So-called ‘love’ hormone can make you FEAR new experiences

The so-called ‘love hormone,’ oxytocin, may make you more fearful of new social situations, new research indicates.

A study from the University of California, Berkeley (UC Berkeley), shows that instead of making every social situation better, oxytocin may simply exaggerate whatever a given interaction makes you feel.

Oxytocin is released by the brain when we are in social settings. 

For female mice in the study who had gone through negative social experiences, the oxytocin released in new social interactions just increased their anxiety.

Once the oxytocin was reduced using a blocking agent, the mice were more open to new social interactions. 

The effect was essentially the same as that of common anti-anxiety or antidepressant drugs that take about four weeks to start working. 

Oxytocin has gotten a lot of press, Dr Brian Trainor, who co-authored the Berkeley study, says it’s been misunderstood and misrepresented. 

The hormone is released in many situations, but most notably during social bonding. This has led to the theory that a dose of the hormone could improve social experiences in general. 

But ‘if you look at the science of how oxytocin works in the lab, we’re finding that the data that are coming out are moving away from this “oxytocin is good” view to one that is more sophisticated,’ says Dr Trainor. 

The study he and his fellow researchers published in Biological Psychiatry looked specifically at how oxytocin and oxytocin-inhibitors worked in female mice that had been ‘bullied,’ which meant that they had had negative social experiences. 

In new social experiences, the female mice were, unsurprisingly, fearful, and the oxytocin their brains were releasing was doing nothing to help them. 

Then the researchers gave the mice a dose of an oxytocin aggravator, that blocked the mice’s oxytocin receptors and inhibits the hormone’s effects.

Instead of continuing to be afraid of new social situations, the mice were more bold and open to the new experiences. 

In the case of the bullied female mice, more oxytocin meant more social anxiety, and less oxytocin meant better social experiences. 

In recent research, scientists have begun to think that ‘if oxytocin is being released during a certain situation, it’s going to “turn up the volume,” taking experiences and amplifying the effects,’ whether those are positive or negative,’ Trainor says.  

So when the female mice were deprived of some of the oxytocin their brains would have been releasing in social situations, the ‘volume’ got turned down on their anxieties. 

‘The theory fits the data, but how can oxytocin have these positive and negative effects at same time?’ asked Trainor.  

To answer that, the UC Berkeley researchers looked more closely at what was happening in what part of the brain. 

Oxytocin was overactive in the region of the brain referred to as the extended amygdala in the female mice that had been bullied and were being socially avoidant. 

This part of the brain is important to anxiety, and is also connected to many other parts of the brain, making it important to social behaviors and experiences. So when the oxytocin-blocker targeted this part of the brain, the females had almost immediate responses, and behaved more socially. 

Putting the bullied mice in social situations was essentially the researchers’ way of modeling the effects of anxiety and depression.

‘This is exciting because if we used something like Prozac, to get the same effect, we would have to treat the mice, every day, for four weeks, just like in humans,’ Trainor says. 

The oxytocin inhibitor, on the other hand, worked in about 30 minutes. 

In recent years, oxytocin has become commercially available. Its use is completely unregulated, and you can buy it in nasal spray on Amazon for about $30. 

Oxytocin-inhibitors, on the other hand, are a ways away from that. Prescription inhibitors are used primarily by doctors to slow down premature labor, when a woman’s body is over-producing the hormone. 

It’s not yet clear how long the effects of blocking oxytocin last in the mice, but, in theory, ‘science would say you don’t want to inhibit it all the time,’ Trainor says. 

‘But if you have had a prior bad experience…reducing oxytocin during those brief periods could maybe be beneficial,’ he says. 

Notably, the researchers did not observe the same responses from male mice. 

Oxytocin may be overactive in the area of the brain referred to as the extended amygdala. In females mice, the new UC Berkeley study found that this could lead to social avoidance, but when they were given an oxytocin blocker that targeted that part of the brain, the mice relaxed

Trainor says that oxytocin seems to work in same areas of the male mice’s brains more as a ‘social reward,’ than to induce anxiety. When they gave the male mice the targeted oxytocin aggravator, it had no significant effect. But when the blocker was administered ‘all over,’ the males actually had ‘reduced social behavior,’ he says. 

This aligns with the researchers’ observation that bullying also affected the males differently than it did the females. 

While females became socially avoidant, males became more erratic in familiar environments, like their own cages, and had trouble with cognitive flexibility, or learning how to play the same game when a rule was changed.

Trainor says this could have to do with the different hormones present in each sex. Just like humans, female mice experience different hormone fluctuations with their ovarian cycles, for example, than do the males. 

These differences may have gone unnoticed previously because testing two sexes of mice is more expensive than testing one sex. Until 2015, the National Institutes for Health, which fund a majority of research in the US, did not require that research use sex as a biological variable.

‘Oxytocin seems to be somewhat specific to these social domains,’ says Trainor. ‘It’s not just this hormone with all these positive effects, it may be in some cases, but it’s clear in science that all the effects of oxytocin depend on your environment; it’s context dependent.’