吗啡剂量及给药方式对大鼠运动敏感化的影响

Effects of Injection Dose and Pattern on Locomotor Sensitization to Morphine in Rat

目的:比较不同剂量吗啡皮下注射及给药方式(每日三次给药与每日一次给药)对Sprague-Dawley大鼠运动敏感化的影响。方法:实验大鼠共分为五组,即生理盐水组、吗啡每日一次皮下注射组(1mg/kg组、3mg/kg组及10mg/kg组)以及吗啡每日三次皮下注射组(10mg/kg/次),每组8只大鼠。连续用药7天,隔日检测大鼠自发活动,然后停止药物处理,停药7天后每组大鼠予以吗啡3mg/kg皮下注射并检测大鼠自发活动。结果:吗啡每日一次皮下注射组中,各剂量组大鼠的运动敏感化均能顺利表达。吗啡每日三次皮下注射组大鼠的运动敏感化表达受到了抑制。结论:低剂量吗啡同样诱发运动敏感化,提示低剂量吗啡也会出现觅药动机敏感化,因此不要冒险尝试毒品即便是低剂量毒品;当每日一次间断用药时,运动敏感化更容易表达,提示负性强化可能是运动敏感化的调节机制之一。

Objective： To study the effects of different doses and patterns of morphine injection （s.c. once per day or s. c. thrice per day） on locomotor sensitization to morphine in Sprague-Dawley rat. Methods： 40 male Sprague-Dawley rats were randomly assigned to five groups （n=8 per group）： Saline group （saline, 1 ml/kg, s.c. once per day）, Morphine groups （morphine, s.c. once per day, Mor-t： 1mg/kg; Mor-2： 3mg/kg; Mor-3： 10mg/kg.） and Mor-4 group （morphine, 10mg/kg, s. c. thrice per day ）. Each rat was treated with saline or morphine for 7 days and locomortor activity was measured every two days. 7 days after saline or morphine treatment, all groups received a challenge injection of morphine （3mg/kg, s.c.） and locomortor activities were tested immediately after injection. Results： Locomotor sensitization to morphine developed and expressed successfully in morphine groups （morphine, s.c. once per day） and expression of locomotor sensitization in Mor- 4 group was suppressed. ConcLusion： Low dose of morphine enables to induce sensitization of incentive salience attribution to the compulsive drug-seeking. Thus drug taking, even of low dose, is not encouraged to try. Intermittent morphine treatment once per day facilitates the expression of locomotor sensitization compared with morphine treatment thrice per day, which implicates that negative reinforcement may be a candidate mechanism underlying locomotor sensitization.