CLOCK and major depressive disorder: Diurnal profiles of clock genes—alterations of which have been previously reported in both depressed patients and animal models of the disease (Li et al. 2013; Savalli et al. 2014)—and neurotrophic and growth factors implicated in the neurobiological alterations of depression were analyzed in Cry2−/− and Cry2+/+ mice by qRT-PCR.