Objective:To observe the effects of paeoniflorin(PF) on bilirubin-induced apoptosis and NF-кB of hippocampal neurons.Methods:Primary cultures of hippocampal neurons from the 17-19 days old embryo rats were used for the study.On the 7th day of incubation

the neurons in the experimental group were treated with bilirubin(10 μg/ml) for 24 h after the pretreatment with PF(1

2.5

and 5 μg/ml).MTT assay was used to detect the effect of paeoniflorin on neuronal activity and then to select the proper dose of PF

and Annexin V-FITC/PI double staining was used to inspect the impact of PF(2.5 μg/ml)on the morphology of neuronal apoptosis and apoptosis rate;and immunocytochemistry was used to detect the expression of NF-кB protein in hippocampal neurons at different time points(3

6

12

and 24 h) after bilirubin treatment.Results:Compared with bilirubin group

pretreatment with PF(2.5 μg/ml) could decrease the neuronal apoptosis rate to(17.11±2.64)%(P<0.05).Moreover

bilirubin induced a significant activity of NF-кB in hippocampal neurons(P<0.05)

especially when acting for 3-6 h(P<0.05);meanwhile

PF(2.5 μg/ml) significantly suppressed NF-кB activity induced by bilirubin stimulating for 3-6 h(P<0.05).Conclusion:PF(2.5 μg/ml) preconditioning for 24 h can inhibit bilirubin-induced apoptosis of hippocampal neurons

which might be associated with its suppression on NF-кB activity at early phase(3-6 h) after bilirubin stimulation.