How The ‘Love Hormone’ Works Its Magic

The secret of how the ‘love hormone’ plays a role in sparking a female’s sexual interest in a male has been discovered.

Oxytocin is popularly known as the body’s natural love potion, or the ‘cuddle hormone’, and helps couples fall in love, mothers bond with their babies and teams to work together.

Now, researchers have unveiled the mechanism that creates the spark between the sexes in certain situations, and it’s all down to a newly discovered class of brain cells.

Oxytocin-responsive neurons are found in many parts of the brain, but it is unclear exactly which cells are targeted by the ‘love hormone,’ or how the hormone affects neural circuits, which process information. The study focused on a new type of interneuron – a specialised neuron that sends messages to other neurons across relatively short distances.

The ‘love hormone’ revealed: Scientists unravel how sexual interest is sparked in females

• Oxytocin is also known as ‘love hormone’ due to its effect on emotions
• Oxytocin-responsive neurons are found in many parts of the brain
• It is not clear which cells are targeted by oxytocin, or how the hormone affects the brain’s circuits
• Study focused on an interneuron that sends messages to other neurons
• Researchers found a number of these neurons that release oxytocin in mice
• When activity of these neurons was disrupted, female lost interest in males
• But, these females retained a normal level of social interest in other females during estrus, and in male mice when not in estrus

Using female mice in heat, researchers found neurons in the medial prefrontal cortex that release the oxytocin receptor.

When the activity of these neurons was disrupted, female mice lost interest in the male mice.

But, the females retained a normal level of social interest in other females when they were on heat, and in male mice when they were not in season.

The social behaviour of male mice was unaffected when the neurons were tampered with.

Doctoral researcher Miho Nakajima said: ‘We don’t yet understand how, but we think oxytocin prompts mice in estrus [heat] to become interested in investigating their potential mates.

‘This suggests that the social computation going on in a female mouse’s brain differs depending on the stage of her reproductive cycle.’

Oxytocin has similar effects for humans as for mice, however, it is not yet clear if the hormone influences the human version of this mouse interaction – or if it works through a similar group of interneurons.

However, the results help explain how humans, mice and other mammals respond to changing social situations.

Professor Heintz said: ‘Oxytocin responses have been studied in many parts of the brain and it is clear that it, or other hormones like it, can impact behaviour in different ways, in different contexts and in response to different physiological cues.

‘In a general sense, this new research helps explain why social behaviour depends on context as well as physiology.

… OXYTOCIN IS FOUND TO MAKE WOMEN MORE FRIENDLY BUT MEN MORE COMPETITIVE

‘Our findings suggest that social interactions that stimulate oxytocin production will recruit this newly identified circuit to help coordinate the complex behavioural responses elicited by changing social situations in all mammals, including humans.

‘Future investigation of the exact mechanisms responsible for activation of this interesting circuit may provide insights into autism spectrum disorder and other social behavioural disorders.’

‘Our work highlights the importance of the prefrontal cortex in social and sexual behaviours and suggests that this critical cell population may mediate other aspects of behaviour in response to the elevated oxytocin levels that occur in a variety of different contexts.’