"These of course play a huge part in reproduction, but the role that the brain and emotional processing play in this process is also very important, and only partially understood."
Kisspeptin, which is naturally occurring, stimulates the release of other reproductive hormones.
In the study, 29 healthy heterosexual young men were given injections of the hormone and asked to look at sexual and romantic pictures, as well as viewing control images that contained no people.
Magnetic Resonance Imaging (MRI) scans showed enhanced activity in regions of the brain linked to sexual arousal and romance. The effect did not occur when the volunteers viewed the control images.
The scientists believe that kisspeptin boosts brain circuits associated with sex and love, triggering reward centres and increasing desire. The study participants using kisspeptin also reported a reduction in negative mood in post-scan questionnaires and the team is now hoping to investigate whether the hormone could additionally be used for treating depression.
The team, whose findings are reported in the Journal of Clinical Investigation, now plans to study the effects of kisspeptin in a larger group that will include women as well as men.