Abstract: 【Objective】 To investigate the role spinal astrocyte activated by reactive oxygen species(ROS) in a rat model of remifentanil-induced hyperalgesia. 【Methods】 Seventy-two rats were randomly separated into 6 groups

12 per group:group control(C)

group remifentanil(R)

group of remifentanil+ intraperitoneal injection of saline(R+Si.p)

group of remifentanil+intraperitoneal injection of ROS scavenger phenyl-N-tert-butylnitrone(PBN)(R+PBN)

group of remifentanil+intrathecal injection of saline(R+Si.t)

group of remifentanil+intrathecal injection of astrocyte inhibitor L-α-aminoadipate(L-α-AA). Mechanical and thermal hyperalgesia was induced by continuous infusion of remifentanil 4 μg/(kg·min)for 2 h. Von Frey test and Hargreaves method were selected to assess the effect of astrocyte inhibitor or ROS scavenger on remifentanil-induced mechanical and thermal hyperalgesia. To detect the expression level of ROS in the spinal cord

mitochondrial superoxide indicator MitoSox Red was intrathecally injected 24 h before remifentanil infusion. Activation of spinal astrocyte was evaluated by immunofluorescence and Western blot analysis. 【Results】Intravenous infusion of remifentanil induced mechanical (R:30.0 ± 2.58; C:50.0 ± 1.80; P < 0.05) and thermal hyperalgesia (R:5.5 ± 1.70; C:10.0 ± 1.21; P < 0.05). Compared with control group

activation of astrocyte (R:0.16 ± 0.009; C:0.10 ± 0.008; P < 0.01) and increased ROS level (R:0.14 ± 0.008; C:0.04 ± 0.005;P < 0.01) in the spinal cord were detected in 2 h following remifentanil infusion. Furthermore

pretreatment with ROS scavenger PBN inhibited activation of spinal astrocyte (R:0.16 ± 0.009; R+PBN:0.10 ± 0.007; P < 0.01) as well as mechanical (R:30.0 ± 2.58; R+PBN:45.0 ± 2.81;P < 0.05) and thermal hyperalgesia (R:5.5±1.70; R+PBN:9.4 ± 1.00; P < 0.05) induced by remifentanil. 【Conclusion】 ROS-mediated activation of spinal astrocyte might contribute to remifentanil-induced hyperalgesia. Inhibition of astrocyte activation induced by ROS in the spinal cordmight be a therapeutic strategy to prevent remifentanil-induced hyperalgesia.