An injection of the hormone that kick-starts puberty could be used to treat psychological sexual problems, scientists have said.

The naturally-occurring hormone, appropriately named 'kisspeptin', has been linked to sexy and romantic feelings and is essential to the body’s reproductive system.

Researchers at Imperial College London gave 29 healthy young men kisspeptin injections and found the hormone boosted the brain’s response to pictures of couples in sexual or romantic situations.

Magnetic Resonance Imaging (MRI) scans showed enhanced activity in regions of the brain stimulated by sexual arousal and romance. The same effect did not occur when the volunteers viewed non-sexual images.

Professor Waljit Dhillo, who led the research, said the findings could be used to treat emotional factors which may lead to infertility. The brain plays an important role in reproduction but its role is only partially understood, he said.

“Our initial findings are novel and exciting as they indicate that kisspeptin plays a role in stimulating some of the emotions and responses that lead to sex and reproduction,” said Professor Dhillo.

“Ultimately, we are keen to look into whether kisspeptin could be an effective treatment for psychosexual disorders, and potentially help countless couples who struggle to conceive.”

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Kisspeptin also seemed to be involved in regulating mood and reducing negativity, the researchers found – suggesting it may help combat depression.

The study found that injecting kisspeptin did not affect positive mood, but did reduce negative moods, affecting the regions of the brain associated with not only romantic love but also maternal love and even unconditional love.

Co-author Dr Alexander Comninos, also from Imperial College, said: “Our study shows that kisspeptin boosts sexual and romantic brain activity as well as decreasing negative mood.

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“This raises the interesting possibility that kisspeptin may have uses in treating psychosexual disorders and depression which are major health problems which often occur together, but further studies would be needed to investigate this.”

The team, whose findings were reported in the Journal of Clinical Investigation, plans to study the effects of kisspeptin in a larger group including women as well as men.