Objective To evaluate the efficacy of intrathecally administered monosialoganglioside (GM-1)for treatment of bupivacaine spinal anesthesia-induced neurotoxicity to rat spinal cord.Methods Adult male Sprague-Dawley rats,weighing 280-300 g,in which the intrathecal catheter was successfully inserted into the L3,4 intervertebral space and advanced toward the tail,were randomly divided into 4 groups (n =36 each):sham operation group (group S),GM-1 group,bupivacaine group (group B) and bupivacaine + GM-1 group (group BG).In B and BG groups,the rats received 5％ bupivacaine 20 μl via the intrathecal catheter 3 times at 1.5-hour intervals.GM-1 20 μg was injected intrathecally 24 h later once a day for 7 days in BG and GM-1 groups.Before bupivacaine injection and on days 1,3,5,7,14 and 28 after bupivacaine injection (T0-T6),tail flick latency (TFL) was measured,MPE (percentage of maximal possible effect) was calculated,and the locomotor recovery was evaluated using the Basso,Beattie,Bresnahan (BBB) Locomotor Rating Scale.Then six rats were randomly chosen and sacrificed in each group.Spinal cord was removed for histopathologic examination (with light and electronic microscope) and for determination of caspase-3 protein and mRNA expression (by immuno-histochemistry and RTPCR).The pathological changes of the spinal cord were scored.Results Compared with S and GM-1 groups,MPE,pathological scores,and caspase-3 protein and mRNA expression were significantly increased and BBB score was decreased at T1-6 in group B (P ＜ 0.05),and MPE was increased at T1-5 (P ＜ 0.05) and returned to the baseline value at T6 (P ＞ 0.05) and pathological scores,and caspase-3 protein and mRNA expression were significantly increased and BBB score was decreased at T1-6 in group BG (P ＜ 0.05).There were no significant differences in each parameter at each time point between S and GM-1 groups (P ＞ 0.05).Compared with group B,MPE and caspase-3 protein and mRNA expression were significantly decreased at T2-6,pathological scores were decreased at T3-6,and BBB score was increased at T4-6 in group BG (P ＜ 0.05).The pathological changes of spinal cord tissues were obvious at T1-6 in group B and at T1-3 in group BG,but the changes gradually recovered at T4-6 in group BG.Conclusion Intrathecally administered GM-1 has therapeutic effect against bupivacaine spinal anesthesia-induced neurotoxicity to rat spinal cord,and inhibition of neuronal apoptosis in the spinal cord may be involved in the underlying mechanism.