title: Adolescent peer-rejection persistently alters pain perception and CB1 receptor expression in female rats.
abstract: Peer-interactions are particularly important during adolescence and teenagers display enhanced sensitivity toward rejection by peers. Social rejection has been shown to induce alterations in pain perception in humans. However, the neurobiological consequences of adolescent social rejection have yet to be extensively characterized, and no appropriate animal model is available. Here, we propose inadequate playful interactions in adolescent rats as a novel animal model for social peer-rejection and examine potential long-term consequences into adulthood. Acute social pairing of female adolescent Wistar rats with an age-matched rat from the less playful Fischer344 strain was found to alter social play and decrease pain reactivity, indicating Fischer rats as inadequate social partners for Wistar animals. Therefore, in a second experiment, adolescent female Wistar rats were either reared with another Wistar rat (adequate social rearing; control) or with a Fischer rat (inadequate social rearing; play-deprived). Beginning on day 50, all Wistar rats were group housed with same-strain partners and tested for behavioral, neurobiological and endocrine differences in adulthood. Playful peer-interactions were decreased during adolescence in play-deprived animals, without affecting social contact behavior. Consequently, adult play-deprived rats showed decreased pain sensitivity and increased startle reactivity compared to controls, but did not differ in activity, anxiety-related behavior or social interaction. Both groups also differed in their endocrine stress-response, and expression levels of the cannabinoid CB1 receptor were increased in the thalamus, whereas FAAH levels were decreased in the amygdala. The present animal model therefore represents a novel approach to assess the long-term consequences of peer-rejection during adolescence.
authors.affiliation: Research Group Developmental Neuropsychopharmacology, Institute of Psychopharmacology, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.
authors.forename: Peggy
authors.initials: P
authors.lastname: Schneider
authors.affiliation: Research Group Developmental Neuropsychopharmacology, Institute of Psychopharmacology, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.
authors.forename: Christin
authors.initials: C
authors.lastname: Hannusch
authors.affiliation: Department of Psychosomatic Medicine and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Schmahl
authors.affiliation: Department of Psychosomatic Medicine and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Bohus
authors.affiliation: Institute of Psychopharmacology, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Spanagel
authors.affiliation: Research Group Developmental Neuropsychopharmacology, Institute of Psychopharmacology, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany. Electronic address: miriam.schneider@zi-mannheim.de.
authors.forename: Miriam
authors.initials: M
authors.lastname: Schneider
mesh_terms: D000679:Amygdala / Q000254:growth & development / Q000502:physiology; D000818:Animals; D001007:Anxiety / Q000503:physiopathology; D001921:Brain / Q000254:growth & development* / Q000502:physiology*; D003345:Corticosterone / Q000097:blood; D005260:Female; D006358:Hot Temperature; D009043:Motor Activity / Q000502:physiology; D058748:Pain Perception / Q000502:physiology*; D010988:Play and Playthings; D051381:Rats; D011916:Rats, Inbred F344; D017208:Rats, Wistar; D043884:Receptor, Cannabinoid, CB1 / Q000378:metabolism*; D013216:Reflex, Startle / Q000502:physiology; D012919:Social Behavior; D013045:Species Specificity; D013788:Thalamus / Q000254:growth & development / Q000502:physiology
chemical_list: D043884:Receptor, Cannabinoid, CB1; D003345:Corticosterone
keywords: Adolescence; CB1 receptor; FAAH; Pain; Social play behavior; Social rejection