Research of anti-nociceptive effects with sucrose stimulus on pain in human adults

背景：蔗糖诱导镇痛（SIA）已被认为是大鼠幼鼠和婴儿疼痛缓解的非药物干预措施。SIA的机制可能是由内源性阿片系统等中枢调节系统利用甜味介导的。这种效果是由甜味产生的，而不是由蔗糖的吸收产生的。SIA经常被研究用于婴儿的疼痛缓解，但对成人的疼痛缓解研究较少，为什么在大鼠和婴儿中，SIA的效果会随着生长而下降。本研究旨在探讨蔗糖刺激是否能诱导成人痛觉的镇痛作用。方法：采用随机对照交叉研究。40名健康成年人参加了这项研究。实验疼痛采用冷压试验（CPT），受试者将手浸入冷水中。受试者在CPT前和CPT期间分别将24%的蔗糖溶液和蒸馏水含在嘴里作为对照。疼痛反应通过六种工具测量：疼痛阈值、疼痛耐受性、唾液生物标志物、情绪状态的心理评分、疼痛和味觉的视觉模拟量表（VAS）评分。在解释了本研究的目的和程序后，受试者签署了一份同意书。本研究得到川崎大学研究机构伦理委员会的批准。结果：相对于蒸馏水，成年男性含蔗糖溶液时疼痛阈值明显增加。然而，在成年女性中没有观察到显著差异。结论：蔗糖刺激可诱导成年男性的抗伤害性作用。此外，性别差异增加了参与蔗糖镇痛表达的可能性。

Background : Sucrose-induced analgesia (SIA) has been known as non-pharmacological intervention for pain relief in both rat pups and infants. The mechanism underlying SIA is suggested to be mediated by the central regulating systems such as the endogenous opioids system, taking advantage of sweet taste. This effect is produced by the sweet sensation rather than by the absorption of sucrose. The SIA has been frequently investigated for the pain relief in infants but less so for SIA in adults why the effects are known to decline with growth in rats and infants. The aim of study is to examine whether sucrose stimulus induce the analgesic effects on nociception in adults.Methods : This study was carried out a randomized control with crossover study. Forty healthy adults participated in this study. Experimental pain was induced using the cold pressor test (CPT), and subjects immersed their hand in cold water. Subjects held a 24% sucrose solution and distilled water as a control in their mouths before and during CPT, respectively. Pain reactivity was measured by six instruments : pain threshold, pain tolerance, biomarker in saliva, psychological ratings with the profile of mood states, each visual analogue scales (VAS) score of pain and taste. Subjects signed a consent form after the purpose and procedures of this study had been explained. This study is approved by the ethical committee at the research institution at Kawasaki University.Results : The pain threshold increased significantly when male adults held sucrose solution in the mouth relative to distilled water. However, no significant difference in female adults was observed.Conclusion : These finding suggest the sucrose stimulus could induce the anti-nociceptive effects in male adults. In addition, the gender differences raise the possibility of involvement in expression of sucrose analgesia.