Behavioural characterization of oxytocin mutant mice: implications for autism

There is a growing interest in the neuropeptide oxytocin (OT) and its receptor (OTR) in the pathogenesis of autism. OT controls the ability to remember individuals previously encountered, a form of social recognition that is essential for the establishment of all complex relationships (Hollander et al., 2003) , suggesting that the OT system is involved in the normal processing of socially relevant cues. The crucial role of OT in regulating the social brain has been recently confirmed in knockout OTR-/- mice, an animal model characterized by marked defects in maternal and social behaviour (Takayanagi et al., 2005). Aim of the present study was to examine the behavioural phenotype of heterozygous OTR+/- and knockout OTR-/- mice in comparison to wild type OTR+/+ mice with particular attention for more specialized behavioural tasks relevant for autism such as the social approach to stranger mouse, the preference for social novelty and reversal of a position habit in an appetitive T-maze task (Crawley, 2007). Preliminary results indicate that both OTR+/- and knockout OTR-/- mice have a good general health and normal neurological reflexes. However, they are severely impaired in : social recognition and social novelty test, reversal learning in the T-maze task. These findings further confirm that the OTR may play a role in core symptoms characterizing autistic disorders. Furthermore, the deficit found in the heterozygous OTR+/- mice makes these animals an interesting model for the in vivo screening of new pharmacological compounds targeting the OT/OTR system.