Rising TRPV4 expression in the central nucleus of amygdala is involved in tooth movement pain

Abstract

Pain is the most common adverse effect of orthodontic treatment. Transient receptor potential vanilla-like protein 4 (TRPV4) plays an important role in pain regulation, and central amygdala (CeA) is also an important nuclear mass in pain regulation, but there is a paucity of literature on the roles of TRPV4 in CeA on tooth movement pain. C57BL/6 J mice were divided into control group, 0 g group and 30 g group. After establishing the experimental tooth movement model, behavioral tests were first performed, which showed that pain behavior peaked on day 1 and then dropped to baseline on day 7. The 30 g group developed anxiety-like behavior after 14 days of application, and the degree increased over time. In addition, immunofluorescence staining and western blot was performed on CeA tissues. The results showed that tooth movement significantly increased the fluorescence intensity of TRPV4 and protein expression of TRPV4, NLRP3, P65 and the phosphorylation of P65 proteins in CeA. Administration of TRPV4 antagonists in CeA through intraperitoneal injection effectively alleviated tooth movement induced pain and anxiety-like behaviors. This suggests that TRPV4 within CeA may mediate the regulation of tooth movement pain through NLRP3-NF-κB signaling pathway, which not only clarify the mechanism of CeA regulating tooth movement pain, but also help regulating tooth movement pain precisely.