Strassman A M, Mineta Y, Vos B P
Department of Neurology, Massachusetts General Hospital, Charlestown.
J Neurosci. 1994 Jun;14(6):3725-35. doi: 10.1523/JNEUROSCI.14-06-03725.1994.
Neurophysiological studies have generally failed to find evidence of a specific ascending pathway for visceral nociception. However, pain that arises from deep or visceral tissues typically differs from cutaneous pain, particularly in its diffuse, poorly localized quality. In this study, the c-fos mapping technique was used in order to investigate possible differences in the distribution of central neurons activated by afferent pathways from cutaneous and deep tissues that may be related to the differing quality of the sensations they evoke. The distribution of neurons in the upper cervical and medullary dorsal horn that displayed fos-like immunoreactivity (fos-LI) was examined following mechanical stimulation of dural blood vessels (transverse and superior sagittal sinuses), and was compared to that found following mechanical, thermal, and chemical stimulation of facial sites. Dural stimulation was carried out Brevital anesthesia in rats that had received a chronic surgical exposure of the transverse and superior sagittal sinuses 2 d earlier. Localized mechanical stimulation of the dural surface of the transverse sinus produced a predominantly ipsilateral increase in the number of fos-LI neurons in the medullary and upper cervical dorsal horn (primarily laminae I and V), and in the transition region between the trigeminal nucleus caudalis and interpolaris. Stimulation of the superior sagittal sinus produced increases in fos-LI labeling that were generally smaller than those produced by transverse sinus stimulation. The distribution of fos-LI labeling in the dorsal horn induced by dural stimulation differed from that induced by facial stimulation in two ways. (1) Dural stimulation produced a more diffuse distribution of fos-LI than facial stimulation in the dorsal horn. Whereas facial stimulation produced a dense, localized zone of fos-LI labeling in the dorsal horn, dural stimulation produced fos-LI labeling that extended from the midlevel of caudalis to C2/C3, and also extended across a large portion of the ventrolateral-to-dorsomedial axis of the dorsal horn. This distribution roughly corresponds to the representation of most of the dorsal half of the head and face. (2) Dural stimulation produced a more restricted laminar distribution of fos-LI labeling than facial stimulation, in that the dural-induced labeling in the superficial dorsal horn was primarily restricted to lamina I, whereas facial stimulation typically induced substantial labeling in both lamina I and the outer part of lamina II. These differences in the central organization of the afferent pathways from dural and facial sites may contribute to the differences in the quality of sensations evoked by these pathways.
神经生理学研究一般未能找到内脏痛觉有特定上行通路的证据。然而，源自深部或内脏组织的疼痛通常与皮肤痛不同，尤其是其具有弥漫性、定位不清晰的特点。在本研究中，采用c-fos图谱技术来探究由皮肤和深部组织的传入通路激活的中枢神经元分布可能存在的差异，这些差异可能与它们所引发的感觉性质不同有关。在对硬脑膜血管（横窦和上矢状窦）进行机械刺激后，检查上颈段和延髓背角中显示fos样免疫反应性（fos-LI）的神经元分布，并将其与对面部区域进行机械、热和化学刺激后发现的分布进行比较。硬脑膜刺激在2天前接受过横窦和上矢状窦慢性手术暴露的大鼠中，在硫喷妥钠麻醉下进行。对横窦硬脑膜表面进行局部机械刺激，导致延髓和上颈段背角（主要是I层和V层）以及三叉神经尾侧核和极间核之间的过渡区域中fos-LI神经元数量主要在同侧增加。对上矢状窦的刺激产生的fos-LI标记增加通常小于横窦刺激产生的增加。硬脑膜刺激在背角诱导的fos-LI标记分布与面部刺激诱导的分布在两个方面存在差异。（1）硬脑膜刺激在背角产生的fos-LI分布比面部刺激更弥散。面部刺激在背角产生密集、局部化的fos-LI标记区，而硬脑膜刺激产生的fos-LI标记从上段尾侧核中部延伸至C2/C3，并且还延伸穿过背角腹外侧至背内侧轴的大部分区域。这种分布大致对应于头面部大部分背侧半区的代表区域。（2）硬脑膜刺激产生的fos-LI标记的层状分布比面部刺激更局限，因为硬脑膜诱导的标记在浅表背角主要局限于I层，而面部刺激通常在I层和II层外部都诱导出大量标记。来自硬脑膜和面部区域的传入通路在中枢组织上的这些差异可能导致这些通路所引发的感觉性质的差异。
