OR22 - Involvement of Transient Receptor Potential Ankyrin 1 (TRPA1) in Pain and Inflammation in the Dental Pulp

Objective: TRPA1 a polymodal cation channel activates pain detecting neurons and inflammatory signaling. TRPA1 is present in multiple cell types within the dental pulp and associated with hypersensitivity and inflammation. However, its role in pulpitis has not been studied. The aim of this study is to investigate the role of TRPA1 in the development of pain behaviors and the neural activation using a mouse model of LPS-induced pulpitis.

Methods: Wild-type (WT) and TRPA1 knockout (KO) mice were used. Pulp exposure was performed on all mice, followed by multiple applications of LPS or saline (resulting in four groups). Tooth cap material was then placed. Pain-like behavior was assessed on days 1, 3, and 7 post-surgery using behavioral tests, including the Mouse Grimace Scale which measures spontaneous pain, mechanical hypersensitivity test, and nesting tests, which measure the affective component of pain. Additionally, markers of nociceptive pathway activation were quantified in the brainstem using c-Fos expression.

Results: The KO groups showed reduced pain-like behavior in all tests compared to the WT groups. In particular, three-way ANOVA showed significant delay in nesting test in WT mice compared to KO mice (p < 0.05). c-Fos expression in mice brainstem was elevated in WT mice but significantly reduced by 19.2% in KO mice (p < 0.05), indicating decreased neural activation in TRPA1 KO mice.

Conclusion: These findings demonstrate that TRPA1 KO mice showed lower pain-like behavior and neural activation compared to WT following pulp exposure and LPS application. This research underscores TRPA1 as a viable target for therapeutic intervention for pain management in dental pulp.