TRPV1 translocated to astrocytic membrane to promote migration and inflammatory infiltration thus promotes epilepsy after hypoxic ischemia in immature brain

Cell-specific Nav1.6 knockdown reduced astrocyte-derived Aβ by reverse Na+-Ca2+ transporter-mediated autophagy in alzheimer-like mice

INTRODUCTION

Nav1.6 is closely related to the pathology of Alzheimer's Disease (AD), and astrocytes have recently been identified as a significant source of β-amyloid (Aβ). However, little is known about the connection between Nav1.6 and astrocyte-derived Aβ.

OBJECTIVE

This study explored the crucial role of Nav1.6 in mediated astrocyte-derived Aβ in AD and knockdown astrocytic Nav1.6 alleviates AD progression by promoting autophagy and lysosome-APP fusion.

METHODS

A mouse model for astrocytic Nav1.6 knockdown was constructed to study the effects of astrocytic Nav1.6 on amyloidosis. The role of astrocytic Nav1.6 on autophagy and lysosome-APP(amyloid precursor protein) fusion was used by transmission electron microscope, immunostaining, western blot and patch clamp. Glial cell activation was detected using immunostaining. Neuroplasticity and neural network were assessed using patch-clamp, Golgi stain and EEG recording. Behavioral experiments were performed to evaluate cognitive defects.

RESULTS

Astrocytic Nav1.6 knockdown reduces amyloidosis, alleviates glial cell activation and morphological complexity, improves neuroplasticity and abnormal neural networks, as well as promotes learning and memory abilities in APP/PS1 mice. Astrocytic Nav1.6 knockdown reduces itself-derived Aβ by promoting lysosome- APP fusion, which is related to attenuating reverse Na+-Ca2+ exchange current thus reducing intracellular Ca2+ to facilitate autophagic through AKT/mTOR/ULK pathway.

CONCLUSION

Our findings unveil the crucial role of astrocyte-specific Nav1.6 in reducing astrocyte-derived Aβ, highlighting its potential as a cell-specific target for modulating AD progression.

Multiple effects of spicy flavors on neurological diseases through the intervention of TRPV1: a critical review

The spicy properties of foods are contributed by various spicy flavor substances (SFs) such as capsaicin, piperine, and allicin. Beyond their distinctive sensory characteristics, SFs also influence health conditions and numerous studies have associated spicy flavors with disease treatment. In this review, we enumerate different types of SFs and describe their role in food processing, with a specific emphasis on critically examining their influence on human wellness. Particularly, detailed insights into the mechanisms through which SFs enhance physiological balance and alleviate neurological diseases are provided, and a systematic analysis of the significance of transient receptor potential vanilloid type-1 (TRPV1) in regulating metabolism and nervous system homeostasis is presented. Moreover, enhancing the accessibility and utilization of SFs can potentially amplify the physiological effects. This review aims to provide compelling evidence for the integration of food flavor and human health.

TRPA1, TRPV1, and Caffeine: Pain and Analgesia

Caffeine (1,3,7-trimethylxanthine) is a naturally occurring methylxanthine that acts as a potent central nervous system stimulant found in more than 60 different plants and fruits. Although caffeinated beverages are widely and casually consumed, the application of caffeine beyond dietary levels as pharmacologic therapy has been recognized since the beginning of its recorded use. The analgesic and vasoactive properties of caffeine are well known, but the extent of their molecular basis remains an area of active research. There is existing evidence in the literature as to caffeine's effect on TRP channels, the role of caffeine in pain management and analgesia, as well as the role of TRP in pain and analgesia; however, there has yet to be a review focused on the interaction between caffeine and TRP channels. Although the influence of caffeine on TRP has been demonstrated in the lab and in animal models, there is a scarcity of data collected on a large scale as to the clinical utility of caffeine as a regulator of TRP. This review aims to prompt further molecular research to elucidate the specific ligand-host interaction between caffeine and TRP by validating caffeine as a regulator of transient receptor potential (TRP) channels-focusing on the transient receptor potential vanilloid 1 (TRPV1) receptor and transient receptor potential ankyrin 1 (TRPA1) receptor subtypes-and its application in areas of pain.

TRPV1 channel in the pathophysiology of epilepsy and its potential as a molecular target for the development of new antiseizure drug candidates

Identification of transient receptor potential cation channel, subfamily V member 1 (TRPV1), also known as capsaicin receptor, in 1997 was a milestone achievement in the research on temperature sensation and pain signalling. Very soon after it became evident that TRPV1 is implicated in a wide array of physiological processes in different peripheral tissues, as well as in the central nervous system, and thereby could be involved in the pathophysiology of numerous diseases. Increasing evidence suggests that modulation of TRPV1 may also affect seizure susceptibility and epilepsy. This channel is localized in brain regions associated with seizures and epilepsy, and its overexpression was found both in animal models of seizures and in brain samples from epileptic patients. Moreover, modulation of TRPV1 on non-neuronal cells (microglia, astrocytes, and/or peripheral immune cells) may have an impact on the neuroinflammatory processes that play a role in epilepsy and epileptogenesis. In this paper, we provide a comprehensive and critical overview of currently available data on TRPV1 as a possible molecular target for epilepsy management, trying to identify research gaps and future directions. Overall, several converging lines of evidence implicate TRPV1 channel as a potentially attractive target in epilepsy research but more studies are needed to exploit the possible role of TRPV1 in seizures/epilepsy and to evaluate the value of TRPV1 ligands as candidates for new antiseizure drugs.

Dual Role of TRPV1 Channels in Cerebral Stroke: An Exploration from a Mechanistic and Therapeutic Perspective

Transient receptor potential vanilloid subfamily member 1 (TRPV1) has been strongly implicated in the pathophysiology of cerebral stroke. However, the exact role and mechanism remain elusive. TPRV1 channels are exclusively present in the neurovascular system and involve many neuronal processes. Numerous experimental investigations have demonstrated that TRPV1 channel blockers or the lack of TRPV1 channels may prevent harmful inflammatory responses during ischemia-reperfusion injury, hence conferring neuroprotection. However, TRPV1 agonists such as capsaicin and some other non-specific TRPV1 activators may induce transient/slight degree of TRPV1 channel activation to confer neuroprotection through a variety of mechanisms, including hypothermia induction, improving vascular functions, inducing autophagy, preventing neuronal death, improving memory deficits, and inhibiting inflammation. Another factor in capsaicin-mediated neuroprotection could be the desensitization of TRPV1 channels. Based on the summarized evidence, it may be plausible to suggest that TPRV1 channels have a dual role in ischemia-reperfusion-induced cerebral injury, and thus, both agonists and antagonists may produce neuroprotection depending upon the dose and duration. The current review summarizes the dual function of TRPV1 in ischemia-reperfusion-induced cerebral injury models, explains its mechanism, and predicts the future.

TRPV1: Receptor structure, activation, modulation and role in neuro-immune interactions and pain

In the 1990s, the identification of a non-selective ion channel, especially responsive to capsaicin, revolutionized the studies of somatosensation and pain that were to follow. The TRPV1 channel is expressed mainly in neuronal cells, more specifically, in sensory neurons responsible for the perception of noxious stimuli. However, its presence has also been detected in other non-neuronal cells, such as immune cells, β- pancreatic cells, muscle cells and adipocytes. Activation of the channel occurs in response to a wide range of stimuli, such as noxious heat, low pH, gasses, toxins, endocannabinoids, lipid-derived endovanilloid, and chemical agents, such as capsaicin and resiniferatoxin. This activation results in an influx of cations through the channel pore, especially calcium. Intracellular calcium triggers different responses in sensory neurons. Dephosphorylation of the TRPV1 channel leads to its desensitization, which disrupts its function, while its phosphorylation increases the channel's sensitization and contributes to the channel's rehabilitation after desensitization. Kinases, phosphoinositides, and calmodulin are the main signaling pathways responsible for the channel's regulation. Thus, in this review we provide an overview of TRPV1 discovery, its tissue expression as well as on the mechanisms by which TRPV1 activation (directly or indirectly) induces pain in different disease models.

In silico analyses of the involvement of GPR55, CB1R and TRPV1: response to THC, contribution to temporal lobe epilepsy, structural modeling and updated evolution

Introduction

The endocannabinoid (eCB) system is named after the discovery that endogenous cannabinoids bind to the same receptors as the phytochemical compounds found in Cannabis. While endogenous cannabinoids include anandamide (AEA) and 2-arachidonoylglycerol (2-AG), exogenous phytocannabinoids include Δ-9 tetrahydrocannabinol (THC) and cannabidiol (CBD). These compounds finely tune neurotransmission following synapse activation, via retrograde signaling that activates cannabinoid receptor 1 (CB1R) and/or transient receptor potential cation channel subfamily V member 1 (TRPV1). Recently, the eCB system has been linked to several neurological diseases, such as neuro-ocular abnormalities, pain insensitivity, migraine, epilepsy, addiction and neurodevelopmental disorders. In the current study, we aim to: (i) highlight a potential link between the eCB system and neurological disorders, (ii) assess if THC exposure alters the expression of eCB-related genes, and (iii) identify evolutionary-conserved residues in CB1R or TRPV1 in light of their function.

Methods

To address this, we used several bioinformatic approaches, such as transcriptomic (Gene Expression Omnibus), protein-protein (STRING), phylogenic (BLASTP, MEGA) and structural (Phyre2, AutoDock, Vina, PyMol) analyzes.

Results

Using RNA sequencing datasets, we did not observe any dysregulation of eCB-related transcripts in major depressive disorders, bipolar disorder or schizophrenia in the anterior cingulate cortex, nucleus accumbens or dorsolateral striatum. Following in vivo THC exposure in adolescent mice, GPR55 was significantly upregulated in neurons from the ventral tegmental area, while other transcripts involved in the eCB system were not affected by THC exposure. Our results also suggest that THC likely induces neuroinflammation following in vitro application on mice microglia. Significant downregulation of TPRV1 occurred in the hippocampi of mice in which a model of temporal lobe epilepsy was induced, confirming previous observations. In addition, several transcriptomic dysregulations were observed in neurons of both epileptic mice and humans, which included transcripts involved in neuronal death. When scanning known interactions for transcripts involved in the eCB system (n = 12), we observed branching between the eCB system and neurophysiology, including proteins involved in the dopaminergic system. Our protein phylogenic analyzes revealed that CB1R forms a clade with CB2R, which is distinct from related paralogues such as sphingosine-1-phosphate, receptors, lysophosphatidic acid receptors and melanocortin receptors. As expected, several conserved residues were identified, which are crucial for CB1R receptor function. The anandamide-binding pocket seems to have appeared later in evolution. Similar results were observed for TRPV1, with conserved residues involved in receptor activation.

Conclusion

The current study found that GPR55 is upregulated in neurons following THC exposure, while TRPV1 is downregulated in temporal lobe epilepsy. Caution is advised when interpreting the present results, as we have employed secondary analyzes. Common ancestors for CB1R and TRPV1 diverged from jawless vertebrates during the late Ordovician, 450 million years ago. Conserved residues are identified, which mediate crucial receptor functions.

Desflurane improves electrical activity of neurons and alleviates oxygen-glucose deprivation-induced neuronal injury by activating the Kcna1-dependent Kv1.1 channel

Several volatile anesthetics have presented neuroprotective functions in ischemic injury. This study investigates the effect of desflurane (Des) on neurons following oxygen-glucose deprivation (OGD) challenge and explores the underpinning mechanism. Mouse neurons HT22 were subjected to OGD, which significantly reduced cell viability, increased lactate dehydrogenase release, and promoted cell apoptosis. In addition, the OGD condition increased oxidative stress in HT22 cells, as manifested by increased ROS and MDA contents, decreased SOD activity and GSH/GSSG ratio, and reduced nuclear protein level of Nrf2. Notably, the oxidative stress and neuronal apoptosis were substantially blocked by Des treatment. Bioinformatics suggested potassium voltage-gated channel subfamily A member 1 (Kcna1) as a target of Des. Indeed, the Kcna1 expression in HT22 cells was decreased by OGD but restored by Des treatment. Artificial knockdown of Kcna1 negated the neuroprotective effects of Des. By upregulating Kcna1, Des activated the Kv1.1 channel, therefore enhancing K+ currents and inducing neuronal repolarization. Pharmacological inhibition of the Kv1.1 channel reversed the protective effects of Des against OGD-induced injury. Collectively, this study demonstrates that Des improves electrical activity of neurons and alleviates OGD-induced neuronal injury by activating the Kcna1-dependent Kv1.1 channel.

Astrocytes and brain-derived neurotrophic factor (BDNF)

Astrocytes are emerging in the neuroscience field as crucial modulators of brain functions, from the molecular control of synaptic plasticity to orchestrating brain-wide circuit activity for cognitive processes. The cellular pathways through which astrocytes modulate neuronal activity and plasticity are quite diverse. In this review, we focus on neurotrophic pathways, mostly those mediated by brain-derived neurotrophic factor (BDNF). Neurotrophins are a well-known family of trophic factors with pleiotropic functions in neuronal survival, maturation and activity. Within the brain, BDNF is the most abundantly expressed and most studied of all neurotrophins. While we have detailed knowledge of the effect of BDNF on neurons, much less is known about its physiology on astroglia. However, over the last years new findings emerged demonstrating that astrocytes take an active part into BDNF physiology. In this work, we discuss the state-of-the-art knowledge about astrocytes and BDNF. Indeed, astrocytes sense extracellular BDNF through its specific TrkB receptors and activate intracellular responses that greatly vary depending on the brain area, stage of development and receptors expressed. Astrocytes also uptake and recycle BDNF / proBDNF at synapses contributing to synaptic plasticity. Finally, experimental evidence is now available describing deficits in astrocytic BDNF in several neuropathologies, suggesting that astrocytic BDNF may represent a promising target for clinical translation.

Further advances in epilepsy

In 2017, one of us reviewed advances in epilepsy (Manford in J Neurol 264:1811-1824, 2017). The current paper brings that review up to date and gives a slight change in emphasis. Once again, the story is of evolution rather than revolution. In recognition that most of our current medications act on neurotransmitters or ion channels, and not on the underlying changes in connectivity and pathways, they have been renamed as antiseizure (ASM) medications rather than antiepileptic drugs. Cenobamate is the one newly licensed medication for broader use in focal epilepsy but there have been a number of developments for specific disorders. We review new players and look forward to new developments in the light of evolving underlying science. We look at teratogenicity; old villains and new concerns in which clinicians play a vital role in explaining and balancing the risks. Medical treatment of status epilepticus, long without evidence, has benefitted from high-quality trials to inform practice; like buses, several arriving at once. Surgical treatment continues to be refined with improvements in the pre-surgical evaluation of patients, especially with new imaging techniques. Alternatives including stereotactic radiotherapy have received further focus and targets for palliative stimulation techniques have grown in number. Individuals' autonomy and quality of life continue to be the subject of research with refinement of what clinicians can do to help persons with epilepsy (PWE) achieve control. This includes seizure management but extends to broader considerations of human empowerment, needs and desires, which may be aided by emerging technologies such as seizure detection devices. The role of specialist nurses in improving that quality has been reinforced by specific endorsement from the International League against Epilepsy (ILAE).

Differential outcomes of high-fat diet on age-related rescaling of cochlear frequency place coding

Auditory frequency coding is place-specific, which depends on the mechanical coupling of the basilar membrane-outer hair cell (OHC)-tectorial membrane network. Prestin-based OHC electromotility improves cochlear frequency selectivity and sensitivity. Cochlear amplification determines the frequency coding wherein discrete sound frequencies find a 'best' place along the cochlear length. Loss of OHC is the leading cause of age-related hearing loss (ARHL) and is the most common cause of sensorineural hearing loss and compromised speech perception. Lipid interaction with Prestin impacts OHC function. It has been established that high-fat diet (HFD) is associated with ARHL. To determine whether genetic background and metabolism preserve cochlear frequency place coding, we examined the effect of HFD in C57BL/6J (B6) and CBA/CaJ (CBA) on ARHL.We found a significant rescuing effect on ARHL in aged B6 HFD cohort. Prestin levels and cell sizes were better maintained in the experimental B6-HFD group. We also found that distortion product otoacoustic emission (DPOAE) group delay measurement was preserved, which suggested stable frequency place coding. In contrast, the response to HFD in the CBA cohort was modest with no appreciable benefit to hearing threshold. Notably, group delay was shortened with age along with the control. In addition, the frequency dependent OHC nonlinear capacitance gradient was most pronounced at young age but decreased with age. Cochlear RNA-seq analysis revealed differential TRPV1 expression and lipid homeostasis. Activation of TRPV1 and downregulation of arachidonic acid led to downregulation of inflammatory response in B6 HFD, which protects the cochlea from ARHL. The genetic background and metabolic state-derived changes in OHC morphology and function collectively contribute to a redefined cochlear frequency place coding and improved age-related pitch perception.

Carcinogenesis and Metastasis: Focus on TRPV1-Positive Neurons and Immune Cells

Both sensory neurons and immune cells, albeit at markedly different levels, express the vanilloid (capsaicin) receptor, Transient Receptor Potential, Vanilloid-1 (TRPV1). Activation of TRPV1 channels in sensory afferent nerve fibers induces local effector functions by releasing neuropeptides (most notably, substance P) which, in turn, trigger neurogenic inflammation. There is good evidence that chronic activation or inactivation of this inflammatory pathway can modify tumor growth and metastasis. TRPV1 expression was also demonstrated in a variety of mammalian immune cells, including lymphocytes, dendritic cells, macrophages and neutrophils. Therefore, the effects of TRPV1 agonists and antagonists may vary depending on the prominent cell type(s) activated and/or inhibited. Therefore, a comprehensive understanding of TRPV1 activity on immune cells and nerve endings in distinct locations is necessary to predict the outcome of therapies targeting TRPV1 channels. Here, we review the neuro-immune modulation of cancer growth and metastasis, with focus on the consequences of TRPV1 activation in nerve fibers and immune cells. Lastly, the potential use of TRPV1 modulators in cancer therapy is discussed.

An update on the role of Hippo signaling pathway in ischemia-associated central nervous system diseases

The most frequent reason of morbidity and mortality in the world, cerebral ischemia sets off a chain of molecular and cellular pathologies that associated with some central nervous system (CNS) disorders mainly including ischemic stroke, Alzheimer's disease (AD), Parkinson's disease (PD), epilepsy and other CNS diseases. In recent times, despite significant advancements in the treatment of the pathological processes underlying various neurological illnesses, effective therapeutic approaches that are specifically targeted to minimizing the damage of such diseases remain absent. Hippo signaling pathway, characterized by enzyme linked reactions between MSTI/2, LAST1/2, and YAP or TAZ proteins, controls cell division, survival, and differentiation, as well as being engaged in a variety of biological activities, such as the development and transformation of the nervous system. Recently, accumulating studies demonstrated that Hippo pathway takes part in the processes of ischemic stroke, AD, PD, etc., including but not limited to oxidative stress, inflammatory response, blood-brain barrier damage, mitochondrial disorders, and neural cells death. Thus, it's crucial to understand the molecular basis of the Hippo signaling pathway for determining potential new therapeutic targets against ischemia-associated CNS diseases. Here, we discuss latest advances in the deciphering of the Hippo signaling pathway and highlight the therapeutic potential of targeting the pathway in treating ischemia-associated CNS diseases.

AQP4 Aggravates Cognitive Impairment in Sepsis-Associated Encephalopathy through Inhibiting Nav 1.6-Mediated Astrocyte Autophagy

The pathology of sepsis-associated encephalopathy (SAE) is related to astrocyte-inflammation associated with aquaporin-4 (AQP4). The aim here is to investigate the effects of AQP4 associated with SAE and reveal its underlying mechanism causing cognitive impairment. The in vivo experimental results reveal that AQP4 in peripheral blood of patients with SAE is up-regulated, also the cortical and hippocampal tissue of cecal ligation and perforation (CLP) mouse brain has significant rise in AQP4. Furthermore, the data suggest that AQP4 deletion could attenuate learning and memory impairment, attributing to activation of astrocytic autophagy, inactivation of astrocyte and downregulate the expression of proinflammatory cytokines induced by CLP or lipopolysaccharide (LPS). Furthermore, the activation effect of AQP4 knockout on CLP or LPS-induced PPAR-γ inhibiting in astrocyte is related to intracellular Ca2+ level and sodium channel activity. Learning and memory impairment in SAE mouse model are attenuated by AQP4 knockout through activating autophagy, inhibiting neuroinflammation leading to neuroprotection via down-regulation of Nav 1.6 channels in the astrocytes. This results in the reduction of Ca2+ accumulation in the cell cytosol furthermore activating the inhibition of PPAR-γ signal transduction pathway in astrocytes.

Etanercept ameliorates psoriasis progression through regulating high mobility group box 1 pathway

BACKGROUND

As a common skin disease, psoriasis is related to inflammation and immune response. Due to the frequent recurrence of psoriasis, the treatment of psoriasis remains a clinical challenge. As an effective tumor necrosis factor-alpha (TNF-α) inhibitor, etanercept has been used for the treatment of psoriasis. However, some patients with psoriasis have no response to etanercept or discontinue treatment. To improve the therapeutic effect of etanercept, searching the potential biomarkers and investigating the related mechanisms of etanercept in the treatment of psoriasis are vital.

MATERIALS AND METHODS

We stimulated HaCaT cells with lipopolysaccharide (LPS) to generate cellular psoriatic changes and established an imiquimod (IMQ)-induced psoriasis-like mouse model, and then used an etanercept to treat cell and mouse model.

RESULTS

Etanercept alleviated IMQ-induced pathological changes and inflammation, and it also decreased the protein expression of high mobility group box 1 (HMGB1), receptor for advanced glycation end-products, and toll-like receptor 4. Moreover, the results of in vitro experiments showed that etanercept inhibited proliferation and inflammation, and promoted cell cycle arrest and apoptosis in LPS-treated HaCaT cells. Knockdown of HMGB1 further enhanced the inhibitory effects of etanercept on LPS-treated HaCaT cell viability and inflammation, while overexpression of HMGB1 notably reversed the inhibitory effects of etanercept on LPS-induced HaCaT cell viability and inflammation.

CONCLUSION

Etanercept inhibited proliferation and inflammation and promoted cell cycle arrest and apoptosis in LPS-induced HaCaT cells, and etanercept ameliorated inflammation in a psoriasis-like mouse model.

NLRP3 upregulation related to sleep deprivation-induced memory and emotional behavior changes in TRPV1-/- mice

Sleep deprivation, which is a common problem in modern society, impairs memory function and emotional behavior. TRPV1, a subfamily of transient receptor potential cation channels, is abundantly expressed in the central nervous system and is associated with animal behavior. In this article, we report that TRPV1 deficiency in mice alleviates sleep deprivation-induced abnormal behaviors. We found that in the sleep-deprived mice, TRPV1 knockout increased the duration and visits in the central area in the open field task and increased visits to the open arms in the elevated plus maze. The TRPV1^-/- mice performed better during the test stage in the Morris water maze phase after sleep deprivation. In the mPFC and hippocampus regions, western blotting results showed that TRPV1^-/- attenuated sleep deprivation-induced increases in GFAP, NLRP3, and ASC and increased the expression of the mitochondrial marker Tom20. Immunofluorescence results showed that the action of TRPV1 knockout on NLRP3 was negatively correlated with Tom20 after sleep deprivation. Our results confirm that TRPV1 knockout attenuates sleep deprivation-induced behavioral disorders. The effect of TRPV1 on the behavior of sleep-deprived mice may be related to the neuroinflammation associated with mitochondria in the mPFC and hippocampus.

Anesthesia and analgesia for experimental craniotomy in mice and rats: a systematic scoping review comparing the years 2009 and 2019

Experimental craniotomies are a common surgical procedure in neuroscience. Because inadequate analgesia appears to be a problem in animal-based research, we conducted this review and collected information on management of craniotomy-associated pain in laboratory mice and rats. A comprehensive search and screening resulted in the identification of 2235 studies, published in 2009 and 2019, describing craniotomy in mice and/or rats. While key features were extracted from all studies, detailed information was extracted from a random subset of 100 studies/year. Reporting of perioperative analgesia increased from 2009 to 2019. However, the majority of studies from both years did not report pharmacologic pain management. Moreover, reporting of multimodal treatments remained at a low level, and monotherapeutic approaches were more common. Among drug groups, reporting of pre- and postoperative administration of non-steroidal anti-inflammatory drugs, opioids, and local anesthetics in 2019 exceeded that of 2009. In summary, these results suggest that inadequate analgesia and oligoanalgesia are persistent issues associated with experimental intracranial surgery. This underscores the need for intensified training of those working with laboratory rodents subjected to craniotomies.

Systematic review registration

https://osf.io/7d4qe.

Alteration in Neuregulin 1/ERbB4 in Absence Epilepsy: Regulatory Effect on TRPV1 Expression

Introduction

The footprint of Neuregulin 1 (NRG1) / ERbB4 in the pathophysiology of some neurological disorders and TRPV1 regulation has been indicated. The alterations in NRG1 and ErbB4 as well as the TRPV1 signaling pathway were investigated during the development of absence epilepsy in the genetic animal model of absence epilepsy.

Methods

Male WAG/Rij and Wistar rats were divided into four experimental groups of two and six months of age. The protein levels of NRG1, ERbB4, and TRPV1 were measured in the somatosensory cortex and hippocampus.

Results

The cortical protein levels of NRG1 and ErbB4 in the 6-month-old WAG/Rij rats were lower than in Wistar rats. Protein levels of TRPV1 were lower in two- and six-month-old WAG/Rij rats compared to age-matched Wistar rats.Hippocampal protein levels of NRG1 in 6-month-old WAG/Rij rats were lower than two-month-old WAG/Rij rats. Low levels of ErbB4 protein in two-month-old and high levels in six-month-old WAG/Rij rats were found compared to Wistar rats. Protein levels of TRPV1 were lower in the two-month-old and higher in the six-month-old WAG/Rij rats compared to age-matched Wistar rats.Furthermore, a high correlation between NRG1/ERbB4 and TRPV1 expressions in the cortex and hippocampus was indicated. The expression of NRG1/ERbB4 and TRPV1 followed a similar pattern during the life span of Wistar and WAG/Rij rats.

Conclusion

Our findings indicated the potential role of the NRG1/ErbB4 pathway as well as TRPV1 in the pathogenesis of absence epilepsy. The regulatory effect of the ERbB4 receptor on the TRPV1 expression has been suggested following the similar pattern of expression.

New Phenylglycinamide Derivatives with Hybrid Structure as Candidates for New Broad-Spectrum Anticonvulsants

In the present study, a focused combinatorial chemistry approach was applied to merge structural fragments of well-known TRPV1 antagonists with a potent anticonvulsant lead compound, KA-104, that was previously discovered by our group. Consequently, a series of 22 original compounds has been designed, synthesized, and characterized in the in vivo and in vitro assays. The obtained compounds showed robust in vivo antiseizure activity in the maximal electroshock (MES) test and in the 6 Hz seizure model (using both 32 and 44 mA current intensities). The most potent compounds 53 and 60 displayed the following pharmacological profile: ED₅₀ = 89.7 mg/kg (MES), ED₅₀ = 29.9 mg/kg (6 Hz, 32 mA), ED₅₀ = 68.0 mg/kg (6 Hz, 44 mA), and ED₅₀ = 73.6 mg/kg (MES), ED₅₀ = 24.6 mg/kg (6 Hz, 32 mA), and ED₅₀ = 56.3 mg/kg (6 Hz, 44 mA), respectively. Additionally, 53 and 60 were effective in the ivPTZ seizure threshold and had no influence on the grip strength and body temperature in mice. The in vitro binding and functional assays indicated a multimodal mechanism of action for 53 and 60. These molecules, beyond TRPV1 antagonism, inhibited calcium currents and fast sodium currents in patch-clamp assays. Further studies proved beneficial in vitro ADME-Tox properties for 53 and 60 (i.e., high metabolic stability, weak influence on CYPs, no neurotoxicity, etc.). Overall, 53 and 60 seem to be interesting candidates for future preclinical development in epilepsy and pain indications due to their interaction with the TRPV1 channel.

Transient Receptor Potential Vanilloid 1 Function at Central Synapses in Health and Disease

The transient receptor potential vanilloid 1 (TRPV1), a ligand-gated nonselective cation channel, is well known for mediating heat and pain sensation in the periphery. Increasing evidence suggests that TRPV1 is also expressed at various central synapses, where it plays a role in different types of activity-dependent synaptic changes. Although its precise localizations remain a matter of debate, TRPV1 has been shown to modulate both neurotransmitter release at presynaptic terminals and synaptic efficacy in postsynaptic compartments. In addition to being required in these forms of synaptic plasticity, TRPV1 can also modify the inducibility of other types of plasticity. Here, we highlight current evidence of the potential roles for TRPV1 in regulating synaptic function in various brain regions, with an emphasis on principal mechanisms underlying TRPV1-mediated synaptic plasticity and metaplasticity. Finally, we discuss the putative contributions of TRPV1 in diverse brain disorders in order to expedite the development of next-generation therapeutic treatments.

Neuroinflammation and Proinflammatory Cytokines in Epileptogenesis

Increasing evidence corroborates the fundamental role of neuroinflammation in the development of epilepsy. Proinflammatory cytokines (PICs) are crucial contributors to the inflammatory reactions in the brain. It is evidenced that epileptic seizures are associated with elevated levels of PICs, particularly interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α), which underscores the impact of neuroinflammation and PICs on hyperexcitability of the brain and epileptogenesis. Since the pathophysiology of epilepsy is unknown, determining the possible roles of PICs in epileptogenesis could facilitate unraveling the pathophysiology of epilepsy. About one-third of epileptic patients are drug-resistant, and existing treatments only resolve symptoms and do not inhibit epileptogenesis; thus, treatment of epilepsy is still challenging. Accordingly, understanding the function of PICs in epilepsy could provide us with promising targets for the treatment of epilepsy, especially drug-resistant type. In this review, we outline the role of neuroinflammation and its primary mediators, including IL-1β, IL-1α, IL-6, IL-17, IL-18, TNF-α, and interferon-γ (IFN-γ) in the pathophysiology of epilepsy. Furthermore, we discuss the potential therapeutic targeting of PICs and cytokine receptors in the treatment of epilepsy.

Contribution of non-selective membrane channels and receptors in epilepsy

Overcoming refractory epilepsy's resistance to the combination of antiepileptic drugs (AED), mitigating side effects, and preventing sudden unexpected death in epilepsy are critical goals for therapy of this disorder. Current therapeutic strategies are based primarily on neurocentric mechanisms, overlooking the participation of astrocytes and microglia in the pathophysiology of epilepsy. This review is focused on a set of non-selective membrane channels (permeable to ions and small molecules), including channels and ionotropic receptors of neurons, astrocytes, and microglia, such as: the hemichannels formed by Cx43 and Panx1; the purinergic P2X7 receptors; the transient receptor potential vanilloid (TRPV1 and TRPV4) channels; calcium homeostasis modulators (CALHMs); transient receptor potential canonical (TRPC) channels; transient receptor potential melastatin (TRPM) channels; voltage-dependent anion channels (VDACs) and volume-regulated anion channels (VRACs), which all have in common being activated by epileptic activity and the capacity to exacerbate seizure intensity. Specifically, we highlight evidence for the activation of these channels/receptors during epilepsy including neuroinflammation and oxidative stress, discuss signaling pathways and feedback mechanisms, and propose the functions of each of them in acute and chronic epilepsy. Studying the role of these non-selective membrane channels in epilepsy and identifying appropriate blockers for one or more of them could provide complementary therapies to better alleviate the disease.

Exercise-linked consequences on epilepsy

OBJECTIVE

Epilepsy is a brain disorder that leads to seizures and neurobiological, cognitive, psychological, and social consequences. Physical inactivity can contribute to worse epilepsy pathophysiology. Here, we review how physical exercise affects epilepsy physiopathology.

METHODS

An extensive literature search was performed and the mechanisms of physical exercise on epilepsy were discussed. The search was conducted in Scopus and PubMed. Articles with relevant information were included. Only studies written in English were considered.

RESULTS

The regular practice of physical exercise can be beneficial for individuals with neurodegenerative diseases, such as epilepsy by decreasing the production of pro-inflammatory and stress biomarkers, increasing socialization, and reducing the incidence of epileptic seizures. Physical exercise is also capable of reducing the symptoms of depression and anxiety in epilepsy. Physical exercise can also improve cognitive function in epilepsy. The regular practice of physical exercise enhances the levels of brain-derived neuro factor (BDNF) in the hippocampi, induces neurogenesis, inhibits oxidative stress and reactive gliosis, avoids cognitive impairment, and stimulates the production of dopamine in the epileptic brain.

CONCLUSION

Physical exercise is an excellent non-pharmacological tool that can be used in the treatment of epilepsy.

Inhibition of TLR4 prevents hippocampal hypoxic-ischemic injury by regulating ferroptosis in neonatal rats

Inflammation and cell death play important roles in the pathogenesis of hypoxic-ischemic brain damage (HIBD). Toll-like receptor 4 (TLR4) triggers the activation of the inflammatory pathway. Ferroptosis, a newly identified type of regulated cell death, is implicated in various diseases involving neuronal injury. However, the role of ferroptosis in HIBD has not been elucidated. The objectives of this study were to explore the function and mechanism of TLR4 in neuronal ferroptosis in the context of HIBD. A neonatal rat model of hypoxia-ischemia (HI) and a cell model of oxygen-glucose deprivation (OGD) were employed. TAK-242, a TLR4-specific antagonist, was used to evaluate the effect of TLR4 on neuronal ferroptosis in vivo. A TAK-242 inhibitor and a p38 inhibitor (SB203580) were administered to HT22 hippocampal neurons to explore the association between TLR4 in inflammation and ferroptosis in vitro. The effects of TLR4 on ferroptosis were assessed by the Western blot, real-time PCR, immunofluorescence staining, cell viability and transmission electron microscopy (TEM) assays. HI insult significantly upregulated the TLR4, increased the p53 level, reduced the SLC7A11 and GPX4 levels, and caused mitochondrial damage, thereby inducing neuronal ferroptosis in the hippocampus. Inhibition of TLR4 inhibited the expression of ferroptosis-related proteins, decreased the expression of ferroptosis-related genes and the proinflammatory milieu, attenuated oxidative stress and mitochondrial injury and, finally, ameliorated the activation of hippocampal neuronal ferroptosis following HIBD. Consistent with the results of these in vivo experiments, TLR4 inhibition also attenuated OGD-induced ferroptosis by suppressing oxidative stress and p38MAPK signaling, ultimately increasing neuronal cell viability. Finally, the in vitro and in vivo results demonstrated that TAK-242 exerted neuroprotective and antiferroptotic effects by suppressing TLR4-p38 MAPK signaling. TLR4 activation induced neuronal ferroptosis following both HIBD and OGD. Inhibition of TLR4 attenuated oxidative stress-induced damage, decreased the activation of ferroptosis, and attenuated neuroinflammation following HIBD. In this study, we demonstrated that the inhibition of TLR4-p38 MAPK signaling modulates HIBD- or OGD-induced ferroptosis in neuronal cells and may play a novel role in brain homeostasis.

Complement C3 Aggravates Post-epileptic Neuronal Injury Via Activation of TRPV1

Epilepsy is a brain condition characterized by the recurrence of unprovoked seizures. Recent studies have shown that complement component 3 (C3) aggravate the neuronal injury in epilepsy. And our previous studies revealed that TRPV1 (transient receptor potential vanilloid type 1) is involved in epilepsy. Whether complement C3 regulation of neuronal injury is related to the activation of TRPV1 during epilepsy is not fully understood. We found that in a mouse model of status epilepticus (SE), complement C3 derived from astrocytes was increased and aggravated neuronal injury, and that TRPV1-knockout rescued neurons from the injury induced by complement C3. Circular RNAs are abundant in the brain, and the reduction of circRad52 caused by complement C3 promoted the expression of TRPV1 and exacerbated neuronal injury. Mechanistically, disorders of neuron-glia interaction mediated by the C3-TRPV1 signaling pathway may be important for the induction of neuronal injury. This study provides support for the hypothesis that the C3-TRPV1 pathway is involved in the prevention and treatment of neuronal injury and cognitive disorders.

Beyond Neuronal Heat Sensing: Diversity of TRPV1 Heat-Capsaicin Receptor-Channel Functions

Transient receptor potential vanilloid 1 (TRPV1) is a calcium-permeable ion channel best known for its ability to be gated by the pungent constituent of red chili pepper, capsaicin, and related chemicals from the group of vanilloids as well as by noxious heat. As such, it is mostly expressed in sensory neurons to act as a detector of painful stimuli produced by pungent chemicals and high temperatures. Its activation is also sensitized by the numerous endogenous inflammatory mediators and second messengers, making it an important determinant of nociceptive signaling. Except for such signaling, though, neuronal TRPV1 activation may influence various organ functions by promoting the release of bioactive neuropeptides from sensory fiber innervation organs. However, TRPV1 is also found outside the sensory nervous system in which its activation and function is not that straightforward. Thus, TRPV1 expression is detected in skeletal muscle; in some types of smooth muscle; in epithelial and immune cells; and in adipocytes, where it can be activated by the combination of dietary vanilloids, endovanilloids, and pro-inflammatory factors while the intracellular calcium signaling that this initiates can regulate processes as diverse as muscle constriction, cell differentiation, and carcinogenesis. The purpose of the present review is to provide a clear-cut distinction between neurogenic TRPV1 effects in various tissues consequent to its activation in sensory nerve endings and non-neurogenic TRPV1 effects due to its expression in cell types other than sensory neurons.

Cannabidiol in the treatment of epilepsy: Current evidence and perspectives for further research

The therapeutic potential of cannabidiol (CBD) in seizure disorders has been known for many years, but it is only in the last decade that major progress has been made in characterizing its preclinical and clinical properties as an antiseizure medication. The mechanisms responsible for protection against seizures are not fully understood, but they are likely to be multifactorial and to include, among others, antagonism of G protein-coupled receptor, desensitization of transient receptor potential vanilloid type 1 channels, potentiation of adenosine-mediated signaling, and enhancement of GABAergic transmission. CBD has a low and highly variable oral bioavailability, and can be a victim and perpetrator of many drug-drug interactions. A pharmaceutical-grade formulation of purified CBD derived from Cannabis sativa has been evaluated in several randomized placebo-controlled adjunctive-therapy trials, which resulted in its regulatory approval for the treatment of seizures associated with Dravet syndrome, Lennox-Gastaut syndrome and tuberous sclerosis complex. Interpretation of results of these trials, however, has been complicated by the occurrence of an interaction with clobazam, which leads to a prominent increase in the plasma concentration of the active metabolite N-desmethylclobazam in CBD-treated patients. Despite impressive advances, significant gaps in knowledge still remain. Areas that require further investigation include the mechanisms underlying the antiseizure activity of CBD in different syndromes, its pharmacokinetic profile in infants and children, potential relationships between plasma drug concentration and clinical response, interactions with other co-administered medications, potential efficacy in other epilepsy syndromes, and magnitude of antiseizure effects independent from interactions with clobazam. This article is part of the special issue on 'Cannabinoids'.

Chrysene accelerates the proceeding of chronic obstructive pulmonary disease with the aggravation of inflammation and apoptosis in cigarette smoke exposed mice

Chrysene, one of the basic polycyclic aromatic hydrocarbons (PAHs), has been reported to make damages to human health and living environment. Chronic obstructive pulmonary disease (COPD) is a progressive disorder with high morbidity and mortality. To investigate the role of chrysene in the development of COPD, male C57BL/6 mice were exposed to the cigarette smoke (CS) followed with the administration of chrysene. Morphological analyses indicated that chrysene caused earlier and severer pathological changes in CS-exposed mice. Besides, CS-exposed mice with chrysene treatment showed obvious collagen deposition, elevated α-smooth muscle actin (α-SMA) expression and reduced E-cadherin abundance at earlier stage, which suggested the acceleration and aggravation of pulmonary fibrosis. Moreover, quantification of leukocytes and pro-inflammatory cytokines in bronchoalveolar lavage fluid (BALF) and lung tissues implied that chrysene significantly exacerbated the proceeding of inflammation in CS-exposed mice. Furthermore, significantly increased apoptotic rates, augmented expressions of apoptotic related proteins and highly expressed TRPV1 were determined in CS-exposed mice with chrysene treatment, which indicated the association between COPD pathogenesis and TRPV1 channel. In summary, our findings elucidate that chrysene accelerates the development of COPD in a murine model with new molecular mechanisms.

Perinatal Brain Injury and Inflammation: Lessons from Experimental Murine Models

Perinatal brain injury or neonatal encephalopathy (NE) is a state of disturbed neurological function in neonates, caused by a number of different aetiologies. The most prominent cause of NE is hypoxic ischaemic encephalopathy, which can often induce seizures. NE and neonatal seizures are both associated with poor neurological outcomes, resulting in conditions such as cerebral palsy, epilepsy, autism, schizophrenia and intellectual disability. The current treatment strategies for NE and neonatal seizures have suboptimal success in effectively treating neonates. Therapeutic hypothermia is currently used to treat NE and has been shown to reduce morbidity and has neuroprotective effects. However, its success varies between developed and developing countries, most likely as a result of lack of sufficient resources. The first-line pharmacological treatment for NE is phenobarbital, followed by phenytoin, fosphenytoin and lidocaine as second-line treatments. While these drugs are mostly effective at halting seizure activity, they are associated with long-lasting adverse neurological effects on development. Over the last years, inflammation has been recognized as a trigger of NE and seizures, and evidence has indicated that this inflammation plays a role in the long-term neuronal damage experienced by survivors. Researchers are therefore investigating the possible neuroprotective effects that could be achieved by using anti-inflammatory drugs in the treatment of NE. In this review we will highlight the current knowledge of the inflammatory response after perinatal brain injury and what we can learn from animal models.

TRPV1 Contributes to the Neuroprotective Effect of Dexmedetomidine in Pilocarpine-Induced Status Epilepticus Juvenile Rats

To investigate the antiepileptic and neuroprotective effects of dexmedetomidine (Dex) in pilocarpine- (Pilo-) induced status epilepticus (SE) juvenile rats, rats were randomly assigned to the following six groups (n = 20): normal, normal+Dex, SE, SE+Cap, SE+Dex, and SE+Dex+Cap. The rats were treated with either diazepam (i.p., an antiepileptic drug) or Dex after the onset of SE. The Morris water maze was used to assess rat cognitive behavior. Flow cytometry was used to detect the concentrations of Ca²⁺, mitochondrial membrane potential, and reactive oxygen species. Transmission electron microscopy was performed to evaluate specimens of brain tissue. The levels of caspase 3 and TRPV1 were examined by western blot and immunohistochemistry (IHC). Treatment with Dex significantly decreased the escape latency of the SE rats (P < 0.05). Capsaicin, a TRPV1 agonist, delivery aggravated the performance of SE rats. Pathological changes in SE rat were attenuated by Dex and deteriorated by capsaicin. Swollen mitochondria and abnormal endoplasmic reticulum were found in SE rats and were then aggravated by capsaicin and reversed by Dex. Moreover, our data showed that Dex significantly restrained calcium overload, ROS production, and mitochondrial membrane potential loss, all of which were induced by Pilo and capsaicin (P < 0.05). Dex decreased the apoptotic rate in the Model SE group (P < 0.05) and TRPV1 and caspase 3 expression in the Dex treatment group (P < 0.05). Interestingly, all these effects of Dex were partially counteracted by the TRPV1 agonist, capsaicin (P < 0.05). Our study showed that Dex exerted a neuroprotective effect in Pilo-induced SE rats by inhibiting TRPV1 expression and provided information for therapy to SE patients.

Transplantation of umbilical cord blood mononuclear cells attenuates the expression of IL-1β via the TLR4/NF-κB pathway in hypoxic-ischemic neonatal rats

Objective:

This study aims to observe the effects of transplantation of umbilical cord blood mononuclear cells (UCBMCs) on the expression of interleukin (IL)-1β and explore the mechanism via the toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) pathway in hypoxic-ischemic neonatal rats.

Methods:

Seven-day-old Sprague-Dawley neonatal rats were randomly divided into Sham, hypoxic-ischemic brain damage (HIBD), and UCBMC groups. The HIBD model was prepared by Rice-Vannucci method, and UCBMC were transplanted 24 h after HIBD in the UCBMC group. At 7 days after transplantation, changes in neurons and the TLR4 protein were examined by neuronal nuclei (NeuN)/TLR4 immunofluorescence staining. The expression of pNF-κB and IL-1β proteins was detected by immunohistochemical staining and enzyme linked immunosorbent assay (ELISA).

Results:

The percentage of NeuN⁺DAPI⁺ cells in the injured cortex in the UCBMC group was significantly higher than that in the HIBD group and lower than that in the Sham group (P < 0.05). The number of NeuN⁺TLR4⁺DAPI⁺cells in the UCBMC group was significantly lower than that in the HIBD group (P < 0.05) but higher than that in the Sham group (P < 0.05). More pNF-κB⁺ cells were observed in the HIBD group than in Sham and UCBMC groups (P < 0.05), and more pNF-κB⁺ cells were observed in the UCBMC group than in the Sham group (P < 0.05). ELISA results showed that the IL-1β expression in the injured cerebral cortex in the UCMBC group was significantly lower than that in the HIBD group but remained higher than that in the Sham group (P < 0.05).

Conclusions:

UCBMC transplantation could inhibit the IL-1β protein expression in the injured cortex, thereby alleviating HIBD in neonatal rats. The underlying mechanism might be associated with the down- regulation of TLR4 and pNF-κB proteins.