ラット椎間板ヘルニアモデルに対する各種NSAIDsの鎮痛効果―c-Fosによる検討

Effect of NSAIDs on c-fos Expression in the Spinal Cord in Experimental Disk Herniation : Immunohistochemical Investigation

　抄録：〔目的〕脊髄後角に発現するc-fosを痛覚受容の指標として用い，ラット椎間板ヘルニアモデルに対する各種NSAIDsの鎮痛効果を検討した．

　〔対象〕Wistar系雌ラット60匹を用いた．

　〔方法〕ラットを全身麻酔後，L4/5椎間板の髄核を脱出させた椎間板ヘルニアモデルを作成した．モデルにloxoprofen-Na，diclofenac-Na，indometacin，etodolacを経口投与した．対照として生理食塩水を用いた（各群n＝5）．術後2時間と24時間で灌流固定後，第5腰髄のc-Fos陽性細胞を染色した．c-Fos陽性細胞数を層別に計測し，分散分析を用いて検定を行った．

　〔結果〕手術2時間後：c-Fos陽性細胞数は，対照群とNSAIDsを投与した群の間に有意差を認めなかった．手術24時間後：loxoprofen-Naを投与した群でのみ，対照群と比較して有意にc-Fos陽性細胞の発現が抑制された（p＜0.05）．

　〔結語〕c-Fos陽性細胞数は，手術2時間後では薬剤による差はなかったが，24時間後では，薬剤による差が認められた．

　Objective：The analgesic effect of the various NSAIDs in a rat lumbar disc herniation model was assessed on the basis of c-fos expression in the dorsal horn of the spinal cord.

　Methods：Under anesthesia a model of herniation of the nucleus of the L4/5 vertebral disc was created in adult female Wistarrats. Loxoprofen-Na, diclofenac-Na, indometacin, etodolac, and saline（control）were orally administered to the rats（n＝5 per group）, and the numbers of c-Fos-positive cells in dorsal horn of the 5^thlumbar spinal cord were counted 2 hours and 24 hours postoperatively. The lamine of the 5^thlumbar spinal cord were classified into three groups：laminae Ⅰ-Ⅱ, laminae Ⅲ-Ⅳ, and laminae Ⅴ-Ⅵ, and the differences between the numbers of c-Fos-positive cells in the three groups were statistically analyzed by analysis of variance（ANOVA）followed by pairwise post hoc comparisons（Tukey test）

　Results：At two hours after the operation there were no statistical differences between any of the groups. At 24 hours after the operation the number of c-Fos-positive cells in laminae Ⅰ-Ⅱwas lower in the group given loxoprofen-Na, than in the control group（p＜0.05）.

　Conclusion：The analgesic effect of the various NSAIDs in a rat model of lumbar disc herniation was assessed by c-fos immunochemistry, and a statistical difference was found among the NSAIDs.