Effects of intrathecal 6-hydroxydopamine, α_1 and α_2 adrenergic receptor antagonists on antinociception of propofol in mice

摘要

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. The effects of subcutaneous ( sc ), intrathecal ( ith ) and intracerebroventricular ( icv ) injection propofol on pain threshold were observed. The influences of pretreatment with ith 6-hydroxydopamine, α_1 R antagonist prazosin, or α _2 R antagonist yohimbine on the antinociception 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 < 0.01 ). Icv propofol ( 10, 20, and 40 μg ) did not produce any effect on pain threshold in mice ( P > 0.05 ). The 6-hydroxydopamine ( 5 and 10 μg ), prazosin ( 5 and 10 μg ), or yohimbine ( 5 and 10 μg ) ith alone did not affect basal tai-flick latency ( TFL ) in conscious mice, but significantly reduced the TFL as measured by tail-immersion test in propofol ( 50 mg/kg, sc )-treated mice, compared with basal TFL and vehicle groups ( P < 0.05 or P < 0.01 ). Conclusion: The spinal cord is a target of propofol antinociception. In mice propofol antinociception is partly mediated by spinal norepinephrine, α_1 R and α_2 R.