Identification of a Nonelectrophilic and Selective TRPA1 Agonist for Alleviation of Inflammatory Pain through Channel Desensitization

Transient receptor potential ankyrin 1 (TRPA1) agonists exert long-lasting analgesic effects by inducing neuronal desensitization, a similar strategy has been confirmed in the approval of capsaicin, a transient receptor potential vanilloid 1 (TRPV1) agonist for the management of neuropathic pain associated with postherpetic neuralgia. However, currently available TRPA1 agonists are limited by insufficient selectivity or undesirable side effects, highlighting the urgent need for the discovery of novel TRPA1 agonists as potential analgesics. In this study, we reported a selective TRPA1 agonist N-(3-methoxypropyl)-4-(p-tolyl)thiazol-2-amine named NMTA based on screening our compound library. Calcium imaging and whole-cell patch clamp recordings demonstrated NMTA as a TRPA1 agonist with an EC₅₀ value of 50.05 ± 5.39 μM for hTRPA1. Repetitive administration of NMTA caused channel desensitization in TRPA1-overexpressing HEK-293T cells, suggesting a potential analgesic effect in vivo. Oral administration of NMTA significantly alleviated pain hypersensitivity in Complete Freund's Adjuvant (CFA)-induced inflammatory pain in mice, indicating an analgesic effect of NMTA for inflammatory pain. Molecular docking suggested T684 was critical for the activation of NMTA on TRPA1 channel. In summary, we have identified NMTA as a highly selective TRPA1 agonist capable of alleviating inflammatory pain in mice through channel desensitization, thereby verifying a feasible strategy for developing TRPA1-targeted analgesics based on desensitization.

NMTA; agonist; antinociception; desensitization; inflammatory pain; transient receptor potential ankyrin 1.