Abstract： Objective To evaluate the change in α2-adrenergic receptors (α2-Ars) gene expression after high-level iniury of the spinal cord (SCI),aiming as developing a more effective perioperative anesthetic management for high-level SCI patients.Methods Adult male Wistar rats were anesihetized and severe spinal crush injury at T4 was produced using modified Aliens device.The expression of α2-Ars mRNA at different levels of spinal cord in normal control rats (C),injured segment (Ⅰ),above (A) and below (B) the site of injured segment,were measured by reverse transcription-polymerase chain reaction (RT-PCR) 1 day,3 days,1 week,2 weeks,3 weeks and 4 weeks,respectively after SCI.Results Compared with group C(sham group),in group A the expression of α2-Ars mRNA decreased 1 day after SCI (P＜ 0.05) and dropped to the nadir 2 weeks later (P＜0.01),but the expression was restored to the normal level 4 weeks later.In group Ⅰ the lowering of α2-Ars mRNA expression occurred immediately after SCI and down to the lowest value 1 week later (P＜0.01),and did not recover to normal level 4 weeks later (P＜0.05).In group B downregulation of α2-Ars mRNA expression was detected 1 day after SCI (P＜0.05),but it was upregulated 1 week later reaching the normal level,which was maintained for 4 weeks.Conclusion In a chronic SCI rat model,α2-Ars gene expression is downregulated in the injured segment,but returns to the normal level above and below the injured segment. The changes in α2-Ars may he a pivotal factor contributing to a series of abnormal responses after high-level SCI.