Effects of sufentanil on β-endorphin and oxygen free radical in rabbit

Objective To observe the influence of intravenous or epidural analgesia with sufentanil on β-endorphin(β-EP) and oxygen free radical(OFR) expression in rabbits with formalin-induced pain.Methods Eighteen healthy rabbits were equally randomized into three groups(n=6): intravenous analgesia group(group A),epidural analgesia group(group B) and control group(group C).All rabbits were injected with 5% formal 0.5 ml to establish formalin-induced pain model.Then sufentanil 0.46 μg/kg and 0.64 μg/kg were intravenously and epidurally injected in group A and group B,respectively.The same volume of saline was intravenously injected in group C as control.Pain scores were recorded every 5 min from 5 min after administration to 45 min after administration.The level of β-EP was detected before formalin injection(T0) and at 10 min,20 min,40 min,2,8,24 h and 48 h(T1-T7) after sufentanil or saline injection,and the level of OFR was evaluated through the level of MDA.Results Compared with T0,the level of β-EP increased at T2-T7 in group A and group B and at T1-T7 in group C(P0.05).The level of MDA at T1-T7 decreased in group A and group B and increased in group C.Compared with group C at the same time points,pain scores,and the levels of β-EP and MDA were lower in group A and group B than in group C(P0.05).Conclusion Intravenous or epidural analgesia with sufentanil may effectively inhibit the expression of β-EP and OFR in rabbits with formalin-induced pain.