Aim:To investigate the relationship between spinal cord norepinephrine,α_1 andα_2 adrenergic receptors and antinociception of propofol in mice.Methods:Kunming mice were used.Antinociceptive tests were investigated with the tail-immersion test and the acetic acid-induced writhing test.The effects of subcuta-neous(sc),intrathecal(ith)and intracerebroventricular(icv)injection propofolon pain threshold were observed.The influences of pretreatment with ith 6-hydroxydopamine,α_1R antagonist prazosin,or α_2R antagonist yohimbine on theantinociception of propofol were studied.Results:Significant antinociceptionwas produced by propofol(25,50 mg/kg,sc)and propofol(20,40μg,ith)in tail-immersion test and acetic the acid-induced writhing test(P<0.05 or P<0.01).Icvpropofol(10,20,and 40 μg)did not produce any effect on pain threshold in mice(P>0.05).The 6-hydroxydopamine(5 and 10μg),prazosin(5 and 10μg),oryohimbine(5 and 10μg)ith alone did not affect basal tai-flick latency(TFL)inconscious mice,but significantly reduced the TFL as measured by tail-immersiontest in propofol(50mg/kg,sc)-treated mice,compared with basal TFL and ve-hicle groups(P<0.05 or P<0.01).Conclusion:The spinal cord is a target ofpropofol antinociception.In mice propofol antinociception is partly mediated byspinal norepinephrine,α_1R and α_2R. Aim: To investigate the relationship between spinal cord norepinephrine, α_1 and α_2 adrenergic receptors and antinociception of propofol in mice. Methods: Kunming mice were used. Antinociceptive tests were investigated with the tail-immersion test and the acetic acid-induced writhing test. Effects of subcuta-neous (sc), intrathecal (ith) and intracerebroventricular (icv) injection propofolon pain threshold were observed. These influences of pretreatment with ith 6-hydroxydopamine, α_1R antagonist prazosin, or α_2R antagonist yohimbine on theantinociception of propofol were studied. Results : Significant antinociception was produced by propofol (25,50 mg / kg, sc) and propofol (20,40 μg, ith) in tail-immersion test and acetic the acid- induced writhing test (P <0.05 or P < (5 and 10 μg), oryohimbine (5 and 10 μg) ith alone did not affect basal tai-flick latency (TFL) unconcious m ice, but significantly reduced the TFL as measured by tail-immersion test in propofol (50 mg / kg, sc) -treated mice, compared with basal TFL and ve-hicle groups (P <0.05 or P <0.01) .Conclusion: The spinal cord is a target of propofol antinociception. In mice propofol antinociception is part of a pathway mediated by the norepinephrine, α_1R and α_2R.