LAUSR

Dexmedetomidine (DEX) is a highly selective α2 adrenoceptor agonist. In this study, we evaluated the antalgic effect of DEX on acetic acid–induced acute inflammatory visceral pain (AIVP) in rats. Additionally, we evaluated the role of Nrf2 signalling in antinociception. We administered acetic acid to male Sprague Dawley rats that were treated with DEX or saline. Twenty rats were randomly classified into the following groups: normal, model, vehicle, or DEX group. Both q‐RT PCR and enzyme‐linked immunosorbent assay data suggested that interleukin 1β (IL‐1β), tumour necrosis factor α, and IL‐6 were upregulated in the spinal cord. Western blotting and q‐RT PCR analyses were performed to detect the protein and mRNA expression levels of Nrf2, Keap1, and HO‐1 in the spinal cord. The DEX group exhibited a significant downregulation in Nrf2/Keap1/HO‐1 signal activation compared with the model group. Furthermore, we used the Nrf2‐/‐ knockout AIVP rat model to determine the role of Nrf2 in the antinociceptive effect of DEX. We observed that the Nrf2 knockout blocked the Keap1/Nrf2/HO‐1 signal transduction and partially abated the antinociceptive and the anti‐inflammatory effects of DEX. Moreover, our data also indicated that DEX treatment decreased the activation and expression of nuclear factor (NF)‐κB. However, Nrf2 silencing restored the expression of NF‐κB and its phosphorylated form to physiological levels. In summary, our results suggested that Nrf2 signalling plays an important role in the antinociceptive effect of DEX in the AIVP rat model and that Nrf2 exerts its function by enhancing the activation of the NF‐κB sensor.