The neuropeptide kisspeptin is established as a master regulator of the reproductive axis within the hypothalamus. Kisspeptin and its receptor are also extensively distributed in extrahypothalamic brain regions and an expanding pool of animal data demonstrates that kisspeptin sits within an extensive functional and neuroanatomical framework through which
it can integrate a range of internal and external cues with appropriate behavioural and neuroendocrine responses. In keeping with this, recent studies have revealed wide-reaching effects of kisspeptin on key behaviours such as olfactory-mediated partner preference, sexual responses, mood and emotions. To date, only one human study has investigated the effects of kisspeptin on extra-hypothalamic brain pathways, with findings that peripheral kisspeptin administration enhances limbic brain processing in healthy men in response to sexually arousing and couple-bonding images. In this thesis, I have used a combination of hormonal, psychometric and functional neuroimaging techniques to study the effects of kisspeptin on two
currently unexplored aspects of human behaviour and their underlying brain processes; 1) olfactory and visually stimulated sexual attraction; 2) appetite and food intake. My results show that kisspeptin enhances brain processing in response to olfactory and visual cues of attraction but has no effect on brain responses to food images, with no associated changes in appetite or food intake. Collectively, the findings of this thesis generate novel human data which support and extend the animal literature regarding the role of kisspeptin in sexual attraction and related behaviours, while answering key functional and mechanistic questions concerning the role of kisspeptin in human appetite and food intake.