吗啡对切口痛大鼠的致痛敏作用

目的观察具有镇痛效能的低、高剂量吗啡对大鼠切口痛的影响。方法选用清洁级雄性SD大鼠,随机分为生理盐水(NS)组、低剂量吗啡(LM)(0.6 mg/kg)组和高剂量吗啡(HM)(6 mg/kg)组3组,每组11只。间隔30 min予两次用药后按Brennan法制成切口痛模型,模型制作完成后追加一次用药,NS组皮下注射等容量的生理盐水。自术前至术后第8天,每天以von Frey细丝法检测大鼠的机械性痛阈值,拟在行为学水平探讨吗啡对切口痛大鼠的致痛敏作用。结果术后每组机械痛阈值均显著低于基础值(P<0.05)、术后第2天,HM组机械痛阈值显著高于NS组(P<0.05);术后第3天,HM组低于LM组(P<0.05);术后第8天,HM组低于NS组(P<0.05)。结论在大鼠切口痛模型中,全身反复应用镇痛剂量吗啡能产生机械痛敏,且HM组吗啡致痛敏作用较LM组更显著。

Hyperalgesia induced by morphine on incision pain in rats

Objective To investigate the roles of different effective dosages of morphine on incision pain in rats.Methods Clean-degree male SD rats were randomly allocated to three groups(n=11): normal saline group(NS group),low-dose morphine group(LM group,0.6 mg/kg) and high-dose morphine group(HM group,6 mg/kg).After administration of morphine twice at 30 min interval,the incision pain models of rats were prepared according to the Brennan's method.Morphine was administered once again following the operation,while the NS group was administrated isovolumic normal saline.Then the mechanical threshold of rats was detected with von Frey filaments from the pre-operation to the 8th postoperative day,and the hyperalgesia induced by morphine on the praxiology level was explored. ResultsThe values of mechanical threshold postoperation in each group were significantly lower than those of the baseline.The mechanical threshold of HM group was significantly higher than the NS group on the second day postoperation(P<0.05).It was lower in the HM group than in the LM group on the third day postoperation(P<0.05),and was lower in the HM group than in the NS group on the eighth day postoperation(P<0.05). Conclusion On incision pain model in rats,morphine given systemically for several times will induce mechanical hyperalgesia.Different dosage has different effect on hyperalgesia during the recovery period,with HM group be more sensitive.