丙帕他莫对福尔马林致痛大鼠行为学及脊髓c-fos蛋白表达的影响

目的通过观察比较福尔马林致痛大鼠行为学和脊髓背角c-Fos样免疫反应神经元（FLIN）数量的变化,探讨静脉注射丙帕他莫的镇痛效能与机制。方法雄性SD大鼠30只,随机均分为5组,生理盐水组（NS组）、福尔马林组（F组）、丙帕他莫组（B组）、丙帕他莫预处理组（BF组）和福尔马林丙帕他莫组（FB组）。前4组中NS组和B组在注射NS、丙帕他莫10 min后分别于右后足趾皮下注射NS 100μl,F组和BF组分别在注射NS、丙帕他莫10 min后均注射5%福尔马林100μl。FB组给予福尔马林痛刺激10 min后静脉注射丙帕他莫480 mg/kg。各组行清醒静脉穿刺,注入NS或不同剂量的丙帕他莫后,观察行为表现,注射后立即以5 min为一时间段连续记录1 h内的缩腿、舔咬时间。足底注射后2 h取一脊髓节段做c-Fos免疫组化染色,计算FLIN数量。结果①BF组第一期急性早反应时间短于F组（P〈0.0 5）;FB组第二期时间短于F组（P〈0.05）。Fos蛋白表达NS组和B组未见或偶见淡染FLIN。F组见大量FLIN主要分布在Ⅰ、Ⅱ层及Ⅴ、Ⅵ层。BF组各区FLIN均减少（P〈0.01）。FB组各区FLIN均少于F组相应区域（P〈0.01）。结论静脉注射丙帕他莫能有效抑制大鼠的伤害性行为和致痛侧脊髓背角c-fos蛋白的表达。

Effect of intravenous propacetamol on behavior and c-fos protein expression in rat with formalin hurting

Objective To investigate the antinociceptive effect of intravenous propacetamol on behavior and expression of c-fos protein in the spinal cord in rat model of formalin hurting. Methods Thirty healthy male adult SD rats were randomized into 5 groups. In the normal saline control group （group NS）, 100μl of normal saline was injected intravenously,which was followed by a subcu taneous administration of 100μl of normal saline into the hind plantar skin of rats 10 min later. In the formalin control group（group F）, 20 μl of normal saline was injected intravenously, and followed by intraplantar administration of 100 μl of 5 % formalin respectively, and followed by rat intra-plantar administration of 100μl of 5 % formalin. The graded pain behavior was observed per 5 min during one hour immediately after the intra-plantar injection. At the 2-hour time point, and then, the spinal cord was removed for analysis of c-fos protein like immunoreactive neurons（FLIN）at the dorsal horn in the L4-L6 segments. Results Almost no pain response was observed in group NS,The typical biphasic pain response was observed in the formalin group. Aeutal reaction time in group BF were shorter than that in group F. Tardy time of group FB were shorter than that in group F. c-fos protein expression in group NS and B were not visible,a plenty of FLIN were mainly distributed in layer Ⅰ Ⅱ Ⅴ Ⅵ in group F. FLIN in group BF were reduced in every layer,FLIN in group FB were fewer than that in group F. Conclusion Intravenous propacetamol can successfully inhibit nociceptive behavior and c-fos expression in spinal dorsal horn of formalin test rats, which is the pain relief mechanism of propacetamol.