Behaviorally, we examined the rats’ performance of the FST to index the helplessness component of depressive behavior, and neurochemically, we examined the tissue concentrations of 5-HT and its metabolite 5-HIAA in three areas highly related to depression, i.e., the hippocampus, prefrontal cortex, and amygdala, so as to explore the possible involvement of the postsynaptic 5-HT1A receptors. Here, HTR1A is linked to major depressive disorder.