Distinct serotonergic systems regulate anxiety, depression, and impulsivity

[Speaker] Yu Ohmura:1
[Co-author] Kenji F Tanaka:2, Akihiro Yamanaka:3, Mitsuhiro Yoshioka:1
1:Department of Neuropharmacology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Japan, 2:Department of Neuropsychiatry, School of Medicine, Keio University, Japan, 3:Department of Neuroscience II, Research Institute of Environmental Medicine (RIEM), Nagoya University, Japan

Many studies have indicated that central serotonergic systems are involved in several emotional/cognitive functions including anxiety, depression, and impulse control. However, it remains unclear whether each function is regulated by distinct serotonergic systems. To address this issue, we examined the effects of selective manipulations of serotonergic activity in each brain region and of specific serotonin receptor on emotional/cognitive functions by using recently developed optogenetic tools and serotonin receptor knockout mouse. We used an elevated plus maze test, a forced swim test, and a 3-choice serial reaction time task to assess anxiety-, depressive-like behavior, and impulsive action, respectively. Our results demonstrated that serotonergic activity in the dorsal raphe nucleus has a pivotal role in depressive-like behavior and impulsive action, but not anxiety-like behavior while that in the median raphe nucleus is responsible for impulsive action and anxiety-like behavior, but not for depressive-like behavior. Furthermore, preliminary results indicated that region-specific activation of serotonergic terminals affected depressive-like behavior, but not impulsive action, and that 5-HT2C receptor knockout altered anxiety-like behavior, but not impulsive action. Thus it is likely that distinct serotonergic circuits regulate anxiety, depression, and impulsivity.
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