Versteeg Ninja, Wellauer Vanessa, Wittenwiler Selina, Aerenhouts Dirk, Clarys Peter, Clijsen Ron
Rehabilitation and Exercise Science Laboratory (RESlab), Department of Business Economics, Health and Social Care, University of Applied Sciences and Arts of Southern Switzerland, Landquart, Switzerland.
Department of Movement and Sport Sciences, Vrije Universiteit Brussel, Brussels, Belgium.
Front Physiol. 2024 Apr 19;15:1347196. doi: 10.3389/fphys.2024.1347196. eCollection 2024.
Methyl salicylate, the main compound of wintergreen oil, is widely used in topical applications. However, its vascular and thermosensory effects are not fully understood. The primary aim was to investigate the effects of topical methyl salicylate on skin temperature (T), skin microcirculation (MC) and muscle oxygen saturation (SmO) compared to a placebo gel. The secondary aim was to assess thermosensory responses (thermal sensation, thermal comfort) and to explore to which extent these sensations correspond to the physiological responses over time.
21 healthy women (22.2 ± 2.9 years) participated in this single-blind, randomized controlled trial. Custom-made natural wintergreen oil (12.9%), containing methyl salicylate (>99%) and a placebo gel, 1 g each, were applied simultaneously to two paravertebral skin areas (5 cm × 10 cm, Th4-Th7). T (infrared thermal imaging), MC (laser speckle contrast imaging) and SmO (deep tissue oxygenation monitoring) and thermosensation (Likert scales) were assessed at baseline (BL) and at 5-min intervals during a 45 min post-application period (T0-T45).
Both gels caused an initial decrease in T, with T(min) at T5 for both methyl salicylate (BL-T5: Δ-3.36°C) and placebo (BL-T5: Δ-3.90°C), followed by a gradual increase ( < .001). Methyl salicylate gel resulted in significantly higher T than placebo between T5 and T40 ( < .05). For methyl salicylate, MC increased, with MC(max) at T5 (BL-T5: Δ88.7%). For placebo, MC decreased (BL-T5: Δ-17.5%), with significantly lower values compared to methyl salicylate between T0 and T45 ( < .05). Both gels had minimal effects on SmO, with no significant differences between methyl salicylate and placebo ( > .05). Thermal sensation responses to topical methyl salicylate ranged from "cool" to "hot", with more intense sensations reported at T5.
The findings indicate that topical methyl salicylate induces short-term cutaneous vasodilation, but it may not enhance skeletal muscle blood flow. This study highlights the complex sensory responses to its application, which may be based on the short-term modulation of thermosensitive transient receptor potential channels.
水杨酸甲酯是冬青油的主要成分，广泛用于局部应用。然而，其对血管和热感觉的影响尚未完全了解。主要目的是研究与安慰剂凝胶相比，局部应用水杨酸甲酯对皮肤温度（T）、皮肤微循环（MC）和肌肉氧饱和度（SmO）的影响。次要目的是评估热感觉反应（热感觉、热舒适度），并探讨这些感觉在多大程度上随时间与生理反应相对应。
21名健康女性（22.2±2.9岁）参与了这项单盲随机对照试验。将定制的天然冬青油（12.9%），其中含有水杨酸甲酯（>99%）和安慰剂凝胶，各1克，同时涂抹于两个椎旁皮肤区域（5厘米×10厘米，T4 - T7）。在基线（BL）以及涂抹后45分钟的时间段内（T0 - T45），每隔5分钟评估一次T（红外热成像）、MC（激光散斑对比成像）和SmO（深部组织氧合监测）以及热感觉（李克特量表）。
两种凝胶均导致T最初下降，水杨酸甲酯（BL - T5：Δ - 3.36°C）和安慰剂（BL - T5：Δ - 3.90°C）在T5时达到T（min），随后逐渐升高（P <.001）。在T5至T40之间，水杨酸甲酯凝胶导致的T显著高于安慰剂（P <.05）。对于水杨酸甲酯，MC增加，在T5时达到MC（max）（BL - T5：Δ88.7%）。对于安慰剂，MC下降（BL - T5：Δ - 17.5%），在T0至T45之间与水杨酸甲酯相比显著更低（P <.05）。两种凝胶对SmO的影响最小，水杨酸甲酯和安慰剂之间无显著差异（P >.05）。对局部应用水杨酸甲酯的热感觉反应范围从“凉爽”到“炎热”，在T5时报告的感觉更强烈。
研究结果表明，局部应用水杨酸甲酯可诱导短期皮肤血管舒张，但可能不会增强骨骼肌血流。本研究强调了对其应用的复杂感觉反应，这可能基于热敏瞬时受体电位通道的短期调节。
