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

Objective: To observe the changes of mRNA for GABA_A receptor α₂ and γ₂ subunit 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 CO₂ laser. CCI rats were killed at post- operative days 3（group PD3）,7（group PD7） and 14（group PD14）,each group has five rats.L_4～5 spinal cords of CCI rats and control rats were dissected out and changes of mRNA for GABA_A receptor α₂ andγ₂ subunit were measured by RT-PCR. Results: Mechanical allodynia and hyperalgsia were observed on the ligatedside of group PD3 post-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_A receptorα₂ andγ₂subunit was significantly decreased as compared withcontrol, and decreased more in group PD14. Conclusion: mRNA for GABA_A receptorα₂ andγ₂subunit is down-regulated in rat CCImodel. Its exact role on the pathogenesis of neuropathic pain deservesto be studied furthermore.