Oxytocin...

The love hormone is two-faced

Surprise finding shows oxytocin strengthens bad memories and can increase fear and anxiety

July 24, 2013

Oxtr mediates the enhancement of fear by social-defeat stress. (a) GFP immunostaining (anti-GFP) shows the localization of Oxtr-positive neurons in the lateral septum of Venus+/+ ‘Oxtr reporter’ mice (top; LSD, lateral septum dorsal; LSI, lateral septum intermediate; LSV, lateral septum ventral; cc, corpus callosum); Cre immunostaining (anti-Cre) in wild-type mice injected with rAAV-Cre (bottom right), and X-gal cytochemical staining of β-galactosidase in B6.129S4-Gt(ROSA) reporter mice injected with rAAV-Cre (Cre-ROSA; bottom left). We targeted the viral injections to anteroposterior coordinates corresponding to the highest number of Oxtr-positive neurons (dashed lines demonstrate injection sites that correspond to septal region rich in Oxtr). (Credit: Yomayra F Guzmán et al./Nature Neuroscience)

Oxytocin has long been known as the warm, fuzzy hormone that promotes feelings of love, social bonding and well-being. It’s even being tested as an anti-anxiety drug.

But new Northwestern Medicine research shows oxytocin also can cause emotional pain, an entirely new, darker identity for the hormone.

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, Northwestern scientists discovered.

Intensifying memory

If a social experience is negative or stressful, the hormone activates a part of the brain that intensifies the memory. Oxytocin also increases the susceptibility to feeling fearful and anxious during stressful events going forward.

(Presumably, oxytocin also intensifies positive social memories and, thereby, increases feelings of well being, but that research is ongoing.)

The findings are important because chronic social stress is one of the leading causes of anxiety and depression, while positive social interactions enhance emotional health. The research, which was done in mice, is particularly relevant because oxytocin currently is being tested as an anti-anxiety drug in several clinical trials.

“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,” said Jelena Radulovic, the senior author of the study and the Dunbar Professsor of Bipolar Disease at Northwestern University Feinberg School of Medicine. The paper was published July 21 in Nature Neuroscience.

This is the first study to link oxytocin to social stress and its ability to increase anxiety and fear in response to future stress. Northwestern scientists also discovered the brain region responsible for these effects — the lateral septum — and the pathway or route oxytocin uses in this area to amplify fear and anxiety./.../