Gustatory Afferent Organization in the Solitary Nucleus

描述（由申请人提供）：味觉信息被传递到中枢神经系统，为分析摄取的化学成分提供感官辨别信息，影响食欲行为的动机信号，以及驱动头期和躯体运动反射的触发信号。味觉中继，即孤立束的吻侧核，在空间上沿多个维度组织：反映外周神经支配的吻侧轴，反映细胞形态和投射的亚核表征，以及反映味觉刺激后立即早期基因表达的区域专门化。当前提案中的实验将开始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将使用来自臂旁核（PBN）的反向刺激来验证NST神经元有不同群体的假设，暗示不同的功能。特别是，我们预测口腔前部和后部的苦味反应神经元将具有反应概况和投影，表明各自在椎间盘/m/天然与反射功能中的作用。目的2将使用双重标记来确定投射到PBN，网状形成（RF）或内脏NST的不同NST输出神经元群是否具有神经化学特异性。据推测，每个群体的相当大比例将包含谷氨酸神经传递的标记物，最近描述的谷氨酸转运体的mRNA， DNIP/VGLUT2，但氮能，儿茶酚胺能和肽能表型更为分离。目的3将使用GABAA激动剂muscimol可逆地灭活NST，以确定苦味引起的运动性排斥反射是否具有区域空间地形，正如fos激活的神经元在这些味觉剂反应中的有限分布所表明的那样。Aim 4将开始定义神经元中表达fos样免疫反应的神经递质，以应对苦味。哺乳动物的味觉系统在调节食物摄入和体内平衡中起着至关重要的作用。目前的实验将开始揭示味觉系统实现这些复杂相互作用的平行途径。强调苦味刺激将澄清味觉系统的保护机制，以避免有害的，潜在的有毒食物。

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.