Oxytocin (OXT) promote a variety of social behaviors in humans after intranasal application.In men, it can increase the perceived attractiveness of unfamiliar women and strengthen bonds in existing relationship. It is also shown to increase trust nd cooperation.It is unclear how OXT’s effects are mediated i.e. is it through dopamine reward pathways?
It is thought that OXT may enhance the pleasure value of social interactions by specifically acting on D2R in dopaminergic reward centers, especially in striatum.
German researchers led by Nadine Striepens investigated whether OXT facilitation of perceived attractiveness of unfamiliar women by men was associated both with activation of dopaminergic brain reward centers and increased liberation of DA using PET study (double-blind, placebo controlled, within-subjects design) among 18 adult male volunteers.
The main objective was to establish changes in dopamine activity associated with altered face attraction. Subjects were presented with pictures of unfamiliar, neutral expression female faces. Each participant completed two sessions ( first session: placebo or intranasal Oxt second session: alternative one) of testing separated by at least 4 days.
Participants rated unfamiliar female faces as more attractive under OXT than placebo treatment. All 18 subjects showed an increased average attractiveness rating under OXT compared to placebo. The findings were not dependent on the sequence participants took the intervention. Neither OXT per se nor its effect on attractiveness ratings for unfamiliar female faces resulted in altered DA release in the striatum .There is no evidence to support increased dopaminergic activity in reward-related brain area.
It is interesting to note that oxytocin increased attractiveness for the faces which were given higher ratings under placebo treatment. (i.e. oxytocin makes beautiful more beautiful? )
This study had only male participants. would the results be different in women? Oxytocin’s effects could be mediated differently in men and women
Other mechanisms ( other than dopamine mediated) ?
Striatal activity changes in the study correlated with attractiveness ratings. Perfusion indicators changed in both striatal reward and face-processing regions. One possibility is opioid release and m-opioid receptors which have also been shown to be important for pair-bonding.Perfusion pattern also suggest that OXT ( reduced frontal mad parietal activation) reduce cognitive appraisal of and negative emotional and judgmental responses toward the female faces,( i.e. not enhancing their reward value per se).
Conclusion: Intranasal oxytocin increase the perceived attractiveness of female faces in young men. This is no evidence to support that this is mediated via dopamine reward systems.
Summary of the article:
Oxytocin enhances attractiveness of unfamiliar female faces independent of the dopamine rewardsystem.Striepens N, Matusch A, Kendrick KM, Mihov Y, Elmenhorst D, Becker B, Lang M, Coenen HH, Maier W, Hurlemann R, Bauer A. Psychoneuroendocrinology. 2014 Jan;39:74-87.