GDNF and depressive disorder: We have previously shown that an aqueous extract of Polygalae Radix, a component herb of KIT, suppresses depression-like behavior, abnormalities in accumbal dendritic spines and decreases in accumbal GDNF, but does not affect spatial memory impairment or reduced hippocampal cell survival and number of hippocampal new-born immature neurons, in CORT-treated mice.4