Oxytocin (OT) and arginine vasopressin (AVP) are two small, related neuropeptides found in many mammalian species, including humans. These neuropeptides are associated with a range of social behaviors and their dysregulation has been associated with deficits in social behavior. In particular, the OT neuropeptide system has been investigated in Autism Spectrum Disorder (ASD), as well as in Prader-Willi Syndrome (PWS), Williams Syndrome (WS) and Fragile X Syndrome (FXS), all of which are characterized by marked social deficits. PWS, WS and FXS are caused by identified genetic mutations and provide insight into the developmental influences of the OT system. In particular, FXS is caused by a mutation in a single gene and up to 47 % of patients with FXS are diagnosed with ASD or also have autism related behaviors. Animal models of genetic neurodevelopmental disorders (NDD) are becoming a valuable tool to examine the role and relatedness of OT and AVP in the developing brain. We provide an example of how OT and AVP systems are altered with a mutation in the mouse Fragile X mental retardation 1 (Fmr1) gene which leads to FXS-like symptoms in Fmr1 knockout (KO) mice. By studying the OT and AVP systems in these rare disorders, we may further understand their mechanisms of action in ASD and in typical development. This chapter will summarize the current data pertaining to these NDD and the systems of OT and AVP.
- Fragile X