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

免疫细胞化学分析表明，P物质(SP)、脑啡肽(EnK)、降钙素基因相关肽(CGRP)、生长抑素等物质存在于初级感觉神经元和脊髓背角，这些多肽参与痛觉传递使我们望而却步。但目前还不清楚每种多肽在疼痛传递中扮演的角色。参与特定感觉传递的特定物质可能是从脊髓背角初级感觉神经元的中央终末释放出来的。在此基础上，采用推-拉式灌流插管系统，在三叉神经感觉复合体尾侧亚核(SpVc-I、SpVc-II)浅层注入人工脑脊液，SpVc-I、SpVc-II是牙齿疼痛的第一个中转站。测定牙髓刺激后释放到灌流液中的免疫反应性多肽以识别…。在SpVc-I，II.1中更多地识别了传递牙齿痛觉的物质。40V方波刺激后，SP和Met-Enk的释放量明显增加，CGRP的释放量有增加的趋势。然而，在初级感觉神经元中未观察到神经激肽A的释放，神经激肽A是速激肽家族中的一员，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，这种抑制作用可被纳洛酮拮抗。观察5-羟色胺和肾上腺素的自发释放。吗啡4可显著增加5-羟色胺而不是肾上腺素的释放。在SpVc-I和SpVc-II内局部应用5-羟色胺或电刺激5-羟色胺下行系统的起源--中缝大核，均可抑制刺激引起的SP释放。这些结果表明，SP是SpVc-I和SpVc-II中参与牙痛传递的潜在递质，刺激诱发的SP释放可能受脑啡肽能系统(节段性抑制系统)和5-羟色胺能系统(下行抑制系统)的调节。较少

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