We also found that various sub regions of hippocampus showed
different vulnerability to the substances either AF64A or the plant
extract. The difference in this vulnerability might be associatedwith the difference in distribution of various types of neuronal
system such as cholinergic neurons, granule cells, the different
distribution of various factors contributing important roles on the
survival of neurons and cholinergic neurons including the ability to
form free radicals, the distribution of antioxidant system, the distribution
of calcium binding proteins and the difference in the trophic
factor particularly nerve growth factor (NGF) and brain derived
growth factor (BDNF) distribution. However, the precise underlying
mechanisms still required further investigation.