Oxytocin and AVP

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Oxytocin Vassopressin and ASD

Neural Systemrelated brain structuresGenetics
Oxytocin and AVPSocial Memoryamygdala
dorsal striatum
Otr contained in 3p25
SNPs rs2254298 and rs53576
PMID 19129382PMID 18498743, PMID 15821089, PMID 7735292, PMID 15589267, PMID 11240311PMID 12082568 PMID 15098001 PMID 16520824 PMID 16205737 PMID 15647115 PMID 16288458 PMID 15992526 PMID 17893705


Oxytocin(OT) and arginine vassopressin (AVP) have been considered to play a key role in the development of several mental disorders, such as social anxiety disorders, obsessive-compulsive disorder, borderline personality disorder, depression, social deficits associated with ASD, and other mental disorders. Some social deficits in ASD mimic the behavior of animals that lack OT, causing some to hypothesize that there may be a link between ASD and OT/AVP. Recent studies have emphasized the 3p25 region containing the Otr gene as a promising linkage site for ASD, as well as two single nucleotide polymorphisms (rs2254298 460 and rs53576 and Avpr-1a genes).1

OT has been implicated in enabling non-human mammals to overcome their natural avoidance of proximity and to inhibit defensive behavior. AVP has been shown to be involved in male-typical social behaviors, including aggression, pair-bond formation, scent marking, and courtship in animals. Both OT and AVP are distributed throughout several brain regions in relation with central nervous control of stress and anxiety and with social behavior, such as parental control, pair-bonding, social memory, and social aggression.1

Additionally, OT shows significant binding in the limbic system for humans and there is elevated AVP expression in the hypothalamic paraventricular nucleous which is involved with increased behavioral and neuroendocrine anxiety levels. Most studies on OT and AVP have been done on animal models but some recent studies have found social and stress-related effects from both neuropeptides in humans.There have been studies which support a role of OT in facial processing and interpersonal communication. The behavioral effects of neuropeptides in humans have been examined through correlational studies measuring OT or AVP in urine, saliva, blood, or CSF, genotyping of receptor polymorphisms, and experimental studies manipulating the availability of OT or AVP using intravenous or intranasal methods. However, results have been inconsistent. 1 One study on 13 subjects with high functioning autism showed that after nasal inhalation of oxytocin, subjects reported more feelings of trust toward their partner in a ball game and displayed stronger interactions. Additionally, when viewing pictures of faces, participants spend more time looking at the socially relevant portion of the faces (the eyes) after inhaling oxytocin.5

Anaphase IF.gifGenetics

A study to identify CNV variants on 119 probands from multiplex autism families found a deletion in the oxytocin receptor gene OXTR in one proband. DNA methylation analysis of the mother and sibling found increased methylation of the promoter region of the OXTR gene in both the mother and sibling. In particular, a single dinucleotide within the region independently had a statstically significant increase in methylation in the and temporal cortext of autism patients as compared to controls. Since there are similar methylation profiles in both the temporal cortex and the peripheral blood suggests that the methylation statuses were established early on in development. Methylation status of this gene may then be senstive to enviromental cues during the first few weeks of pregnancy.2

It is possible that methylation status can have an affect on the development of autism. 79% of autism cases have decreased MECP2 expression in the frontal cortex, and the decrease in MECP2 expression correlates with increased abberrant DNA methylation.2 This has raised the possibility that there may be environmental factors which can reprogram the epigenotype of the embryo, thereby changing the methylation status. 3

Animal Models


While there have been many studies reporting associations between OTR and AVP gene variants, the reports find associations between different gene variants. There is also little evidence that these variants are functional. One study reported a significant reduction in OT in children with autism compared to age-matched controls, but few other studies have attempted to reproduce these findings.

As a therapeutic agent, three studies so far have looked at the effects of intranasal oxytocin on high functioning autistic patients. These trials show that relative to a placebo, patients who received oxytocin show improved eye contact, social memory, and use of social information. However, if autism involves altered receptor distribution rather than a simple deficit in neuropeptide, giving autistic subjects more oxytocin will not reverse deficits. 4

Tests for Oxytocin and AVP

The behavioral effects of neuropeptides in humans have been examined through correlational studies measuring OT or AVP in

  1. urine, saliva, blood, or CSF,
  2. genotyping of receptor polymorphisms
  3. experimental studies manipulating the availability of OT or AVP using intravenous or intranasal methods.

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