Nucleus accumbens shell modulates seizure propagation in a mouse temporal lobe epilepsy model.

Temporal lobe epilepsy (TLE) is the most common form of epilepsy with focal seizures which in some conditions can develop into secondarily generalized tonic-clonic seizures by the propagation of epileptic activities in the temporal lobe to other brain areas. The nucleus accumbens (NAc) has been suggested as a treatment target for TLE as accumulating evidence indicates that the NAc, especially its shell, participates in the process of epileptic seizures of patients and animal models with TLE. The majority of neurons in the NAc are GABAergic medium spiny neurons (MSNs) expressing dopamine receptor D1 (D1R) or dopamine receptor D2 (D2R). However, the direct evidence of the NAc shell participating in the propagation of TLE seizures is missing, and its cell type-specific modulatory roles in TLE seizures are unknown. In this study, we microinjected kainic acid into basolateral amygdala (BLA) to make a mouse model of TLE with initial focal seizures and secondarily generalized seizures (SGSs). We found that TLE seizures caused robust c-fos expression in the NAc shell and increased neuronal excitability of D1R-expressing MSN (D1R-MSN) and D2R-expressing MSN (D2R-MSN). Pharmacological inhibition of the NAc shell alleviated TLE seizures by reducing the number of SGSs and seizure stages. Cell-type-specific chemogenetic inhibition of either D1R-MSN or D2R-MSN showed similar effects with pharmacological inhibition of the NAc shell. Both pharmacological and cell-type-specific chemogenetic inhibition of the NAc shell did not alter the onset time of focal seizures. Collectively, these findings indicate that the NAc shell and its D1R-MSN or D2R-MSN mainly participate in the propagation and generalization of the TLE seizures.

TRESK channel contributes to depolarization-induced shunting inhibition and modulates epileptic seizures.

Glutamatergic and GABAergic synaptic transmission controls excitation and inhibition of postsynaptic neurons, whereas activity of ion channels modulates neuronal intrinsic excitability. However, it is unclear how excessive neuronal excitation affects intrinsic inhibition to regain homeostatic stability under physiological or pathophysiological conditions. Here, we report that a seizure-like sustained depolarization can induce short-term inhibition of hippocampal CA3 neurons via a mechanism of membrane shunting. This depolarization-induced shunting inhibition (DShI) mediates a non-synaptic, but neuronal intrinsic, short-term plasticity that is able to suppress action potential generation and postsynaptic responses by activated ionotropic receptors. We demonstrate that the TRESK channel significantly contributes to DShI. Disruption of DShI by genetic knockout of TRESK exacerbates the sensitivity and severity of epileptic seizures of mice, whereas overexpression of TRESK attenuates seizures. In summary, these results uncover a type of homeostatic intrinsic plasticity and its underlying mechanism. TRESK might represent a therapeutic target for antiepileptic drugs.

Emerging Role of Microglia-Mediated Neuroinflammation in Epilepsy after Subarachnoid Hemorrhage.

Epilepsy is a common and serious complication of subarachnoid hemorrhage (SAH), giving rise to increased morbidity and mortality. It's difficult to identify patients at high risk of epilepsy and the application of anti-epileptic drugs (AEDs) following SAH is a controversial topic. Therefore, it's pressingly needed to gain a better understanding of the risk factors, underlying mechanisms and the optimization of therapeutic strategies for epilepsy after SAH. Neuroinflammation, characterized by microglial activation and the release of inflammatory cytokines, has drawn growing attention due to its influence on patients with epilepsy after SAH. In this review, we discuss the risk factors for epilepsy after SAH and emphasize the critical role of microglia. Then we discuss how various molecules arising from pathophysiological changes after SAH activate specific receptors such as TLR4, NLRP3, RAGE, P2X7R and initiate the downstream inflammatory pathways. Additionally, we focus on the significant responses implicated in epilepsy including neuronal excitotoxicity, the disruption of blood-brain barrier (BBB) and the change of immune responses. As the application of AEDs for seizure prophylaxis after SAH remains controversial, the regulation of neuroinflammation targeting the key pathological molecules could be a promising therapeutic method. While neuroinflammation appears to contribute to epilepsy after SAH, more comprehensive experiments on their relationships are needed.

Primary central nervous system T-cell lymphoma: An analysis from the surveillance, epidemiology, and end results program.

BACKGROUND: Primary central nervous system T-cell lymphoma (PCNSTCL) is a rare neoplasm with few data regarding its common features and survival characteristics. OBJECTIVE: To explore the Surveillance, Epidemiology, and End Results 18 (SEER 18) database to determine the epidemiology of PCNSTCL. METHODS: The SEER 18 registry database was queried to identify patients diagnosed with PCNSTCL from 1973 to 2014 and extract their information. Age-specific rates and Kaplan-Meier overall survival (OS) were calculated. A Cox proportional hazards model was applied to investigate relationships between various demographic/treatment variables and OS. RESULTS: The age-specific incidence rates were higher in the older population (≥60 years). Among 59 PCNSTCL cases from the SEER 18, the mean age at presentation was 55.8 years (SD, ±17.95), with a male predominance (1.36:1.00). The median follow-up was 8 months, and the median OS was 8 months (SE, ±4.162). The 1-, 3-, and 5-year OS was 46.3% [95% CI, 33.4%-59.2%], 32.8% [20.3%-45.3%], and 32.8% [20.3%-45.3%], respectively. Seventeen of the 59 patients survived at last follow-up. Patients < 60 years had a greater 3-year OS compared with patients ≥ 60 years (52.6% [33.6%-71.6%] vs 13.9% [1.4%-26.4%]. Multivariate analysis has demonstrated that only age at diagnosis (≥60/<60 years) exhibited a significant relationship with OS (HR, 3.495 [1.688-7.235];p = 0.001). Sex (female/male) was observed to have a doubted trend towards significance (HR, 0.487 [0.231-1.030]; p = 0.060). CONCLUSIONS: PCNSTCL is generally of poor prognosis but younger age at diagnosis (<60 years) predicts a better prognosis.

Nucleus accumbens shell: A potential target for drug-resistant epilepsy with neuropsychiatric disorders.

The nucleus accumbens (NAc) is an important component of the ventral striatum, involving motivational and emotional processes, limbic-motor interfaces. Recently, experimental and clinical data have shown that NAc, particularly NAc shell (NAcs), participates in ictogenesis and epileptogensis in drug-resistant epilepsy (DRE). Therefore, we summarize the existing literature on NAcs and potential role in epilepsy, from the bench to the clinic. Connection abnormalities between NAcs and remainings, degeneration of NAc neurons, and an aberrant distribution of neuroactive substances have been reported in patients with DRE. These changes may be underlying the pathophysiological mechanism of the involvement of NAcs in DRE. Furthermore, alterations in NAcs may also be involved in neuropsychiatric disorders in patients with DRE. These observational studies demonstrate the multiple properties of NAcs and the complex relationship between the limbic system and DRE with neuropsychiatric disorders. NAcs can be a potential target for DBS and stereotactic lesioning to manage DRE with neuropsychiatric disorders. Future studies are warranted to further clarify the role of NAcs in epilepsy.

Silencing of microRNA-708 promotes cell growth and epithelial-to-mesenchymal transition by activating the SPHK2/AKT/ß-catenin pathway in glioma.

Aberrant microRNA-708 (miR-708) expression is frequently reported in cancer studies; however, its role in glioma has not been examined in detail. We investigated miR-708 function in glioma and revealed that miR-708 expression was significantly down-regulated in glioma tissues and cell lines. Restoration of miR-708 inhibited glioma cell growth and invasion both in vitro and in vivo. The oncogene SPHK2 (sphingosine kinase 2) was identified as a downstream target of miR-708 using luciferase and western blot assays. miR-708 inhibited AKT/ß-catenin signaling, which is activated by SPHK2. In addition, we revealed that miR-708 was transcriptionally repressed by EZH2 (enhancer of zeste homolog 2)-induced histone H3 lysine 27 trimethylation and promoter methylation. In summary, our findings revealed that miR-708 is a glioma tumor suppressor and suggest that miR-708 is a potential therapeutic target for glioma patients.

Connectivity-based parcellation of the nucleus accumbens into core and shell portions for stereotactic target localization and alterations in each NAc subdivision in mTLE patients.

The nucleus accumbens (NAc), an important target of deep brain stimulation for some neuropsychiatric disorders, is thought to be involved in epileptogenesis, especially the shell portion. However, little is known about the exact parcellation within the NAc, and its structural abnormalities or connections alterations of each NAc subdivision in temporal lobe epilepsy (TLE) patients. Here, we used diffusion probabilistic tractography to subdivide the NAc into core and shell portions in individual TLE patients to guide stereotactic localization of NAc shell. The structural and connection abnormalities in each NAc subdivision in the groups were then estimated. We successfully segmented the NAc in 24 of 25 controls, 14 of 16 left TLE patients, and 14 of 18 right TLE patients. Both left and right TLE patients exhibited significantly decreased fractional anisotropy (FA) and increased radial diffusivity (RD) in the shell, while there was no significant alteration in the core. Moreover, relatively distinct structural connectivity of each NAc subdivision was demonstrated. More extensive connection abnormalities were detected in the NAc shell in TLE patients. Our results indicate that neuronal degeneration and damage caused by seizure mainly exists in NAc shell and provide anatomical evidence to support the role of NAc shell in epileptogenesis. Remarkably, those NAc shell tracts with increased connectivities in TLE patients were found decreased in FA, which indicates disruption of fiber integrity. This finding suggests the regeneration of aberrant connections, a compensatory and repair process ascribed to recurrent seizures that constitutes part of the characteristic changes in the epileptic network.

Effect of accumbens nucleus shell lesioning on bitemporal lobe epilepsy in rat model.

INTRODUCTION: To explore the effect of accumbens nucleus shell (ACbSh) lesioning on bitemporal lobe epilepsy. MATERIAL AND METHODS: Adult Wistar rats (male) were enrolled and randomly assigned into the control group and epilepsy groups with multiple time-points. Lithium-pilocarpine was used to establish the rat epilepsy model, while the control group received an equal amount of saline. Ibotenic acid stereotaxic injection was performed to cause accumbens nucleus shell lesioning for specific groups. Cascade software was used for electroencephalogram (EEG) examination. Fluoro-Jade C staining was performed to examine neuronal degeneration. RESULTS: Latency period of the epilepsy in epilepsy groups was 15.3 ± 1.1 min, and epilepsy intensity was 4.8 ± 0.5 events/ 12 h. ACbSh lesioning significantly reduced aggressive behavior. Compared with epilepsy groups without ACbSh lesioning, ACbSh lesioning significantly decreased epileptic seizures and reduced epileptic duration (p < 0.05). EEG showed that there were still sharp waves in the hippocampus and amygdala region after ACbSh lesioning, but epileptic discharge in prefrontal cortex was significantly decreased (p < 0.05), while epilepsy groups without ACbSh lesioning had more sharp waves in the prefrontal cortex, hippocampus and amygdala region. Fluoro-Jade C staining showed that ACbSh lesioning significantly decreased grades of neuronal degeneration (p < 0.05). CONCLUSIONS: Recurrent epilepsy caused neuronal degeneration via ACbSh region-related pathways, and ACbSh lesioning could mitigate epilepsy-caused neuronal degeneration by reducing epileptic discharge.

Blocking mPTP on Neural Stem Cells and Activating the Nicotinic Acetylcholine Receptor α7 Subunit on Microglia Attenuate Aß-Induced Neurotoxicity on Neural Stem Cells.

ß-Amyloid (Aß) can stimulate microglia to release a variety of proinflammatory cytokines and induce neurotoxicity. Nicotine has been reported to inhibit TNF-α, IL-1, and ROS production in microglia. Mitochondrial permeability transition pore (mPTP) plays an important role in neurotoxicity as well. Here, we investigated whether activating the microglial α7-nAChR has a neuroprotective role on neural stem cells (NSCs) and the function of mPTP in NSCs in this process. The expression of α7-nAChR in rat NSCs was detected by immunocytochemistry and RT-PCR. The viability of microglia and NSCs was examined by MTT assay. The mitochondrial membrane potential (ΔΨm) and morphological characteristics of NSCs was measured by JC-1 staining and transmission electron microscopy respectively. The distribution of cytochrome c in the subcellular regions of NSCs was visualized by confocal laser scanning microscopy, and the expression levels of cyclophilin D and cleaved caspase-3 were assayed by western blot. The apoptotic rate of NSCs was measured by flow cytometry. The expression of α7-nAChR was detected in microglial cells, but no expression was found in NSCs. The viability of rat microglial cells and NSCs was not affected by reagents or coculture itself. Aß1-42-mediated microglial activation impaired the morphology and the ΔΨm of mitochondria of NSCs as well as increased cell apoptosis. However, the damage was attenuated when the α7-nAChRs on microglial cells were activated or the mPTPs on NSCs were blocked. Blockade of mPTPs on NSCs and activation of α7-nAChRs on microglia exhibit neuroprotective roles in Aß-induced neurotoxicity of NSCs.

Nicotine contributes to the neural stem cells fate against toxicity of microglial-derived factors induced by Aß via the Wnt/ß-catenin pathway.

Recent studies have demonstrated that the molecules secreted from microglias play important roles in the cell fate determination of neural stem cells (NSCs), and nicotinic acetylcholine receptor agonist treatment could reduce neuroinflammation in some neurodegenerative disease models, such as Alzheimer's disease (AD). However, it is not clear how nicotine plays a neuroprotective role in inflammation-mediated central nervous diseases, and its possible mechanisms in the process remain largely elusive. The aim of this study is to improve the survival microenvironment of NSCs co-cultured with microglias in vitro by weakening inflammation that mediated by accumulation of ß-amyloid peptide (Aß). The viability, proliferation, differentiation, apoptosis of NSCs and underlying mechanisms associated with Wnt signaling pathway were investigated. The results showed that Aß could directly damage NSCs. Furthermore, concomitant to elevated levels of TNF-α, IL-1ß derived from microglias, the NSCs had been damaged more severely with the upregulation of Axin 2, p-ß-catenin and the downregulation of ß-catenin, p-GSK-3ß, microtubule-associated protein-2, choline acetyltransferase. However, addition of 10 µmol/L nicotine before microglias treated with Aß was beneficial to protect the NSCs against neurotoxicity of microglial-derived factors induced by Aß, which partially rescued proliferation, differentiation and inhibited apoptosis of NSCs via activation of Wnt/ß-catenin pathway. Taken together, these data imply that low concentration nicotine attenuates NSCs injury induced by microglial-derived factors via Wnt signaling pathway. Thus, treatment with nicotinic acetylcholine receptor agonist provides a promising research field for neural stem cell fate and therapeutic intervention in neuroinflammation diseases.

Huperzine A protects neural stem cells against Aß-induced apoptosis in a neural stem cells and microglia co-culture system.

OBJECTIVES: This study aims to explore whether Huperzine A (HupA) could protect neural stem cells against amyloid beta-peptide Aß induced apoptosis in a neural stem cells (NSCs) and microglia co-culture system. METHODS: Rat NSCs and microglial cells were isolated, cultured and identified with immunofluorescence Assays (IFA). Co-culture systems of NSCs and microglial cells were employed using Transwell Permeable Supports. The effects of Aß1-42 on NSCs were studied in 4 groups using co-culture systems: NSCs, Aß+NSCs, co-culture and Aß+co-culture groups. Bromodeoxyuridine (BrdU) incorporation and flow cytometry were utilized to assess the differences of proliferation, differentiation and apoptosis of NSCs between the groups. LQ test was performed to assess the amounts of IL-6, TNF-α and MIP-α secreted, and flow cytometry and Western blotting were used to assess apoptosis of NSCs and the expressions of Bcl-2 and Bax in each group. RESULTS: IFA results showed that isolated rat NSCs were nestin-positive and microglial cells were CD11b/c-positive. Among all the groups, the Aß+co-culture group has the lowest BrdU expression level, the lowest MAP2-positive, ChAT-positive cell counts and the highest NSC apoptosis rate. Smaller amounts of IL-6, TNF-α and MIP-α were being secreted by microglial cells in the HupA+Aß+co-culture group compared with those in the Aß+ co-culture group. Also the Bcl-2: Bax ratio was much higher in the HupA+Aß+co-culture group than in the Aß+co-culture group. CONCLUSIONS: HupA inhibits cell apoptosis through restraining microglia's inflammatory response induced by Aß1-42.

Stereotactic neurosurgical technique and electrophysiological study in ablating the ventromedial shell of the nucleus accumbens.

OBJECTIVE: To describe in as much detail as possible the method for ablating the ventromedial shell of the nucleus accumbens (NAc) and investigate the efficacy and safety of the ablation treatment. METHODS: Sixty-five patients with drug addictions received operations within the time frame from 2004 to 2009. The ablation targets were located in the bilateral medial posterior inferior shell of the NAc. Intraoperative electrophysiological monitoring was performed. RESULTS: Tissue impedance in the shell of the NAc varied from 185 to 355 Ω. When stimulated with a low frequency (2 Hz) and a voltage above 3 V, 57 out of 65 (87.7%) patients experienced slight throbbing sensations. During the lesion procedure, fever was detected on the head and face of 59 patients (90.8%), the heart rate decreased in 19 cases (29.2%), and restlessness, irritability and hyperalgia were noted for all patients. Among the 65 patients, 52 (80%) no longer experienced a psychological craving for the drug. CONCLUSIONS: The shell of the NAc may be a promising surgical target for psychosurgery. Electrophysiological recordings revealed that the shell is indeed an appropriate structure.

Identification of α7 nicotinic acetylcholine receptor on hippocampal astrocytes cultured in vitro and its role on inflammatory mediator secretion.

The present study found expressions of α7 nicotinic acetylcholine receptor on hippocampal slices and hippocampal astrocytes using double immunofluorescence stainings. Expression of glial fibrillary acidic protein in the cultured hippocampal slices and hippocampal astrocytes significantly increased, and levels of macrophage inflammatory protein 1α, RANTES, interleukin-1ß, interleukin-6, and tumor necrosis factor-α increased in the supernatant of cultured astrocytes following exposure to 200 nM amyloid ß protein 1-42. Preconditioning of 10 µM nicotine, a nicotinic acetylcholine receptor agonist, could attenuate the influence of amyloid ß protein 1-42 in inflammatory mediator secretion of cultured astrocytes. Experimental findings indicated that α7 nicotinic acetylcholine receptor was expressed on the surface of hippocampal astrocytes, and activated α7 nicotinic acetylcholine receptor was shown to inhibit inflammation induced by amyloid ß protein 1-42.

[Effect of imatinib at different concentrations on rat C6 glioma cell apoptosis and cell cycle].

OBJECTIVE: To investigate the effect of imatinib on rat C6 glioma cell apoptosis and cell cycle. METHODS: MTT assay was used to determine the OD value of C6 glioma cells following treatment with imatinib at different concentrations (0.156, 10 and 15 micromo/L) for 24, 48 and 72 h. The cell apoptosis was assayed by Hochest/PI staining and the cell cycle changes were analyzed by flow cytometry. RESULTS: Imatinib treatment resulted in increased number of apoptotic cells in a time- and dose-dependent manner. A 72-h treatment of the cells with imatinib at 10 and 15 micromo/L caused increased cell percentage in G(0)/G(1) phase to (68.53-/+0.83)% and (70.41-/+0.62)%, (P<0.01), decreased the percentage of G(2) phase cells to (14.48-/+0.12)% and (13.84-/+2.86)% (P<0.01), and decreased the percentage of S phase cells to (16.98-/+0.72)% and (15.78-/+2.28)%, respectively (P<0.01). CONCLUSION: Imatinib can induce apoptosis and affect the distribution of the cell cycle of C6 cells in vitro.

[Proton magnetic resonance spectroscopic imaging of the hippocampus in schizophrenia patients before and after surgery].

OBJECTIVE: To explore the features of proton magnetic resonance spectroscopy (1H-MRS) of the hippocampus in schizophrenia patients before and after stereotactic neurosurgery. METHODS: 1H-MRS was performed to determine NAA/Cr and CHO/Cr ratios on the bilateral hippocampal regions before and after stereotactic neurosurgery in 20 schizophrenia patients, with 20 healthy individuals as the controls. RESULTS: The NAA/Cr ratio in the hippocampal regions was significantly lower and the CHO/Cr ratio significantly higher in schizophrenia patients before the surgery than in the healthy controls (P<0.01). The NAA/Cr and CHO/Cr ratios in the hippocampal regions underwent no significant changes in the patients after the surgeries (P>0.05). CONCLUSION: Neuronal and cell membrane metabolism impairment is present in the hippocampus of schizophrenia patients, and stereotactic neurosurgery does not produce obvious adverse effects on the cell membrane metabolism in the hippocampus of the patients.

[Histomorphology of angiogenesis patterns in different areas of human astrocytomas].

OBJECTIVE: To study angiogenesis patterns in the edematous area and the center of human astrocytomas by histological observation, and to reveal histological basis of vasculogenic mimicry. METHOD: Tissue samples were drawn from the tumor center and the edematous area in 51 patients with human astrocytomas during operation MR and were examined by CD34 endothelial marker periodic acid-Schiff (PAS) dual staining. RESULTS: Vessels or capillaries stained by both PAS and CD34 were found in edematous areas of human astrocytomas. Besides vessels or capillaries stained by both PAS and CD34, vasculogenic mimicries (PAS-positive and CD34-negative tubes containing red blood cells and lined by neoplastic cells), PAS-positive and CD34-negative tubes containing red blood cells and without cells around, PAS-positive and partial CD34-positive vessels or capillaries, and PAS-positive and CD34-negtive vessels or capillaries were detected in the center of tumor of 4 human glioblastomas. CONCLUSIONS: Vasculogenic mimicries in the center of some high-grade astrocytomas may be caused by blood capillary dysplasia, while angiogenesis patterns are vessels or capillaries in the edematus area and the center of most human astrocytomas.

[Ultrastructural features of cultured rat cortical astrocytes with stretch-induced injury].

OBJECTIVE: To investigate the changes of ultrastructural features of cultured rat cortical astrocytes after stretch-induced injury. METHODS: Rat cortical astrocytes isolated from 1- to 2-day-old rats were cultured till confluency, and then plated in tissue culture wells with flexible silastic bottom after purification. A computer-controlled device was used to produce stretch-induced injury in the astrocytes with the imposed pressure of 50, 150, and 250 kPa respectively, followed by observation of the ultrastructural changes in the astrocytes with light and electron microscopy. RESULTS: Obvious ultrastructural destruction of the astrocytes occurred when the imposed stretch pressure was 50 kPa, and scanning electron microscopy demonstrated increased intercellular space and laceration of the cell body and its processes. Transmission electron microscopy revealed mitochondria swelling 1 h after stretch-induced injury and 6 h after the injury, vacuolar degeneration of the mitochondria occurred. Increased stretch pressure caused further decrease in the amount of glial filaments and densification of astrocytes. CONCLUSIONS: Stress, even at a relatively small scale, can cause disruption of intercellular juncture and ultrastructural change of the cultured astrocyte, which may be related with extensive brain edema after traumatic brain injury.

Radiosurgical treatment of intractable epilepsy with low radiation dose.

OBJECTIVE: To localize the epileptic foci with positron emission tomography (PET), and study the principles of target definition and method to determine the optimal range of exposure in radiosurgery for intractable epilepsy. METHODS: This study included 176 patients with intractable epilepsy, who received linear accelerator radiosurgery after (18)F-FDG PET for epileptic foci localization. The patients were divided according to different peripheral doses used in the treatment into Group A in which radiation dose of 9 to 11 Gy was used, Group B with 11 to 13 Gy and Group C with exposure to over 13 Gy. Follow-up study was conducted in all the patients for a period ranging from 3 to 16 months, during which the frequency of seizure after treatment was recorded to evaluate the therapeutic effect. RESULTS: The seizure frequency significantly decreased after radiosurgical treatment in all the groups, but between the groups, the decrement evinced no significant difference. According to Wieser's classification of the effect after operation, 46.9% cases belonged to grade I to II and 41.5% to grade III to IV. Obvious complications were not observed, nor did disability or mortality occurred in these cases. CONCLUSIONS: Stereotactic radiosurgery with low radiation dose under the guidance of PET provides a safe, effective and minimally invasive surgical approach for patients with intractable epilepsy, and peripheral radiation doses of 9 to 11 Gy for the epileptic foci localized by PET is sufficient to ensure good clinical outcome.

Association of epileptiform activity with neuronal death in the CA3 subfield of the hippocampus following focally evoked limbic seizures.

OBJECTIVE: To investigate the relationnship between epileptiform activity and cell death in the CA3 subfield of hippocampus following focally evoked limbic seizures through a quantitative study. METHODS: Wistar rats used in this study received intra-amygdaloid injection of kainic acid to induce type epileptiform activity of different duration with continuous electroencephalographic (EEG) monitoring. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) was used to detect apoptotic cells. The number of CA3 neurons survived and TUNEL-positive cells were counted to estimate the number of necrotic cells. RESULTS: Epileptiform activity induced necrosis in the major form of apoptosis of the cells in CA3 subfield of the hippocampus following focally evoked limbic seizures. The longer the type epileptiform activity lasted, the less neurons survived, with consequent increase in the number of both necrotic and apoptotic cells. CONCLUSION: Prolongation of type IV seizures dose-dependently causes increase in apoptotic and necrotic cells in CA3 subfield of the hippocampus.