摘要
目的 观察慢性坐骨神经收缩损伤 (CCI)大鼠触摸刺激后机械痛阈和热痛阈的变化 ,以研究吗啡 (2mg/kg)腹腔注射后对非伤害性刺激后脊髓后角c fos表达的影响 ,探讨脊髓痛觉调控机制。方法 选择雌性SD大鼠 30只 ,随机分为假手术组、CCI组和吗啡组 ,分别于术前 2d、术后 4、7、14d给予机械痛阈和热痛阈测试。大鼠处死前 3h给于非伤害性触摸刺激 ,处死后取脊髓切片 ,免疫组织化学方法检测c fos表达。结果 CCI组和吗啡组大鼠坐骨神经结扎 4d后均呈现不同程度的痛觉过敏 ,以术后 14d为甚 ,触摸刺激导致的脊髓c fos的表达明显增加 ,主要集中分布于脊髓背角表层Ⅰ～Ⅱ层的中间内侧部 ,Ⅴ～Ⅹ层也有一定程度增多。 2mg/kg腹腔注射不能有效的阻断慢性缩神经损伤大鼠痛觉过敏。吗啡组与CCI组相比c fos的表达无明显减少 ,两组相比差异无显著性意义 (P >0 0 5 )。结论 2mg/kg吗啡腹腔注射不能有效抑制非伤害性刺激诱发痛觉过敏以及脊髓背角c fos的表达 ,可能与吗啡用药途径和用量过小有关 。
Objective To explore the mechanisms of the hyperalgesia in the spinal cord and the effect of the morphine on the c-fos expression in spinal dorsal horn by investigating the changes of pain threshold elicited by touch-stimulus after the chronic constriction injury(CCI)of the sciatic nerve in rat.Methods Thirty female Sprague-Dawley rats were randomly divided into sham-operation group,CCI group and morphine group.Mechanic pain threshold and thermal pain threshold were assessed on the second day before operation and on the 4,7,14 th postoperative day in three groups.The rats were given innoxious touch-stimulus for 3 hours before killed.The spinal cord was obtained after death.Immunohistochemistry was employed to investigate the expression of the c-fos.Results The hyperalgesia appeared on the 4 th day after CCI-operation of the sciatic nerve and reached its maximal level on the 14 th day after CCI operation,the expression of c-fos elicited by touch-stimulus increased significantly and it mainly distributed at middle of superficial layer in laminal Ⅰ-Ⅱ in spinal dorsal horn in CCI group by touch-stimulus.There was an increase in laminal Ⅴ-Ⅹ.The hyperalgesia was not attenuated after 2 mg/kg morphine injected intraperitoneally after chronic constriction injury of the sciatic nerve in rats.The expression of c-fos did not significantly decrease in morphine group(P<0.05)and there had no significant difference in c-fos expression between the CCI and morphine group.Conclusion Hyperalgesia and the expression of the c-fos were not inhibited effectively following 2 mg/kg morphine injected intraperitoneally after chronic constriction injury of sciatic nerve in rats.The results may be related to the administration pathway and the doses of morphine used in this study was too low to disrupt the hyperalgesia,or mechanism may relate to excitability elevation of the secondary sensory neurons in the spinal dorsal horn.
出处
《临床麻醉学杂志》
CAS
CSCD
2004年第5期286-289,共4页
Journal of Clinical Anesthesiology
基金
湖北省自然科学基金资助 (编号 :2 0 0 2AA3 0 1D0 9)
