Vaccarino Anthony L, Tasker R A R, Melzack Ronald
Department of Psychology, McGill University, 1205 Dr. Penfield Avenue, Montreal, Que. H3A 1B1 Canada Department of Anatomy and Physiology, Atlantic Veterinary College, University of Prince Edward Island, P.O. Box 2400, Charlottetown, PE1 C1A 8C1 Canada.
Pain. 1989 Jan;36(1):103-109. doi: 10.1016/0304-3959(89)90117-6.
In a recent study [30] it was reported that naloxone, at doses normally employed for opioid antagonism, produced a dose-dependent analgesia in BALB/c mice in the formalin test. We report here that another opioid antagonists, naltrexone, also produces analgesia under these conditions. Female BALB/c mice were injected subcutaneously with naltrexone (0.01-1.0 mg/kg) or saline alone and tested for analgesia using the formalin test. Naltrexone produced a statistically significant dose-dependent analgesia, with an ED50 of 0.05 mg/kg and almost total analgesia at doses of 0.1 mg/kg or greater. To determine the relationship between naloxone analgesia and better documented forms of opioid analgesia, BALB/c mice were injected with naloxone or saline following the administration of a pre-determined ED50 for morphine and tested for analgesia using the tail-flick and formalin tests. Naloxone antagonized morphine analgesia in the tail-flick test at both doses used (0.3 and 10 mg/kg). In the formalin test, however, naloxone attenuated morphine analgesia at the lower doses (0.1 and 0.3 mg/kg) and potentiated morphine analgesia at the highest dose (10 mg/kg). The implications of this finding are discussed.
在最近的一项研究[30]中，有报道称，纳洛酮在通常用于阿片类拮抗作用的剂量下，在福尔马林试验中对BALB/c小鼠产生了剂量依赖性镇痛作用。我们在此报告，另一种阿片类拮抗剂纳曲酮在这些条件下也会产生镇痛作用。将雌性BALB/c小鼠皮下注射纳曲酮（0.01 - 1.0毫克/千克）或单独注射生理盐水，并使用福尔马林试验测试镇痛效果。纳曲酮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0.05毫克/千克，在0.1毫克/千克或更高剂量时几乎完全镇痛。为了确定纳洛酮镇痛与记录更充分的阿片类镇痛形式之间的关系，在给予预定的吗啡半数有效剂量后，给BALB/c小鼠注射纳洛酮或生理盐水，并使用甩尾试验和福尔马林试验测试镇痛效果。在甩尾试验中，所用的两种剂量（0.3和10毫克/千克）的纳洛酮均拮抗了吗啡镇痛作用。然而，在福尔马林试验中，较低剂量（0.1和0.3毫克/千克）的纳洛酮减弱了吗啡镇痛作用，而最高剂量（10毫克/千克）的纳洛酮增强了吗啡镇痛作用。本文讨论了这一发现的意义。
