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Objective To investigate the regulation mechanism of dendrobium nobile polysaccharides (DNP) for nuclear factor kappa B (NF-κB) signal pathway in focal cerebral ischemia/reperfusion rats.Methods According to the digital random method,90 SD rats were divided into 6 groups:sham operation,model,DNP low-dose (DL,50 mg/kg),moderate-dose (DM,100 mg/kg) and high-dose (DH,200 mg/kg),and nimodipine (10 mg/kg) groups (n =15 in each group),and according to the random number method,selecting 5 in each group for the corresponding index detection.A focal cerebral ischemia/reperfusion model in SD rats was induced by middle cerebral artery occlusion.The improvement effect of DNP on rat neurological deficit (Bederson behavioral score) and brain water content,and infarct volume were observed.Enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of proinflammatory cytokine tumor necrosis factor-α (TNF-α) and interleukin-β (IL-1 β) in brain tissue.Real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) was used to detect microglial cell marker BCL-2-related protein A1 α (A1) and astrocyte marker glial fibrillary acidic protein (GFAP) mRNA transcription levels.Western blot was used to detect the NF-κB signaling pathway phosphorylated IκBα protein and nuclear p65 protein expression levels.Single factor variance analysis was used to compare the measurement data among the groups.Results (1) There were significant differences in the neurological deficit score,brain water content,cerebral infarction volume,brain tissue TNF-α and IL-1β levels,A 1 and GFAP mRNA transcription levels and phosphorylated IκBα protein and nuclear p65 protein levels among the 6 groups (F =22.24,8.699,33.89,19.26,27.53,109.5,15.28,66.86,and 41.63,respectively (all P ＜ 0.01).(2) The neurological deficit score,cerebral water content,and cerebral infarction volume in the model group were 2.8 ± 0.3,86.1 ±3.8％,and 31.0 ±4.5％,respectively.The TNF-α and IL-1β levels,A1 and GFAP m RNA transcription levels in brain tissue,and phosphorylated IκBα protein and nuclear p65 protein levels were increased significantly compared with those in the sham operation group.There were significant differences (all P ＜0.01).(3)The above indices in the DH group were 1.5 ± 0.5,72.9 ±5.4％,and 17.5 ±4.1％,respectively.Compared with the model group (including TNF-α and IL-1 β levels,A1 and GFAP mRNA transcription levels and phosphorylation of IκBα protein and nuclear p65 protein levels in brain tissue).There were significant differences (all P ＜ 0.05).Compared with the nimodipine group,there were no significant differences (all P ＞ 0.05).Compared with the sham operation group,except for there were no significant difference in brain water content,phosphorylated IκBα protein and nuclear p65 protein (P ＞0.05),there were significant differences in other indices (all P ＜ 0.05).(4) Compared with the model group,only IL-1 β and phosphorylated IκBα protein levels were decreased significantly in the DM group,there were no significant differences in other indices (all P ＞ 0.05).Compared with the sham operation group,there were significant differences in other indices (all P ＜ 0.05).(5) Compared with the model group,there were no significant differences in other indices in the DL group (P ＞ 0.05).Compared with the sham operation group,there were significant differences in all indices (all P ＜ 0.05).Conclusion Highdose DNP may reduce focal cerebral ischemia/reperfusion injury in rats.The mechanism of may be associated with the inhibition of activation of early NF-κB signaling pathway.The effects of low-and moderate-dose DNP on reducing inflammatory brain damage of focal cerebral ischemia/reperfusion may be not obvious.