Kainic acid modifies mu-receptor binding in young,adult, and elderly rat brain

-Receptor binding changes were evaluated following the kainic acid (KA)-induced status epilepticus (SE) in young, adult, and elderly animals. Male Wistar rats were used as follows: young rats (15 days old) were treated with KA (7 mg/kg) and sacrificed 72 h (YKA3d) or 35 days (YKA35d) after SE; adult (90 days old) (AKA1d and AKA40d) and elderly rats (1-year-old) (EKA1d and EKA40d) were injected with KA (10 mg/kg) and then sacrificed 24 h or 40 days following SE. Their brains were processed for an autoradiography assay for -receptors. The YKA3d group showed increased values in dentate gyrus (39%) and a decrease in substantia nigra (26%); YKA35d animals had a reduction in caudate putamen (29%) and in substantia nigra (20%). The AKA1d group exhibited increased -receptors in caudate putamen (49%), cingulate (415%), frontal (52%), and temporal (53%) cortices; substantia nigra (56%), dentate gyrus (48%), and CA2 field of hippocampus (53%). The AKA40d group showed increased values in sensorimotor cortex (45%), anterior (39%), medial (65%), basolateral (202%), and central (32%) amygdaloid nuclei; dentate gyrus (80%) as well as CA2 (80%) and CA3 (49%) fields of hippocampus. The EKA1d group presented decreased -receptor binding in piriform (16%) and enthorinal (22%) cortices as well as in anterior amygdala nucleus (17%). The EKA40d group showed reduced values in sensorimotor cortex (14%) and substantia nigra (27%). The present results indicate that the -binding changes following SE depend on the rate of brain maturation.     

Synthesis and Characterization of N,N-Dichlorinated Amino Acids: Taurine,Homotaurine, GABA and L-Leucine

Epilepsy, trauma and other circumstances leading to hyperexcitable conditions in the CNS tend neurochemically to be associated with excessive stimulated release of glutamic acid and/or a failure of GABA modulated inhibition. Somewhat to a lesser extent, taurine and its homologue homotaurine, have also been shown to antagonize the excitatory actions of glutamic acid. Here we report the successful synthesis and isolation in pure form of N,N-dichlorinated GABA, taurine, homotaurine and leucine. These compounds are much more lipophilic than their parent compounds and may therefore more readily penetrate the blood-brain barrier systems into the neural tissue, where they can be easily dechlorinated. Very preliminary biological testing shows that this may indeed occur. The synthesis and purification methodology will likely also be applicable to a number of other amino acids as well as certain peptides or selected proteins.     

Extending julius seizure,a bang-sensitive gene,as a model for studying epileptogenesis: Cold shock,and a new insertional mutation

The bang-sensitive (BS) mutants of Drosophila are an important model for studying epilepsy. We recently identified a novel BS locus, julius seizure (jus), encoding a protein containing two transmembrane domains and an extracellular cysteine-rich loop. We also determined that jus^{sda iso7.8}, a previously identified BS mutation, is an allele of jus by recombination, deficiency mapping, complementation testing, and genetic rescue. RNAi knockdown revealed that jus expression is important in cholinergic neurons and that the critical stage of jus expression is the mid-pupa. Finally, we found that a functional, GFP-tagged genomic construct of jus is expressed mostly in axons of the neck connectives and of the thoracic abdominal ganglia. In this Extra View article, we show that a MiMiC GFP-tagged Jus is localized to the same nervous system regions as the GFP-tagged genomic construct, but its expression is mostly confined to cell bodies and it causes bang-sensitivity. The MiMiC GFP-tag lies in the extracellular loop while the genomic construct is tagged at the C-terminus. This suggests that the alternate position of the GFP tag may disrupt Jus protein function by altering its subcellular localization and/or stability. We also show that a small subset of jus-expressing neurons are responsible for the BS phenotype. Finally, extending the utility of the BS seizure model, we show that jus mutants exhibit cold-sensitive paralysis and are partially sensitive to strobe-induced seizures.     

载脂蛋白E与癫痫的关系

载脂蛋白E（apolipoprotein E,ApoE）在中枢神经系统修复受损细胞膜、轴索生长和突触形成的过程中起重要作用.研究证明,在外伤、中毒、免疫应答以及痫性放电引起的脑部损伤的病灶组织中都存在载脂蛋白E表达的上调现象.载脂蛋白E的基因多态性和表达量与难治性癫痫的发生和发展有一定的相关性,提示载脂蛋白E的异常可能是难治性癫痫产生机制中的一个重要环节.     

Risk of neurological diseases among survivors of electric shocks: a nationwide cohort study, Denmark, 1968-2008

Several studies suggest a link between electric injuries and neurological diseases, where electric shocks may explain elevated risks for neuronal degeneration and, subsequently, neurological diseases. We conducted a retrospective cohort study on the risk of neurological diseases among people in Denmark who had survived an electric accident in 1968-2008. The cohort included 3,133 people and occurrences of neurological diseases were determined by linkage to the nationwide population-based Danish National Register of Patients. The numbers of cases observed at first hospital contact in the cohort were compared with the respective rates of first hospital contacts for neurological diseases in the general population. We observed significantly increased risks for peripheral nerve diseases (standardized hospitalization ratio (SHR), 1.66; 95% confidence interval (CI), 1.22-2.22), for migraine (SHR, 1.80; 95% CI, 1.23-2.54), for vertigo (SHR, 1.60; 95% CI, 1.22-2.05), and for epilepsy (SHR, 1.45; 95% CI, 1.11-1.85). Only small numbers of cases of other neurological diseases were found, making the risk estimates unstable. These findings suggest an association between a single electric shock and increased risks for peripheral nerve diseases, migraines, vertigo, and epilepsy, but confirmation of these observations is needed.     

Two Types of Seizures in Homocysteine Thiolactone-Treated Adult Rats,Behavioral and Electroencephalographic Study

d,l-Homocysteine thiolactone (H), a reactive homocysteine metabolite, contributes to total homocysteine pool. The aim of the present study was to determine the effects of H after acute application in increasing doses to rats. Adult Wistar rat were intraperitoneally administered saline or H in increasing doses (5.5, 8.0, or 11.0 mmol/kg). For electroencephalographic (EEG) recordings, three gold-plated screws were implanted into the skull and animals were supervised. We observed H-induced two types of seizures, the coexistence of convulsive and nonconvulsive epilepsy. Dose-related increase in the number and severity (0–4) of displaying convulsions was recorded. In H_5.5 group, the majority of seizure episodes were grade 1 (62.5 and 0% lethality), in H₈ 40% grade 2, and in H₁₁ grade 4 in 42.11% (100% lethal outcome). EEGs recordings in convulsive animals showed a high-voltage spike-wave and polyspikes complexes. The second, absence-like, nonconvulsive seizures were accompanied by the EEGs mostly with 6–8 Hz spikes-and-wave discharges (SWD). Latency time to the generalized clonic-tonic seizures overlapped with the time of the maximal median number and median duration of the SWD per 15 min during 90-min observing period. The results show that acute H administration significantly changes neurons, EEG tracings, and behavioral responses and suggests a possible model for studying petit mal epilepsy.     

81 例顽固性癫痫患者发作分类特点分析

目的:分析81例最终接受手术治疗的顽固性癫痫患者发病特点,了解不同分类癫痫的发病规律。方法:对81例最终接受手术治疗的顽固性癫痫患者进行分类,分析性别、发病年龄、病程、发作频率等与癫痫分类间的关系。结果:81例患者的男女比例为1.45:1,男性的平均发病年龄为13.6,女性为14.3,强直阵挛发作的耐受病程最短,平均为5.8年,大多数患者在20岁以前发病。结论:多种癫痫发作分类在性别、发病年龄、病程、发作频率上存在差异。     

Epilepsy, Neurodegeneration, and Extracellular Glutamate in the Hippocampus of Awake and Anesthetized Rats Treated with Okadaic Acid

We have previously shown that the intrahippocampal microinjection of okadaic acid (OKA), a potent inhibitor of serine/threonine protein phosphatases, induces epileptic seizures, neuronal death, and the hyperphosphorylation of the NR2B subunit of the N-methyl-d-aspartate (NMDA) receptor. We administered OKA by reverse microdialysis in the hippocampus of awake and halothane-anesthetized rats, with simultaneous collection of microdialysis fractions and recording of the EEG activity, and subsequent histological analysis. OKA produced intense behavioral and persistent EEG seizure activity in the awake rats but not in the anesthetized animals, and did not significantly alter the extracellular concentration of glutamate and aspartate detected in the microdialysis fractions. One day after the experiment a remarkable neurodegeneration of CA1 hippocampal region was observed in both the awake and the anesthetized rats. We conclude that the OKA-induced epilepsy cannot be ascribed to increased extracellular glutamate, but to an increased sensitivity of NMDA receptor. We propose that halothane protected against the epilepsy because it blocks NMDA receptor overactivation, and that the neurodegeneration of CA1 region is independent of this overactivation and due probably to alterations of cytoskeletal proteins consequent to the OKA-induced hyperphosphorylation.     

CCR7, CCR8, CCR9 and CCR10 in the mouse hippocampal CA1 area and the dentate gyrus during and after pilocarpine-induced status epilepticus

The present study showed CCR7, CCR8, CCR9 and CCR10 in the normal Swiss mouse hippocampus at both protein and mRNA levels. CCR7, CCR9 and CCR10 were mainly localized in hippocampal principal cells and some interneurons. CCR9 was also found in the mossy fibres and/or terminals, suggesting an axonal or presynaptic localization, and CCR10 in apical dendrites of pyramidal neurons in the CA1 area. CCR8 was observed in interneurons. Double-labelling immunocytochemistry revealed that most of calbindin (CB)-, calretinin (CR)- and parvalbumin (PV)-immunopositive neurons expressed CCR7-10, except CR-immunopositive cells in which only 10 to 12% expressed CCR8. During and after pilocarpine-induced status epilepticus, progressive changes of each of CCR7, CCR8, CCR9 and CCR10 proteins occurred in different patterns at various time points. Sensitive real-time PCR showed similar change patterns at mRNA level. At the chronic stage, i.e. at 2 months after pilocarpine-induced status epilepticus, significant reduction of CCR7-10 expression in CB-, CR- and PV-immunpositive interneurons may suggest the phenotype change of surviving interneurons. Double labelling of CCR7, CCR8 and CCR9 with glial fibrillary acidic protein (GFAP) at the chronic stage may suggest an induced expression in reactive astrocytes. The present study may, therefore, for the first time, provide evidence that CCR7-10 may be involved in normal hippocampal activity. The demonstration of the progressive changes of CCR7-10 during and after status epilepticus may open a new area to reveal the mechanism of neuronal loss after status epilepticus and of epileptogenesis.     

Structure-based screening,ADMET profiling,and molecular dynamic studies on mGlu2 receptor for identification of newer antiepileptic agents

Structure-based screening approach targeting mGlu2 receptor was carried out to identify good chemical starting points for anti-epileptic therapy. Interactive modes of final 12 compounds identified on the basis of screening of Asinex library, binding energy analysis, ADME profiling with special emphasis for CNS ranges, and toxicity analysis were studied and showed good binding modes in the mGluR2-active site. Enrichment studies for validating screening protocol were carried out which gave ROC values 0.98 (AUC = 0.96) for SP, 0.97 (AUC = 0.95) for XP with BEDROC analysis. Our results indicate that all the 12 hits showed good CNS drug-like properties, have better binding free energy and ADME profile as compared to co-crystallized ligand with the best ligand hit retaining conserved hydrogen bond interactions with Ala-166, Thr-168, Ser-145, and Arg-61 residues in bilobatevenus fly-trap domain of mGluR2 receptor. Molecular dynamics simulations proved that the two potential hits, qualifying all screening parameters, are stable in the receptor active site pocket, confirming the potential of the identified hits as a specific target for mGluR2. Because the newly discovered mGluR2 agonists are structurally different with T_c values ranging from 0.57 to 0.92, all of them can be considered for further de novo design methods.     

Neuronal and Glial Expression of the Multidrug Resistance Gene Product in an Experimental Epilepsy Model

1. Failure of anticonvulsive drugs to prevent seizures is a common complication of epilepsy treatment known as drug-refractory epilepsy but their causes are not well understood. It is hypothesized that the multidrug resistance P-glycoprotein (Pgp-170), the product of the MDR-1 gene that is normally expressed in several excretory tissues including the blood brain barrier, may be participating in the refractory epilepsy. 2. Using two monoclonal antibodies against Pgp-170, we investigated the expression and cellular distribution of this protein in the rat brain during experimentally induced epilepsy. Repeated seizures were induced in male Wistar rats by daily administration of 3-mercaptopropionic acid (MP) 45 mg/kg i.p. for either 4 days (MP-4) or 7 days (MP-7). Control rats received an equivalent volume of vehicle. One day after the last injection, rats were sacrificed and brains were processed for immunohistochemistry for Pgp-170. As it was previously described, Pgp-170 immunostaining was observed in some brain capillary endothelial cells of animals from control group. 3. Increased Pgp-170 immunoreactivity was detected in MP-treated animals. Besides the Pgp-170 expressed in blood vessels, neuronal, and glial immunostaining was detected in hippocampus, striatum, and cerebral cortex of MP-treated rats. Pgp-170 immunolabeled neurons and glial cells were observed in a nonhomogeneous distribution. MP-4 animals presented a very prominent Pgp-170 immunostaining in the capillary endothelium, surrounding astrocytes and some neighboring neurons while MP-7 group showed increased neuronal labeling. 4. Our results demonstrate a selective increase in Pgp-170 immunoreactivity in the brain capillary endothelial cells, astrocytes, and neurons during repetitive MP-induced seizures. 5. The role for this Pgp-170 overexpression in endothelium and astrocytes as a clearance mechanism in the refractory epilepsy, and the consequences of neuronal Pgp-170 expression remain to be disclosed.     

A polygenic heterogeneity model for common epilepsies with complex genetics

Approximately 40% of epilepsy has a complex genetic basis with an unknown number of susceptibility genes. The effect of each susceptibility gene acting alone is insufficient to account for seizure phenotypes, but certain numbers or combinations of variations in susceptibility genes are predicted to raise the level of neuronal hyperexcitability above a seizure threshold for a given individual in a given environment. Identities of susceptibility genes are beginning to be determined, initially by translation of knowledge gained from gene discovery in the monogenic epilepsies. This entrée into idiopathic epilepsies with complex genetics has led to the experimental validation of susceptibility variants in the first few susceptibility genes. The genetic architecture so far emerging from these results is consistent with what we have designated as a polygenic heterogeneity model for the epilepsies with complex genetics.