GABA-active neurosteroids in contextual fear responses

GABA 活性神经类固醇在情境恐惧反应中的作用

基本信息

批准号：
7995211
负责人：
GRAZIANO PINNA
金额：
$ 18.99万
依托单位：
UNIVERSITY OF ILLINOIS AT CHICAGO
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-12-01 至 2013-03-15
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7995211
关键词：
Affect Affinity Allopregnanolone Amygdaloid structure Anabolism Animal Model Anti-Anxiety Agents Antidepressive Agents Anxiety Anxiety Disorders Area Behavioral Biochemical Biological Assay Biological Availability Biological Markers Brain Cerebrospinal Fluid Chronic Chronic stress Clinical Consensus Disease Dose Down-Regulation Drug Delivery Systems Enzymes Experimental Models Extinction (Psychology)Fluoxetine Fluvoxamine Fright GABA Modulators Glutamates Goals Hippocampus (Brain)Hydroxysteroid Dehydrogenases Injection of therapeutic agent Lasers Link Major Depressive Disorder Mass Fragmentography Measurement Medial Mediating Memory Mental Depression Mental disorders Molecular Mus Neurons Oxidoreductase Panic Patients Pentobarbital Pharmaceutical Preparations Pharmacology Phobic anxiety disorder Physiological Plasma Play Post-Traumatic Stress Disorders Progesterone Psychiatry Radioactive Reflex action Regulation Reporting Reverse Transcriptase Polymerase Chain Reaction Role Selective Serotonin Reuptake Inhibitor Serotonin Slice Social isolation Stereoisomer Stress Structure Symptoms Testing Tissues Western Blotting classical conditioning cofactor conditioned fear depressive symptoms experience frontal lobe gamma-Aminobutyric Acid improved in vivo inhibitor/antagonist mRNA Expression mouse model neuronal circuitry neuropsychiatry neurosteroids neurotransmission prevent protein expression public health relevance receptor research study response reuptake transmission process

项目摘要

DESCRIPTION (provided by applicant): Neurosteroids are involved in the etiopathology of anxiety spectrum disorders and depression. We recently reported that in PTSD, a decrease of CSF allopregnanolone (Allo) levels was correlated with increased PTSD re-experiencing and comorbid depression (Biol. Psychiatry 60, 704-713. 2006). Allo, a potent positive allosteric modulator of GABA action at GABAA receptors, is produced in corticolimbic glutamatergic neurons by the sequential action of 51-reductase type I (51-RI) and 31- hydroxysteroid dehydrogenase (31-HSD). Thus, a deficit of Allo in the brain of PTSD patients could result in a deficit of GABAergic neurotransmission and in increased PTSD re-experiencing and depressive symptoms. In socially isolated (4 weeks) mice that express a neurosteroid biosynthesis downregulation in the medial frontal cortex, hippocampus, and amygdala, excessive contextual fear responses can be normalized by administering neurosteroidogenic drugs, including fluoxetine (FLX) (PNAS 105, 5567-5572. 2008) at doses too low to inhibit serotonin reuptake (Curr Opin Pharmacol 9, 24- 30. 2009). These observations support the hypothesis that: FLX reduces stress-induced excessive contextual fear responses by upregulating Allo levels in selected corticolimbic areas. The purpose of this R21 proposal is to determine whether Allo mediates the effects of FLX in mouse models of stress-induced excessive contextual fear responses and impaired fear extinction. The circuitry and molecular mechanisms underlying FLX-induced behavioral/biochemical actions will also be elucidated. AIM 1 will investigate whether by increasing corticolimbic Allo levels, FLX disrupts acquisition of fear memory, facilitates extinction, and prevents the reinstatement of fear memory following extinction. AIM 2 will study the mechanism by which FLX stimulates Allo biosynthesis in corticolimbic structures. Allo content will be quantified in discrete corticolimbic areas using gas chromatography-mass spectrometry (GC-MS), which allows measurement of femtomolar amounts of neurosteroids in laser microdissected mouse brain structures. Neurosteroidogenic enzyme expression will be investigated by quantitative competitive nested RT-PCR and Western blot. Enzymatic assays will establish whether FLX increases the affinity of 51-RI and/or 31-HSD for the substrate or cofactor. Finally, by using several radioactive substrates, we will study whether FLX stimulates Allo biosynthesis in brain slices by activating 51-RI or 31-HSD. An understanding of the mechanism(s) whereby FLX increases Allo bioavailability in local corticolimbic circuits could help explain the role of GABAA receptor-active neurosteroids in the modulation of stress-induced excessive contextual fear responses and thereby define a biomarker that could be targeted by drugs that improve debilitating neuropsychiatric disorders, including generalized anxiety, panic, and PTSD. PUBLIC HEALTH RELEVANCE: The GABAA receptor-active neurosteroid allopregnanolone is involved in several psychiatric disorders, including anxiety, PTSD, and depression and also in mouse models of these disorders. The goal of this proposal is to identify in several mouse models: a) the role of corticolimbic allopregnanolone levels in the modulation of contextual fear responses and impaired fear extinction; b) the brain structures involved in the pharmacological action of neurosteroidogenic agents, such as fluoxetine; and c) the mechanism whereby fluoxetine upregulates brain allopregnanolone levels.

描述（由申请人提供）：神经类固醇参与焦虑谱和抑郁症的病理学。我们最近报道说，在PTSD中，CSF Allopregnanolone（Allo）水平的降低与PTSD的重新体验和合并症抑郁症的增加相关（Biol。Psychiatry60，704-713.2006）。 Allo是GABA受体中GABA作用的有效阳性变构调节剂，是通过51型I型I型（51-RI）和31-羟基固醇脱氢酶（31-HSD）的顺序作用在皮质脂胶谷氨酸能神经元中产生的。因此，PTSD患者大脑中Allo的缺陷可能导致GABA能神经传递的缺陷，并增加了PTSD的重新体验和抑郁症状。在社会孤立的（4周）的小鼠中，在内侧额叶皮质，海马和杏仁核中表达神经类似生物合成下调下调，可以通过施用神经固醇药物（包括液体（pnas）105，5567-555572。重新摄取（Curr Opin Pharmacol 9，24-30。2009）。这些观察结果支持以下假设：FLX通过上调选定的皮质脂蛋白比区域的Allo水平来减少压力引起的过度上下文恐惧反应。该R21提案的目的是确定Allo是否介导了FLX在压力引起的过度上下文恐惧反应和恐惧灭绝的小鼠模型中的影响。 FLX诱导的行为/生化作用的电路和分子机制也将得到阐明。 AIM 1将通过提高皮质降低层水平来调查，FLX是否会破坏对恐惧记忆的获取，促进灭绝并防止灭绝后恢复恐惧记忆的恢复。 AIM 2将研究FLX刺激皮质脂质结构中的Allo生物合成的机制。使用气相色谱 - 质谱法（GC-MS），将在离散的皮质脂蛋白比区域中定量Allo含量，该含量允许在激光微调小鼠脑结构中测量毒摩尔量的神经类固醇。神经类固醇激发酶表达将通过定量竞争性嵌套RT-PCR和Western印迹研究。酶试验将确定FLX是否会增加对基板或辅因子的51-RI和/或31-HSD的亲和力。最后，通过使用几种放射性底物，我们将研究FLX是否通过激活51-RI或31-HSD来刺激脑切片中的Allo Biosynses。对局部皮质胶质电路中FLX增加同类生物利用度的机制的理解，可以帮助解释GABAA受体活性神经素在压力引起的过度上下文恐惧反应调节中的作用PTSD。公共卫生相关性：GABAA受体活跃的神经类固醇与多种精神疾病有关，包括焦虑，PTSD和抑郁症以及这些疾病的小鼠模型。该提案的目的是在几种小鼠模型中识别：a）皮质细胞异胞素异源性水平在调节上下文恐惧反应和受损恐惧灭绝中的作用； b）神经固醇激素（例如氟西汀）的药理作用所涉及的大脑结构； c）氟西汀上调大脑异源酮水平的机制。