神经慢性挤压伤疼痛模型大鼠脊髓GABA_A受体mRNA表达的变化

Changes of mRNA for GABA_A receptor in spinal cord of rat in chronic constriction injury pain model

目的 :了解大鼠坐骨神经慢性挤压伤 (chronicconstrictioninjury ,CCI)模型脊髓GABAA受体α2 、γ2 亚型mRNA表达的变化。方法 :SD大鼠 2 0只 ,5只为正常对照 ,15只做成CCI模型。用VonFrey细丝和CO2 激光测定大鼠足爪的疼痛阈值变化 ,并于术后 3d、7d和 14d处死 (n =5每组 ) ,取L4～ 5脊髓用RT PCR方法测定不同时点大鼠脊髓GABAA受体α2 、γ2 亚型mRNA的表达量。结果 :CCI大鼠结扎侧在术后 3d即开始出现机械感觉异常和痛觉过敏 ,7d、14d组逐渐加重 (P <0 0 5 )。与正常大鼠比较 ,CCI大鼠GABAA受体α2 、γ2 亚单位mRNA表达量于术后 7d开始出现下降 (P <0 0 5 ) ,且术后 14d组进一步降低 (P <0 0 1)。结论 :CCI大鼠疼痛模型中脊髓GABAA受体α2 、γ2 亚单位的表达量明显下降 ,其在慢性神经性疼痛中发病机制中的确切作用尚待进一步研究。

Objective:To observe the changes of mRNA for GABA Areceptorα 2andγ 2subunit in spinal cord of rat in chronic constrction injury(CCI)pain model. Methods:Five of twenty SD rats were selected as control and CCI was performed on theright sciatic nerves of other fifteen ones . The tests for mechanical allodynia and hyperalgsia of the plantar surface of both hind paws were done by Von Frey filaments and CO 2laser. CCI rats were killed at post- operative days 3(group PD3),7(group PD7) and 14(group PD14),each group has five rats.L 4～5spinal cords of CCI rats and control rats were dissected out and changes of mRNA for GABA Areceptorα 2andγ 2 subunit were measured by RT-PCR .Results:Mechanical allodynia and hyperalgsia were observed on the ligatedside of group PD3post-operatively as compared with unligatedside.Mechanical allodynia and hyperalgsia on the ligatedside of group PD7 and group PD14were aggravatedas comparedwith group PD3. The mRNAexpression of group PD7 for GABA Areceptorα 2andγ 2subunit was significantly decreased as compared withcontrol, and decreased more in group PD14. Conclusion: mRNA for GABA Areceptorα 2andγ 2subunit is down-regulated in rat CCImodel. Its exact role on the pathogenesis of neuropathic pain deservesto be studied furthermore.