Objective:To explore the dynamic process of the expression of brain-derived neurotrophic factor(BDNF)in hippocampus cells after convulsion through in vitro and in vivo experiments. Methods:Seizures with duration of 30 minutes(30min SC) were induced in infant and adult Wistar rats(IRs&ARs) respectively. The rats were sacrificed at 6 different time points after SC termination.Dynamic change of BDNF level in happocampal cells was investigated by immunocytochemistry and ELISA. Primary hippocampal neurons cultured for 9 days were exposed to magnesium-free extracellular solution media for 3h to establish seizure-like discharge model. BDNF protein expressed in cultured hippocampal neurons was detected by immunocytochemistry. Results:(1)The cells expression of BDNF increased in CA1-CA4 and dentate of hippocampus after SC

and the most positive immunoreactivity was in dentate. The expression of BDNF was remarkably up-regulated at 3h(from 6.65±1.60 pg/μg to 11.22±2.44pg/μg) after SC in IRs group (P<0.05)

and at 1d (from5.91±1.63pg/μg to13.37±5.61pg/μg) after SC in ARs group(P<0.05). This increases lasted for at least 7d in both IRs and ARs group

with peak levels at 1d and 3d respectively. The levels of BDNF in IRs group was still remarkably up-regulated at 3d after SC(P<0.05)

but remarkably lower than that in ARs group(P<0.05).(2)Compared with the control group

the expression of BDNF protein in cultured neurons was remarkably up-regulated in seizure-like discharge model group(P<0.05) at 24h after discharge. Conclusions:Convulsion could up-regulate expression of BDNF both in animal model of SC and in seizure-like discharge model of cultured hippocampal neurons. This could be the internal protected response of hippocampal neurons to inhibit brain damage induced by Convulsion. There are differences in speed and degree of the expression of BDNF after convulsion between IRs and ARs

which indicate that there could be an internal protective response in premature brain after SC.