Abstract: Objective To investigate the effects of ketamine on spinal cord ischemia-reperfusion injury (SCII) and ERK1/2 signaling pathway in rats. Methods The rats were randomly divided into sham operation group (S group), SCII group (model was established by Zivin method), low and high-dose ketamine groups (given 50 and 100 mg/kg ketamine respectively every day for 14 days),with 8 rats in each group. The hind limb movement of rats was evaluated, inflammatory factors and oxidative stress indexes of spinal cord tissue were detected. The spinal cord neurons were microscopied by Nissl staining, apoptosis rate was detected by TUNEL assay, and protein expression was detected by Western blot. Results Compared with the S group, the Tarlov score in SCII group decreased after surgery and increased gradually with time,the number of normal nerve cells in the spinal cord decreased and the apoptosis rate increased,the levels of IL-1β, TNF-α, IL-6, VCAM-1 and malonaldehyde (MDA), myeloperoxidase (MPO) was found to be increased (P＜0.05), superoxide dismutase (SOD) and glutathione peroxidase (GPX) were significantly decreased (P＜0.05), the expression of p-ERK1/2 and the ratio of p-ERK/ERK1/2 increased(P＜0.05);Compared with SCII group, The changes of above indexes in ketamine group was reduced (P＜0.05), and was more obvious in the low dose group. Conclusions Low dose ketamine can reduce the degree of SCII, and ERK1/2 signaling pathway may be involved in this process.

Key words: ketamine, spinal cord ischemia reperfusion-injury, signaling pathways, ERK1/2