鞘内注射咪唑安定对福尔马林致痛大鼠镇痛作用ED_(50)的测定

Detectation of Intrathecal Injected Midazolam on Analgesic Effects ED_(50) of a Rat Induced Pain by Formalin

目的:研究在福尔马林致痛大鼠模型鞘内注射咪唑安定镇痛作用的半数有效剂量(ED50)及其对痛行为的影响。方法:选择鞘内成功置管的雄性SD大鼠32只,随机分为4组(n=8):对照组(C组)、生理盐水组(NS组)、致痛前给药组(M1组)及致痛后给药组(M2组)。鞘内置管后5 d,NS组、M1组及M2组大鼠于左后足掌部皮下注射5%福尔马林100μL致痛,致痛前10 min,NS组鞘内注射20μL生理盐水,M1组鞘内注射咪唑安定22μg,C组鞘内注射20μL生理盐水,足底注射100μL生理盐水作为对照。采用大鼠缩腿、舔爪时间之和作为行为学观察指标。结果:NS组、M1组与M2组第二相缩腿、舔爪累计时间显著长于C组(P<0.01);M1组与M2组的缩腿、舔爪累计时间短于NS组(P<0.01);且M1组短于M2组(P<0.01)。结论:在福尔马林致痛大鼠模型中鞘内注射咪唑安定镇痛作用的ED50为21.8μg,咪唑安定具有超前镇痛效应。

Objective：To evaluate the half-effective dosage （ED50）of antinociceptive effect of intrathecal injected Midazolam in a rat model induced pain by Formalin and the effects of the pain behavior. Methods：Thirty-two male SD rats whose intrathecal catheters were implanted successfully were randomly divided into four groups （ n = 8 each）. They were a control group （group C）, a normal saline group （group NS）,a pre-induced pain administration group （group M1 ） and a post-induced pain administration group （group M2 ）. After five days of implanted catheters intrathecally, a subcutaneous injection of 100 μL of 5% Formalin was given into the left plantar surface of the rats in the group NS, the group M1 and the group M2. Before ten min of induced pain, the intrathecal injection of 20 μL of normal saline was given to the group NS, the intrathecal injection of 22 μg of Midazolam was given to the group M1, the intrathecal injection of 20μg of normal saline was given to the group C and the subcutaneous injection of 100 μL of saline was used as control. The sum of time that rats drew back their legs and licked their paws was considered as behavior observation index. Results：The accumulative time of drawing back their legs and licking their paws of the second phase in rats of the group NS, the group M1 and the group M2 was significantly longer than that of the group C （P 〈 0.01 ）. The accumulative time of drawing back their legs and licking their paws of the group M~ and the group M2was significantly shorter than that of the group NS （P 〈 0.01 ）. And the accumulative time of drawing back their legs and licking their paws of the group M1 was shorter than that of the group M2 （P 〈 0.01 ）. Conclusion： The half-effective dosage （ ED50 ） of antinociceptive effect of intrathecal injected Midazolam in a rat model induced pain by Formalin is 21.8 μg and Midazolam is of pre-emptive analgesia effects.