Effects of prolonged seizures on GABAA receptor function

长时间癫痫发作对 GABAA 受体功能的影响

• 批准号: 7097898
• 负责人: ANDRE H LAGRANGE
• 金额: $ 16.4万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-01 至 2009-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7097898
• 关键词: GABA receptor; dentate gyrus; diazepam; drug delivery systems; gamma aminobutyrate; generalized seizures; hippocampus; immunocytochemistry; immunoprecipitation; laboratory rat; lithium; phosphorylation; protein kinase A; protein kinase C; protein structure function; receptor sensitivity; transfection /expression vector; voltage /patch clamp

DESCRIPTION (provided by applicant): Electrical excitability of cortical neurons is regulated, in large part, by excitatory glutamatergic and inhibitory GABAergic input. Dysregulation of this system appears to underlie the initiation and propagation of seizures. With prolonged seizures, there is a change in GABAA receptor function. At an organismic level, this may be associated with benzodiazepine insensitivity, requiring high dose barbiturates to abort seizures. At a cellular level there is attenuation of both benzodiazepine and zinc modulation of GABAA receptors on isolated dentate granule cells. Although CA1 hippocampal neurons become relatively GABA insensitive, no such change in GABA pharmacology at GABAA receptors on granule cells has been seen. However, the effect of seizures on the fast components of GABAA receptor activation/deactivation/desensitization has not been explored. Since synaptically-released GABA is thought to be present in the synaptic cleft for only 1-2 ms, these fast components of GABAA receptor activation may profoundly alter the shape of GABAergic post-synaptic potentials. These studies will investigate the changes in GABAA receptor function on isolated dentate granule cells using a rapid drug delivery system following prolonged seizures induced in rats with Lithium/pilocarpine. Firstly, GABA concentration response relationships will be determined. Next, the rapid components of GABAA receptor kinetics will be determined using a cell-attached voltage clamp technique with rapid drug delivery. Furthermore, single channel kinetics will also be measured in cells from control and animals which have undergone seizures. Finally, the effect of seizures on GABAA receptor allosteric modulators will be determined. In addition to being intrinsically interesting and potentially clinically useful, the pattern of these effects may provide important clues as to whether the changes in GABAA receptor function are due to a rearrangement of the subunits making up those receptors. These studies seek to elucidate the changes in GABAA receptor function seen after prolonged seizures. This may help further our understanding of seizure initiation/abortion as well as normal GABAergic synaptic transmission.

描述（由申请人提供）：皮质神经元的电兴奋性在很大程度上由兴奋性谷氨酸能和抑制性 GABA 能输入调节。该系统的失调似乎是癫痫发作的发生和传播的基础。随着癫痫发作时间的延长，GABAA 受体功能会发生变化。在有机体水平上，这可能与苯二氮卓类药物不敏感有关，需要高剂量巴比妥类药物才能中止癫痫发作。在细胞水平上，苯二氮卓类和锌对分离的齿状颗粒细胞上 GABAA 受体的调节均减弱。尽管 CA1 海马神经元对 GABA 变得相对不敏感，但颗粒细胞上 GABAA 受体的 GABA 药理学尚未见这种变化。然而，癫痫发作对 GABAA 受体激活/失活/脱敏的快速成分的影响尚未被探索。由于突触释放的 GABA 被认为在突触间隙中仅存在 1-2 毫秒，因此 GABAA 受体激活的这些快速成分可能会深刻地改变 GABA 能突触后电位的形状。这些研究将使用快速药物递送系统研究在用锂/毛果芸香碱诱导大鼠长时间癫痫发作后分离的齿状颗粒细胞上 GABAA 受体功能的变化。首先，将确定 GABA 浓度响应关系。接下来，将使用细胞附着电压钳技术和快速药物输送来确定 GABAA 受体动力学的快速成分。此外，还将在对照细胞和癫痫发作动物的细胞中测量单通道动力学。最后，将确定癫痫发作对 GABAA 受体变构调节剂的影响。除了本质上有趣且具有潜在的临床用途外，这些效应的模式还可以提供重要线索，以确定 GABAA 受体功能的变化是否是由于构成这些受体的亚基的重排所致。这些研究旨在阐明长期癫痫发作后 GABAA 受体功能的变化。这可能有助于进一步了解癫痫发作/流产以及正常的 GABA 突触传递。