• Zhi-Jun Ge, Yin-Ming Zeng, and Yong-Fei Tan.
• Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical College, Xuzhou 221002, China.
• Acta Pharmacol. Sin. 2005 Feb 1; 26 (2): 186-91.

AimTo investigate the relationship between spinal cord norepinephrine, alpha1 and alpha2 adrenergic receptors and antinociception of propofol in mice.MethodsKunming 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, alpha1R antagonist prazosin, or alpha2R antagonist yohimbine on the antinociception of propofol were studied.ResultsSignificant antinociception was produced by propofol (25, 50 mg/kg, sc) and propofol (20, 40 microg, 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 microg) did not produce any effect on pain threshold in mice (P>0.05). The 6-hydroxydopamine (5 and 10 microg), prazosin (5 and 10 microg), or yohimbine (5 and 10 microg) ith alone did not affect basal tail-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).ConclusionThe spinal cord is a target of propofol antinociception. In mice propofol antinociception is partly mediated by spinal norepinephrine, alpha1R and alpha2R.

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