Kainic Acid-induced Seizures Research Articles

P38 Regulates Kainic Acid-Induced Seizure and Neuronal Firing via Kv4.2 Phosphorylation.

The subthreshold, transient A-type K+ current is a vital regulator of the excitability of neurons throughout the brain. In mammalian hippocampal pyramidal neurons, this current is carried primarily by ion channels comprising Kv4.2 α-subunits. These channels occupy the somatodendritic domains of these principle excitatory neurons and thus regulate membrane voltage relevant to the input–output efficacy of these cells. Owing to their robust control of membrane excitability and ubiquitous expression in the hippocampus, their dysfunction can alter network stability in a manner that manifests in recurrent seizures. Indeed, growing evidence implicates these channels in intractable epilepsies of the temporal lobe, which underscores the importance of determining the molecular mechanisms underlying their regulation and contribution to pathologies. Here, we describe the role of p38 kinase phosphorylation of a C-terminal motif in Kv4.2 in modulating hippocampal neuronal excitability and behavioral seizure strength. Using a combination of biochemical, single-cell electrophysiology, and in vivo seizure techniques, we show that kainic acid-induced seizure induces p38-mediated phosphorylation of Thr607 in Kv4.2 in a time-dependent manner. The pharmacological and genetic disruption of this process reduces neuronal excitability and dampens seizure intensity, illuminating a cellular cascade that may be targeted for therapeutic intervention to mitigate seizure intensity and progression.

MicroRNA-451 Aggravates Kainic Acid-induced Seizure and Neuronal Apoptosis by Targeting GDNF

Epilepsy is a common and serious neurological disease that causes recurrent episodes, but its molecular mechanism remains unclear. Abnormal miRNA expression is associated with epilepsy, including miR-451. This research investigated the role of miR-451 in seizure and its detailed mechanism. The seizure mice model was induced by kainic acid (KA) injection to the right lateral cerebral ventricle. Behavioral changes in mice were observed and evaluated by the Racine Scale. The miR-451 knockout mice were established by adenovirus infection. The in vitro model was performed by miR-451 mimics transfected HEK-293 cells. The amount of neuronal death and morphological changes were evaluated by Nissl staining and H&E staining. The results showed that miR-451 is up regulated in KA-induced seizure models and miR- 451 knockout decreased the behavior score and improved the pathological changes of the hippocampus. Besides, MiR-451 knockout inhibited the apoptosis of hippocampal neurons. Bioinformatics studies have shown that glial cell line-derived neurotrophic factor (GDNF) is a target gene of miR-451. MiR-451 could negatively regulate the expression of GDNF. GDNF overexpression could reverse the effect of miR-451 on KA induced brain injury and neuronal apoptosis. This research demonstrates that miR-451 can affect the behavior of KA-induced epilepsy mice and hippocampal neuronal damage by regulating GDNF expression. The results would provide an experimental foundation for further research about the potential contribution of mi- RNAs to epilepsy pathophysiology.

Kainic acid-induced seizures in the common marmoset

Treatment of epilepsy remains difficult because patients suffer from pharmacoresistant forms of the disease and drug side-effects. Thus, there is an urgent need to identify not only new antiepileptic drug candidates but also novel epileptic animal models. Here, we characterize seizures induced with kainic acid (KA) in the common marmoset (Callithrix jacchus). Adult marmosets received 0.1, 1, or 10 mg/kg of KA subcutaneously. All animals exhibited early convulsive behavior (seizure scores of I and II on the Racine scale). Seizure scores were low at lower KA doses, but the highest dose of KA tested triggered generalized seizures (scores IV and V on the Racine scale). We next performed preliminary evaluation of the efficacy of the antiepileptic drug diazepam. This drug at 1 mg/kg (delivered subcutaneously) prevented 10 mg/kg KA-induced stage V seizures. KA administration to marmosets reliably triggers generalized seizures; therefore, the marmoset is a useful animal model in which to analyze the seizures of a nonhuman primate brain and to develop new treatments for epilepsy.

Mild Inactivation of RE-1 Silencing Transcription Factor (REST) Reduces Susceptibility to Kainic Acid-Induced Seizures.

RE-1 Silencing Transcription factor (REST) controls several steps in neural development by modulating the expression of a wide range of neural genes. Alterations in REST expression have been associated with the onset of epilepsy; however, whether such alterations are deleterious or represent a protective homeostatic response remains elusive. To study the impact of REST modulation on seizure propensity, we developed a tool for its negative modulation in vivo. The tool is composed of the paired-amphipathic helix 1 (PAH1) domain, a competitive inhibitor of REST activation by mSin3, fused to the light-oxygen-voltage sensing 2 (LOV2) domain of Avena sativa phototropin 1, a molecular switch to alternatively hide or expose the PAH1 inhibitor. We employed the C450A and I539E light-independent AsLOV2 variants to mimic the closed (inactive) and open (active) states of LOV2-PAH1, respectively. Recombinant AAV1/2 viral particles (rAAVs) allowed LOV2-PAH1 expression in HEK293T cells and primary neurons, and efficiently transduced hippocampal neurons in vivo. mRNA expression analysis revealed an increased expression of several neuronal genes in the hippocampi of mice expressing the open probe. AAV-transduced mice received a single dose of kainic acid (KA), a treatment known to induce a transient increase of REST levels in the hippocampus. Remarkably, mice expressing the active variant displayed a reduced number of KA-induced seizures, which were less severe compared to mice carrying the inactive probe. These data support the validity of our tool to modulate REST activity in vivo and the potential impact of REST modulation on epileptogenesis.

SGK1.1 Reduces Kainic Acid-Induced Seizure Severity and Leads to Rapid Termination of Seizures.

Approaches to control epilepsy, one of the most important idiopathic brain disorders, are of great importance for public health. We have previously shown that in sympathetic neurons the neuronal isoform of the serum and glucocorticoid-regulated kinase (SGK1.1) increases the M-current, a well-known target for seizure control. The effect of SGK1.1 activation on kainate-induced seizures and neuronal excitability was studied in transgenic mice that express a permanently active form of the kinase, using electroencephalogram recordings and electrophysiological measurements in hippocampal brain slices. Our results demonstrate that SGK1.1 activation leads to reduced seizure severity and lower mortality rates following status epilepticus, in an M-current-dependent manner. EEG is characterized by reduced number, shorter duration, and early termination of kainate-induced seizures in the hippocampus and cortex. Hippocampal neurons show decreased excitability associated to increased M-current, without altering basal synaptic transmission or other neuronal properties. Altogether, our results reveal a novel and selective anticonvulsant pathway that promptly terminates seizures, suggesting that SGK1.1 activation can be a potent factor to secure the brain against permanent neuronal damage associated to epilepsy.

Intracerebroventricular administration of histidine reduces kainic acid-induced convulsive seizures in mice.

Kainic acid (KA)-induced seizures and other experimental models of epilepsy have been proven to be instrumental in identifying novel targets that could be responsible for human icto- and epileptogenesis. We have previously shown that the ablation of pharmacoresistant voltage-gated Ca2+ channels with Cav2.3 as central ion-conducting pore (R-type Ca2+ channel) reduces the sensitivity towards KA-induced epilepsy in mice. In vivo, Cav2.3 channels are thought to be under tight allosteric control by endogenous loosely bound trace metal cations (Zn2+ and Cu2+) that suppress channel gating via a high-affinity trace metal-binding site. Metal dyshomeostasis in the brain, which is a common feature of (KA-induced) seizures, could therefore alter the normal function of Cav2.3 channels and may shift hippocampal and neocortical signaling towards hyperexcitation. To investigate the role of loosely bound metal ions for KA-induced hyperexcitation in vivo, we examined the effects of manipulating brain trace metal homeostasis in mice. To this end, we developed a murine system for intracerebroventricular administration of trace metal ions and/or histidine (His), which can bind Zn2+ and Cu2+ and is involved in their transendothelial transport at the blood-brain barrier. Unexpectedly, our preliminary findings indicate that application of His alone but not in the presence of Zn2+ has substantial beneficial effects on the outcome of KA-induced epilepsy in mice. As such, our results emphasize previous findings on the complex, two-sided role of loosely bound metal ions with regard to neuronal excitation and degeneration under pathophysiological conditions.

Soluble Epoxide Hydrolase Inhibition Attenuates Excitotoxicity Involving 14,15-Epoxyeicosatrienoic Acid-Mediated Astrocytic Survival and Plasticity to Preserve Glutamate Homeostasis.

Astrocytes play pivotal roles in regulating glutamate homeostasis at tripartite synapses. Inhibition of soluble epoxide hydrolase (sEHi) provides neuroprotection by blocking the degradation of 14,15-epoxyeicosatrienoic acid (14,15-EET), a lipid mediator whose synthesis can be activated downstream from group 1 metabotropic glutamate receptor (mGluR) signaling in astrocytes. However, it is unclear how sEHi regulates glutamate excitotoxicity. Here, we used three primary rat cortical culture systems, neuron-enriched (NE), astrocyte-enriched glia-neuron mix (GN), and purified astrocytes, to delineate the underlying mechanism by which sEHi and 14,15-EET attenuate excitotoxicity. We found that sEH inhibitor 12-(3-adamantan-1-yl-ureido)-dodecanoic acid (AUDA) and 14,15-EET both attenuated N-methyl-D-aspartate (NMDA)-induced neurite damage and cell death in GN, not NE, cortical cultures. The anti-excitotoxic effects of 14,15-EET and AUDA were both blocked by the group 1 mGluR5 antagonist 2-methyl-6-(phenylethynyl)pyridine (MPEP), as were their protective effects against NMDA-disrupted perineuronal astrocyte processes expressing glutamate transporter-1 (GLT-1) and subsequent glutamate uptake. Knockdown of sEH expression also attenuated NMDA neurotoxicity in mGluR5- and GLT-1-dependent manners. The 14,15-EET/AUDA-preserved astroglial integrity was confirmed in glutamate-stimulated primary astrocytes along with the reduction of the c-Jun N-terminal kinase 1 phosphorylation, in which the 14,15-EET effect is mGluR5-dependent. In vivo studies validated that sEHi and genetic deletion of sEH (Ephx2-KO) ameliorated excitotoxic kainic acid-induced seizure, memory impairment, and neuronal loss while preserving GLT-1-expressing perineuronal astrocytes in hippocampal CA3 subregions. These results suggest that 14,15-EET mediates mGluR5-dependent anti-excitotoxicity by protecting astrocytes to maintain glutamate homeostasis, which may account for the beneficial effect of sEH inhibition in excitotoxic brain injury and diseases.

Correlation of phosphorylated S6 protein expression in blood and brain tissue in mice and rats with kainic acid-induced seizure

To determine the correlation of phosphorylated ribosomal S6 protein (P-S6) content in blood and brain tissue in mice and rats with seizure. Seizure models were induced by intraperitoric injection of kainic acid (KA) in C57BL/mice and SD rats. Flow cytometry was used to detect the content of P-S6 in blood; Western blot was used to detect the expression of P-S6 in brain tissues. The correlation between P-S6 expression in blood and in brain tissue was examine by Pearson analysis, and the correlation between P-S6 expression in blood and the severity of seizure was also observed. Western blotting analysis showed that the expression of P-S6 was significantly increased in peripheral blood and brain tissue in mice 1 h after KA-induced seizure,and the expression levels increased to (1.49±0.45) times (P<0.05) and (2.55±0.66) times (P <0.01) of the control group, respectively. Flow cytometry showed that the positive percentage and average fluorescence intensity of P-S6 in the blood of mice increased significantly 1 h after KA-induced seizures (P<0.01), which was consistent with the expression of P-S6 in brain tissue (r=0.8474, P<0.01). Flow cytometry showed that the average fluorescence intensity of P-S6 in blood increased from 14.89±9.75 to 52.35±21.72 (P<0.01) in rats with seizure, which was consistent with the change of P-S6 in brain tissue (r=0.9385, P<0.01). Rats with higher levels of seizure were of higher levels of P-S6 in peripheral blood. Consistent correlation of P-S6 expression is demonstrated in peripheral blood and in brain tissue after KA-induced seizure, suggesting that the expression of P-S6 in blood can accurately reflect the changes of mTOR signaling pathway in brain tissue.

Neuroprotective effects of isoliquiritigenin against cognitive impairment via suppression of synaptic dysfunction, neuronal injury, and neuroinflammation in rats with kainic acid-induced seizures

Epileptogenesis is a dynamic process initiated by insults to brain and commonly accompanied by cognitive impairment. Isoliquiritigenin (ISL), a flavonoid in licorice, has a broad spectrum of biological effects including anti-inflammatory and antioxidant activities. However, the protective effects of ISL against cognitive impairment in epileptic processes and the underlying molecular mechanism are not well understood. To address these questions, we established an reproducible seizure model by intracerebroventricular injection of kainic acid (KA) in 21-day-old rats; ISL was intraperitoneally administered three times prior to KA injection, and changes in cognitive function; synaptic plasticity; neuronal injury; number of glial cells; and expression of pro-inflammatory cytokines and nuclear factor-like (NRF)2 signaling and NACHT, LRR, and PYD domains-containing protein (NLRP)3 inflammasome components in the hippocampus were examined. Rats with KA-induced seizures showed longer average escape latency and decreases in the number of platform crossings and average time spent in the target quadrant in the Morris water maze; ISL pretreatment reversed this decline in cognitive impairment and increased the protein levels of synaptophysin, postsynaptic density-95 and brain-derived neurotrophic factor while reducing the number of Fluoro Jade B-positive cells, microglia, and astrocytes; cleaved-Caspase-3 and -9 protein levels; and tumor necrosis factor-α, interleukin (IL)-1β, and IL-18 production. It also enhanced the nuclear localization of NRF2, hemeoxygenase-1, and NAD(P)H:quinone oxidoreductase (NQO) 1, and reversed the upregulation of NLRP3 inflammasome components NLRP3 and Caspase-1 induced by KA injection. Thus, ISL protects against cognitive impairment in KA-induced epileptic processes possibly through regulation of NRF2 signaling and the NLRP3 inflammasome pathway.

Microglial proliferation and monocyte infiltration contribute to microgliosis following status epilepticus

Microglial activation has been recognized as a major contributor to inflammation of the epileptic brain. Seizures are commonly accompanied by remarkable microgliosis and loss of neurons. In this study, we utilize the CX3CR1GFP/+ CCR2RFP/+ genetic mouse model, in which CX3CR1+ resident microglia and CCR2+ monocytes are labeled with GFP and RFP, respectively. Using a combination of time-lapse two-photon imaging and whole-cell patch clamp recording, we determined the distinct morphological, dynamic, and electrophysiological characteristics of infiltrated monocytes and resident microglia, and the evolution of their behavior at different time points following kainic acid-induced seizures. Seizure activated microglia presented enlarged somas with less ramified processes, whereas, infiltrated monocytes were smaller, highly motile cells that lacked processes. Moreover, resident microglia, but not infiltrated monocytes, proliferate locally in the hippocampus after seizure. Microglial proliferation was dependent on the colony-stimulating factor 1 receptor (CSF-1R) pathway. Pharmacological inhibition of CSF-1R reduced seizure-induced microglial proliferation, which correlated with attenuation of neuronal death without altering acute seizure behaviors. Taken together, we demonstrated that proliferation of activated resident microglia contributes to neuronal death in the hippocampus via CSF-1R after status epilepticus, providing potential therapeutic targets for neuroprotection in epilepsy.

Silencing MicroRNA-155 Attenuates Kainic Acid-Induced Seizure by Inhibiting Microglia Activation

Objective(s): Neuroinflammation is an important contributor to the development of seizures and epilepsy. Micro-RNA-155 (miR-155) plays a critical role in immunity and ­inflammation. This study aims to explore the function of miR-155 and miR-155-mediated inflammation in epilepsy. Methods: About 8-week-old male C57BL/6 mice were administered an intraperitoneal injection (i.p.) of kainic acid (KA) (15 mg/kg) or saline. The mice in the KA group developing acute seizure were further subjected to intracerebroventricular injection (i.c.v.) of antagomir negative control (NC) or miR-155 antagomir. Animal behavior was observed according to Racine’s scale, and electroencephalographs were recorded. Primary microglia were cultured and treated with antagomir NC or antagomir. Whole-cell electrophysiological recording was conducted to detect the spontaneous EPSCs and IPSCs in the neurons treated with different conditioned medium from those microglia. miR-155 were detected by qRT-PCR in those models, as well as in the brain or blood from epileptic patients and healthy controls. Results: miR-155 was abundantly expressed in glial cells compared with neurons, and its expression was markedly elevated in the brain of epilepsy patients and KA-induced seizure mice. Silencing miR-155 attenuated KA-induced seizure, abnormal electroencephalography, proinflammatory cytokine expression, and microglia morphology change. Moreover, conditioned media from KA-treated microglia impaired neuron excitability, whereas conditioned media from KA and miR-155 antagomir co-treated microglia had no such effects. Finally, miR-155 levels were significantly higher in the blood of epilepsy patients than those of healthy controls. Conclusion(s): These findings demonstrate that aberrant upregulation of miR-155 contributes to epileptogenesis through inducing microglia neuroinflammation.

Protective effects of lycopene on kainic acid-induced seizures

Lycopene (LCP) is a carotenoid that protects against many diseases by alleviating oxidative stress. However, the effect of LCP on epileptic seizures has not been examined well in previous studies. In the current work, we employed kainic acid (KA) to induce experimental epileptic seizures in mice, and investigated the function of LCP during this process. We found that the onset and extent of KA-induced seizures were alleviated in LCP-pretreated mice. Nissl staining of hippocampus showed that the granule cell dispersion lesion induced by KA was improved by the LCP treatment. Additionally, we analyzed the oxidative stress levels in mice and found that LCP elevated SOD activity and suppressed MDA level in KA-induced seizures. Moreover, the expression of GABA receptors was influenced by LCP treatment. LCP suppressed the upregulation of gabrb2 and gabrb3 induced by KA, whereas it enhanced the expression of gabrb1. Results suggested that LCP plays a protective function in KA-induced seizures. Hence, it may be a potential functional food alternative for controlling and treating epileptic seizures.

Diving responses elicited by nasopharyngeal irrigation mimic seizure-associated central apneic episodes in a rat model

The spread of epileptic seizure activity to brainstem respiratory and autonomic regions can elicit episodes of obstructive apnea and of central apnea with significant oxygen desaturation and bradycardia. Previously, we argued that central apneic events were not consequences of respiratory or autonomic activity failure, but rather an active brainstem behavior equivalent to the diving response resulting from seizure spread.To test the similarities of spontaneous seizure-associated central apneic episodes to evoked diving responses, we used nasopharyngeal irrigation with either cold water or mist for 10 or 60 s to elicit the diving response in urethane-anesthetized animals with or without kainic acid-induced seizure activity.Diving responses included larger cardiovascular changes during mist stimuli than during water stimuli. Apneic responses lasted longer than 10 s in response to 10 s stimuli or about 40 s in response to 60 s stimuli, and outlasted bradycardia. Repeated 10 s mist applications led to an uncoupling of the apneic episodes (which always occurred) from the bradycardia (which became less pronounced with repetition). These uncoupled events matched the features of observed spontaneous seizure-associated central apneic episodes. The duration of spontaneous central apneic episodes correlated with their frequency, i.e. longer events occurred when there were more events.Based on our ability to replicate the properties of seizure-associated central apneic events with evoked diving responses during seizure activity, we conclude that seizure-associated central apnea and the diving response share a common neural basis and may reflect an attempt by brainstem networks to protect core physiology during seizure activity.

Overexpressed HspB6 Underlines a Novel Inhibitory Role in Kainic Acid-Induced Epileptic Seizure in Rats by Activating the cAMP-PKA Pathway.

Epilepsy is a commonly occurring neurological disease that has a large impact on the patient's daily life. Phosphorylation of heat shock protein B6 (HspB6) has been reported to protect the central nervous system. In this investigation, we explored whether HspB6 played a positive effect on epilepsy with the involvement of the cyclic adenosine monophosphate-protein kinase A (cAMP-PKA) pathway. The epileptic seizure was induced in rats by intraperitoneal injection of kainic acid (KA). The extent of HspB6 phosphorylation and expressions of HspB6, PKA, and inflammatory factors TNF-α, IL-1β, and IL-6 were quantified along with neuronal apoptosis. To further understand the regulatory mechanism of the HspB6 in the hippocampus, we altered the expression and the extent of HspB6 phosphorylation to see whether the cAMP-PKA pathway was inactivated or not in hippocampal neurons of rats post KA. Results showed that HspB6 was poorly expressed, resulting in the inactivation of the cAMP-PKA pathway in rats post KA, as well as an aggravated inflammatory response and hippocampal neuronal apoptosis. HspB6 overexpression and the cAMP-PKA pathway activation decreased the expression of inflammatory factors and inhibited hippocampal neuronal apoptosis. Additionally, HspB6 phosphorylation further augments the inhibitory effects of HspB6 on the inflammatory response and hippocampal neuronal apoptosis. The cAMP-PKA pathway activation was found to result in increased HspB6 phosphorylation. HspB6 decreased apoptosis signal-regulating kinase 1 (ASK1) expression to inhibit inflammatory response and hippocampal neuronal apoptosis. Collectively, our findings demonstrate that activation of the cAMP-PKA pathway induces overexpression and partial phosphorylation of HspB6 lead to the inhibition of ASK1 expression. This in turn protects rats against epilepsy and provides a potential approach to prevent the onset of epileptic seizure in a clinical setting.

Echinacoside, an Active Constituent of Cistanche Herba, Exerts a Neuroprotective Effect in a Kainic Acid Rat Model by Inhibiting Inflammatory Processes and Activating the Akt/GSK3β Pathway.

Echinacoside is a major compound of Cistanche Herb and has glutamate release-inhibiting activity in the brain. Given the involvement of excitotoxicity caused by massive glutamate in the pathophysiology of epilepsy, we explored the antiepileptic effect of echinacoside on kainic acid-induced seizures in rats. The rats were intraperitoneally administrated echinacoside for 30 min prior to intraperitoneal injection with kainic acid. The results showed that kainic acid induced seizure-like behavioral patterns, increased glutamate concentrations, caused neuronal loss and microglial activation, and stimulated proinflammatory cytokine gene expression in the hippocampus. These kainic acid-induced alternations were found to be attenuated by echinacoside pretreatment. Furthermore, decreased Akt and glycogen synthase kinase 3β (GSK3β) phosphorylation as well as Bcl-2 expression in the hippocampus was reversed by the echinacoside pretreatment. These results demonstrate that echinacoside exert its antiepileptic and neuroprotective actions in a kainic acid rat model through suppressing inflammatory response and activating the Akt/GSK3β signaling. Therefore, the present study suggests that echinacoside is the potentially useful in the prevention of epilepsy.

Impaired neural stem cell expansion and hypersensitivity to epileptic seizures in mice lacking the EGFR in the brain

Mice lacking the epidermal growth factor receptor (EGFR) develop an early postnatal degeneration of the frontal cortex and olfactory bulbs and show increased cortical astrocyte apoptosis. The poor health and early lethality of EGFR−/− mice prevented the analysis of mechanisms responsible for the neurodegeneration and function of the EGFR in the adult brain. Here, we show that postnatal EGFR‐deficient neural stem cells are impaired in their self‐renewal potential and lack clonal expansion capacity in vitro. Mice lacking the EGFR in the brain (EGFRΔbrain) show low penetrance of cortical degeneration compared to EGFR−/− mice despite genetic recombination of the conditional allele. Adult EGFRΔ mice establish a proper blood–brain barrier and perform reactive astrogliosis in response to mechanical and infectious brain injury, but are more sensitive to Kainic acid‐induced epileptic seizures. EGFR‐deficient cortical astrocytes, but not midbrain astrocytes, have reduced expression of glutamate transporters Glt1 and Glast, and show reduced glutamate uptake in vitro, illustrating an excitotoxic mechanism to explain the hypersensitivity to Kainic acid and region‐specific neurodegeneration observed in EGFR‐deficient brains.

Morin Prevents Granule Cell Dispersion and Neurotoxicity via Suppression of mTORC1 in a Kainic Acid-induced Seizure Model.

An abnormal reorganization of the dentate gyrus and neurotoxic events are important phenotypes in the hippocampus of patients with temporal lobe epilepsy (TLE). The effects of morin, a bioflavonoid constituent of many herbs and fruits, on epileptic seizures have not yet been elucidated, though its beneficial effects, such as its anti-inflammatory and neuroprotective properties, are well-described in various neurodegenerative diseases. In the present study, we investigated whether treatment with morin hydrate (MH) can reduce the susceptibility to seizures, granule cell dispersion (GCD), mammalian target of rapamycin complex 1 (mTORC1) activity, and the increases in the levels of apoptotic molecules and inflammatory cytokines in the kainic acid (KA)-induced seizure mouse model. Our results showed that oral administration of MH could reduce susceptibility to seizures and lead to the inhibition of GCD and mTORC1 activity in the KA-treated hippocampus. Moreover, treatment with MH significantly reduced the increased levels of apoptotic signaling molecules and pro-inflammatory mediators in the KA-treated hippocampus compared with control mice, suggesting a neuroprotective role. Therefore, these results suggest that morin has a therapeutic potential against epilepsy through its abilities to inhibit GCD and neurotoxic events in the in vivo hippocampus.

RNAseq analysis of hippocampal microglia after kainic acid-induced seizures

Microglia have been shown to be of critical importance to the progression of temporal lobe epilepsy. However, the broad transcriptional changes that these cells undergo following seizure induction is not well understood. As such, we utilized RNAseq analysis upon microglia isolated from the hippocampus to determine expression pattern alterations following kainic acid induced seizure. We determined that microglia undergo dramatic changes to their expression patterns, particularly with regard to mitochondrial activity and metabolism. We also observed that microglia initiate immunological activity, specifically increasing interferon beta responsiveness. Our results provide novel insights into microglia transcriptional regulation following acute seizures and suggest potential therapeutic targets specifically in microglia for the treatment of seizures and epilepsy.

Anticonvulsant effect of dipropofol by enhancing native GABA currents in cortical neurons in mice.

Temporal lobe epilepsy (TLE), the most common pharmacoresistant focal epilepsy disorder, remains a major unmet medical need. Propofol is used as a short-acting medication for general anesthesia and refractory status epilepticus with issues of decreased consciousness and memory loss. Dipropofol, a derivative of propofol, has been reported to exert antioxidative and antibacterial activities. Here we report that dipropofol exerted anticonvulsant activity in a mouse model of kainic acid-induced seizures. Whole cell patch-clamp recordings of brain slices from the medial entorhinal cortex (mEC) revealed that dipropofol hyperpolarized the resting membrane potential and reduced the number of action potential firings, resulting in suppression of cortical neuronal excitability. Furthermore, dipropofol activated native tonic GABAA currents of mEC layer II stellate neurons in a dose-dependent manner with an EC50 value of 9.3 ± 1.6 μM (mean ± SE). Taken together, our findings show that dipropofol activated GABAA currents and exerted anticonvulsant activities in mice, thus possessing developmental potential for new anticonvulsant therapy. NEW & NOTEWORTHY The anticonvulsant effect of dipropofol was shown in a mouse model of kainic acid-induced seizures. Whole cell patch-clamp recordings of brain slices showed suppression of cortical neuronal excitability by dipropofol. Dipropofol activated the native tonic GABAA currents in a dose-dependent manner.

Pathology of nNOS-Expressing GABAergic Neurons in Mouse Model of Alzheimer’s Disease

Alzheimer’s disease (AD) is the most common form of dementia that is often accompanied by mood and emotional disturbances and seizures. There is growing body of evidence that neurons expressing γ-aminobutyric acid (GABA) play an important role in regulation of cognition, mood, and emotion as well as seizure susceptibility, but participation of GABAergic neuronal pathology in Alzheimer’s disease (AD) is not understood well at present. Here, we report that transgenic mice expressing human amyloid precursor protein Swedish–Dutch–Iowa mutant (APPSweDI) exhibit early loss of neurons expressing GAD67, a GABA-synthesizing enzyme, in advance of the loss of pyramidal neurons in hippocampal CA1 region. The loss of GAD67+ neurons in APPSweDI mice accompanied with decreased spatial cognition as well as increased anxiety-like behaviors and kainic acid-induced seizure susceptibility at early phase. In the hippocampal CA1 region, GAD67+ neurons expressed high basal levels of neuronal nitric oxide synthase (nNOS) and nitrosative stress (nitrotyrosine). Similarly, GAD67+ neurons in primary cortical and hippocampal neuron cultures also expressed high basal levels of nNOS and degenerated in response to lower Aβ concentrations due to their high basal levels of nitrosative stress. Given the role of GABAergic neurons in cognitive and neuropsychiatric functions, this study reports the role of nNOS-mediated nitrosative stress in dysfunction of GABAergic neurons and its potential participation in early development of cognitive and neuropsychiatric symptoms in AD.