Study on the presence of the specific substances participating in the transmission of particular kinds of sensation

由于免疫细胞化学分析表明，许多物质如P物质（SP）、脑啡肽（Enk）、降钙素基因相关肽（CGRP）、生长抑素等存在于初级感觉神经元和脊髓背角，这些肽参与疼痛传递阻止了我们的关注。但目前还不清楚每种肽在疼痛传递中的作用。参与传递特定感觉的特定物质有可能从脊髓背角初级感觉神经元的中枢末梢释放出来。在此假设的基础上，采用推拉式灌注插管系统对牙痛的首个中继站——脑干三叉神经感觉核复合体（SpVc-I，II）尾侧亚核浅层灌注人工脑脊液。通过测量牙髓刺激后向灌注液中释放的免疫反应肽来确定SpVc-I，II.1中传递牙痛感觉的物质。超峰值强度40V方波电刺激使SP和Met-Enk的释放明显增加，CGRP的释放有增加的趋势。然而，未观察到刺激诱发的神经激肽a的释放，神经激肽a是速激肽和SP家族中的一员，并与SP共存于初级感觉神经元中。阿片类药物可明显抑制刺激诱发的SP释放，而纳洛酮预处理可拮抗这种抑制作用。观察血清素和肾上腺素的自发释放。吗啡预处理能显著增加血清素而非肾上腺素的释放。刺激诱发的SP释放可通过推拉套管或电刺激中缝大肌局部应用5 -羟色胺至SpVc-I，II，这是5 -羟色胺能下降系统的起源。这些结果表明SP是一种潜在的参与牙痛传递的递质，刺激引起的SP释放可能受脑啡肽系统（节段抑制系统）和血清素系统（下行抑制系统）的调控。少

Since immunocytochemical analyses have demonstrated that many substances such as substance P(SP), enkephalin(Enk), calcitonin gene-related peptide(CGRP), somatostatin, etc. occur in the primary sensory neurons and the spinal dorsal horn, an involvement of these peptides in pain transmission arrest our sttentions. But it has't been made clear what role each peptide plays in the pain transmission. There is possibility that the specific substances which participate in the transmission of particular kinds of sensation may be released from the central endings of the primary sensory neurons in the spinal dorsal horn. On the basis of this assumption, the superficial layer in subnucleus caudalis of the brain-stem trigeminal sensory nuclear complex(SpVc-I,II), the first relay station for dental pain, was perfused with artificial cerebrospinal fluid using a push-pull perfusion cannula system. Immunoreactive peptides released into the perfusate following tooth pulp stimulation were measured to id … More entify substances transmitting dental pain sensation in SpVc-I,II.1. Electrical stimulation with 40V square wave of supramaximal intensity showed a significant increase in the release of SP and Met-Enk, and showed a tendency to increase in the release of CGRP. However, a stimulus-evoked release of neurokinin A, which is one of a family of tachykinins as wellas SP and coexists with SP in the primary sensory neurons, was not observed.2. The administration of opioids markedly inhibited the stimulus-evoked SP release and this inhibition was antagonized by the pretreatment with naloxone.3. The spontaneous release of serotonin and epinephrine were observed. And the release of not epinephrine but serotonin was remarkably increased by the pretreatment with morphine4. The stimulus-evoked SP release was inhibitd by local application of serotonin into SpVc-I,II through the push-pull cannula or an electrical stimulation of raphe magnus, the origin of the descending serotonergic system. These results indicate that SP is a potential transmitter which participate in the transmission of dental pain in SpVc-I,II, and the stimulus-evoked SP release may be regulated by enkephalinergic system(segmental inhibitory system) and serotonergic system(descending inhibitory system). Less