Plasma Oxytocin and Arginine-Vasopressin Levels in Children with Autism Spectrum Disorder in China: Associations with Symptoms

Abstract

Autism spectrum disorder (ASD) is defined by impairments of social interaction and the presence of obsessive behaviors. The "twin" nonapeptides oxytocin (OXT) and arginine-vasopressin (AVP) are known to play regulatory roles in social behaviors. However, the plasma levels and behavioral relevance of OXT and AVP in children with ASD have seldom been investigated. It is also unknown whether their mothers have abnormal plasma peptide levels. Here, using well-established methods of neuropeptide measurement and a relatively large sample size, we determined the plasma levels of the two neuropeptides in 85 normal children, 84 children with ASD, and 31 mothers from each group of children. As expected, children with ASD had lower plasma OXT levels than gender-matched controls (P = 0.028). No such difference was found for plasma AVP concentrations. Correlation analysis showed that ASD children with higher plasma OXT concentrations tended to have less impairment of verbal communication (Rho = -0.22, P = 0.076), while those with higher plasma AVP levels tended to have lower levels of repetitive use of objects (Rho = -0.231, P = 0.079). Unlike the findings in children, maternal plasma OXT levels showed no group difference. However, plasma AVP levels in the mothers of ASD children tended to be lower than in the mothers of normal children (P = 0.072). In conclusion, our results suggest that the OXT system is dysregulated in children with ASD, and that OXT and AVP levels in plasma seem to be associated with specific autistic symptoms. The plasma levels of OXT or AVP in mothers and their ASD children did not seem to change in the same direction.

Keywords: Autism spectrum disorder; Behavioral relevance; Oxytocin; Vasopressin.

Fig. 1

Plasma concentrations of OXT in control and ASD children. Children with ASD showed a lower plasma OXT levels than control children (P = 0.028) after adjusting for covariates (A). Boys with ASD had lower plasma OXT concentrations than control boys (P = 0.028) (B). No significant difference in OXT levels was found between control and autistic girls (C). All values are expressed as mean ± SEM (*P < 0.05; OXT, oxytocin; ASD, autism spectrum disorder).

Fig. 2

Plasma concentrations of AVP in control and ASD children. The levels in the two groups were comparable (A). Boys with ASD did not differ from normal boys with respect to plasma AVP (B), nor were there significant difference between girls (C). All values are presented as mean ± SEM (AVP, arginine-vasopressin; ASD, autism spectrum disorder).

Fig. 3

A, B Scatter-plots showing correlations between OXT and AVP levels within the two groups. The two peptides were positively correlated in plasma of control children (A), but not in children with ASD (B). C The ratio of AVP to OXT in ASD children was higher than that in control children. *P < 0.05; OXT, oxytocin; AVP, arginine-vasopressin.

Fig. 4

Plasma OXT and AVP levels in mothers. A Maternal plasma OXT concentrations were comparable in NMs and AMs. B AVP levels in AMs approached significance versus NMs (P = 0.072). All values are expressed as mean ± SEM (OXT, oxytocin; AVP, arginine-vasopressin; NM, mothers of normal children; AM, mothers of children with ASD).