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: 7452529
• 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 2010-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7452529
• 关键词: Acute; Barbiturates; Benzodiazepines; Cells; Control Animal; Cyclic AMP-Dependent Protein Kinases; DNA Sequence Rearrangement; Diazepam; Dose; Drug Delivery Systems; Glutamates; Hippocampus (Brain); Immunoprecipitation; Kinetics; Lithium; Measures; Mediating; Neurons; Pattern; Pharmacology; Phosphorylation; Pilocarpine; Property; Protein Kinase; Rattus; Receptor Activation; Recombinants; Resistance; Role; Seizures; Shapes; Staining method; Stains; Surface; Synaptic Cleft; Synaptic Potentials; Synaptic Transmission; System; Thinking; Voltage-Clamp Technics; Zinc; abortion; attenuation; barbituric acid salt; desensitization; gamma-Aminobutyric Acid; granule cell; interest; mutant; receptor; receptor function; response

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受兴奋性谷氨酸能和抑制性GABA能输入的调节。该系统的失调似乎是癫痫发作的起始和传播的基础。随着癫痫发作时间的延长，GABAA受体功能发生变化。在器官水平上，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的GABAA受体的调节均减弱。虽然CA 1海马神经元变得相对GABA不敏感，在颗粒细胞上的GABAA受体的GABA药理学没有这样的变化。然而，癫痫发作对GABAA受体激活/失活/脱敏的快速组分的影响尚未探讨。由于突触释放的GABA被认为仅存在于突触间隙中1-2 ms，因此GABAA受体激活的这些快速组分可能深刻地改变GABA能突触后电位的形状。这些研究将使用快速给药系统研究锂/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，GABAA受体动力学的快速组分将使用具有快速药物递送的细胞附着电压钳技术来确定。此外，还将在来自对照和经历癫痫发作的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。除了本质上令人感兴趣和潜在的临床有用性之外，这些效应的模式可以提供关于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而引起的重要线索。这些研究试图阐明GABAA受体功能的变化后，长期癫痫发作。这可能有助于我们进一步了解癫痫发作的启动/流产以及正常的GABA能突触传递。