HTR5A and major depressive disorder: A large number of studies have confirmed that the decreased release of the monoamine neurotransmitter serotonin 5-HT in the brain may be one of the causes of clinical depressive symptoms (Gavioli and Calo, 2013), and DRN is the nucleus with the largest distribution of 5-HT neurons and is closely related to stress-related mental disorders such as anxiety and depression (Vasudeva et al., 2011).