Love and fear

Oxytocin is a powerful hormone. When you hug or kiss a loved one, oxytocin is secreted and helps in the bonding. In some circles it has been dubbed the “cuddle hormone” or the “trust hormone”. Oxytocin also acts as a neurotransmitter in the brain. Prairie voles, one of nature’s most monogamous species, produce large amounts of oxytocin. In humans, as well as cuddling oxytocin production is stimulated during sex, birth and breast feeding. For all of these reasons there is research going to see whether oxytocin might form the basis of a new anti-anxiety drug. However, a new study has shown a twist in the tale of oxytocin.

In the study researchers used three groups of mice: one group that had no receptors for oxytocin, another that had a normal number of oxytocin receptors, and a third that had an increased number of receptors. The three groups were placed separately in cages with aggressive mice so that the mice would experience a socially frustrating situation. Six hours later, the mice were then returned to the cages with the aggressive mice.

The mice without receptors for oxytocin, who therefore would not experience the effects of oxytocin, did not seem to remember the aggressive mice or show fear. By contrast, the group with increased oxytocin receptors showed exaggerated fear (more than the “normal” group) and tried to avoid the aggressive mice from the beginning.

Other experiments supported these effects, so what is oxytocin doing?

It seems that oxytocin enhances social memory by activating a part of the brain called the lateral septum. This lateral septum plays a role in emotional responses and oxytocin seems to strengthen positive social memories but also reinforces stressful memories. This means it can form the basis of anxiety or fear later on.

Perhaps then, oxytocin is not only behind the mind melting transformation of your thought into syrup that takes place when you fall in love, but it might also cause the paranoid fear and bowel-wrenching anxiety that goes with it.

It seems that six hours after a socially stressful event a molecule called ERK is activated and that oxytocin interacts with ERK to strengthen negative memories of the social interaction.

It means a bit more work is needed before oxytocin can become an anti-anxiety drug, but in the meantime a few more cuddles won’t do any harm, provided you avoid aggressive mice afterwards.