ABSTRACT
Major depressive disorder (MDD) is the most commonly diagnosed psychiatric disorder with a 12-month prevalence rate of 6.7% (Waraich et al., 2004). Now, MDD is one of the leading causes to the global health-related burden, and its prevalence was exacerbated even more by the ramifications of the COVID-19 pandemic and its impact on individuals' mobility and health across most cultures. The link between depression and serotonin suggests that reduced 5-HT signaling is a potential risk factor in the etiology of MDD (Ruhe et al., 2007). One of the classic neurotransmitters in the central nervous system, 5-HT plays an important role in the neural transduction that involves, for example, mood and cognition. Thus, it has been the pharmacological target for effective MDD medications. Young et al. (2014) found when 5-HT levels increase, socially desirable behaviors tend to increase as well. The serotonergic system in the brain involves 5HT and SERT. Previous studies have shown a reduced role capacity of SERT impacts one's vulnerability to anxiety and depression. In this protocol, social motivation was measured in mice through a pair of open and operant conditioning paradigms. Comparisons were made between 13 SERT+/+, 16 SERT+/-, and 8 SERT-/- mice siblings from Any-maze tracking data. Results support the conclusion that SERT-/- mice displayed reduced social functioning and showed more depressive-like symptoms and social memory deficits compared to their SERT+/+ and SERT +/- siblings. This suggests the observed differences in social behavior between SERT+/+, SERT+/-, and SERT-/- mice are directly associated with changes in the SERT gene expression. (PsycInfo Database Record (c) 2023 APA, all rights reserved)