The evidence for sweet substance-induced analgesia in adult human

Abstract

Background: Sweet substance-induced analgesia (SIA) has been widely investigated in rodents. The mechanism is thought to be involved in the central regulating systems in the anti-nociceptive process, taking advantage of sweet taste and not acting as a distraction. In human, this SIA is, however, limited in neonatal. The reasons underlying the reduced effects of SIA with growth have been less studied in adults. Consensus regarding SIA thus has not yet to be obtained in adults. Therefore, we aimed to determine the sweet stimulus of sucrose on responses of healthy adults to nociception using cold pressor testing. Methods: The present study was carried out a randomized control with crossover design. Using the cold pressor test (CPT), 13 adult male subjects immersed a hand in cold water to induce nociception. Subjects held either a 24\% weight/volume sucrose solution or distilled water in their mouth before and during CPT. Analgesic effect and emotional state were quantitatively assessed as follows: pain threshold; pain tolerance; pain intensity; taste pleasantness; and the brief Japanese version of the Profile of Mood State (POMS). Results: With subjects held sucrose solution in the mouth, pain threshold was increased significantly (p< 0.05) when compared with distilled water. In addition, the taste pleasantness rating was significantly higher with sucrose solution than that with distilled water (p< 0.05). Conclusions: These data clearly indicate that the sweet stimulus of sucrose induces antinociception associated with taste pleasantness in adults, suggesting sweet substance-induced analgesia can be applied to young male adults.