title: Local oxytocin expression and oxytocin receptor binding in the male rat brain is associated with aggressiveness.
abstract: We recently demonstrated in male wild-type Groningen rats that enhancing brain oxytocin (OXT) levels acutely produces marked pro-social explorative and anti-aggressive effects. Moreover, these pharmacologically-induced changes are moderated by the individual's aggressive phenotype, suggesting an inverse relationship between aggressiveness and tonic endogenous OXT signaling properties. Aim of the present study was to verify the hypothesis that variations in OXT expression and/or OXT receptor (OXTR) binding in selected brain regions are associated with different levels or forms of aggression. To this end, male resident wild-type Groningen rats that repeatedly contested and dominated intruder conspecifics were categorized as being low aggressive, highly aggressive or excessively aggressive. Their brains were subsequently collected and quantified for OXT mRNA expression and OXTR binding levels. Our results showed that OXT mRNA expression in the hypothalamic paraventricular nucleus (PVN), but not in the supraoptic nucleus (SON), negatively correlates with the level of offensiveness. In particular, the excessively aggressive group showed a significantly lower OXT mRNA expression in the PVN as compared to both low and highly aggressive groups. Further, the excessively aggressive animals showed the highest OXTR binding in the central amygdala (CeA) and bed nucleus of the stria terminalis (BNST). These findings demonstrate that male rats with excessively high levels and abnormal forms of aggressive behavior have diminished OXT transcription and enhanced OXTR binding capacities in specific nodes of the social behavioral brain circuitry.
authors.affiliation: Department of Behavioral Physiology, University of Groningen, P.O. Box 11103, 9700 CC Groningen, The Netherlands. Electronic address: f.calcagnoli@rug.nl.
authors.forename: Federica
authors.initials: F
authors.lastname: Calcagnoli
authors.affiliation: Department of Behavioral Physiology, University of Groningen, P.O. Box 11103, 9700 CC Groningen, The Netherlands.
authors.forename: Sietse F
authors.initials: SF
authors.lastname: de Boer
authors.affiliation: Department of Behavioral and Molecular Neuroscience, University of Regensburg, 93053 Regensburg, Germany.
authors.forename: Daniela I
authors.initials: DI
authors.lastname: Beiderbeck
authors.affiliation: Child and Adolescent Psychiatry, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands.
authors.forename: Monika
authors.initials: M
authors.lastname: Althaus
authors.affiliation: Department of Behavioral Physiology, University of Groningen, P.O. Box 11103, 9700 CC Groningen, The Netherlands.
authors.forename: Jaap M
authors.initials: JM
authors.lastname: Koolhaas
authors.affiliation: Department of Behavioral and Molecular Neuroscience, University of Regensburg, 93053 Regensburg, Germany.
authors.forename: Inga D
authors.initials: ID
authors.lastname: Neumann
mesh_terms: D000374:Aggression / Q000502:physiology*; D000818:Animals; D001345:Autoradiography; D001921:Brain / Q000378:metabolism*; D015870:Gene Expression / Q000502:physiology; D008297:Male; D010121:Oxytocin / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011930:Reaction Time / Q000502:physiology; D018045:Receptors, Oxytocin / Q000378:metabolism*; D018709:Statistics, Nonparametric
chemical_list: D012333:RNA, Messenger; D018045:Receptors, Oxytocin; D010121:Oxytocin
keywords: Aggressiveness; Bed nucleus of the stria terminalis; Central amygdala; Oxytocin mRNA; Oxytocin receptor binding; Paraventricular nucleus