Gustatory Afferent Organization in the Solitary Nucleus

描述（由申请人提供）：味觉信息被引导至CNS，以提供用于分析摄取物的化学成分的感官辨别信息、影响食欲行为的动机信号以及驱动头相和躯体orthogonal反射的触发信号。孤束吻侧核是一级味觉传递的核心，它在空间上具有沿着多个维度的结构：反映外周神经支配的吻尾轴，反映细胞形态和投射的亚核表征，以及反映味觉刺激后即刻早期基因表达的区域特化。在当前的提议中，实验将开始，以确定这种组织是否与味觉系统执行的各种任务有关。目的1将使用臂旁核（PBN）的逆向刺激来验证NST神经元具有不同功能的假设。特别是，我们预测，前部和后部口腔E2-反应神经元将有响应曲线和预测，表明各自的作用，在光盘/M/本地与反射功能。目的2将使用双标记来确定投射到PBN、网状结构（RF）或内脏NST的NST输出神经元的不同群体是否是神经化学特化的。据推测，相当大比例的每个人口将包含一个标记谷氨酸神经传递，最近描述的谷氨酸转运蛋白，DNIP/VGLUT 2的mRNA，但氮能，儿茶酚胺能，肽能表型更隔离。目的3将可逆性的NST使用GABAA激动剂，蝇蕈醇，以确定是否有一个区域性的空间拓扑结构，所建议的Fos激活的神经元在这些tastants响应的限制性分布的orbactin引起的排斥反应。目标4将开始定义神经元中表达Fos样免疫反应性的神经递质。哺乳动物的味觉系统在调节食物摄取和体内平衡中起着关键作用。本提案中的实验将开始解开味觉系统实现这些复杂相互作用的平行途径。对苦味刺激的强调将阐明味觉系统在避免有毒、潜在有毒食物方面的保护机制。

DESCRIPTION (provided by applicant): Taste information is channeled to the CNS to provide sensory-discriminative information for analyzing the chemical composition of ingesta, motivational signals to impact appetitive behavior, and triggering signals that drive cephalic phase and somatic oromotor reflexes. The 1storder gustatory relay, the rostral nucleus of the solitary tract rNST), is spatially organized along multiple dimensions: a rostrocaudal axis reflecting peripheral innervation, a subnuclear representation reflecting cellular morphology and projections, and a regional specialization reflecting immediate-early gene expression following taste stimulation. Experiments in the current proposal will begin to determine whether this organization is related to the varied tasks the taste system performs. Aim 1 will use antidromic stimulation from the parabrachial nucleus (PBN) to test the hypothesis that there are distinct populations of NST neurons, suggestive of different functions. In particular, we predict that anterior and posterior oral cavity bitter-responsive neurons will have response profiles and projections indicating respective roles in disc/m/native versus reflex functions. Aim 2 will use double-labeling to determine whether the different populations of NST output neurons that project to the PBN, reticular formation (RF) or visceral NST, are neurochemically specialized. It is hypothesized that substantial proportions of each population will contain a marker for glutamate neurotransmission, the mRNA for recently described glutamate transporter, DNIP/VGLUT2, but that nitrergic, catecholaminergic, and peptidergic phenotypes be more segregated. Aim 3 will reversibly inactivate the NST using the GABAA agonist, muscimol, to determine whether the bitter-elicited oromotor rejection reflex has a regional spatial topography, as suggested by the circumscribed distribution of Fos-activated neurons in response to these tastants. Aim 4 will begin to define neurotransmitters in neurons that express Fos-like immunoreactivity in response to bitter tastants. The mammalian gustatory system plays critical roles in regulating food intake and homeostasis. Experiments in the present proposal will begin to unravel the parallel pathways through which the taste system achieves these complex interactions. The emphasis on bitter stimuli will clarify protective mechanisms of the taste system in avoiding noxious, potentially toxic food.