QUANTITATIVE GENETIC STUDY OF SEIZURES

成熟的DBA/2J和C57BL/6J小鼠在易感性方面存在显著差异 由各种物理和化学刺激引起的癫痫发作。一般而言，DBA 小鼠的特征是相对“癫痫敏感”，而C57小鼠则是 其特征是相对“抗癫痫”。这份提案描述了 一项研究项目，旨在阐明有助于 成年C57BL/6J小鼠与DBA/2J小鼠在体内的差异 红藻氨酸(KA)、戊四唑诱发癫痫的易感性 (PTZ)和最大电休克(MES)治疗。据推测， 与应变相关的敏感性和对惊厥各方面的抵抗力 这些处理引起的反应是由相似的基因介导的 元素。在三个不同的实验中，B6D2F1/J(C57BL/6J x DBA/2J，F1 世代)小鼠将进行杂交繁殖，以产生F2代的 大约500只老鼠。在每个实验中，将对F2小鼠进行研究 癫痫表型。行为癫痫参数--以下情况将进行监测 化学惊厥药物的使用包括首次发作的潜伏期 全身性(强直-阵挛)发作的(阵挛)潜伏期和 离散的癫痫发作。在KA研究中，状态的诱导和潜伏期 癫痫患者也将接受监测。这些参数将用于 量化每只动物的癫痫发作活动。总的癫痫评分将是 通过将加权标尺应用于定量扣押而生成 措施。在第三系列实验中，表型将反映MES 强健后肢伸展的阈值。数量性状座位(QTL) F2代将采用“区间和极值”策略 表现出10%最极端的表型(最高和最低的癫痫发作 严重程度分数或MES阈值)将被选择用于基因分型 实验。基因分型将使用基于聚合酶链式反应的微卫星 (二核苷酸/简单序列重复)DNA标记平均间隔10 cM 整个小鼠基因组的间隔时间。使用计算机程序 对于最大似然法，MapMaker/QTL，基因数据将是 分析以确定基因的大致染色体位置 KA和PTZ在DBA/2J小鼠癫痫易感性中的作用 C57BL/6J小鼠对PTZ惊厥的抵抗力及其与正常对照组的差异 MES阈值中的菌株。在KA和PTZ研究中，分开计算QTL 将针对个别组成部分进行癫痫发作的严重程度 评分(如阵挛潜伏期和癫痫持续状态)以及 癫痫发作总分。MES阈值将直接用于QTL 计算。确认相似的遗传基因座与 对所述特定效应的敏感性和抵抗力 抽搐治疗将表明基因的定位很重要 用于调节小鼠大脑的兴奋性。对这些的识别 基因可能最终导致在理解和研究方面的重大进步 治疗人类癫痫。

Mature DBA/2J and C57BL/6J mice differ significantly in susceptibility to seizures induced by various physical and chemical stimuli. In general, DBA mice are characterized as relatively "seizure sensitive" and C57 mice are characterized as relatively "seizure resistant". This proposal describes a research project intended to elucidate genomic loci which contribute to the large differences observed between mature C57BL/6J and DBA/2J mice in susceptibility to seizures induced by kainic acid (KA), pentylenetetrazole (PTZ), and maximal electroshock (MES) treatment. It is hypothesized that strain-dependent sensitivity and resistance to aspects of the convulsive response induced by these treatments are mediated by similar genetic elements. In three distinct experiments, B6D2F1 /J (C57BL/6J x DBA/2J, F1 generation) mice will be bred in intercross to produce F2 generations of approximately 500 mice. In each experiment, F2 mice will be studied for seizure phenotype. Behavioral seizure parameters-to be monitored following administration of chemoconvulsants include latency to first seizure (clonus) latency to generalized (tonic-clonic) seizure and number of discrete seizures. In the KA study, induction of and latency to status epileptic us will also be monitored. These parameters will be used to quantify seizure activity in each animal. An overall seizure score will be generated by applying a weighted scale to the quantitative seizure measures. In the third series of experiments, phenotypes will reflect MES threshold for tonic hindlimb extension. The quantitative trait loci (QTL) strategy of "intervals and extremes" will be employed in which F2 progeny exhibiting the 10% most extreme phenotypes (the highest and lowest seizure severity scores or MES thresholds) will be selected for use in genotype experiments. Genotyping will be conducted using PCR-based microsatellite (dinucleotide/simple sequence repeat) DNA markers evenly spaced at 10 cM intervals across the entire mouse genome. Employing a computer program for maximum likelihood methods, MAPMAKER/QTL, genotype data will be analyzed to identify the approximate chromosomal locations of genes contributing to KA and PTZ seizure susceptibility in DBA/2J mice, KA and PTZ seizure resistance in C57BL/6J mice and the difference between the strains in MES threshold. In KA and PTZ studies, separate QTL calculations will be carried out for individual components of the seizure severity score (such as latency to clonus and status epileptic us) as well as for the total seizure score. MES thresholds will be used directly in QTL calculations. Confirmation that similar genetic loci are associated with susceptibility and resistance to specific effects of the described convulsive treatments would indicate the localization of genes important for the regulation of excitability in mouse brain. Identification of these genes could ultimately lead to major advances in understanding and treating human epilepsies.