GABA Receptor Activity Suppresses the Transition from Inter-ictal to Ictal Epileptiform Discharges in Juvenile Mouse Hippocampus / 神经科学通报·英文版

Exploring the transition from inter-ictal to ictal epileptiform discharges (IDs) and how GABA receptor-mediated action affects the onset of IDs will enrich our understanding of epileptogenesis and epilepsy treatment. We used Mg-free artificial cerebrospinal fluid (ACSF) to induce epileptiform discharges in juvenile mouse hippocampal slices and used a micro-electrode array to record the discharges. After the slices were exposed to Mg-free ACSF for 10 min-20 min, synchronous recurrent seizure-like events were recorded across the slices, and each event evolved from inter-ictal epileptiform discharges (IIDs) to pre-ictal epileptiform discharges (PIDs), and then to IDs. During the transition from IIDs to PIDs, the duration of discharges increased and the inter-discharge interval decreased. After adding 3 μmol/L of the GABA receptor agonist muscimol, PIDs and IDs disappeared, and IIDs remained. Further, the application of 10 μmol/L muscimol abolished all the epileptiform discharges. When the GABA receptor antagonist bicuculline was applied at 10 μmol/L, IIDs and PIDs disappeared, and IDs remained at decreased intervals. These results indicated that there are dynamic changes in the hippocampal network preceding the onset of IDs, and GABA receptor activity suppresses the transition from IIDs to IDs in juvenile mouse hippocampus.

Study on hippocampal volume with quantitative 3T magnetic resonance imaging in Chinese patients with epilepsy / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>It was still rare for the quantitative magnetic resonance imaging (MRI) research of regional changes in hippocampus sclerosis (HS) in Chinese patients with epilepsy. This study aimed to study the hippocampal volumes (HVs) with quantitative MRI measurement in Chinese patients with epilepsy.</p><p><b>METHODS</b>Forty-six Chinese patients with epilepsy (intractable epilepsy (IE), n = 21; non-intractable epilepsy (NIE), n = 25) and 25 normal controls were collected between July 2007 and March 2008. All of the subjects underwent a 3T high-resolution MRI with oblique coronal thin sections oriented perpendicular to the hippocampal long axis. Hippocampal structures were assessed by visual detection, and HVs were quantitatively studied with a Picture Archiving and Communication System (PACS).</p><p><b>RESULTS</b>Our study suggested that there was no significant difference in gender (P > 0.05) while the right hippocampal head volume (HHV), hippocampal body volume (HBV), and the whole hippocampal volume (HCV) were greater than the left one (P < 0.05), but no significant difference was found in bilateral hippocampal tail volume (HTV) (P > 0.05) in normal controls. That unilateral/diffuse (64%/21%) and bilateral/focal (86%/20%) hippocampal atrophy (HA) were significant in IE and NIE patients, respectively. Anterior hippocampus, especially HHV (26% in IE and 20% in NIE) and HBV (29% in IE and 12% in NIE), had more significant atrophy than the HTV (5% in IE and 0% in NIE) in patients with epilepsy.</p><p><b>CONCLUSION</b>By assessing the volumes of the regional hippocampus with 3T MRI, we could better define the range and distribution of HS, since regional or subtle changes in HVs could be detected earlier with 3T MRI.</p>

Effect of acute stress stimulation on the seizure induction in epileptic model rats / 生理学报

This study was undertaken to observe the effect of acute stress on seizure occurrence in chronic period of epileptic model rats. Lithium-pilocarpine (LiCl-PILO)-induced epileptic rat model was constructed. At the spontaneous recurrent seizure period, acute stress stimulations such as cat's urine and foot electrical shock were applied to observe the behavioral changes and seizure occurrence. The results showed that after the cat's urine stimulation, the self-directed behaviors of the epileptic model rats decreased significantly, while the risk assessment behaviors increased significantly. The seizure occurrence, however, was not observed during the 45 min after the stimulation. Applying electrical foot shocks also did not evoke seizures in epileptic model rats. On the contrast, intra-peritoneal injection of low dose of pentylenetetrazole (PTZ, 30 mg/kg) evoked seizure more efficiently, and the duration of seizure activity was extensively prolonged in epileptic model rats than that of control rats. Taken together, these results indicate that although applying stress stimulations such as cat's urine and electrical foot shock cause several behavioral changes, they are not severe enough to evoke seizure in epileptic model rats.

Predictors of outcome in the surgical treatment for epilepsy / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Knowledge about factors influencing the prognosis of resective epilepsy surgery can be used to identify which patients are most suitable for surgical treatment. The aim of this study was to identify preoperative prognostic factors associated with the chance of achieving long-term seizure freedom.</p><p><b>METHODS</b>We retrospectively reviewed seizure outcomes and clinical, electroencephalography (EEG), magnetic resonance imaging (MRI), histopathology, and surgical variables from 99 epilepsy surgery patients with at least one year of postoperative follow-up. Seizure outcomes were categorized based on the modified classification by the International League Against Epilepsy.</p><p><b>RESULTS</b>We found that the seizure-free rate was 27.9% after one year, and that it stabilized at about 20.0% between two and six years after surgery. Univariate analysis showed that medial temporal lobe epilepsy with hippocampal sclerosis, MRI with visible focal lesions concordant with EEG, and regional ictal EEG and electrocorticography patterns were associated with a favorable surgical outcome. On the other hand, seizure recurrence within six months, incomplete focus resection, and surgical complications were associated with a poor outcome. Multivariate analysis showed that medial temporal lobe epilepsy with hippocampal sclerosis and MRI with visible focal lesions were independent presurgical predictors of a favorable outcome (P < 0.01). Seizure recurrence within six months was the only significant independent predictor associated with a poor outcome (P < 0.01).</p><p><b>CONCLUSION</b>Hippocampal sclerosis and abnormal MRI findings are strongly associated with a favorable surgical outcome, whereas seizure recurrence within six months is associated with a poor outcome.</p>

Exploring spatiotemporal patterns of epileptiform discharge in hippocampal slice using multi-electrode arrays / 生理学报

To investigate the spatiotemporal properties of epileptiform activity in vitro, 400 microm-thick transverse hippocampal slices were prepared from juvenile rat and planar multi-electrode array (MEA) containing 60 electrodes was used to record the electrical activity induced by bath application of high potassium artificial cerebrospinal fluid (ACSF) on slices. Following successful induction of epileptiform bursts, phenobarbital sodium was applied to test for its inhibitory effects on bursting activity in different regions of slice. Region-specific characteristics of epileptiform activity and anticonvulsant actions of phenobarbital sodium in the hippocampal network were determined by comparing the population activity obtained from MEA. The results showed that: (1) 15 min after high-K+ ACSF application, rhythmic and synchronous epileptiform bursts could be detected from all CA sub-regions. Quantitative analysis indicates that the firing patterns of different CA sub-regions were not statistically different (P>0.05). However, no bursting activity was recorded from granular cells in dentate gyrus, only sparse spikes were observed, with frequency significantly lower than that in CA regions (P<0.05). (2) The high-K+-induced bursting activity could last for more than 40 min with stable bursting activities. (3) Bath application of 60 micromol/L phenobarbital sodium inhibited the bursting activities on hippocampal slice. Bursting activities in CA3c and CA1 were firstly suppressed. 10 min after the phenobarbital sodium application, strong bursting activities persisted only in some of pyramidal cells in CA3a and CA3b. These results show that MEA could be applied for studying the spatial and temporal properties of epileptiform activity in vitro, as well as the region-specific effects of anti-epileptic drugs.

Establishment and comparison of DHPG and BMI induced epileptic discharge models / 上海第二医科大学学报

Objective To develop models of epileptic discharge by activating group Ⅰ metabotropic glutamate receptors (mGluR) or by blocking gamma-aminobutyric acid (GABA) receptors on rat hippocampal slices. Methods Rat hippocampal slices were exposed to mGluR group Ⅰ specific agonist dihydroxyphenylglycine (DHPG) or to GABAA receptor antagonists bicuculline methiodide(BMI), and single pyramidal cell in the CA3 region of the slice was recorded by whole cell patch clamp technique. Results Exposure to DHPG or BMI resulted in the induction of spontaneously occurring epileptic discharge in the CA3 region of rat hippocampal slice, and there was no significant difference in the frequency of discharge between them(P>0.05). Conclusion Epileptic discharge can be generated in vitro in response to a loss of balance between excitatory and inhibitory influences.

Alteration of electrophysiology in pilocarpine mice model of epilepsy with impairment of contextual fear memory / 上海第二医科大学学报

0.05).However,there was no significant difference in the AMPAR-mediated basal synaptic transmission on hippocampal CA1 between those at the later period(6 weeks) of epilepsy induced by pilocarpine and controls,while LTP was inhibited(P