Pharmacological evaluation of physcion as a TRPV1 inhibitor with multimodal analgesic efficacy in experimental pain models

Abstract

Background: Pain serves as a vital protective mechanism triggered by tissue damage. While NSAIDs and opioids offer relief, their prolonged usage is hindered by adverse effects. Developing analgesics with fewer side effects is crucial for effective pain treatment. The TRPV1 channel is a key target for pain relief, with its inhibitors effectively reducing hyperalgesia in animals. This research utilized virtual screening to identify TRPV1-selective natural compounds for potent analgesic properties. Results: The physcion exhibited the notable affinity for TRPV1 compared to the compounds examined. After conducting molecular dynamics simulations, physcion emerged as the compound demonstrating the highest binding affinity towards TRPV1, a finding corroborated by calcium imaging, which validated its inhibitory impact. Furthermore, physcion mitigated the stretch number in the acetic acid-induced stretching model, prolonged the latency period in the hot water tail-flick and hot plate assays, and heightened the pain withdrawal threshold lowered by complete Freund’s adjuvant (CFA). Notably, physcion exerted a marked effect in ameliorating bone cancer-induced pain in the hot plate and von Frey tests. Additionally, physcion diminished the levels of inflammatory cytokines and the mRNA expression of both inflammatory and calcium-related genes in the CFA-induced murine model. Furthermore, physcion downregulated the expression of inflammatory genes induced by tumor necrosis factor-α (TNF-α) in RAW264.7 cells. The underlying mechanism potentially involves the suppression of the NF-κB and MAPK signaling cascades. Conclusions: Our investigation underscores the potential of physcion as a promising candidate for analgesic therapy.