QUANTITATIVE GENETIC STUDY OF SEIZURES

成熟的DBA/2 J和C57 BL/6 J小鼠在对 由各种物理和化学刺激引起的癫痫发作。一般来说，DBA 小鼠的特征是相对“癫痫敏感”，C57小鼠 其特征在于相对“抗癫痫”。该提案描述了 一项旨在阐明基因组位点的研究项目， 在成熟的C57 BL/6 J和DBA/2 J小鼠之间观察到的巨大差异， 对海人酸（KA）、戊四氮诱导的癫痫发作的敏感性 (PTZ)最大电休克（MES）治疗。它是假设 应变依赖的敏感性和对惊厥方面的抵抗力 由这些治疗诱导的反应是由类似的基因介导的。 元素在三个不同的实验中，B6 D2 F1/J（C57 BL/6 J × DBA/2 J，F1 代）小鼠进行杂交以产生F2代 大约500只老鼠。在每个实验中，将研究F2小鼠的 癫痫发作表型行为性癫痫发作参数-监测如下 化学惊厥药的给药包括首次癫痫发作的潜伏期 （阵挛）全身性（强直-阵挛）癫痫发作的潜伏期和 不连续的癫痫发作在KA研究中，状态的诱导和潜伏期 癫痫患者也将受到监测。这些参数将用于 量化每只动物的癫痫发作活动。总体癫痫发作评分将为 通过将加权标度应用于定量发作而产生 措施在第三系列实验中，表型将反映MES 强直性后肢伸展阈值。数量性状基因座（QTL） 将采用“区间和极值”策略，其中F2后代 表现出10%最极端的表型（最高和最低的癫痫发作 严重性评分或MES阈值）将被选择用于基因型分析。 实验将使用基于PCR的微卫星进行基因分型 （二核苷酸/简单重复序列）DNA标记，间隔10 cM 在整个小鼠基因组中。 使用计算机程序 对于最大似然法，MAPMAKER/QTL，基因型数据将 分析以确定基因的大致染色体位置 在DBA/2 J小鼠中，KA和 C57 BL/6 J小鼠PTZ癫痫发作抵抗性以及 MES阈值中的菌株。在KA和PTZ研究中，单独的QTL计算 将对癫痫发作严重程度的各个组成部分进行 评分（如阵挛和癫痫持续状态的潜伏期）以及 癫痫总评分MES阈值将直接用于QTL 计算。证实相似的基因位点与 对所描述的特定效应的敏感性和抗性 惊厥性治疗将表明重要基因的定位 调节小鼠大脑的兴奋性。识别这些 基因最终可能会导致理解和 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.