Vaccarino A L, Tasker R A, Melzack R
Department of Psychology, McGill University, Montreal, Que., Canada.
Neurosci Lett. 1988 Jan 11;84(1):103-7. doi: 10.1016/0304-3940(88)90345-x.
Systemic administration of naloxone usually produces either hyperalgesia or no change in nociception depending on the animal species used and/or the pain test employed. This study, however, demonstrates that naloxone produces a dose-dependent analgesia in the formalin pain test using an inbred strain of albino mouse. Female BALB/c, C57BL/6 and CD1 mice were injected subcutaneously with naloxone HCl in saline (0.1 10.0 mg/kg) or saline alone, and tested for analgesia using the formalin test. Naloxone produced a statistically significant dose-dependent analgesia in the BALB/c mice, with an ED50 of 0.24 mg/kg and almost total analgesia at doses of 1 mg/kg or greater. No changes in pain behaviour were observed in the C57BL/6 or CD1 strains of mice. We believe this to be the first report of analgesia following administration of doses of naloxone normally used for opioid antagonism. To determine if this effect was specific to the formalin test, the 3 strains of mice were injected subcutaneously with naloxone HCl and tested in the tail-flick test. Naloxone had no analgesic action in this test in any of the strains.
根据所使用的动物种类和/或采用的疼痛测试，全身给予纳洛酮通常会产生痛觉过敏或对痛觉无影响。然而，本研究表明，在使用近交系白化小鼠的福尔马林疼痛测试中，纳洛酮可产生剂量依赖性镇痛作用。将雌性BALB/c、C57BL/6和CD1小鼠皮下注射溶于生理盐水的盐酸纳洛酮（0.1至10.0毫克/千克）或仅注射生理盐水，并使用福尔马林测试来检测镇痛效果。纳洛酮在BALB/c小鼠中产生了具有统计学意义的剂量依赖性镇痛作用，半数有效剂量（ED50）为0.24毫克/千克，在1毫克/千克或更高剂量时几乎完全镇痛。在C57BL/6或CD1品系小鼠中未观察到疼痛行为的变化。我们认为这是首次关于给予通常用于阿片类药物拮抗作用剂量的纳洛酮后出现镇痛作用的报告。为了确定这种效应是否特定于福尔马林测试，给这3个品系的小鼠皮下注射盐酸纳洛酮，并在甩尾测试中进行检测。在该测试中，纳洛酮对任何品系的小鼠均无镇痛作用。
