HTR1A and major depressive disorder: For example, transient knockout or inhibition of 5-HT1A receptors during the early postnatal-adolescent period results in a persistent anxiety/depression phenotype that is not rescued by gene re-activation in adulthood (Gross et al., 2002; Lo Iacono and Gross, 2008; Donaldson et al., 2014; Garcia-Garcia et al., 2017b).