Min Sam-Hong, Soh Jung-Sub, Park Ji-Yong, Choi Sung-Uk, Lee Hye-Won, Lee Jae-Jin, Kim Jae-Hwan
Department of Anesthesiology and Pain Medicine, Korea University College of Medicine, Seoul, Korea.
Yonsei Med J. 2014 Nov;55(6):1631-9. doi: 10.3349/ymj.2014.55.6.1631.
The aim of this study was to investigate the effect of epidural dexamethasone on analgesia and cytosolic phospholipase A₂ (cPLA₂) expression in the spinal cord in a rat formalin test.
Epidural dexamethasone injection was performed to Sprague-Dawley rats with a 25 gauge needle under fluoroscopy. Following the epidural injection, a formalin induced pain behavior test was performed. Next, the spinal cords corresponding to L4 dorsal root ganglion was extracted to observe the cPLA₂ expression.
There were no differences in pain response during phase I among the groups. The phase II pain response in 300 μg of epidural dexamethasone group decreased as compared to control, 30 μg of epidural dexamethasone, 100 μg of epidural dexamethasone, and 300 μg of systemic dexamethasone groups. The expression of cPLA₂ decreased in Rexed laminae I-II in 300 μg of the epidural dexamethasone group compared with the ones in the control group.
Taken together, these results suggest that 300 μg of epidural dexamethasone has an attenuating effect on the peripheral inflammatory tissue injury induced hyperalgesia and this effect is mediated through the inhibition of intraspinal cPLA₂ expression and the primary site of action is the laminae I-II of the spinal cord.
本研究旨在探讨硬膜外注射地塞米松对大鼠福尔马林试验中脊髓镇痛及胞质型磷脂酶A₂（cPLA₂）表达的影响。
在透视引导下，用25号针头对Sprague-Dawley大鼠进行硬膜外地塞米松注射。硬膜外注射后，进行福尔马林诱导的疼痛行为试验。接下来，提取与L4背根神经节对应的脊髓，观察cPLA₂表达。
各实验组在福尔马林注射后第1期（0-5分钟）的疼痛行为无明显差异。与对照组、30μg硬膜外地塞米松组、100μg硬膜外地塞米松组及300μg全身地塞米松组相比，300μg硬膜外地塞米松组在福尔马林注射后第2期（15-60分钟）疼痛反应减轻。与对照组相比，300μg硬膜外地塞米松组脊髓Rexed I-II层cPLA₂表达降低。
综上所述，这些结果表明300μg硬膜外地塞米松可减轻外周炎症组织损伤诱导的痛觉过敏，其作用机制可能是通过抑制脊髓内cPLA₂的表达，作用部位可能位于脊髓I-II层。
