Dorsomedial Hypothalamic Signaling Pathways and Energy Balance

描述(由申请人提供)：下丘脑在维持能量平衡方面起着核心作用。在下丘脑中，不同的核团已被证明在控制食物摄入和能量消耗方面发挥着不同的作用。虽然早有数据表明下丘脑背内侧核(DMH)在摄食和体重控制中起作用，但DMH损伤导致摄食量、体重和线性生长减少的神经机制或该核对整体能量平衡的基本贡献仍有待辨别。这项建议的长期目标是确定DMH信号通路的特征，并确定DMH多肽信号如何影响食物摄入量和体重。建议的实验重点是DMH神经肽Y(NPY)和促肾上腺皮质激素释放因子(CRF)的作用。对NPY的关注是基于观察到DMH NPY在各种状态下过度表达，如哺乳、慢性食物限制和运动，并在一些肥胖综合征中升高。对CRF的关注源于我们最近的数据，即在运动性厌食症中，DMH CRF的表达被诱导或上调。我们假设DMH NPY在大脑CCK的控制下，DMH CRF可能在黑素皮质素信号的控制下，提供DMH的主要功能厌氧和厌氧输出。我们提出了两个具体目标。在第一个特定目标中，我们将通过原位杂交、c-Fos免疫组织化学和荧光金逆行示踪技术来表征CCK在DMH NPY神经元信号转导中的作用，并确定介导DMH NPY在控制摄食量和体重中作用的途径。我们还将通过用腺相关病毒(AAV)诱导的过度表达或RNA干扰来改变DMH NPY的表达，从而确定DMH NPY在能量平衡控制中的作用。在第二个特定目标中，我们将评估下丘脑黑素皮质素和/或神经肽Y信号系统(S)与DMH CRF神经信号的潜在关系，并通过评估AAV介导的CRF特异性RNA干扰的效果来研究DMH CRF在摄食控制中的作用。总体而言，阐明这些DMH多肽系统在摄食和体重控制中的作用将极大地促进我们对这个下丘脑核在维持能量平衡方面的作用的理解。

DESCRIPTION (provided by applicant): The hypothalamus plays a central role in maintaining energy homeostasis. Within the hypothalamus, different nuclei have been shown to play distinct roles in controlling food intake and energy expenditure. Although a role for the dorsomedial hypothalamus (DMH) in feeding and body weight controls has long been suggested from data demonstrating that DMH lesions result in decreases in food intake, body weight and linear growth, the neural mechanisms underlying the effects of DMH lesions or the basic contributions of this nucleus to overall energy homeostasis remain to be discerned. The long-term goal of this proposal is to characterize DMH signaling pathways and identify how DMH peptide signaling affects food intake and body weight. The proposed experiments focus on the actions of DMH neuropeptide Y (NPY) and corticotrophin releasing factor (CRF). The focus on NPY is based on the observations that DMH NPY is overexpressed in a variety of states such as lactation, chronic food restriction, and exercise, and is elevated in a number of obesity syndromes. The focus on CRF derives from our recent data demonstrating that DMH CRF expression is induced or up-regulated in exercise-induced anorexia. We hypothesize that DMH NPY, under the control of brain CCK, and that DMH CRF, potentially under the control of melanocortin signaling, provide the main functional orexigenic and anorexigenic outputs of the DMH. We propose two Specific Aims. In the first Specific Aim, we will characterize the actions of CCK on DMH NPY neuronal signaling and identify pathways that mediate the actions of DMH NPY in the control of food intake and body weight by using in situ hybridization, c-Fos like immunohistochemstry and Fluorogold retrograde tracing techniques. We will also identify DMH NPY functions in energy balance control by altering DMH NPY expression with adeno- associated virus (AAV)-induced overexpression or RNA interference. In the second Specific Aim, we will assess the potential relationships of hypothalamic melanocortin and/or NPY signaling system(s) with DMH CRF neural signaling and examine the role of DMH CRF in feeding control by assessing the effects of site- specific AAV-mediated CRF RNA interference. Overall, the elucidation of the actions of these DMH peptide systems in feeding and body weight control would significantly advance our understanding of the role of this hypothalamic nucleus in maintaining energy homeostasis.