Gustatory Afferent Organization in the Solitary Nucleus

描述(申请人提供)：味觉信息被引导到中枢神经系统，以提供感官辨别信息，用于分析Instera的化学成分，激励信号来影响食欲行为，以及触发信号来驱动头部阶段和躯体口腔运动反射。第一级味觉传递，即孤束嘴核(RNST)，在空间上是沿着多个维度组织的：反映周围神经支配的吻尾轴，反映细胞形态和投射的亚核表示，以及反映味觉刺激后即刻-早期基因表达的区域专化。目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使用臂旁核(PBN)的逆行刺激来验证NST神经元有不同群体的假设，暗示不同的功能。特别是，我们预测前部和后部口腔苦味反应神经元将有反应轮廓和投射，表明各自在盘/m/自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的NST输出神经元的不同群体，网状结构(RF)或内脏NST，是否具有神经化学特化。假设每个种群的相当大一部分将包含谷氨酸神经传递的标志，最近描述的谷氨酸转运体DNIP/VGLUT2的mRNA，但硝能、儿茶酚胺和多肽能表型更加分离。Aim 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排斥反射是否具有区域性的空间地形图，这一点从Fos激活的神经元对这些味觉的反应的限定分布中得到了暗示。目标4将开始定义神经元中表达Fos样免疫反应的神经递质，以响应苦味。哺乳动物的味觉系统在调节食物摄取和动态平衡方面起着关键作用。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路径。强调苦味刺激将澄清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.