NEUROANATOMIC MECHANIMS OF LEPTIN ACTION

瘦素作用的神经解剖学机制

• 批准号: 6363006
• 负责人: JOEL K. ELMQUIST
• 金额: $ 26.52万
• 依托单位: BETH ISRAEL DEACONESS MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-03-25 至 2002-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6363006
• 关键词: bioenergetics; brain regulatory center; chemical structure function; fluorescence microscopy; homeostasis; hormone receptor; hormone regulation /control mechanism; hypothalamus; immunocytochemistry; in situ hybridization; innervation; laboratory rat; leptin; medulla oblongata; microinjections; neurochemistry; neuroendocrine system; neurons; neurophysiology; paraventricular nucleus; radioimmunoassay; receptor expression; spinal cord; stereotaxic techniques; telemetry

An increased understanding of the basic physiology and neurobiology of energy metabolism and homeostasis is critical in the prevention of obesity and eating disorders such as anorexia nervosa. Recent studies indicate that leptin, produced by white adipose tissue, is critical in regulation of energy balance and neuroendocrine function. It is now clear that the central nervous system (CNS), particularly the hypothalamus, is intimately involved in responding to circulating leptin, but the specific neuroanatomy underlying these responses remain poorly characterized. In this proposal, we offer a unique neuroanatomical model of leptin action and describe experiments designed to characterize the role of the dorsomedial hypothalamic nucleus (DMH) in the production of the physiological responses to circulating leptin. We hypothesize that the DMH is a key component of a neuroanatomic pathway which produces leptin responses as the DMH contains leptin receptors, is activated by intravenous leptin, and projects to the paraventricular hypothalamic nucleus (PVH). The PVH is ideally positioned to regulated multiple aspects of responses to leptin and changing energy availability because it possesses chemically and anatomically specific projections to autonomic and endocrine control sites involved in maintenance of homeostasis. This proposal describes anatomic and physiologic experiments designed to critically test specific component of our model. First, we will determine the chemical phenotype of leptin-activated neurons in both fed and fasted rats. This will be accomplished using immunohistochemistry for the FOS protein, and immunohistochemistry or in situ hybridization for neuronal phenotypic markers. Second, using retrograde tracing techniques, immunohistochemistry for the Fos protein, and immunohistochemistry or in situ hybridization for neural phenotypic markers, we will determine the chemical phenotypes of leptin-activated neurons that innervate the PVH. Third, using anterograde tracer injections into the DMH, retrograde tracer injections into the medulla and spinal cord, and immunohistochemistry for Fos and neuronal markers, we will determine whether DMH efferents innervate leptin-activate PVH neurons that project to autonomic preganglionic neurons. Fourth, using a novel experimental preparation which allows us to assess physiological responses and Fos distributions following microinjections into the hypothalamus, we will directly microinject leptin into the DMH, ventromedial hypothalamic nucleus, and arcuate nucleus of the hypothalamus (regions which contain leptin receptors and project to the PVH). These experiments will determine whether activation of leptin receptors in different hypothalamic sites produces distinct physiological responses.

加深对基础生理学和神经生物学的了解 能量代谢和体内平衡对于预防肥胖至关重要 以及饮食失调，例如神经性厌食症。最近的研究表明 由白色脂肪组织产生的瘦素对于调节至关重要 能量平衡和神经内分泌功能。现在很清楚的是 中枢神经系统（CNS），特别是下丘脑，与 参与对循环瘦素的反应，但具体 这些反应背后的神经解剖学仍然知之甚少。在 根据这个提议，我们提供了瘦素作用的独特神经解剖模型 并描述旨在表征作用的实验 下丘脑背内侧核（DMH）在产生 对循环瘦素的生理反应。我们假设 DMH 是产生瘦素的神经解剖学途径的关键组成部分 由于 DMH 含有瘦素受体，因此会被激活 静脉注射瘦素，投射到室旁下丘脑 核（PVH）。 PVH 非常适合监管多个方面 对瘦素的反应和改变能量可用性，因为它 具有化学和解剖学上对自主神经的特定预测 和参与维持体内平衡的内分泌控制位点。这 提案描述了旨在 严格测试我们模型的特定组件。首先，我们将确定 进食和禁食时瘦素激活神经元的化学表型 老鼠。这将通过 FOS 的免疫组织化学来完成 蛋白质、神经元的免疫组织化学或原位杂交 表型标记。其次，采用逆行追踪技术， Fos 蛋白的免疫组织化学，以及免疫组织化学或 神经表型标记的原位杂交，我们将确定 支配 PVH 的瘦素激活神经元的化学表型。 三、采用顺行示踪剂注入DMH，逆行示踪剂 髓质和脊髓注射，免疫组化 Fos 和神经元标记物，我们将确定 DMH 传出神经是否 神经支配瘦素激活的 PVH 神经元，投射到自主神经 节前神经元。四、采用新颖的实验制剂 这使我们能够评估生理反应和 Fos 分布 下丘脑显微注射后，我们将直接 将瘦素显微注射到 DMH、下丘脑腹内侧核中， 下丘脑弓状核（含有瘦素的区域 受体并投射到PVH）。这些实验将决定 下丘脑不同部位的瘦素受体是否被激活 产生不同的生理反应。