Oxytocin and Vasopressin: Mechanisms for Potential Sex Differences Observed in Autism Spectrum Disorders
The effects of oxytocin and vasopressin on the brain and behavior can be sexually dimorphic, especially during the course of development (Bales, Kim, et al., 2004; Bales, Pfeifer, et al., 2004; Bales, Plotsky, et al., 2007; Bielsky et al., 2005a; Carter, 2003; Thompson et al., 2006; Yamamoto et al., 2005; Yamamoto et al., 2004). Given the sexual discrepancy observed in autism spectrum disorders (ASDs), these two neuropeptides, oxytocin (OT) and arginine vasopressin (AVP), have received attention for their potential role in ASDs (Green and Hollander, 2010; Insel et al., 1999; Leckman & Herman, 2002; Welch et al., 2005; Winslow, 2005; Young et al., 2002). Changes in either OT or AVP and their receptors could be capable of influencing symptom domains or behaviors associated with ASDs. Arginine vasopressin is androgen dependent in some brain regions (De Vries & Panzica, 2006), and males are more sensitive to AVP, especially during development. We hypothesize here that AVP, which has a unique role in males, must be present in optimal levels to be protective against ASDs. Either excess AVP or disruptions in the AVP system could play a role in development of the traits found in ASDs. In contrast, OT may possibly be secreted in response to adversity, especially in females, serving as a protective factor.