Serotonin and oxytocin are important neuromodulators involved in human affect and sociality as well as depression and autism. Here the authors show that the amygdala is central in the regulation of serotonin by oxytocin. Oxytocin is known to inhibit amygdala activity and results in a decrease in anxiety. Conversely high amygdala activity and serotonin dysregulation have been associated with increased anxiety. The present study reveals a previously unidentified interaction between these two systems in the human brain, namely, the role of oxytocin in the inhibitory regulation of serotonin signaling, which could lead to novel therapeutic strategies for mental disorders such as social anxiety, depression and autism.

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Mottolese R, Redouté J, Costes N, Le Bars D, Sirigu A: Switching brain serotonin with oxytocin. Proc. Natl. Acad. Sci. USA [ Epub ahead of print May 27, 2014, doi: 10.1073/pnas.1319810111 ].
http://www.pnas.org/content/early/2014/05/21/1319810111.abstract