鞘内和侧脑室注射异氟烷对小鼠镇痛作用的比较

目的比较鞘内注射和侧脑室注射异氟烷对小鼠的镇痛作用,从整体水平探讨异氟烷的镇痛作用部位。方法用热板法、甲醛法观察、比较鞘内注射（it）和侧脑室注射（icv）异氟烷对小鼠热板法痛阈（HPPT）及抖足时间和抬足次数的影响。用免疫组化方法观察鞘内注射异氟烷对甲醛小鼠脊髓Fos蛋白表达的影响。结果热板实验中,与人工脑脊液组相比,it异氟烷0.02、0.04、0.08μl/g能够剂量依赖性地引起HPPT的增高（P〈0.01或P〈0.05）;icv以上剂量的异氟烷对HPPT均无明显影响（P〉0.05）。甲醛法实验中,it异氟烷0.01、0.02、0.04μl/g能剂量依赖性地减少抖足时间和抬足次数（P〈0.01或P〈0.05）;相同剂量的异氟烷icv对抖足时间和抬足次数均无明显影响（P〉0.05）。鞘内注射异氟烷可抑制甲醛小鼠脊髓Fos表达（P〈0.01）。结论在正常小鼠整体水平异氟烷镇痛部位主要在脊髓,脑可能不是主要镇痛部位。

The comparison of the analgesic effects of intrathecal and intracerebroventricular injection of isoflurane in mice

Objective To compare the anesthetic effects of intrathecal and intracerebroventricular injections of isoflurane in mice and investigate the sites where isoflurane exerts its effects of anesthesia.Methods Hot-plate test and formaldehyde test were used to compare the effects of intrathecal（i.t.） and intracerebroventricular（i.c.v） injections of isoflurane on the pain threshold in hot-plate test（HPPT）,paw shaking duration and times of paw lifting.Immunohistochemical method was used to observe the effect of intrathecal of isoflurane on the Fos expression in the spinal cord in mice under formaldehyde stimulation.Results In the hot-plate test,isoflurane at 0.02,0.04 and 0.08 μl/g（i.t.） significantly and dose-dependently increased the HPPI（the pain index in hot-plate test） in mice（P0.05 or P0.01）,while isoflurane at the same dosages had no marked effect（P0.05）.In the formaldehyde test,isoflurane at 0.01,0.02 and 0.04 μl/g（i.t.） significantly and dose-dependently decreased the paw-shaking duration and the times of paw-lifting in phase Ⅰ and phase Ⅱ（P0.01,P0.05）,while isoflurane of the same dosages had no evident effect under formaldehyde stimulation（P0.05）.Intrathecal injection of isoflurane could inhibit the Fos expression in the spinal cord in mice under formaldehyde stimulation.（P0.01）.Conclusion The primary mediator of analgesic effect produced by isoflurane might be situated in the spinal cord rather than the brain.