Travers Susan P, Travers Joseph B
Section of Oral Biology, College of Dentistry, The Ohio State University, Columbus, Ohio 43210-1267, USA.
J Comp Neurol. 2007 Feb 1;500(4):746-60. doi: 10.1002/cne.21213.
The current investigation used double labeling for NADPHd and Fos-like immunoreactivity to define the relationship between nitric oxide synthase-containing neural elements and taste-activated neurons in the nucleus of the solitary tract (NST) and subjacent reticular formation (RF). Stimulation of awake rats with citric acid and quinine resulted in significant increases in the numbers of double-labeled neurons in both the NST and RF, suggesting that some medullary gustatory neurons utilize nitric oxide (NO) as a transmitter. Overall, double-labeled neurons were most numerous in the caudal reaches of the gustatory zone of the NST, where taste neurons receive inputs from the IXth nerve, suggesting a preferential role for NO neurons in processing gustatory inputs from the posterior oral cavity. However, double-labeled neurons also exhibited a preferential distribution depending on the gustatory stimulus. In the NST, double-labeled neurons were most numerous in the rostral central subnucleus after either stimulus but had a medial bias after quinine stimulation. In the RF, after citric acid stimulation, there was a cluster of double-labeled neurons with distinctive large soma in the parvicellular division of the lateral RF, subjacent to the rostral tip of NST. In contrast, in response to quinine, there was a cluster of double-labeled neurons with much smaller soma in the intermediate zone of the medial RF, a few hundred micrometers caudal to the citric acid cluster. These differential distributions of double-labeled neurons in the NST and RF suggest a role for NO in stimulus-specific gustatory autonomic and oromotor reflex circuits.
当前的研究采用了NADPHd和Fos样免疫反应双标记法，以确定含一氧化氮合酶的神经元与孤束核（NST）及相邻网状结构（RF）中味觉激活神经元之间的关系。用柠檬酸和奎宁刺激清醒大鼠后，NST和RF中双标记神经元的数量显著增加，这表明一些延髓味觉神经元利用一氧化氮（NO）作为神经递质。总体而言，双标记神经元在NST味觉区的尾端最为密集，此处味觉神经元接收来自第九对脑神经的输入，这表明NO神经元在处理来自口腔后部的味觉输入方面具有优先作用。然而，双标记神经元也根据味觉刺激表现出优先分布。在NST中，两种刺激后，双标记神经元在吻侧中央亚核中数量最多，但在奎宁刺激后有向内侧的偏向。在RF中，柠檬酸刺激后，在RF外侧的小细胞部，紧邻NST吻端处，有一群双标记神经元，其胞体较大且独特。相反，对奎宁的反应是，在内侧RF的中间区，距柠檬酸刺激引起的神经元群尾侧几百微米处，有一群双标记神经元，其胞体要小得多。NST和RF中双标记神经元的这些差异分布表明NO在刺激特异性味觉自主和口运动反射回路中发挥作用。
