We had recently reported that linalool odor exposure induced significant analgesic effects in mice and that the effects were disappeared in olfactory-deprived mice in which the olfactory epithelium was damaged, thus indicating that the effects were triggered by chemical senses evoked by linalool odor exposure. However, the peripheral neuronal mechanisms, including linalool receptors that contribute toward triggering the linalool odor-induced analgesia, still remain unexplored. In vitro studies have shown that the transient receptor potential ankyrin 1 (TRPA1) responded to linalool, thus raising the possibility that TRPA1 expressed on the trigeminal nerve terminal detects linalool odor inhaled into the nostril and triggers the analgesic effects. To address this hypothesis, we measured the behavioral pain threshold for noxious mechanical stimulation in TRPA1-deficient mice. In contrast to our expectation, we found a significant increase in the threshold after linalool odor exposure in TRPA1-deficient mice, indicating the analgesic effects of linalool odor even in TRPA1-deficient mice. Furthermore, intranasal application of TRPA1 selective antagonist did not alter the analgesic effect of linalool odor. These results showed that the linalool odor-induced analgesia was triggered by a TRPA1-independent pathway in mice.

中文翻译：

---

芳樟醇气味诱导的镇痛作用是由小鼠中的 TRPA1 非依赖性途径触发的

我们最近报道了芳樟醇气味暴露在小鼠中引起了显着的镇痛作用，并且在嗅觉上皮细胞受损的嗅觉剥夺小鼠中这种作用消失了，因此表明这些作用是由芳樟醇气味暴露引起的化学感觉触发的。然而，周围神经元机制，包括有助于触发芳樟醇气味引起的镇痛的芳樟醇受体，仍未得到探索。体外研究表明，瞬时受体电位锚蛋白1（TRPA1）对芳樟醇有反应，从而提高了表达于三叉神经末梢的TRPA1检测到吸入鼻孔的芳樟醇气味并触发镇痛作用的可能性。为了解决这个假设，我们测量了 TRPA1 缺陷小鼠中有害机械刺激的行为疼痛阈值。与我们的预期相反，我们发现在 TRPA1 缺陷小鼠中暴露芳樟醇气味后阈值显着增加，表明芳樟醇气味即使在 TRPA1 缺陷小鼠中也具有镇痛作用。此外，TRPA1 选择性拮抗剂的鼻内应用并未改变芳樟醇气味的镇痛作用。这些结果表明，芳樟醇气味诱导的镇痛是由小鼠中的 TRPA1 非依赖性途径触发的。TRPA1选择性拮抗剂的鼻内应用并未改变芳樟醇气味的镇痛作用。这些结果表明，芳樟醇气味诱导的镇痛是由小鼠中的 TRPA1 非依赖性途径触发的。TRPA1选择性拮抗剂的鼻内应用并未改变芳樟醇气味的镇痛作用。这些结果表明，芳樟醇气味诱导的镇痛是由小鼠中的 TRPA1 非依赖性途径触发的。