MEDULLARY SEROTONERGIC SYSTEM AND RESPIRATORY CONTROL IN THE UNANESTHETIZED PIG

未麻醉猪的髓质血清素系统和呼吸控制

• 批准号: 7410020
• 负责人: EUGENE Edward NATTIE
• 金额: $ 26.79万
• 依托单位: BOSTON CHILDREN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-04-01 至 2008-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7410020
• 关键词: Affect; Agonist; All Sites; Anatomy; Antibodies; Apnea; Asphyxia; Autoreceptors; Binding; Blood Pressure; Brain Stem; Breathing; Carbon Dioxide; Carrier Proteins; Cells; Chemicals; Development; Dialysis procedure; Disruption; Event; Family suidae; Goals; Hypoxia; Immunohistochemistry; Infant; Injection of therapeutic agent; Lateral; Life; Localized; Location; Microdialysis; Modeling; Muscarinic Acetylcholine Receptor; Muscarinic M1 Receptor; Muscarinics; Neurons; Newborn Infant; Nuclear; Pathogenesis; Peptides; Phenotype; Physical Dialysis; Process; Production; Reflex action; Reflex control; Role; Serotonin; Serotonin Agonists; Side; Site; Sleep; Stanolone; Substance P; Substance P Receptor; Sudden Death; Sudden infant death syndrome; Sus scrofa; System; Testing; Thyroid Gland; Thyrotropin-Releasing Hormone; Tissues; Toxin; Triiodothyronine; Wakefulness; base; inhibitor/antagonist; interest; killings; m1-toxin1; medullary serotonergic system; noradrenergic; receptor; research study; respiratory; response; serotonin receptor; serotonin transporter; substance P-saporin; telenzepine; thermal stress

Based on observations made in brainstem tissue of SIDS cases we hypothesize that the pathogenesis of SIDS involves abnormalities in what we now call the 'medullary serotonergic system'. In this project we define in newborn piglets the neuroehemical and receptor anatomy of the neurons in the medullary serotonergic system, we specifically disrupt them focally or widely, and we observe the resultant effects on an army of homeostatic processes. These include the ventilatory responses to increased CO2 and decreased O2, upper airway reflexes, and blood pressure effects on breathing. We use an unanesthetized newborn piglet model in which we can easily test this array of homeostatic processes in both wakefulness and sleep. Initially we inhibit serotoncrgic neurons by microdialysis of an agonist for the 5-HT(1A) autorceeptor or kill them by injection of 5, 7 DHT or a conjugate of anantibody for the serotonin transport protein (SERT) and the cell toxin saporin (SAP). We will also inhibit and kill neurons within the medullary serotonergic system that express the NK1 or muscarinic M1 subtype receptors. For neurons with NK1 receptors we use an NK1 antagonist or substance P-SAP. For neurons with M1 receptors we use telenzepine or the m1-toxin1 (a highly specific long acting M1 receptor antagonist). These experiments will involve focal application at various sites within three rostral-to-caudal colulumns that define the medullary serotonergic system or widely at 'all' sites simultaneously. With focal application we ask if each homeostatic process can be localized to a specific site within the medullary serotonergic system. With wide application we ask if these homeostatic processes utilize neurons distributed at many locations. Serotonergic neurons within the meduliary serotonergic system can be further classified by peptides that are co-localized within them. Thyrotropin releasing hormone (TRH) and substance P (SP) are two such that are of particular interest in that they have known strong effects on breathing and blood pressure. We will microdialyze T3 in the medullary raphe, which will bind to nuclear beta2 thyroid receptors and inhibit TRH production and release allowing us to examine the role of endogenous TRH in the function of our array of homeostatic processes. Overall, the goal of this project is to see if a induced focal or widely distributed abnormality in the medullary semtonergic system couid affect function in our array of homeostatic processes such as to contribute to sudden death.

根据对小儿麻痹症患者脑干组织的观察，我们推测小儿麻痹症的发病机制涉及我们现在所说的“延髓5-羟色胺能系统”的异常。在这个项目中，我们定义了新生仔猪延髓5-羟色胺能系统中神经元的神经化学和受体解剖，我们特定地局部或广泛地干扰它们，并观察其对一系列体内平衡过程的结果。这些包括对二氧化碳增加和氧气减少的呼吸反应，上呼吸道反射，以及 血压对呼吸有影响。我们使用了一个未麻醉的新生小猪模型，在这个模型中，我们可以很容易地在清醒和睡眠中测试这一系列的动态平衡过程。最初，我们通过微透析5-羟色胺(1A)受体激动剂或注射5，7-二羟色胺或5-羟色胺转运蛋白(SERT)和细胞毒素皂苷(SAP)抗体的结合物来抑制5-羟色胺能神经元。我们还将抑制和杀死延髓5-羟色胺能系统中表达NK1或M_1亚型受体的神经元。对于有NK1受体的神经元，我们使用NK1拮抗剂或P-SAP物质。对于有M1受体的神经元，我们使用替伦西平或M1毒素1(一种高度特异的长效M1受体拮抗剂)。这些实验将涉及在定义延髓5-羟色胺能系统的三个嘴端到尾端的柱体内的不同部位集中应用，或者广泛地同时在所有部位应用。在局部应用的情况下，我们询问每个内稳态过程是否可以定位于延髓5-羟色胺能系统中的特定部位。随着广泛的应用，我们问这些动态平衡过程是否利用了分布在许多位置的神经元。延髓5-羟色胺能系统内的5-羟色胺能神经元可以通过共同定位在其中的多肽进一步分类。促甲状腺激素释放激素(TRH)和P物质(SP)是两种特别令人感兴趣的物质，因为它们对呼吸和血压有很强的影响。我们将微透析延髓缝中的T3，它将与核β2甲状腺受体结合，并抑制TRH的产生和释放，从而使我们能够检查 内源性TRH在我们的一系列动态平衡过程中的作用。总体而言，这个项目的目标是看看延髓语义能系统中诱发的局灶性或广泛分布的异常是否会影响我们的一系列体内平衡过程的功能，例如导致猝死。