超低剂量纳洛酮对地佐辛治疗切口痛模型大鼠术后疼痛效能的影响

目的: 观察超低剂量纳洛酮(＜1 μg/kg)对地佐辛镇痛作用的影响。方法: 选择24只雄性SD大鼠，按照随机数字表法均分为生理盐水组、纳洛酮组、地佐辛组、地佐辛+纳洛酮组，每组6只，参照Brennan法建立大鼠切口痛模型，模拟临床患者手术后疼痛。分别于术后经尾静脉给予等体积生理盐水、纳洛酮(1 ng/kg)、地佐辛(1 mg/kg)、地佐辛(1 mg/kg)＋纳洛酮(1 ng/kg)。分别于术前1 d和术后2 h、1 d、3 d、5 d、7 d测量大鼠手术足机械缩足反应阈值(PWT)，评价不同药物的镇痛效果。结果： 术后2 h，与生理盐水组比较，纳洛酮组PWT值无显著差异(P＞0.05)，地佐辛组与地佐辛+纳洛酮组PWT值显著增高(P<0.01)；地佐辛+纳洛酮组PWT值明显高于地佐辛组(P<0.01)。术后1、3、5、7 d 4组间PWT值差异无统计学意义(P＞0.05)；与术前相比，4组术后1 d、3 d PWT值明显降低(P<0.01)；术后5 d、7 d差异无统计学意义(P＞0.05)。 结论： 超低剂量纳洛酮无镇痛作用，但与地佐辛联用，可以增强后者的镇痛作用。

Effects of ultra low dose naloxone on analgesia of dezocine in rats with incisional pain

Objective: To investigate the effects of ultra low dose naloxone on analgesia of dezocine in rats with incisional pain. Methods: Models of postoperative incision pain (Brennan′s method) in 24 male SD rats were eatablished. Rats were randomly divided into 4 groups(n=6, each group) receiving normal saline, ultra low dose naloxone(1 ng/kg), dezocine(1 mg/kg) and dezocine(1 mg/kg)+naloxone(1 ng/kg) respectively via the tail vein. PWT values in ipsilateral side of hind paws were measured 1 d before surgery, 2 h after surgery, and 1 d, 3 d, 5 d, 7 d after surgery. Results: There were no statistical significance in the PWT values at 1 d, 3 d, 5 d and 7 d among the four groups(P＞0.05). Within each group, compared with baseline, PWT values were significantly decreased on 1 d, and 3 d after surgery, while no difference on 5 d, 7d after surgery(P＜0.01). There was no difference of PWT values between naloxone group and normal saline group(P＞0.05) 2 h after the incision. Dezocine group and dezocine+naloxone group were shown to have significantly higher PWT values than the normal saline group(P<0.01). Dezocine+naloxone group was shown to have significantly higher PWT values than dezocine group (P<0.01). Conclusion: Though ultra low dose of naloxone has no analgesic effect when used alone, it could enhance the analgesic efficacy of dezocine.