鞘内注射氯胺酮对镜像痛大鼠热痛敏的影响及可能机制

EFFECT OF INTRATHECAL KETAMINE ON THE THERMAL HYPERALGESIA IN A RAT MODEL OF MIRROR IMAGE PAIN

目的:探讨氯胺酮鞘内注射对镜像痛大鼠热痛敏的影响及可能机制。方法:30只雄性SD大鼠建立大鼠坐骨神经镜像痛模型,随机分为3组(n=10):Ⅰ组鞘内注射生理盐水,Ⅱ组鞘内注射氯胺酮25μg,Ⅲ组鞘内注射氯胺酮50μg,分别测定鞘内给药前(T1)、给药后2h(T2)、4h(T3)、6h(T4)的大鼠热缩足反射潜伏期(TWL)、运动功能。每组大鼠在给药6h后处死,取出腰段脊髓背角,石蜡切片,采用免疫组化检测单核细胞趋化蛋白-1(MCP-1)的表达。结果:鞘内给药后,Ⅱ组、Ⅲ组在各时间点与Ⅰ组及给药前相比,两侧TWL明显延长,比较有显著差异(P<0.01)。Ⅰ组MCP-1平均积分光密度值(IOD)表达明显高于Ⅱ组和Ⅲ组(P<0.01),鞘内注射氯胺酮后大鼠运动功能不受明显影响。结论:鞘内注射氯胺酮可抑制镜像痛大鼠的热痛觉过敏,该作用可能与抑制脊髓背角的MCP-1表达有关。

Objective ： To investigate the effect of intrathecal ketamine on the thermal hyperalgesia in a rat model of mirror image pain and the underlying mechanisms. Methods： Thirty male Sprague-Dawely rats weighting 200 - 250 g were randomly divided into three groups （ n = 10 ） ： group Ⅰ , mirror image pain model ＋0.9% saline; group Ⅱ ,mirror image pain model ＋ ketamine 25μg; group m ,mirror image pain model ＋ ketamine 50 μg. Thermal hyperalgesia threshold were measured with paw thermal withdrawal latency, before intrathecal injection （ T1 ）, and after intrathecal ketamine 2 h （ T2 ）, 4 h （ T3 ）, 6h （T4 ） respectively. After 6h the rats were killed and the segment （ L5 -6 ） of Lumbar spinal cord dorsal horn of rat was taken out, then paraffinum section was made, the expression of MCP-1 was detected by the immunohistochemical technique. Results： The rats have shown mirror image pain, the thermal hyperalgesia threshold is parallel on the bilateral lower limbs of rats. The TWL of the group Ⅲ and group Ⅱafter administration were extended comparing with group Ⅰ , and the average integrated optical density values（IOD） of MCP-1 were significantly lowerer （P 〈 0.01 ）. Rats of intrathecal ketamine have no hypokinesia. Conclusion： Intrathecal injection of ketamine can reduce thermal hyperalgesia on mirror image pain of rats, and the underlying mechainism was correlated with the decreasing expression of MCP-1 in the spinal cord dorsal horn .