Lipid signaling in experimental epilepsy

The investigation of the molecular changes during lipopolysaccharide-induced systemic inflammation on rat hippocampus by using FTIR spectroscopy

The aim of this study is to reveal the molecular changes accompanying the neuronal hyper-excitability during lipopolysaccharide (LPS)-induced systemic inflammation on rat hippocampus using Fourier transform infrared (FTIR) spectroscopy. For this aim, the body temperature of Wistar albino rats administered LPS or saline was recorded by radiotelemetry. The animals were decapitated when their body temperature began to decrease by 0.5°C after LPS treatment and the hippocampi of them were examined by FTIR spectroscopy. The results indicated that systemic inflammation caused lipid peroxidation, an increase in the amounts of lipids, proteins and nucleic acids, a decrease in membrane order, an increase in membrane dynamics and changes in the secondary structure of proteins. Principal component analysis successfully separated control and LPS-treated groups. In conclusion, significant structural, compositional and functional alterations occur in the hippocampus during systemic inflammation and these changes may have specific characteristics which can lead to neuronal hyper-excitability.

Virus-Induced Epilepsy vs. Epilepsy Patients Acquiring Viral Infection: Unravelling the Complex Relationship for Precision Treatment

The intricate relationship between viruses and epilepsy involves a bidirectional interaction. Certain viruses can induce epilepsy by infecting the brain, leading to inflammation, damage, or abnormal electrical activity. Conversely, epilepsy patients may be more susceptible to viral infections due to factors, such as compromised immune systems, anticonvulsant drugs, or surgical interventions. Neuroinflammation, a common factor in both scenarios, exhibits onset, duration, intensity, and consequence variations. It can modulate epileptogenesis, increase seizure susceptibility, and impact anticonvulsant drug pharmacokinetics, immune system function, and brain physiology. Viral infections significantly impact the clinical management of epilepsy patients, necessitating a multidisciplinary approach encompassing diagnosis, prevention, and treatment of both conditions. We delved into the dual dynamics of viruses inducing epilepsy and epilepsy patients acquiring viruses, examining the unique features of each case. For virus-induced epilepsy, we specify virus types, elucidate mechanisms of epilepsy induction, emphasize neuroinflammation's impact, and analyze its effects on anticonvulsant drug pharmacokinetics. Conversely, in epilepsy patients acquiring viruses, we detail the acquired virus, its interaction with existing epilepsy, neuroinflammation effects, and changes in anticonvulsant drug pharmacokinetics. Understanding this interplay advances precision therapies for epilepsy during viral infections, providing mechanistic insights, identifying biomarkers and therapeutic targets, and supporting optimized dosing regimens. However, further studies are crucial to validate tools, discover new biomarkers and therapeutic targets, and evaluate targeted therapy safety and efficacy in diverse epilepsy and viral infection scenarios.

Impact of drug treatment and drug interactions in post-stroke epilepsy

Stroke is a huge burden on our society and this is expected to grow in the future due to the aging population and the associated co-morbidities. The improvement of acute stroke care has increased the survival rate of stroke patients, and many patients are left with permanent disability, which makes stroke the main cause of adult disability. Unfortunately, many patients face other severe complications such as post-stroke seizures and epilepsy. Acute seizures (ASS) occur within 1 week after the stroke while later occurring unprovoked seizures are diagnosed as post-stroke epilepsy (PSE). Both are associated with a poor prognosis of a functional recovery. The underlying neurobiological mechanisms are complex and poorly understood. There are no universal guidelines on the management of PSE. There is increasing evidence for several risk factors for ASS/PSE, however, the impacts of recanalization, drugs used for secondary prevention of stroke, treatment of stroke co-morbidities and antiseizure medication are currently poorly understood. This review focuses on the common medications that stroke patients are prescribed and potential drug interactions possibly complicating the management of ASS/PSE.

Mass Spectrometry Imaging Deciphers Dysregulated Lipid Metabolism in the Human Hippocampus Affected by Temporal Lobe Epilepsy

Temporal lobe epilepsy (TLE) is the most prevalent form of human epilepsy, often accompanied by neurodegeneration in the hippocampus. Like other neurological diseases, TLE is expected to disrupt lipid homeostasis. However, the lipid architecture of the human TLE brain is relatively understudied, and the molecular mechanism of epileptogenesis is poorly understood. We performed desorption electrospray ionization mass spectrometry imaging of 39 fresh frozen surgical specimens of the human hippocampus to investigate lipid profiles in TLE with hippocampal sclerosis (n = 14) and control (non-TLE; n = 25) groups. In contrast to several previous studies on animal models of epilepsy, we report reduced expression of various important lipids, notably phosphatidylcholine (PC) and phosphatidylethanolamine (PE), in the human TLE hippocampus. In addition, metabolic pathway analysis suggested the possible dysregulation of the Kennedy pathway in TLE, resulting in striking reductions of PC and PE levels. This revelation opens up opportunities to further investigate the associated molecular mechanisms and possible therapeutic targets for TLE.

Inflammatory and immune mechanisms underlying epileptogenesis and epilepsy: From pathogenesis to treatment target

Epilepsy is a brain disease associated with epileptic seizures as well as with neurobehavioral outcomes of this condition. In the last century, inflammation emerged as a crucial factor in epilepsy etiology. Various brain insults through activation of neuronal and non-neuronal brain cells initiate a series of inflammatory events. Growing observations strongly suggest that abnormal activation of critical inflammatory processes contributes to epileptogenesis, a gradual process by which a normal brain transforms into the epileptic brain. Increased knowledge of inflammatory pathways in epileptogenesis has unveiled mechanistic targets for novel antiepileptic therapies. Molecules specifically targeting the pivotal inflammatory pathways may serve as promising candidates to halt the development of epilepsy. The present paper reviews the pieces of evidence conceptually supporting the potential role of inflammatory mechanisms and the relevant blood-brain barrier (BBB) disruption in epileptogenesis. Also, it discusses the mechanisms underlying inflammation-induced neuronal-glial network impairment and highlights innovative neuroregulatory actions of typical inflammatory molecules. Finally, it presents a brief analysis of observations supporting the therapeutic role of inflammation-targeting tiny molecules in epileptic seizures.

Aspirin attenuates spontaneous recurrent seizures in the chronically epileptic mice

OBJECTIVE

Neuroinflammatory processes are pathologic hallmarks of both experimental and human epilepsy, and could be implicated in the neuronal hyperexcitability. Aspirin represents one of the non-selective nonsteroidal anti-inflammatory drugs with fewer side effects in long-term application. This study was carried out to assess the anti-epileptic effects of aspirin when administered during the chronic stage of temporal lobe epilepsy [TLE] in mice. The alteration of hippocampal neurogenesis was also examined for raising a possible mechanism underlying the protective effect of anti-inflammatory treatment in the TLE.

METHODS

Two months after pilocarpine-induced status epilepticus, the chronically epileptic mice were treated with aspirin (20 mg, 60 mg or 80 mg/kg) once a day for 10 weeks. Spontaneous recurrent seizures were monitored by video camera for 2 weeks. To evaluate the profile of hippocampal neurogenesis, the newly generated cells in the dentate gyrus were labeled by the proliferation marker BrdU. The newborn neurons that extended axons to CA3 area were visualized by cholera toxin B subunit retrograde tracing.

RESULTS

Administration of aspirin with a dosage of 60 mg or 80 mg/kg initiated at 2 months after pilocarpine-induced status epilepticus significantly reduced the frequency and duration of spontaneous recurrent seizures. Aspirin treatment also increased the number of newborn neurons with anatomic integration through improving the survival of the newly generated cells.

CONCLUSION

Aspirin treatment during the chronic stage of TLE could attenuate the spontaneous recurrent seizures in mice. Promotion of hippocampal neurogenesis and inhibition of COX-PGE2 pathway might partly contribute to this anti-epileptic effect. Highlights • Aspirin attenuates spontaneous recurrent seizures of chronically epileptic mice • Aspirin increases neurogenesis of chronically epileptic hippocampus by improving the survival of newly generated cells • Promotion of hippocampal neurogenesis and inhibition of COX-PGE2 pathway might partly contribute to anti-epileptic effects of aspirin.

Characterization of the Functional Domains of a Mammalian Voltage-Sensitive Phosphatase

Voltage-sensitive phosphatases (VSPs) are proteins that directly couple changes in membrane electrical potential to inositol lipid phosphatase activity. VSPs thus couple two signaling pathways that are critical for cellular functioning. Although a number of nonmammalian VSPs have been characterized biophysically, mammalian VSPs are less well understood at both the physiological and biophysical levels. In this study, we aimed to address this gap in knowledge by determining whether the VSP from mouse, Mm-VSP, is expressed in the brain and contains a functional voltage-sensing domain (VSD) and a phosphatase domain. We report that Mm-VSP is expressed in neurons and is developmentally regulated. To address whether the functions of the VSD and phosphatase domain are retained in Mm-VSP, we took advantage of the modular nature of these domains and expressed each independently as a chimeric protein in a heterologous expression system. We found that the Mm-VSP VSD, fused to a viral potassium channel, was able to drive voltage-dependent gating of the channel pore. The Mm-VSP phosphatase domain, fused to the VSD of a nonmammalian VSP, was also functional: activation resulted in PI(4,5)P2 depletion that was sufficient to inhibit the PI(4,5)P2-regulated KCNQ2/3 channels. While testing the functionality of the VSD and phosphatase domain, we observed slight differences between the activities of Mm-VSP-based chimeras and those of nonmammalian VSPs. Although the properties of VSP chimeras may not completely reflect the properties of native VSPs, the differences we observed in voltage-sensing and phosphatase activity provide a starting point for future experiments to investigate the function of Mm-VSP and other mammalian VSPs. In conclusion, our data reveal that both the VSD and the lipid phosphatase domain of Mm-VSP are functional, indicating that Mm-VSP likely plays an important role in mouse neurophysiology.

Phosphatidic acid and neurotransmission

Lipids play a vital role in the health and functioning of neurons and interest in the physiological role of neuronal lipids is certainly increasing. One neuronal function in which neuronal lipids appears to play key roles in neurotransmission. Our understanding of the role of lipids in the synaptic vesicle cycle and neurotransmitter release is becoming increasingly more important. Much of the initial research in this area has highlighted the major roles played by the phosphoinositides (PtdIns), diacylglycerol (DAG), and phosphatidic acid (PtdOH). Of these, PtdOH has not received as much attention as the other lipids although its role and metabolism appears to be extremely important. This lipid has been shown to play a role in modulating both exocytosis and endocytosis although its precise role in either process is not well defined. The currently evidence suggest this lipid likely participates in key processes by altering membrane architecture necessary for membrane fusion, mediating the penetration of membrane proteins, serving as a precursor for other important SV cycling lipids, or activating essential enzymes. In this review, we address the sources of PtdOH, the enzymes involved in its production, the regulation of these enzymes, and its potential roles in neurotransmission in the central nervous system.

Dysfunctional epileptic neuronal circuits and dysmorphic dendritic spines are mitigated by platelet-activating factor receptor antagonism

Temporal lobe epilepsy or limbic epilepsy lacks effective therapies due to a void in understanding the cellular and molecular mechanisms that set in motion aberrant neuronal network formations during the course of limbic epileptogenesis (LE). Here we show in in vivo rodent models of LE that the phospholipid mediator platelet-activating factor (PAF) increases in LE and that PAF receptor (PAF-r) ablation mitigates its progression. Synthetic PAF-r antagonists, when administered intraperitoneally in LE, re-establish hippocampal dendritic spine density and prevent formation of dysmorphic dendritic spines. Concomitantly, hippocampal interictal spikes, aberrant oscillations, and neuronal hyper-excitability, evaluated 15–16 weeks after LE using multi-array silicon probe electrodes implanted in the dorsal hippocampus, are reduced in PAF-r antagonist-treated mice. We suggest that over-activation of PAF-r signaling induces aberrant neuronal plasticity in LE and leads to chronic dysfunctional neuronal circuitry that mediates epilepsy.

Molecular analysis of acute and chronic reactive astrocytes in the pilocarpine model of temporal lobe epilepsy

Astroglia, the most abundant glial cells in the mammalian central nervous system (CNS), are considered an emerging key player in seizure induction and progression. Although astrocytes undergo reactive gliosis in temporal lobe epilepsy (TLE) with dramatic morphological and molecular changes, specific astrocyte targets/molecular pathways that contribute to the induction and progression of seizure remain largely unknown. By combining translating ribosomal affinity purification (TRAP) with the pilocarpine model of TLE in BAC aldh1l1 TRAP mice, we profiled translating mRNAs from hippocampal or cortical astrocytes at different phases (3days, 30days, and 60days post-pilocarpine injections) of pilocarpine-induced epilepsy models. Our results found that hippocampal (but not cortical) astrocytes undergo early and unique molecular changes at 3days post-pilocarpine injections. These changes indicate a potentially primary pathogenic role of hippocampal astrocytes in seizure induction and progression and provide new insights about the involvement of specific astrocytic pathways/targets in epilepsy. In particular, we validated expression changes of ocrl and aeg1 in pilocarpine models. Follow-up studies on these genes may reveal new roles of hippocampal astrocytes in TLE.

SDS, a structural disruption score for assessment of missense variant deleteriousness

We have developed a novel structure-based evaluation for missense variants that explicitly models protein structure and amino acid properties to predict the likelihood that a variant disrupts protein function. A structural disruption score (SDS) is introduced as a measure to depict the likelihood that a case variant is functional. The score is constructed using characteristics that distinguish between causal and neutral variants within a group of proteins. The SDS score is correlated with standard sequence-based deleteriousness, but shows promise for improving discrimination between neutral and causal variants at less conserved sites. The prediction was performed on 3-dimentional structures of 57 gene products whose homozygous SNPs were identified as case-exclusive variants in an exome sequencing study of epilepsy disorders. We contrasted the candidate epilepsy variants with scores for likely benign variants found in the EVS database, and for positive control variants in the same genes that are suspected to promote a range of diseases. To derive a characteristic profile of damaging SNPs, we transformed continuous scores into categorical variables based on the score distribution of each measurement, collected from all possible SNPs in this protein set, where extreme measures were assumed to be deleterious. A second epilepsy dataset was used to replicate the findings. Causal variants tend to receive higher sequence-based deleterious scores, induce larger physico-chemical changes between amino acid pairs, locate in protein domains, buried sites or on conserved protein surface clusters, and cause protein destabilization, relative to negative controls. These measures were agglomerated for each variant. A list of nine high-priority putative functional variants for epilepsy was generated. Our newly developed SDS protocol facilitates SNP prioritization for experimental validation.

The role of inflammation in epileptogenesis

One compelling challenge in the therapy of epilepsy is to develop anti-epileptogenic drugs with an impact on the disease progression. The search for novel targets has focused recently on brain inflammation since this phenomenon appears to be an integral part of the diseased hyperexcitable brain tissue from which spontaneous and recurrent seizures originate. Although the contribution of specific proinflammatory pathways to the mechanism of ictogenesis in epileptic tissue has been demonstrated in experimental models, the role of these pathways in epileptogenesis is still under evaluation. We review the evidence conceptually supporting the involvement of brain inflammation and the associated blood-brain barrier damage in epileptogenesis, and describe the available pharmacological evidence where post-injury intervention with anti-inflammatory drugs has been attempted. Our review will focus on three main inflammatory pathways, namely the IL-1 receptor/Toll-like receptor signaling, COX-2 and the TGF-β signaling. The mechanisms underlying neuronal-glia network dysfunctions induced by brain inflammation are also discussed, highlighting novel neuromodulatory effects of classical inflammatory mediators such as cytokines and prostaglandins. The increase in knowledge about a role of inflammation in disease progression, may prompt the use of specific anti-inflammatory drugs for developing disease-modifying treatments. This article is part of the Special Issue entitled 'New Targets and Approaches to the Treatment of Epilepsy'.

Aspirin attenuates spontaneous recurrent seizures and inhibits hippocampal neuronal loss, mossy fiber sprouting and aberrant neurogenesis following pilocarpine-induced status epilepticus in rats

Accumulating data suggest that inflammation may contribute to epileptogenesis in experimental models as well as in humans. However, whether anti-inflammatory treatments can prevent epileptogenesis still remains controversial. Here, we examined the anti-epileptogenic effect and possible mechanisms of aspirin, a non-selective Cyclooxygenase (COX) inhibitor, in a rat model of lithium-pilocarpine-induced status epilepticus (SE). Epileptic rats were treated with aspirin (20mg/kg) at 0h, 3h, or 24h after the termination of SE, followed by once daily treatment for the subsequent 20 days. We found that aspirin treatment significantly reduced the frequency and duration of spontaneous recurrent seizures during the chronic epileptic phase. Hippocampal neuronal loss five weeks after SE was also attenuated in the CA1, CA3 and hilus following aspirin administration. Furthermore, the aberrant migration of newly generated granule cells and the formation of hilar basal dendrites were prevented by aspirin. Treatment with aspirin starting at 3h or 24h after SE also suppressed the development of mossy fiber sprouting. These findings suggest the possibility of a relative broad time-window for aspirin intervention in the epileptogenic process after injury. Aspirin may serve as a potential adjunctive therapy for individuals susceptible to chronic epilepsy.

Frontier of epilepsy research - mTOR signaling pathway

Studies of epilepsy have mainly focused on the membrane proteins that control neuronal excitability. Recently, attention has been shifting to intracellular proteins and their interactions, signaling cascades and feedback regulation as they relate to epilepsy. The mTOR (mammalian target of rapamycin) signal transduction pathway, especially, has been suggested to play an important role in this regard. These pathways are involved in major physiological processes as well as in numerous pathological conditions. Here, involvement of the mTOR pathway in epilepsy will be reviewed by presenting; an overview of the pathway, a brief description of key signaling molecules, a summary of independent reports and possible implications of abnormalities of those molecules in epilepsy, a discussion of the lack of experimental data, and questions raised for the understanding its epileptogenic mechanism.

Small molecule analysis and imaging of fatty acids in the zebra finch song system using time-of-flight-secondary ion mass spectrometry

Fatty acids are central to brain metabolism and signaling, but their distributions within complex brain circuits have been difficult to study. Here we applied an emerging technique, time-of-flight secondary ion mass spectrometry (ToF-SIMS), to image specific fatty acids in a favorable model system for chemical analyses of brain circuits, the zebra finch (Taeniopygia guttata). The zebra finch, a songbird, produces complex learned vocalizations under the control of an interconnected set of discrete, dedicated brain nuclei 'song nuclei'. Using ToF-SIMS, the major song nuclei were visualized by virtue of differences in their content of essential and non-essential fatty acids. Essential fatty acids (arachidonic acid and docosahexaenoic acid) showed distinctive distributions across the song nuclei, and the 18-carbon fatty acids stearate and oleate discriminated the different core and shell subregions of the lateral magnocellular nucleus of the anterior nidopallium. Principal component analysis of the spectral data set provided further evidence of chemical distinctions between the song nuclei. By analyzing the robust nucleus of the arcopallium at three different ages during juvenile song learning, we obtain the first direct evidence of changes in lipid content that correlate with progression of song learning. The results demonstrate the value of ToF-SIMS to study lipids in a favorable model system for probing the function of lipids in brain organization, development and function.

Inflammation and prevention of epileptogenesis

CNS injuries such as trauma, stroke, viral infection, febrile seizures, status epilepticus occurring either in infancy or during a lifetime are considered common risk factors for developing epilepsy. Long term CNS inflammation develops rapidly after these events, suggesting that a pro-inflammatory state in the brain might play a role in the development of the epileptic process. This hypothesis is corroborated by two main lines of evidence: (1) the upregulation of pro-inflammatory signals during epileptogenesis in brain areas of seizure onset/generalization; (2) pharmacological targeting of specific pro-inflammatory pathways after status epilepticus or in kindling shows antiepileptogenic effects. The mechanisms by which pro-inflammatory molecules might favor the establishment of chronic neuronal network hyperexcitability involve both rapid, non-transcriptional effects on glutamate and GABA receptors, and transcriptional activation of genes involved in synaptic plasticity. This emerging evidence predicts that pharmacological interventions targeting brain inflammation might provide a key to new antiepileptic drug design.

Why mesial temporal lobe epilepsy with hippocampal sclerosis is progressive: uncontrolled inflammation drives disease progression?

Mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) is a group of chronic disorders characterized by prominent neuronal loss and gliosis in the hippocampus and amygdala. Newly published data indicate that it may be a progressive disease, but the mechanism underlying the progressive nature remains unknown. Recently, substantial evidence for an inflammatory mechanism in MTLE has been documented. We are therefore presenting a review of literature concerning the effects of uncontrolled inflammation on the disease progression of MTLE-HS. We found that increasing amounts of evidence support the association between uncontrolled inflammation and progression of the disease. Uncontrolled inflammatory processes may be a main mechanism underlying the self-propagating cycle of uncontrolled inflammation, blood-brain barrier damage, and seizures that drive the progressive nature. Thus it is important to unravel the principles of communication between the different factors in this cycle. The dynamic modulation of inflammatory processes aimed at preventing or interrupting this cycle has the potential to emerge as a novel therapeutic strategy. This line of therapy might offer new perspectives on the pharmacologic treatment of seizures, and possibly on delaying disease progression or retarding epileptogenesis as well.

Soman increases neuronal COX-2 levels: possible link between seizures and protracted neuronal damage

Nerve agent-induced seizures cause neuronal damage in brain limbic and cortical circuits leading to persistent behavioral and cognitive deficits. Without aggressive anticholinergic and benzodiazepine therapy, seizures can be prolonged and neuronal damage progresses for extended periods of time. The objective of this study was to determine the effects of the nerve agent soman on expression of cyclooxygenase-2 (COX-2), the initial enzyme in the biosynthetic pathway of the proinflammatory prostaglandins and a factor that has been implicated in seizure initiation and propagation. Rats were exposed to a toxic dose of soman and scored behaviorally for seizure intensity. Expression of COX-2 was determined throughout brain from 4h to 7 days after exposure by immunohistochemistry and immunoblotting. Microglial activation and astrogliosis were assessed microscopically over the same time-course. Soman increased COX-2 expression in brain regions known to be damaged by nerve agents (e.g., hippocampus, amygdala, piriform cortex and thalamus). COX-2 expression was induced in neurons, and not in microglia or astrocytes, and remained elevated through 7 days. The magnitude of COX-2 induction was correlated with seizure intensity. COX-1 expression was not changed by soman. Increased expression of neuronal COX-2 by soman is a late-developing response relative to other signs of acute physiological distress caused by nerve agents. COX-2-mediated production of prostaglandins is a consequence of the seizure-induced neuronal damage, even after survival of the initial cholinergic crisis is assured. COX-2 inhibitors should be considered as adjunct therapy in nerve agent poisoning to minimize nerve agent-induced seizure activity.

Synchrotron FTIR micro-spectroscopy study of the rat hippocampal formation after pilocarpine-evoked seizures

In the present work, synchrotron radiation Fourier transform infrared (SRFTIR) micro-spectroscopy and imaging were used for topographic and semi-quantitative biochemical analysis of rat brain tissue in cases of pilocarpine-induced epilepsy. The tissue samples were analyzed with a beam defined by small apertures and spatial resolution steps of 10 microm which allowed us to probe the selected cellular layers of hippocampal formation. Raster scanning of the samples has generated 2D chemical cartographies revealing the distribution of proteins, lipids and nucleic acids. Spectral analysis has shown changes in the saturation level of phospholipids and relative secondary structure of proteins. Special interest was put in the analysis of two areas of the hippocampal formation (sector 3 of the Ammon's horn, CA3 and dentate gyrus, DG) in which elemental abnormalities were observed during our previous studies. Statistically significant increase in the saturation level of phospholipids (increased ratio of the absorption intensities at around 2921 and 2958 cm(-1)) as well as conformational changes of proteins (beta-type structure discrepancies as shown by the increased ratio of the absorbance intensities at around 1631 and 1657 cm(-1) as well as the ratio of the absorbance at 1548 and 1657 cm(-1)) were detected in pyramidal cells of CA3 area as well as in the multiform and molecular layers of DG. The findings presented here suggest that abnormalities in the protein secondary structure and increases in the level of phospholipid saturation could be involved in mechanisms of neurodegenerative changes following the oxidative stress evoked in brain areas affected by pilocarpine-induced seizures.

The COX-2 inhibitor parecoxib is neuroprotective but not antiepileptogenic in the pilocarpine model of temporal lobe epilepsy

The enzyme cyclooxygenase-2 (COX-2), which catalyzes the production of pro-inflammatory prostaglandins, is induced in the brain after various insults, thus contributing to brain inflammatory processes involved in the long-term consequences of such insults. Mounting evidence supports that inflammation may contribute to epileptogenesis and neuronal injury developing after brain insults. Anti-inflammatory treatments, such as selective COX-2 inhibitors, may thus constitute a novel approach for anti-epileptogenesis or disease-modification after brain injuries such as head trauma, cerebral ischemia or status epilepticus (SE). However, recent rat experiments with prophylactic administration of two different COX-2 inhibitors after SE resulted in conflicting results. In the present study, we evaluated whether treatment with parecoxib, a pro-drug of the highly potent and selective COX-2 inhibitor valdecoxib, alters the long-term consequences of a pilocarpine-induced SE in rats. Parecoxib was administered twice daily at 10 mg/kg for 18 days following SE. Five weeks after termination of treatment, spontaneous recurrent seizures were recorded by continuous video/EEG monitoring. Prophylactic treatment with parecoxib prevented the SE-induced increase in prostaglandin E(2) and reduced neuronal damage in the hippocampus and piriform cortex. However, the incidence, frequency or duration of spontaneous seizures developing after SE or the behavioral and cognitive alterations associated with epilepsy were not affected by parecoxib. Only the severity of spontaneous seizures was reduced, indicating a disease-modifying effect. These results substantiate that COX-2 contributes to neuronal injury developing after SE, but inhibition of COX-2 is no effective means to modify epileptogenesis.

Blood-brain barrier breakdown-inducing astrocytic transformation: novel targets for the prevention of epilepsy

Epileptogenesis is common following brain insults such as trauma, ischemia and infection. However, the mechanisms underlying injury-related epileptogenesis remain unknown. Recent studies demonstrated impaired integrity of the blood-brain barrier (BBB) during epileptogenesis. Here we review accumulating experimental evidence supporting the potential involvement of primary BBB lesion in epileptogenesis. Data from animal experiments demonstrate that primary breakdown of the BBB prone animals to develop focal neocortical epilepsy that is followed by neuronal loss and impaired functions. The extravasation of albumin from the circulation into the brain neuropil was found to be sufficient for the induction of epileptogenesis. Albumin binds to transforming growth factor beta receptor 2 (TGFbetaR2) in astrocytes and induces rapid transcriptional modifications, astrocytic transformation and dysfunction. We highlight a novel cascade of events which is initiated by increased BBB permeability, eventually leading to neuronal dysfunction, epilepsy and cell loss. We review potential mechanisms and existing experimental evidence for the important role of astrocytes and the TGFbeta pathway in epileptogenesis. Finally, we review evidence from human clinical data supporting the involvement of BBB lesion in epilepsy. We propose that primary vascular injury, and specifically BBB breakdown and repair, are key elements in altered interactions within the neurovascular unit and thus may serve as new therapeutic targets.

Dopaminergic but not glutamatergic neurotransmission is increased in the striatum after selective cyclooxygenase-2 inhibition in normal and hemiparkinsonian rats

In the present work, we studied the effect of the selective cyclooxygenase-2 (COX-2) inhibitors, compound 11 g, celecoxib and selective COX-1 inhibitor SC-560 (intraperitoneally and acutely) on striatal glutamatergic and dopaminergic neurotransmission in normal and substantia nigra pars compacta (SNc)-lesioned rats using the microdialysis technique. We also investigated the effect of acute COX inhibition on the damaged SNc neurons. Our results indicate a significant increase in dopaminergic neurotransmission and a decrease in glutamatergic neurotransmission (P<0.05) only after selective COX-2 inhibition in the striatum of normal and hemiparkinsonian rats. Nonetheless, neither COX-1 nor COX-2 inhibitors showed any improvement in the damaged SNc neurons.

Simultaneous determination ofmyo-inositol andscyllo-inositol by MEKC as a rapid monitoring tool for inositol levels

A simple and rapid MEKC method was developed for the simultaneous determination of myo-inositol, scyllo-inositol, and glucose. Prior to electrophoretic separation, the nonfluorescent inositols and glucose were derivatized by N-methylisatoic anhydride at 25 degrees C for 10 min so that they could be detected by a fluorescence detector during separation. The good separation with high efficiency by MEKC was achieved in 13 min with a glycine buffer containing SDS and PEG 4000. Several parameters affecting the separation were studied, including the pH of BGE, the concentrations of glycine, SDS, and PEG 4000, and the applied voltage. Using glycerol as an internal standard, the linear ranges of the method for myo-inositol, scyllo-inositol, and glucose were 0.03-10, 0.01-5, and 0.05-20 mM; the concentration LODs of myo-inositol, scyllo-inositol, and glucose were 0.020, 0.0078, and 0.026 mM, respectively. The method was applied to analyze extracellular myo-inositol and glucose in the microdialysates from rat brain cortex of ischemia animal model and intracellular myo-inositol and scyllo-inositol in the rat brain extract.

Non-steroidal anti-inflammatory drugs in Parkinson's disease

Parkinson's disease (PD) is known to be a chronic and progressive neurodegenerative disease caused by a selective degeneration of dopaminergic (DAergic) neurons in the substantia nigra pars compacta (SNc). A large body of experimental evidence indicates that the factors involved in the pathogenesis of this disease are several, occurring inside and outside the DAergic neuron. Recently, the role of the neuron-glia interaction and the inflammatory process, in particular, has been the object of intense study by the research community. It seems to represent a new therapeutic approach opportunity for this neurological disorder. Indeed, it has been demonstrated that the cyclooxygenase type 2 (COX-2) is up-regulated in SNc DAergic neurons in both PD patients and animal models of PD and, furthermore, non-steroidal anti-inflammatory drugs (NSAIDs) pre-treatment protects against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) or 6 hydroxydopamine (6-OHDA)-induced nigro-striatal dopamine degeneration. Moreover, recent epidemiological studies have revealed that the risk of developing PD is reduced in humans who make therapeutical use of NSAIDs. Consequently, it is hypothesized that they might delay or prevent the onset of PD. However, whether or not these common drugs may also be of benefit to those individuals who already have Parkinson's disease has not as yet been shown. In this paper, evidence relating to the protective effects of aspirin or other NSAIDs on DAergic neurons in animal models of Parkinson's disease will be discussed. In addition, the pharmacological mechanisms by which these molecules can exert their neuroprotective effects will be reviewed. Finally, epidemiological data exploring the effectiveness of NSAIDs in the prevention of PD and their possible use as adjuvants in the therapy of this neurodegenerative disease will also be examined.

Non-targeted profiling of lipids during kainate-induced neuronal injury

Kainate is a glutamate analog that has been widely used in pharmacological studies of neuronal injury related to ischemic conditions and epilepsy. While altered lipid metabolism has been implicated in kainate action, no study has yet investigated the associated changes in lipid metabolites on a systems scale. Here we describe a mass spectrometry-based approach for profiling of lipid mixtures in a nontargeted fashion. Combined with tandem mass spectrometry, this method aims to identify lipids that are altered between two conditions, the kainate-treated and the control hippocampal tissues. In addition to reductions in major phospholipids with mainly polyunsaturated fatty acyl chains, we find elevated levels of ions that correspond to acylated forms of phosphatidylethanolamines and ceramides. Acylated phosphatidylethanolamines are neuroprotective lipids and precursors for anandamide, which signals via cannabinoid receptors. Quantitative analysis of ceramides shows that many molecular species with different acyl compositions are increased during kainate treatment. This increase is mainly restricted to neurons rather than other brain cells in the hippocampus as revealed by immunohistochemistry of brain slices.