Post-Hypoxic Regulation of GABA-A Receptor Function

GABA-A 受体功能的缺氧后调节

• 批准号: 7546993
• 负责人: Lazar John GREENFIELD
• 金额: $ 25.92万
• 依托单位: UNIVERSITY OF TOLEDO HEALTH SCI CAMPUS
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-01-01 至 2010-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7546993
• 关键词: Accounting; Affect; Aftercare; Aminobutyric Acids; BHLH Protein; Behavior; Calcium; Calcium Channel; Cell Nucleus; Cells; Cerebral Hypoxia; Chloride Channels; Chloride Ion; Chlorides; Complementary DNA; Deferoxamine; Disease; Dominant-Negative Mutation; Electric Capacitance; Exposure to; Functional disorder; GABA-A Receptor; Genes; Genetic Transcription; Goals; Hypoxia; Hypoxia Inducible Factor; Immunoblotting; In Vitro; Iodoacetamide; Kinetics; Link; Measures; Mediating; Messenger RNA; Modeling; Myoclonus; Neuronal Plasticity; Neurons; Oxygen; Pharmacology; Phosphorylation; Physiological; Property; Proteins; Rattus; Regulation; Relative (related person); Reverse Transcriptase Polymerase Chain Reaction; Role; Seizures; Signal Pathway; Signal Transduction; Stroke; Time; Transactivation; Transfection; Whole-Cell Recordings; clinically significant; cytotoxicity; density; gamma-Aminobutyric Acid; in vivo; inhibitor/antagonist; mRNA Expression; mutant; neuronal excitability; novel; prevent; receptor; receptor function; voltage; voltage gated channel

Stroke and hypoxia frequently cause seizures or myoclonus, disorders of excessive neuronal excitability. Hypoxia-induced hyperexcitability is linked to dysfunction of inhibitory GABAA receptors (GABAARs), but the underlying mechanisms are poorly understood. GABAARs are chloride channels activated by y-aminobutyric acid (GABA), composed of subunits that determine their pharmacology and kinetic properties. We have studied the effects of hypoxia on GABAAR function and subunit mRNA expression in NT2-N neuronal cells and primary cortical neurons in vitro. Maximal GABA-evoked currents increased 1 h after transient hypoxia but then decreased to 60% of control after 48 h, associated with reductions in a1, a5, 02 and y2 subunit mRNAs. These changes are associated with induction of the bHLH transcription factor, hypoxia-inducible factor-1a(HIF1a) and calcium entry via voltage-gated channels opened by hypoxia-induced depolarizaton. Our long-term goal is to understand the mechanisms of hypoxia-induced GABAAR neuroplasticity, with these specific aims: 1. Determine the mechanisms underlying the early increase in GABAAR current after hypoxia. Hypothesis 1 is that the initial increase in GABAAR current is related to increased GABAAR channel density or phosphorylation. We will use whole-cell, perforated patch and single channel recordings to measure GABAAR currents, pharmacology, and single channel properties of post-hypoxic GABAAR currents. 2. Determine whether transcriptional changes account for the late reduction in GABAAR currents. Hypothesis 2 is that the reduction in GABAAR currents 48 h after hypoxia is related to altered GABAAR subunit transcription, and that specific subunit changes account for altered GABAAR pharmacology. We will use whole-cell recordings and RT-PCR to assess changes in GABAAR pharmacology and subunit expression. 3. Determine whether HIF-1a is involved in altered GABAAR subunit expression. Hypothesis 3 is that hypoxic induction of HIF-1a participates in regulating GABAAR subunit expression in concert with other signaling mechanisms. We will determine a. whether hypoxia alters HIF-1a expression, b. whether elevated HIF-1a reproduces hypoxia-related GABAR changes, and c. whether voltage-gated calcium channels mediate GABAAR regulation. These studies implicate a novel mechanism underlying post- hypoxic hyperexcitability, and could result in new treatments for post-hypoxic seizures and myoclonus.

中风和缺氧经常引起癫痫发作或肌阵挛，这是神经兴奋性过度引起的疾病。