio (p = .032) were decreased. Regarding to dopaminergic system, neither dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) contents nor the turnover rate of DA showed statistically significant differences between WT and mutant mice. Data demonstrated that audiogenic seizures of tremor mice are associated with progressive motor impairment as well as to hippocampal alterations of the Egr3 and Gabra1 gene expression and amino acid and monoamine content. In addition, the tremor mice could be useful for study of neurotransmission pathways as modulators of epilepsy and the pathogenesis of epilepsies occurring with generalized clonic seizures.

Research Advances on Acupuncture Analgesia

Pain is a widespread and complex symptom which causes serious emotional and social burdens to individuals and society. Most patients with pain rely heavily on over the counter (OTC) and prescription pain killers. However, there would be a number of issues that arise from the use of pain killers, in which safety and addiction are the most critical issues. For traditional Chinese medicine (TCM), pain is a result of the meridians being blocked. This could occur as a symptom of or be caused by various diseases. In this case, the key to relieve pain depends on dredging the meridian or meridians. Acupuncture has been practiced in China for over 2000 years to lessen pain. It is based on the “meridian theory”. Acupuncture is being used more widely and with a growing number of people in the treatment of pain because it is safer and has fewer side effects. Along with growing use and interest in acupuncture to treat pain, more attention has been paid to the mechanism underlying its analgesic effect, which is mainly associated with the changes of neurotransmitters. In this review, we summarize and analyze the range and mechanism of acupuncture analgesia treatment.

Monoaminergic System Modulation in Depression and Alzheimer's Disease: A New Standpoint?

The prevalence of depression has dramatically increased, and it has been estimated that over 300 million people suffer from depression all over the world. Depression is highly comorbid with many central and peripheral disorders. In this regard, depressive states have been associated with the development of neurological disorders such as Alzheimer's disease (AD). Accordingly, depression is a risk factor for AD and depressive symptomatology is common in pre-clinical AD, representing an early manifestation of this disease. Neuropsychiatric symptoms may represent prodromal symptoms of dementia deriving from neurobiological changes in specific cerebral regions; thus, the search for common biological substrates is becoming an imperative and intriguing field of research. Soluble forms of beta amyloid peptide (Aβ) have been implicated both in the development of early memory deficits and neuropsychiatric symptoms. Indeed, soluble Aβ species have been shown to induce a depressive-like phenotype in AD animal models. Alterations in monoamine content are a common feature of these neuropathologies. Interestingly, serotonergic system modulation has been implicated in alteration of Aβ production. In addition, noradrenaline is considered crucially involved in compensatory mechanisms, leading to increased Aβ degradation via several mechanisms, including microglia modulation. In further agreement, antidepressant drugs have also been shown to potentially modulate cognitive symptoms in AD and depression. Thus, the present review summarizes the main knowledge about biological and pathological substrates, such as monoamine and related molecules, commonly involved in AD and depression pathology, thus shading light on new therapeutic approaches.

Targeting metabotropic glutamate receptors in the treatment of epilepsy: rationale and current status

INTRODUCTION

Several drugs targeting the GABAergic system are used in the treatment of epilepsy, but only one drug targeting glutamate receptors is on the market. This is surprising because an imbalance between excitatory and inhibitory neurotransmission lies at the core of the pathophysiology of epilepsy. One possible explanation is that drug development has been directed towards the synthesis of molecules that inhibit the activity of ionotropic glutamate receptors. These receptors mediate fast excitatory synaptic transmission in the central nervous system (CNS) and their blockade may cause severe adverse effects such as sedation, cognitive impairment, and psychotomimetic effects. Metabotropic glutamate (mGlu) receptors are more promising drug targets because these receptors modulate synaptic transmission rather than mediate it. Areas covered: We review the current evidence that links mGlu receptor subtypes to the pathophysiology and experimental treatment of convulsive and absence seizures. Expert opinion: While mGlu₅ receptor negative allosteric modulators have the potential to be protective against convulsive seizures and hyperactivity-induced neurodegeneration, drugs that enhance mGlu₅ and mGlu₇ receptor function may have beneficial effects in the treatment of absence epilepsy. Evidence related to the other mGlu receptor subtypes is more fragmentary; further investigations are required for an improved understanding of their role in the generation and propagation of seizures.

CB2R induces a protective response for epileptic seizure via the PI3K 110α-AKT signaling pathway

Epilepsy is a chronic brain disease caused by abnormal discharging in the brain, which induces momentary brain dysfunction. Cannabinoid 2 receptor (CB2R) is expressed in central nervous system (CNS) and serves an important role in the pathogenesis of CNS diseases. The aim of the present study was to explore the effects of CB2R activation on phosphoinositide 3-kinase (PI3K) 110α-protein kinase B (AKT) signaling in an astrocyte model of epilepsy. Rat CTX TNA2 astrocytes were treated with Mg free solution to establish a cell model of epilepsy and were subsequently treated with a CB2R agonist (JWH133) and antagonist (AM630). Cell cycle analysis revealed that treatment using Mg free solution inhibited cell cycle transition. JWH133 facilitated cell cycle progression while AM630 inhibited it. Western blotting results demonstrated that treatment with Mg free solution downregulated the expression of cyclin D1, cyclin E, phosphorylated Retinoblastoma (p-Rb), B-cell lymphoma 2 (Bcl-2), PI3K 110α, p-AKT and p-mammalian target of rapamycin, whereas JWH133 treatment upregulated these proteins. AM630 ameliorated the JWH133-induced upregulation of these proteins. To confirm the involvement of AKT signaling, the AKT inhibitor wortmannin was used. The results revealed that wortmannin inhibited the effect of JWH133 on p-AKT, cyclin D1, p-Rb and Bcl-2 expression. In addition, the effects of JWH133 and AM630 on PI3K 110α-AKT signaling were verified using a rat model of epilepsy. In conclusion, the present study demonstrates that CB2R activation induces astrocyte proliferation and survival via activation of the PI3K 110α-AKT signaling pathway.

Sex Differences in Neurotoxicogenetics

A major development in biomedical research is the recognition that the sex of an individual plays a key role in susceptibility, treatment, and outcomes of most diseases. In this contribution, we present evidence that sex is also important in the toxicity of many environmental toxicants and contributes to the effect of genetics. Thus, individual differences in response to toxicants includes genetic makeup, the environment and sex; in fact, sex differences may be considered a part of genetic constitution. In this review, we present evidence for sex contribution to susceptibility for a number of toxicants.

Treatment of drug-induced seizures

Seizures are a common complication of drug intoxication, and up to 9% of status epilepticus cases are caused by a drug or poison. While the specific drugs associated with drug-induced seizures may vary by geography and change over time, common reported causes include antidepressants, stimulants and antihistamines. Seizures occur generally as a result of inadequate inhibitory influences (e.g., gamma aminobutyric acid, GABA) or excessive excitatory stimulation (e.g. glutamate) although many other neurotransmitters play a role. Most drug-induced seizures are self-limited. However, status epilepticus occurs in up to 10% of cases. Prolonged or recurrent seizures can lead to serious complications and require vigorous supportive care and anticonvulsant drugs. Benzodiazepines are generally accepted as the first line anticonvulsant therapy for drug-induced seizures. If benzodiazepines fail to halt seizures promptly, second line drugs include barbiturates and propofol. If isoniazid poisoning is a possibility, pyridoxine is given. Continuous infusion of one or more anticonvulsants may be required in refractory status epilepticus. There is no role for phenytoin in the treatment of drug-induced seizures. The potential role of ketamine and levetiracetam is promising but not established.