Introduction

The present paper summarizes research using animal models to investigate the roles of thermosensitive transient receptor potential (TRP) channels in somatosensory functions including touch, temperature, and pain. We present new data assessing the effects of eugenol and carvacrol, agonists of the warmth-sensitive TRPV3, on thermal, mechanical, and pain sensitivity in rats.

Methods

Thermal sensitivity was assessed using a thermal preference test, which measured the amount of time the animal occupied one of two adjacent thermoelectric plates set at different temperatures. Pain sensitivity was assessed as an increase in latency of hindpaw withdrawal away from a noxious thermal stimulus directed to the plantar hindpaw (Hargreaves’ test). Mechanical sensitivity was assessed by measuring the force exerted by an electronic von Frey filament pressed against the plantar surface that elicited withdrawal.

Results

Topical application of eugenol and carvacrol did not significantly affect thermal preference, although there was a trend toward avoidance of the hotter surface in a 30 vs. 45 °C preference test for rats treated with 1 or 10 % eugenol and carvacrol. Both eugenol and carvacrol induced a concentration-dependent increase in thermal withdrawal latency (analgesia), with no significant effect on mechanosensitivity.

Conclusions

The analgesic effect of eugenol and carvacrol is consistent with previous studies. The tendency for these chemicals to increase the avoidance of warmer temperatures suggests a possible role for TRPV3 in warmth detection, also consistent with previous studies. Additional roles of other thermosensitive TRP channels (TRPM8 TRPV1, TRPV2, TRPV4, TRPM3, TRPM8, TRPA1, and TRPC5) in touch, temperature, and pain are reviewed.

中文翻译：

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使用动物模型评估的热敏瞬态受体电位（TRP）通道激动剂及其在机械，热和伤害感受中的作用。

介绍

本文总结了使用动物模型进行的研究，以研究热敏瞬时受体电位（TRP）通道在体感功能（包括触摸，温度和疼痛）中的作用。我们目前提供新的数据，以评估丁香酚和香芹酚，对温度敏感的TRPV3的激动剂对大鼠的热，机械和疼痛敏感性的影响。

方法

使用热偏好测试评估热敏感性，该热偏好测试测量了动物占据设置在不同温度的两个相邻热电板之一的时间。疼痛敏感性被评估为后脚撤离针对有毒的脚底刺激的有害热刺激的潜伏期增加（Hargreaves's test）。通过测量电子von Frey细丝压在引起足部退缩的足底表面上的力来评估机械敏感性。

结果

丁香酚和香芹酚的局部应用并没有显着影响热偏好，尽管在30％和45°C的偏好测试中有一种趋势是避免用1％或10％丁香酚和香芹酚处理的大鼠避开较热的表面。丁子香酚和香芹酚均引起热量依赖潜伏期（镇痛）的浓度依赖性增加，而对机械敏感性没有显着影响。

结论

丁子香酚和香芹酚的镇痛作用与以前的研究一致。这些化学物质增加了避免回暖的趋势，这表明TRPV3在回暖检测中可能发挥作用，这也与先前的研究一致。审查了其他热敏TRP通道（TRPM8，TRPV1，TRPV2，TRPV4，TRPM3，TRPM8，TRPA1和TRPC5）在触摸，温度和疼痛方面的其他作用。