Endogenous neurosteroids constrain network activity and limit seizure susceptibility

内源性神经类固醇限制网络活动并限制癫痫发作的易感性

基本信息

批准号：
10170601
负责人：
Jamie Lynn Maguire
金额：
$ 45.38万
依托单位：
TUFTS UNIVERSITY BOSTON
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-04-15 至 2023-09-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10170601
关键词：
5 Alpha-Reductase Inhibitor Acute Allopregnanolone Anticonvulsants Brain Brain region Cholesterol Chronic Development Electroencephalography Enzymes Epilepsy Epileptogenesis Finasteride Frequencies Glial Fibrillary Acidic Protein Hippocampus (Brain)Internal Ribosome Entry Site Interneurons Kainic Acid Knock-out Knowledge LoxP-flanked allele Measurement Measures Mediating Mus Neuroglia Neurons Output Oxidoreductase Patients Pattern Perforant Pathway Pharmacology Predisposition Process Recurrence Rodent Role Seizures Slice Status Epilepticus Temporal Lobe Epilepsy Testing Visualization calmodulin-dependent protein kinase II cell type extracellular knock-down mouse model neuronal excitability neurosteroids novel positive allosteric modulator pre-clinical receptor response steroid hormone metabolism tetrahydrodeoxycorticosterone tool

项目摘要

Project Summary There is extensive preclinical evidence for anticonvulsant effects of neuroactive steroids, which are thought to be mediated through their actions as positive allosteric modulators (PAMs) on GABAA receptors (GABAARs). These studies have relied on the administration of exogenous neuroactive steroids, although, neurosteroids can also be synthesized in the brain. However, we know very little about the function of endogenous neurosteroids due to the lack of tools necessary to investigate their function. The rate-limiting enzymes involved in neurosteroid synthesis, 5α-reductase 1 or 2, are expressed in the hippocampus and given their actions as PAMs at GABAARs, they are well-suited to constrain network excitability in this region. To investigate the function of endogenous neurosteroids, we generated novel mouse models (floxed Srd5a1- IRES-GFP and floxed Srd5a2-IRES-tdTomato) enabling visualization and quantification of changes in the expression of these enzymes associated as well as the ability to knockout these enzymes in a cell type- and brain region-specific manner. Here we propose to utilize these novel tools to test the hypothesis that endogenous neurosteroids constrain neuronal excitability and that deficits in 5α-reductase 1 and 2 expression in the hippocampus contributes to seizure susceptibility. We will determine whether 5α-reductase 1 and/or 2 expression is altered in chronically epileptic mice (Specific Aim 1) and if loss of 5α-reductase 1 and/or 2 expression in the hippocampus increases network excitability and acute seizure susceptibility (Specific Aim 2) or increases seizure frequency in chronically epileptic mice (Specific Aim 3).

项目概要有大量临床前证据表明神经活性类固醇具有抗惊厥作用，人们认为通过其作为 GABAA 受体的正变构调节剂 (PAM) 的作用来介导（GABAAR）。尽管如此，这些研究依赖于外源性神经活性类固醇的施用。神经类固醇也可以在大脑中合成，但是我们对其功能知之甚少。内源性神经类固醇由于缺乏研究其功能所需的工具而受到限制。参与神经类固醇合成的酶，5α-还原酶 1 或 2，在海马体中表达并给予它们作为 GABAAR 中的 PAM 的行为非常适合限制该区域的网络兴奋性。为了研究内源性神经类固醇的功能，我们构建了新型小鼠模型（floxed Srd5a1- IRES-GFP 和 floxed Srd5a2-IRES-tdTomato）能够可视化和量化变化这些酶的表达以及在细胞类型中敲除这些酶的能力相关在这里，我们建议利用这些新颖的工具来检验以下假设：内源性神经类固醇会限制神经兴奋性并导致 5α-还原酶 1 和 2 表达缺陷我们将确定海马体中的 5α-还原酶 1 和/或 2 是否会导致癫痫发作。如果 5α-还原酶 1 和/或 2 缺失，则慢性癫痫小鼠的表达会发生改变（具体目标 1）海马体中的表达增加网络兴奋性和急性癫痫发作易感性（具体目标 2）或增加慢性癫痫小鼠的癫痫发作频率（具体目标 3）。