title: Oxytocin's impact on social face processing is stronger in homosexual than heterosexual men.
abstract: Oxytocin is an evolutionarily highly preserved neuropeptide that contributes to the regulation of social interactions including the processing of facial stimuli. We hypothesized that its improving effect on social approach behavior depends on perceived sexual features and, consequently, on sexual orientation. In 19 homosexual and 18 heterosexual healthy young men, we investigated the acute effect of intranasal oxytocin (24IU) and placebo, respectively, on the processing of social stimuli as assessed by ratings of trustworthiness, attractiveness and approachability for male and female faces. Faces were each presented with a neutral, a happy, and an angry expression, respectively. In heterosexual subjects, the effect of oxytocin administration was restricted to a decrease in ratings of trustworthiness for angry female faces (p<0.02). In contrast, in homosexual men oxytocin administration robustly increased ratings of attractiveness and approachability for male faces regardless of the facial expression (all p ≤ 0.05), as well as ratings of approachability for happy female faces (p<0.01). Results indicate that homosexual in comparison to heterosexual men display higher sensitivity to oxytocin's enhancing impact on social approach tendencies, suggesting that differences in sexual orientation imply differential oxytocinergic signaling.
authors.affiliation: Department of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen 72076, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Thienel
authors.affiliation: Department of Psychology, Laboratory for Biological and Personality Psychology, University of Freiburg, Freiburg 79104, Germany; Freiburg Brain Imaging Center, University Medical Center, University of Freiburg, Freiburg 79106, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Heinrichs
authors.affiliation: Department of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen 72076, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Fischer
authors.affiliation: Department of Neuroendocrinology, University of Lübeck, Lübeck 23562, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Ott
authors.affiliation: Department of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen 72076, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Born
authors.affiliation: Department of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen 72076, Germany. Electronic address: manfred.hallschmid@uni-tuebingen.de.
authors.forename: Manfred
authors.initials: M
authors.lastname: Hallschmid
mesh_terms: D000281:Administration, Intranasal; D000328:Adult; D004644:Emotions / Q000187:drug effects*; D005149:Facial Expression; D020010:Heterosexuality / Q000187:drug effects* / Q000523:psychology; D006716:Homosexuality / Q000187:drug effects* / Q000523:psychology; D006801:Humans; D007398:Interpersonal Relations; D008297:Male; D010121:Oxytocin / Q000008:administration & dosage*; D010775:Photic Stimulation; D012938:Social Perception
chemical_list: D010121:Oxytocin
keywords: Affiliation; Approach behavior; Face perception; Homosexuality; Oxytocin; Sexual orientation