C-Fos mapping and EEG characteristics of multiple mice brain regions in pentylenetetrazol-induced seizure mice model

Cellular and molecular mechanisms involved in the analgesic effects of botulinum neurotoxin: A literature review

Botulinum neurotoxins (BoNTs), derived from Clostridium botulinum, have been employed to treat a range of central and peripheral neurological disease. Some studies indicate that BoNT may be beneficial for pain conditions as well. It has been hypothesized that BoNTs may exert their analgesic effects by preventing the release of pain-related neurotransmitters and neuroinflammatory agents from sensory nerve endings, suppressing glial activation, and inhibiting the transmission of pain-related receptors to the neuronal cell membrane. In addition, there is evidence to suggest that the central analgesic effects of BoNTs are mediated through their retrograde axonal transport. The purpose of this review is to summarize the experimental evidence of the analgesic functions of BoNTs and discuss the cellular and molecular mechanisms by which they can act on pain conditions. Most of the studies reviewed in this article were conducted using BoNT/A. The PubMed database was searched from 1995 to December 2022 to identify relevant literature.

Examining memory linking and generalization using scFLARE2, a temporally precise neuronal activity tagging system

How memories are organized in the brain influences whether they are remembered discretely versus linked with other experiences or whether generalized information is applied to entirely novel situations. Here, we used scFLARE2 (single-chain fast light- and activity-regulated expression 2), a temporally precise tagging system, to manipulate mouse lateral amygdala neurons active during one of two 3 min threat experiences occurring close (3 h) or further apart (27 h) in time. Silencing scFLARE2-tagged neurons showed that two threat experiences occurring at distal times are dis-allocated to orthogonal engram ensembles and remembered discretely, whereas the same two threat experiences occurring in close temporal proximity are linked via co-allocation to overlapping engram ensembles. Moreover, we found that co-allocation mediates memory generalization applied to a completely novel stimulus. These results indicate that endogenous temporal evolution of engram ensemble neuronal excitability determines how memories are organized and remembered and that this would not be possible using conventional immediate-early gene-based tagging methods.

Elevated susceptibility to exogenous seizure triggers and impaired interneuron excitability in a mouse model of Leigh syndrome epilepsy

Mutations in the NADH dehydrogenase (ubiquinone reductase) iron‑sulfur protein 4 (NDUFS4) gene, which encodes for a key structural subunit of the OXFOS complex I (CI), lead to the most common form of mitochondrial disease in children known as Leigh syndrome (LS). As in other mitochondrial diseases, epileptic seizures constitute one of the most significant clinical features of LS. These seizures are often very difficult to treat and are a sign of poor disease prognosis. Mice with whole-body Ndufs4 KO are a well-validated model of LS; they exhibit epilepsy and several other clinical features of LS. We have previously shown that mice with Ndufs4 KO in only GABAergic interneurons (Gad2-Ndufs4-KO) reproduce the severe epilepsy phenotype observed in the global KO mice. This observation indicated that these mice represent an excellent model of LS epilepsy isolated from other clinical manifestations of the disease. To further characterize this epilepsy phenotype, we investigated seizure susceptibility to selected exogenous seizure triggers in Gad2-Ndufs4-KO mice. Then, using electrophysiology, imaging, and immunohistochemistry, we studied the cellular, physiological, and neuroanatomical consequences of Ndufs4 KO in GABAergic interneurons. Homozygous KO of Ndufs4 in GABAergic interneurons leads to a prominent susceptibility to exogenous seizure triggers, impaired interneuron excitability and interneuron loss. Finally, we found that the hippocampus and cortex participate in the generation of seizure activity in Gad2-Ndufs4-KO mice. These findings further define the LS epilepsy phenotype and provide important insights into the cellular mechanisms underlying epilepsy in LS and other mitochondrial diseases.

In Silico Analysis, Anticonvulsant Activity, and Toxicity Evaluation of Schisandrin B in Zebrafish Larvae and Mice

The aim of this study is to evaluate the anticonvulsant potential of schisandrin B, a main ingredient of Schisandra chinensis extracts. Schisandrin B showed anticonvulsant activity in the zebrafish larva pentylenetetrazole acute seizure assay but did not alter seizure thresholds in the intravenous pentylenetetrazole test in mice. Schisandrin B crosses the blood-brain barrier, which we confirmed in our in silico and in vivo analyses; however, the low level of its unbound fraction in the mouse brain tissue may explain the observed lack of anticonvulsant activity. Molecular docking revealed that the anticonvulsant activity of the compound in larval zebrafish might have been due to its binding to a benzodiazepine site within the GABAA receptor and/or the inhibition of the glutamate NMDA receptor. Although schisandrin B showed a beneficial anticonvulsant effect, toxicological studies revealed that it caused serious developmental impairment in zebrafish larvae, underscoring its teratogenic properties. Further detailed studies are needed to precisely identify the properties, pharmacological effects, and safety of schisandrin B.

Neuronal activity dynamics in the dentate gyrus during early epileptogenesis

Epileptogenesis is a complex process involving a multitude of changes at the molecular, cellular and network level. Previous studies have identified several key alterations contributing to epileptogenesis and the development of hyper-excitability in different animal models, but only a few have focused on the early stages of this process. For post status epilepticus (SE) temporal lobe epilepsy in particular, understanding network dynamics during the early phases might be crucial for developing accurate preventive treatments to block the development of chronic spontaneous seizures. In this study, we used a viral vector mediated approach to examine activity of neurons in the dentate gyrus of the hippocampus during early epileptogenesis. We find that while granule cells are active 8 h after SE and then gradually decrease their activity, Calretinin-positive mossy cells and Neuropeptide Y-positive GABAergic interneurons in the hilus show a delayed activation pattern starting at 24 and peaking at 48 h after SE. These data suggest that indirect inhibition of granule cells by mossy cells through recruitment of local GABAergic interneurons could be an important mechanisms of excitability control during early epileptogenesis, and contribute to our understanding of the complex role of these cells in normal and pathological conditions.

Endothelin-1, over-expressed in SOD1G93A mice, aggravates injury of NSC34-hSOD1G93A cells through complicated molecular mechanism revealed by quantitative proteomics analysis

Endothelin-1 (ET-1), a secreted signaling peptide, is suggested to be involved in multiple actions in various tissues including the brain, but its role in amyotrophic lateral sclerosis (ALS) remains unknown. In this study, we detected the expression changes as well as the cellular localization of ET-1, endothelin A (ET-A) and endothelin B (ET-B) receptors in spinal cord of transgenic SOD1-G93A (TgSOD1-G93A) mice, which showed that the two ET receptors (ET-Rs) expressed mainly on neurons and decreased as the disease progressed especially ET-B, while ET-1 expression was up-regulated and primarily localized on astrocytes. We then explored the possible mechanisms underlying the effect of ET-1 on cultured NSC34-hSOD1G93A cell model. ET-1 showed toxic effect on motor neurons (MNs), which can be rescued by the selective ET-A receptor antagonist BQ-123 or ET-B receptor antagonist BQ-788, suggesting that clinically used ET-Rs pan-antagonist could be a potential strategy for ALS. Using proteomic analysis, we revealed that 110 proteins were differentially expressed in NSC34-hSOD1G93A cells after ET-1 treatment, of which 54 were up-regulated and 56 were down-regulated. Bioinformatic analysis showed that the differentially expressed proteins (DEPs) were primarily enriched in hippo signaling pathway-multiple species, ABC transporters, ErbB signaling pathway and so on. These results provide further insights on the potential roles of ET-1 in ALS and present a new promising therapeutic target to protect MNs of ALS.

Delayed Impairment of Hippocampal Synaptic Plasticity after Pentylenetetrazole-Induced Seizures in Young Rats

Data on the long-term consequences of a single episode of generalized seizures in infants are inconsistent. In this study, we examined the effects of pentylenetetrazole-induced generalized seizures in three-week-old rats. One month after the seizures, we detected a moderate neuronal loss in several hippocampal regions: CA1, CA3, and hilus, but not in the dentate gyrus. In addition, long-term synaptic potentiation (LTP) was impaired. We also found that the mechanism of plasticity induction was altered: additional activation of metabotropic glutamate receptors (mGluR1) is required for LTP induction in experimental rats. This disturbance of the plasticity induction mechanism is likely due to the greater involvement of perisynaptic NMDA receptors compared to receptors located in the core part of the postsynaptic density. This hypothesis is supported by experiments with selective blockades of core-located NMDA receptors by the use-dependent blocker MK-801. MK-801 had no effect on LTP induction in experimental rats and suppressed LTP in control animals. The weakening of the function of core-located NMDA receptors may be due to the disturbed clearance of glutamate from the synaptic cleft since the distribution of the astrocytic glutamate transporter EAAT2 in experimental animals was found to be altered.

Activity-dependent translation dynamically alters the proteome of the perisynaptic astrocyte process

Within eukaryotic cells, translation is regulated independent of transcription, enabling nuanced, localized, and rapid responses to stimuli. Neurons respond transcriptionally and translationally to synaptic activity. Although transcriptional responses are documented in astrocytes, here we test whether astrocytes have programmed translational responses. We show that seizure activity rapidly changes the transcripts on astrocyte ribosomes, some predicted to be downstream of BDNF signaling. In acute slices, we quantify the extent to which cues of neuronal activity activate translation in astrocytes and show that this translational response requires the presence of neurons, indicating that the response is non-cell autonomous. We also show that this induction of new translation extends into the periphery of astrocytes. Finally, synaptic proteomics show that new translation is required for changes that occur in perisynaptic astrocyte protein composition after fear conditioning. Regulation of translation in astrocytes by neuronal activity suggests an additional mechanism by which astrocytes may dynamically modulate nervous system functioning.

Immediate Early Gene c-fos in the Brain: Focus on Glial Cells

The c-fos gene was first described as a proto-oncogene responsible for the induction of bone tumors. A few decades ago, activation of the protein product c-fos was reported in the brain after seizures and other noxious stimuli. Since then, multiple studies have used c-fos as a brain activity marker. Although it has been attributed to neurons, growing evidence demonstrates that c-fos expression in the brain may also include glial cells. In this review, we collect data showing that glial cells also express this proto-oncogene. We present evidence demonstrating that at least astrocytes, oligodendrocytes, and microglia express this immediate early gene (IEG). Unlike neurons, whose expression changes used to be associated with depolarization, glial cells seem to express the c-fos proto-oncogene under the influence of proliferation, differentiation, growth, inflammation, repair, damage, plasticity, and other conditions. The collected evidence provides a complementary view of c-fos as an activity marker and urges the introduction of the glial cell perspective into brain activity studies. This glial cell view may provide additional information related to the brain microenvironment that is difficult to obtain from the isolated neuron paradigm. Thus, it is highly recommended that detection techniques are improved in order to better differentiate the phenotypes expressing c-fos in the brain and to elucidate the specific roles of c-fos expression in glial cells.

Effects of Noninvasive Low-Intensity Focus Ultrasound Neuromodulation on Spinal Cord Neurocircuits In Vivo

Although neurocircuits can be activated by focused ultrasound stimulation, it is unclear whether this is also true for spinal cord neurocircuits. In this study, we used low-intensity focused ultrasound (LIFU) to stimulate lumbar 4–lumbar 5 (L4–L5) segments of the spinal cord of normal Sprague Dawley rats with a clapper. The activation of the spinal cord neurocircuits enhanced soleus muscle contraction as measured by electromyography (EMG). Neuronal activation and injury were assessed by EMG, western blotting (WB), immunofluorescence, hematoxylin and eosin (H&E) staining, Nissl staining, enzyme-linked immunosorbent assay (ELISA), immunohistochemistry (IHC), somatosensory evoked potentials (SEPs), motor evoked potentials (MEPs), and the Basso–Beattie–Bresnahan locomotor rating scale. When the LIFU intensity was more than 0.5 MPa, LIFU stimulation induced soleus muscle contraction and increased the EMG amplitudes (P < 0.05) and the number of c-fos- and GAD65-positive cells (P < 0.05). When the LIFU intensity was 3.0 MPa, the LIFU stimulation led to spinal cord damage and decreased SEP amplitudes for electrophysiological assessment (P < 0.05); this resulted in coagulation necrosis, structural destruction, neuronal loss in the dorsal horn by H&E and Nissl staining, and increased expression of GFAP, IL-1β, TNF-α, and caspase-3 by IHC, ELISA, and WB (P < 0.05). These results show that LIFU can activate spinal cord neurocircuits and that LIFU stimulation with an irradiation intensity ≤1.5 MPa is a safe neurostimulation method for the spinal cord.

Naturally Occurring HMGB1 Inhibitor, Glycyrrhizin, Modulates Chronic Seizures-Induced Memory Dysfunction in Zebrafish Model

Glycyrrhizin (GL) is a well-known pharmacological inhibitor of high mobility group box 1 (HMGB1) and is abundantly present in the licorice root (Glycyrrhiza radix). HMGB1 protein, a key mediator of neuroinflammation, has been implicated in several neurological disorders, including epilepsy. Epilepsy is a devastating neurological disorder with no effective disease-modifying treatment strategies yet, suggesting a pressing need for exploring novel therapeutic options. In the current investigation, using a second hit pentylenetetrazol (PTZ) induced chronic seizure model in adult zebrafish, regulated mRNA expression of HMGB1 was inhibited by pretreatment with GL (25, 50, and 100 mg/kg, ip). A molecular docking study suggests that GL establishes different binding interactions with the various amino acid chains of HMGB1 and Toll-like receptor-4 (TLR4). Our finding suggests that GL pretreatment reduces/suppresses second hit PTZ induced seizure, as shown by the reduction in the seizure score. GL also regulates the second hit PTZ induced behavioral impairment and rescued second hit PTZ related memory impairment as demonstrated by an increase in the inflection ratio (IR) at the 3 h and 24 h T-maze trial. GL inhibited seizure-induced neuronal activity as demonstrated by reduced C-fos mRNA expression. GL also modulated mRNA expression of BDNF, CREB-1, and NPY. The possible mechanism underlying the anticonvulsive effect of GL could be attributed to its anti-inflammatory activity, as demonstrated by the downregulated mRNA expression level of HMGB1, TLR4, NF-kB, and TNF-α. Overall, our finding suggests that GL exerts an anticonvulsive effect and ameliorates seizure-related memory disruption plausibly through regulating of the HMGB1-TLR4-NF-kB axis.

Spatiotemporal Correlation of Epileptiform Activity and Gene Expression in vitro

Epileptiform activity alters gene expression in the central nervous system, a phenomenon that has been studied extensively in animal models. Here, we asked whether also in vitro models of seizures are in principle suitable to investigate changes in gene expression due to epileptiform activity and tested this hypothesis mainly in rodent and additionally in some human brain slices. We focused on three genes relevant for seizures and epilepsy: FOS proto-oncogene (c-Fos), inducible cAMP early repressor (Icer) and mammalian target of rapamycin (mTor). Seizure-like events (SLEs) were induced by 4-aminopyridine (4-AP) in rat entorhinal-hippocampal slices and by 4-AP/8 mM potassium in human temporal lobe slices obtained from surgical treatment of epilepsy. SLEs were monitored simultaneously by extracellular field potentials and intrinsic optical signals (IOS) for 1–4 h, mRNA expression was quantified by real time PCR. In rat slices, both duration of SLE exposure and SLE onset region were associated with increased expression of c-Fos and Icer while no such association was shown for mTor expression. Similar to rat slices, c-FOS induction in human tissue was increased in slices with epileptiform activity. Our results indicate that irrespective of limitations imposed by ex vivo conditions, in vitro models represent a suitable tool to investigate gene expression. Our finding is of relevance for the investigation of human tissue that can only be performed ex vivo. Specifically, it presents an important prerequisite for future studies on transcriptome-wide and cell-specific changes in human tissue with the goal to reveal novel candidates involved in the pathophysiology of epilepsy and possibly other CNS pathologies.

Effects of Constitutive and Acute Connexin 36 Deficiency on Brain-Wide Susceptibility to PTZ-Induced Neuronal Hyperactivity

Connexins are transmembrane proteins that form hemichannels allowing the exchange of molecules between the extracellular space and the cell interior. Two hemichannels from adjacent cells dock and form a continuous gap junction pore, thereby permitting direct intercellular communication. Connexin 36 (Cx36), expressed primarily in neurons, is involved in the synchronous activity of neurons and may play a role in aberrant synchronous firing, as seen in seizures. To understand the reciprocal interactions between Cx36 and seizure-like neural activity, we examined three questions: (a) does Cx36 deficiency affect seizure susceptibility, (b) does seizure-like activity affect Cx36 expression patterns, and (c) does acute blockade of Cx36 conductance increase seizure susceptibility. We utilize the zebrafish pentylenetetrazol [PTZ; a GABA(A) receptor antagonist] induced seizure model, taking advantage of the compact size and optical translucency of the larval zebrafish brain to assess how PTZ affects brain-wide neuronal activity and Cx36 protein expression. We exposed wild-type and genetic Cx36-deficient (cx35.5-/-) zebrafish larvae to PTZ and subsequently mapped neuronal activity across the whole brain, using phosphorylated extracellular-signal-regulated kinase (pERK) as a proxy for neuronal activity. We found that cx35.5-/- fish exhibited region-specific susceptibility and resistance to PTZ-induced hyperactivity compared to wild-type controls, suggesting that genetic Cx36 deficiency may affect seizure susceptibility in a region-specific manner. Regions that showed increased PTZ sensitivity include the dorsal telencephalon, which is implicated in human epilepsy, and the lateral hypothalamus, which has been underexplored. We also found that PTZ-induced neuronal hyperactivity resulted in a rapid reduction of Cx36 protein levels within 30 min. This Cx36 reduction persists after 1-h of recovery but recovered after 3–6 h. This acute downregulation of Cx36 by PTZ is likely maladaptive, as acute pharmacological blockade of Cx36 by mefloquine results in increased susceptibility to PTZ-induced neuronal hyperactivity. Together, these results demonstrate a reciprocal relationship between Cx36 and seizure-associated neuronal hyperactivity: Cx36 deficiency contributes region-specific susceptibility to neuronal hyperactivity, while neuronal hyperactivity-induced downregulation of Cx36 may increase the risk of future epileptic events.

Intranasal Allopregnanolone Confers Rapid Seizure Protection: Evidence for Direct Nose-to-Brain Delivery

Allopregnanolone, a positive modulator of GABAA receptors with antiseizure activity, has potential in the treatment of seizure emergencies. Instillation of allopregnanolone in 40% sulfobutylether-β-cyclodextrin into the nose in mice rapidly elevated the seizure threshold in the timed intravenous pentylenetetrazol (ED50, 5.6 mg/kg), picrotoxin (ED50, 5.9 mg/kg), and bicuculline seizure tests. The effect peaked at 15 min, decayed over 1 h, and was still evident in some experiments at 6 h. Intranasal allopregnanolone also delayed the onset of seizures in the maximal PTZ test. At an allopregnanolone dose (16 mg/kg) that conferred comparable effects on seizure threshold as the benzodiazepines midazolam and diazepam (both at doses of 1 mg/kg), allopregnanolone caused minimal sedation or motor toxicity in the horizontal screen test whereas both benzodiazepines produced marked behavioral impairment. In addition, intranasal allopregnanolone failed to cause loss-of-righting reflex in most animals, but when the same dose was administered intramuscularly, all animals became impaired. Intranasal allopregnanolone (10 mg/kg) caused a rapid increase in brain allopregnanolone with a Tmax of ~5 min after initiation of the intranasal delivery. High levels of allopregnanolone were recovered in the olfactory bulb (Cmax, 16,000 ng/mg) whereas much lower levels (Cmax, 670 ng/mg) were present in the remainder of the brain. We conclude that the unique ability of intranasal allopregnanolone to protect against seizures without inducing behavioral adverse effects is due in part to direct nose-to-brain delivery, with preferential transport to brain regions relevant to seizures. Benzodiazepines are commonly administered intranasally for acute seizure therapy, including for the treatment of acute repetitive seizures, but are not transported from nose-to-brain. Intranasal allopregnanolone acts with greater speed, has less propensity for adverse effects, and has the ability to overcome benzodiazepine refractoriness. This is the first study demonstrating rapid functional central nervous system activity of a nose-to-brain-delivered steroid. Intranasal delivery circumvents the poor oral bioavailability of allopregnanolone providing a route of administration permitting its evaluation as a treatment for diverse neuropsychiatric indications.

The retinoid X receptor: a nuclear receptor that modulates the sleep-wake cycle in rats

RATIONALE

The nuclear receptor retinoid X receptor (RXR) belongs to a nuclear receptor superfamily that modulates diverse functions via homodimerization with itself or several other nuclear receptors, including PPARα. While the activation of PPARα by natural or synthetic agonists regulates the sleep-wake cycle, the role of RXR in the sleep modulation is unknown.

OBJECTIVES

We investigated the effects of bexarotene (Bexa, a RXR agonist) or UVI 3003 (UVI, a RXR antagonist) on sleep, sleep homeostasis, levels of neurochemical related to sleep modulation, and c-Fos and NeuN expression.

METHODS

The sleep-wake cycle and sleep homeostasis were analyzed after application of Bexa or UVI. Moreover, we also evaluated whether Bexa or UVI could induce effects on dopamine, serotonin, norepinephrine epinephrine, adenosine, and acetylcholine contents, collected from either the nucleus accumbens or basal forebrain. In addition, c-Fos and NeuN expression in the hypothalamus was determined after Bexa or UVI treatments.

RESULTS

Systemic application of Bexa (1 mM, i.p.) attenuated slow-wave sleep and rapid eye movement sleep. In addition, Bexa increased the levels of dopamine, serotonin, norepinephrine epinephrine, adenosine, and acetylcholine sampled from either the nucleus accumbens or basal forebrain. Moreover, Bexa blocked the sleep rebound period after total sleep deprivation, increased in the hypothalamus the expression of c-Fos, and decreased NeuN activity. Remarkably, UVI 3003 (1 mM, i.p.) induced opposite effects in sleep, sleep homeostasis, neurochemicals levels, and c-Fos and NeuN activity.

CONCLUSIONS

The administration of RXR agonist or antagonist significantly impaired the sleep-wake cycle and exerted effects on the levels of neurochemicals related to sleep modulation. Moreover, Bexa or UVI administration significantly affected c-Fos and NeuN expression in the hypothalamus. Our findings highlight the neurobiological role of RXR on sleep modulation.

MS275 reduces seizure-induced brain damage in developing rats by regulating p38 MAPK signaling pathways and epigenetic modification

Seizure is a common acute and severe disease in infants and children. Recurrent seizures or persistent seizures may cause irreversible brain damage. Mitogen activated protein kinase (MAPK) signaling pathway is associated with an inflammatory response, however it's involvement in the pathological process of seizures is not clear. Histone deacetylase inhibitors (HDACi) have promising neuroprotective effects through epigenetic regulation. Therefore, this study aimed to investigate the mechanism of HDACi MS275 on p38 MAPK signaling pathway and p38 histone modifications in developing rats post-seizure. Intraperitoneal administration of Pentylenetetrazole (PTZ) was used to induce developing rat seizures, and MS275 (5 or 10 mg/kg) was injected intraperitoneally 2 h before PTZ injection. Hippocampal tissues were sampled at 24 h post-seizures for protein and mRNA levels of p38、MK2、CREB and IL-6. Neuronal apoptosis and microglia activation significantly increased after PTZ treatment. However, pretreatment with MS275 attenuated these effects as well as increased seizure latency and decreased seizure scores. Furthermore, MS275 was found to inhibit the expression of p38 by increasing histone H3 and H4 acetylation and decreasing histone H3 and H4 methylation. This study thereby demonstrates that HDACi MS275 can reduce the inflammatory response associated with seizure-induced brain injury through inhibiting the p38 MAPK signaling pathway and p38 gene expression.

Neural Activities in Multiple Rat Brain Regions in Lithium-Pilocarpine-Induced Status Epilepticus Model

To clarify the different regional brain electroencephalogram (EEG) activities and biochemical responses in seizure and epilepsy models, we assessed the EEG and c-Fos immunolabeling characteristics in a lithium-pilocarpine-induced status epilepticus (SE) model and pentylenetetrazol (PTZ)-induced seizure model. The regional brain activities were evaluated by EEG and c-Fos immunolabeling. ZnT3 immunostaining was performed to observe hippocampal mossy fiber sprouting (MFS) within 7 days after the induction of SE in the lithium-pilocarpine model. The EEG recordings showed distinctive features of activation in different brain areas. With the aggravation of the behavioral manifestations of the seizures, the frequency and amplitude of the discharges on EEG gradually increased. SE was eventually induced and sustained. The labeling of c-Fos was enhanced in the cortex and hippocampal CA1, CA3, and dentate gyrus (DG); however, compared to the PTZ-induced seizure model, c-Fos staining could only be observed in the striatum and thalamus in the lithium-pilocarpine-induced epilepsy model. In each brain region, prominent c-Fos labeling was observed 2 h and 4 h after the induction of SE or seizures and diminished at 24 h. During the lithium-pilocarpine-induced chronic epilepsy phase after SE induction, MFS was observed 7 days after SE and was accompanied by the dynamic evolution of epileptic EEG activities. These findings validated the lithium-pilocarpine-induced SE model as an epilepsy model with a specific spatial-temporal profile of neural activation. The EEG characteristics and c-Fos expression patterns differ from those presented in a previous study using a PTZ-induced seizure model. Hippocampal mossy fiber spouting might be associated with spontaneous seizures during the chronic phase and can be detected at least within 1 week by ZnT3 staining after stimulation.