Object To investigate the effect of neonatal BDE-209 exposure on the expression levels of the core SNAREs(Synaptobrevin 2/VAMP 2,SNAP-25,Syntaxin 1A/Stx 1A)and Synaptophysin/Syp in hippocampus of adolescent rats.Methods 80 neonatal SD rats from 10 litters were randomly divided into 4 groups,that is,the vehicle(peanut oil)control group,1,10 and 20 mg/kg body weight BDE-209 treatment groups.The treatment was conducted by oral gavage from PND 5 to PND 10.During the adolescence period(approximately PND 70),the Morris water maze was used to evaluate the learning and memory abilities,the eight-arm radial maze was used to determine work and reference memory,transmission electron microscope was used to observe the ultrastructure of hippocampal neuron,QRT-PCR and western blot method were used to detect the expression levels of core SNAREs and Synaptophysin.Results Compared with the vehicle control group,BDE-209 treatment groups showed significant longer latencies to located the escape platform during the same training period and less number of times crossing the original platform(P<0.05).Rate of work memory errors and reference memory errors were both significantly increase in 10 and 20 mg/kg body weight BDE-209 treatment groups(P<0.05).The ultrastructure of hippocampal neurons were altered in BDE-209 treatment groups.The expression of Synaptobrevin was significant down-regulated in 20mg/kg body weight BDE-209 treatment group,the expression of SNAP-25 was significant down-regulated in 10 and 20mg/kg body weight BDE-209 treatment groups(P<0.05),the expression of Syntaxin and Synaptophysin were significant down-regulated in all three dose BDE-209 treatment groups(P<0.05).Conclusion Neonatal BDE-209 exposure can induce deficits in learning and memory and alterations in the ultrastructure of hippocampal neurons during the adolescence period,the mechanism underlying the impairments of learning and memory abilities and the ultrastructure of hippocampal may be the down-regulation of the core SNAREs and Synaptophysin in hippocampus.