Regulation of intracellar Ca^<2+> concentration and transcription factors in absence seizures

在这项研究中，我研究了GABA_B受体的参与和核转录因子的协同诱导在失神发作的两种遗传模型--昏睡型(1H/1H)和观星型(STG/STG)小鼠中的协同诱导。昏睡和观星小鼠的脑电记录显示6赫兹的棘波和波放电(SWD_S)，并伴随着运动的同时停止。在两种模型中，典型的抗缺神药物乙琥胺和GABA_B拮抗剂CGp 35348和CGp 46381抑制SWD_S。凝胶位移分析显示，嗜睡和观星小鼠丘脑和大脑皮层的核环磷酸腺苷反应元件(Cre)和激活蛋白1(AP-1DNA)结合活性显著高于非癫痫对照组(+/+)，而小脑等其他部位则不明显。两种模型小鼠的Cre和AP-1DNA结合活性均被乙琥胺或CGP 46831抑制，抑制剂量为SWD_s。这些结果表明，GABA_B受体在全身性失神发作的发病机制中起重要作用，丘脑皮质核内Cre和AP-1DNA结合活性增强与昏睡和观星小鼠失神发作的发生和/或传播有关。此外，昏睡小鼠大脑皮层CRE结合活性被抗GRE结合蛋白(CREB)抗体超移，并被抗磷酸化CREB抗体部分抑制。抗c-Fos和抗c-jun抗体可抑制AP-1的DNA结合活性。这些结果表明，增强的Cre结合活性是由于激活了至少部分被磷酸化的CREB的结合活性，c-Fos-c-jun复合体(AP-1蛋白)是增强的AP-1 DNA结合活性的主要成分。

In this study, I examined the involvement of the GABA_B receptors and the coordinated induction of nuclear transcription factors in generalized absence seizures in lethargic (lh/lh) and stargazer (stg/stg) mice, genetic models of absence seizures. electroencephalographic recordings of lethargic and stargazer mice revealed 6 Hz spike and wave discharges (SWD_S) accompanied by simultaneous arrest of movement for the duration of the SWDs. Ethosuximide, a typical antiabsence drug, and CGP 35348 and CGP 46381, GABA_B antagonist, suppressed SWD_S in both models Gel-shift assays showed that nuclear cyclic AMP responsive element (CRE)- and activator protein 1 (AP-1) DNA-binding activities in the thalamus and cerebral cortex, but not in other regions such as the cerebellum of lethargic and stargazer mice were significantly higher than those of each nonepileptic control (+/+) mice. The CRE- and AP-1 DNA-binding activities in both model mice, but not control mice, were inhibited by ethosuximide or CGP 46831, at a dose which suppressed SWD_S. These results suggest that GABA_B receptors play a significant role in the pathogenesis of generalized absence seizures and that enhanced nuclear CRE- and AP-1 DNA-binding activities in the thalamocortical region are related to generation and/or propagation of absence seizures in lethargic and stargazer mice. Furthermore, cerebral cortical CRE-binding activity was supershifted by the anti-GRE-binding protein (CREB) antibody and partially inhibited by anti-phospho-CREB antibody in lethargic mice. The AP-1 DNA-binding activity was inhibited by anti-c-Fos and anti-c-Jun antibodies.These results suggest that the enhanced CRE-binding activity is attributable to the activation of the binding activity of CREB which is phosphorylated at least in part and that the c-Fos-c-Jun complex (AP-1 protein) is a major component of the enhanced AP-1 DNA-binding activity.