Long Term Changes of BDNF Expression of Hippocampus in Vascular Dementia Rats

Objective To observe the long-term dynamic changes of brain-derived neutrophic factor(BDNF) expression of hippocampus in vascular dementia(VD) rats and explore the primary role of BDNF in the VD onset and development.Methods VD rat models were established.Sixty rats were randomly divided into the sham-operated group(SO),7-day VD model group(7dM),15-day VD model group(15dM),1-month VD model group(1mM),2-month VD model group(2mM) and 4-month VD model group(4mM).There were 10 rats in each group.The expression of BDNF in hippocampus was detected by immnohistochemical staining and assaying.Results ①Compared with SO group,the BDNF expression in hippocampal CA1 area was increased in 7dM group but decreased in the other model groups;the arrangement of the BDNF-positive neurons was intensive and regular,the staining deepened and clear in 7dM group,but the arrangement of the BDNF-positive neurons were sparse and disorganized and the staining shallowed,some of the BDNF positive neurons were shrinked and smaller in the other model groups.②The number and the total area of BDNF positive neurons were more increased in 7dM group(P0.01) but more decreased in the other model groups(P0.01) than that in SO group.Compared with each other among the model groups,the number and the total area of BDNF positive neurons were gradually decreased from 7dM group to 4mM group and the differences were significant among the model groups each other(P0.05,P0.01)except for 2mM and 4mM group(P0.05).Conclusion The BDNF expression in hippocampus increased at early stage after cerebral ischemia/reperfusion but decreased at the later stage for a long time,which suggested that a neuroprotective role of BDNF on the hippocampal ischemic neurons was revealed at early stage but weakened at the later stage after cerebral ischemia/reperfusion.