HCRT and depressive disorder: Increased depression- and anxiety-like behaviors were correlated with the attenuation of orexin fibers and a decrease in the number of serotonin neurons in the DRN of Nile grass rats, along with a lower density of serotonin fibers/terminals in the anterior cingulate cortex (Deats et al., 2014; Leach et al., 2013a).