The 5-HT1A heteroreceptor as well as the 5-HT1A autoreceptor expressed on raphe serotonergic neurons plays significant roles in the stress responses and anxiety- and depression-like behaviors, as demonstrated in various genetic 5-HT1A receptor models (e.g., knockout, suppression, or overexpression of auto- and hetero-receptors) (Albert et al., 2014). This evidence concerns the gene HTR1A and depressive disorder.