Effect of Killing or Removing GABA from NPY/AgRP Neurons

杀死或去除 NPY/AgRP 神经元中 GABA 的效果

• 批准号: 7652490
• 负责人: Richard D. Palmiter
• 金额: $ 15.29万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-25 至 2011-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7652490
• 关键词: ART protein; Ablation; Address; Adult; Affect; Alleles; Aminobutyric Acids; Anabolism; Animals; Behavioral; Body Weight; Brain; Brain region; Cells; Desire for food; Diphtheria Toxin; Enzymes; Feeding behaviors; Financial compensation; Gene Silencing; Genes; Genetic; Genetic Techniques; Glutamate Decarboxylase; Goals; Hormonal; Hypothalamic structure; Knockout Mice; Lead; Leptin; Lesion; Masks; Mediator of activation protein; Melanocortin 4 Receptor; Messenger RNA; Metabolism; Methods; Middle Hypothalamus; Molecular; Monitor; Mus; Neonatal; Neurons; Obesity; Peptides; Phenotype; Physiological; Population; Pro-Opiomelanocortin; Protein Isoforms; Regulation; Role; Signal Pathway; Signal Transduction; Signaling Molecule; Starvation; Structure of nucleus infundibularis hypothalami; Synapses; Tamoxifen; Techniques; Testing; Up-Regulation; base; diphtheria toxin receptor; energy balance; feeding; gamma-Aminobutyric Acid; insight; killings; leptin receptor; neonate; neural circuit; neuropeptide Y; paraventricular nucleus; pup; recombinase; research study; response

DESCRIPTION (provided by applicant): A small population of neurons (~ 5000 cells) in the arcuate region of hypothalamus that make neuropeptide Y (NPY) and agouti-related protein (AgRP) become essential for survival in adult mice. We targeted the diphtheria toxin receptor (DTR) to these NPY/AgRP neurons to allow their ablation by administration of diphtheria toxin (DT). Ablation of these neurons in adult mice results in starvation. However, their ablation in neonatal mice results in circuit-based compensation such that mice grow almost normally. Although neonatally DT-lesioned mice grow to normal size, we experimentally explore whether they manifest deficits in physiological responses that normally depend on NPY/AgRP neurons. We propose to determine the critical signaling molecules made by NPY/AgRP neurons and whether they function primarily by regulating the melanocortin-signaling pathway or other circuits. A prime candidate for the critical signaling molecule is ?-aminobutyric acid (GABA); thus, we propose to make conditional alleles of the two genes, GAD1 and GAD2 encoding the biosynthetic enzymes such that they can be inactivated in NPY/AgRP neurons and temporally controlled manner by the action of Cre recombinase. If GABA is the critical signaling molecule, then we predict that inactivation of GABA biosynthesis in NPY/AgRP neurons of neonatal mice will lead to compensation such that the cells are no longer necessary for survival. In contrast, inactivation of GABA biosynthesis in NPY/AgRP neurons of adult mice may promote starvation. NPY/AgRP neurons are known to inhibit neighboring neurons in the arcuate nucleus that make proopiomelanocortin (POMC) and their target neurons in the paraventricular nucleus that express melanocortin-4 receptor. Activation of POMC neurons inhibits feeding. Thus, we include experiments to directly test whether up-regulation of this melanocortin-signaling pathway after sudden ablation of NPY/AgRP neurons is critically involved in the starvation phenotype. However, because NPY/AgRP neurons also project to several other brain regions, we include experiments that address which of these projection regions are affected the most and whether they contribute to feeding behavior. These experiments should provide insight into the neural circuits and signaling molecules that are critical for feeding.

描述（由申请人提供）：在下丘脑的弧形区域中，少数神经元（约5000个细胞）使神经肽Y（NPY）和Agouti相关蛋白（AGRP）成为成年小鼠的生存至关重要。我们将白喉毒素受体（DTR）靶向这些NPY/AGRP神经元，以通过给药毒素毒素（DT）来消融。这些神经元在成年小鼠中的消融导致饥饿。但是，它们在新生儿小鼠中的消融会导致基于电路的补偿，因此小鼠几乎正常生长。尽管新生儿DT剂量的小鼠生长到正常的大小，但我们通过实验探索它们是否表现出通常取决于NPY/AGRP神经元的生理反应的缺陷。我们建议确定NPY/AGRP神经元产生的临界信号分子，以及它们是否主要通过调节黑色素皮质素信号途径或其他电路来发挥作用。临界信号分子的主要候选者是 - 氨基丁酸（GABA）；因此，我们建议将两个基因的有条件等位基因组成编码生物合成酶的GAD1和GAD2，以使它们可以通过NPY/AGRP神经元灭活，并通过Cre Recombinase的作用将其暂时控制。如果GABA是关键的信号分子，那么我们预测，新生儿小鼠NPY/AGRP神经元中GABA生物合成的灭活将导致补偿，因此细胞不再是生存所必需的。相反，成年小鼠NPY/AGRP神经元中GABA生物合成的失活可能会促进饥饿。已知NPY/AGRP神经元在弧形核中抑制邻近的神经元，从而在表达黑素素-4受体的旁腔内核中抑制促蛋白酶皮质素（POMC）及其靶神经元。 POMC神经元的激活抑制喂养。因此，我们包括直接测试NPY/AGRP神经元突然消融后这种黑色素质素信号途径上调的实验是否与饥饿表型有关。但是，由于NPY/AGRP神经元也将其投射到其他几个大脑区域，因此我们包括实验，以解决这些投影区域中哪个受影响最大，以及它们是否有助于进食行为。这些实验应提供对喂养至关重要的神经回路和信号分子的见解。