Background: Successful reproduction relies on integration of sensory cues of attraction with corresponding emotions and behaviours. However, the intrinsic factors integrating these fundamental aspects of human attraction with limbic and reproductive pathways have not been fully identified. Kisspeptin is a crucial activator of the reproductive axis and together with its receptor is widely expressed throughout the limbic and olfactory systems in humans suggesting a potential role in this integration. We therefore hypothesised that kisspeptin modulates brain responses to olfactory and visual cues of attraction in men.
Methods: To test our hypothesis, we utilised fMRI to examine the effects of kisspeptin versus placebo on brain activity during olfactory and facial attractiveness tasks in 33 healthy heterosexual men (age 24.5±0.7 years, BMI 22.9±0.8 kg/m2). During the olfactory task, participants received a pleasant feminine scent and during the facial attractiveness task they viewed unfamiliar female faces. Psychometric and hormone analyses were also performed.
Results: Kisspeptin enhanced brain activity in olfactory (P<0.01) and limbic behavioural circuits (P<0.05), in response to a pleasant feminine scent. On viewing female faces, kisspeptin augmented brain activity in established areas associated with the evaluation of beauty (P<0.01). Additionally, we observed correlations between the effects of kisspeptin on brain activity and psychometric parameters of reward (P<0.01). Of particular translational relevance, the effects of kisspeptin were more pronounced in men reporting lower sexual quality of life (P<0.01), suggesting that kisspeptin-mediated pathways may provide therapeutic avenues for patients with psychosexual disorders.
Conclusion: Collectively, we demonstrate for the first time that kisspeptin enhances brain responses to olfactory and visual cues of attraction with key correlations to psychometric parameters providing functional relevance. Our data provide a novel framework for understanding hormones and human attraction, while also laying the foundations for future therapeutic applications of kisspeptin in associated reproductive and psychosexual disorders.