New research reported in the journal Nature Neuroscience says that oxytocin, a hormone that promotes feelings of love, social bonding and well-being, can cause emotional pain – an entirely new, darker identity for the hormone.

The study is the first to link oxytocin to social stress and its ability to increase anxiety and fear in response to future stress.

Oxytocin appears to be the reason stressful social situations, perhaps being bullied at school or tormented by a boss, reverberate long past the event and can trigger fear and anxiety in the future. That’s because the hormone actually strengthens social memory in one specific region of the brain.

Prof Jelena Radulovic from the Northwestern University’s Feinberg School of Medicine and her colleagues discovered that oxytocin strengthens negative social memory and future anxiety by triggering an important signaling molecule called extracellular signal regulated kinase (ERK) that becomes activated for 6 hours after a negative social experience.

“ERK causes enhanced fear by stimulating the brain’s fear pathways, many of which pass through the lateral septum. The region is involved in emotional and stress responses,” Prof Radulovic explained.

“By understanding the oxytocin system’s dual role in triggering or reducing anxiety, depending on the social context, we can optimize oxytocin treatments that improve well-being instead of triggering negative reactions.”

The study, which was done in mice, is also relevant because oxytocin currently is being tested as an anti-anxiety drug in several clinical trials.

“Oxytocin is usually considered a stress-reducing agent based on decades of research. With this novel animal model, we showed how it enhances fear rather than reducing it and where the molecular changes are occurring in our central nervous system,” said study lead author Yomayra Guzman, also from the Northwestern University’s Feinberg School of Medicine.

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Bibliographic information: Guzmán YF et al. Fear-enhancing effects of septal oxytocin receptors. Nature Neuroscience, published online July 21, 2013; doi: 10.1038/nn.3465