Objective To investigate the expressions of neurite outgrowth inhibitor (Nogo),myelin-associated glycoprotein (MAG) and Nogo receptor-1 (NgR1),and neuro-protective effect of N-Butylphthalide (NBP) in rat brain tissues following acute CO poisoning.Methods Sixty Sprague-Dawley rats were randomly divided into normal group,CO poisoning group and NBP treatment group (n=20).Rats in CO poisoning group and NBP treatment group were induced acute CO poisoning in hyperbaric chamber and received hyperbaric oxygen therapy.Meanwhile,rats in the NBP treatment group were subjected to oral NBP 6 mg/100 g twice a day additionally.The expressions ofNogo,MAG and NgR1 were investigated in rat brain tissues by immunohistochemistry and double immunofluorescence staining 1 day,3 days,1 week and 4 weeks after CO exposure.Results With the prolongation of CO poisoning,the levels ofNogo,MAG and NgR1 in brain tissues of the CO poisoning group were gradually increased,and their expressions could still be detected at 4 weeks after CO poisoning.NBP treatment group had significantly reduced Nogo and NgR1 protein levels,and statistical differences were noted as compared with those in the CO poisoning group at each time point (P＜0.05).The level of MAG in NBP treatment group was slightly lower than that in CO poisoning group without statistical difference (P＞ 0.05).Conclusions The levels ofNogo,MAG and NGR1 proteins may be associated with brain injury and demyelination induced by CO poisoning.NBP can downregulate the levels of Nogo and NgR1 proteins (but not MAG),and may play a neuro-protective role in brain damage after acute CO poisoning.