静脉泵注瑞芬太尼对福尔马林致痛大鼠脊髓敏感化的影响

EFFECTS OF SHORTLY INFUSION REMIFENTANIL ON HYPERALGESIA EVOKED BY SUBCUTANEOUS FORMALIN IN RATS

目的：观察短期静脉泵注不同剂量瑞芬太尼后对福尔马林致痛大鼠行为学和脊髓后角c-Fos蛋白表达的影响。方法：选择体重250~300g,右侧颈内静脉置管后恢复良好的雄性SD大鼠18只,随机分为3组（n=6）：对照组（C组）、低剂量瑞芬太尼组（LR组）和高剂量瑞芬太尼组（HR组）。三组大鼠均在右侧跖底皮下注射5%福尔马林50μl,注射前5min LR组和HR组分别经右侧颈内静脉持续泵注瑞芬太尼5μg/kg/min、30μg/kg/min,对照组（C组）泵注生理盐水至注射后5min停止泵注。记录福尔马林注射后第一阶段（0~5min）和第二阶段（15~90min）内累计舔爪时间和注射后2h,L4~5脊髓后角Ⅰ-Ⅱ、Ⅲ-Ⅳ、Ⅴ-Ⅵ板层c-Fos蛋白表达阳性的神经细胞数量。结果：持续静脉泵注瑞芬太尼5μg/kg/min和30μg/kg/min均可完全抑制第一阶段疼痛行为,推迟第二阶段的疼痛行为开始和中止,HR组尤为显著（P〈0.01）,但第二阶段总的累计舔爪时间三组差异无统计学意义。三组脊髓c-Fos蛋白表达阳性的神经细胞数量差异也无统计学意义。结论：短期应用瑞芬太尼不加重福尔马林致痛大鼠的痛觉过敏。

Objective： To observe the effects of shortly i.v.infusion of remifentanil on formalin-evoked pain behavior and c-Fos expression in the spinal cord in rats.Methods： Experiments were performed on male Sprague-Dawley rats,weighing 250～300g.18 rats were divided randomly into three groups（n=6 in each group）.To infuse remifentanil /saline continuously,indwelling venous catheters were implanted through the internal jugular vein under pentobarbital anesthesia（50～60mg/kg） three days before performing experiment.5% Formalin 50μl was subcutaneouosly injected into the plantar of the right hind paw.（1） group C（control group） was infused continuously 0.9% physiologic saline from the catheter from 5mins before formalin injection to 5mins after injection;（2） group LR（low dose of remifentanil） was infused remifentanil 5μg/kg/min according to the prior experiment;（3） group HR（high dose of remifentanil） was infused remifentanil 30μg/kg/min according to the prior experiment.The rate of infusion is 25μl/kg in all groups.Licking time during phase 1（minutes 0～5） and phase 2（minutes 15～90） were separately evaluated.Two hours after the formalin injection,the rats were deeply anesthetized with pentobarbital（100mg/kg,i.p.） followed immediately by intracardiac perfusion,the fourth and fifth segment of lumbar spinal cord was removed,postfixed,dehydrated and cut to the forty micron meter frozen sections.The sections were then immunostained for c-Fos protein by the avidin-biotin-peroxidase（ABC） method in order to count the total number of c-Fos-LI（Fos-like immunoreactivity） neurons in