Oxytocin and Autism

1. Oxytocin and Autism Nicole Stokes & Jennifer Morales

2. Oxytocin

3. Overview of Oxytocin • Located at the human gene locus 20p13, oxytocin (OT) is synthesized in the neurons in the hypothalamus as a protein precursor. Enzymes then cleave, amidate and transport OT axonally. These steps spur the production of OT-extended form (OT-X), which is OT with an addition C-terminal of three-amino-acid-extension. OT-X is then cleaved through the enzymes convertase 2 (PC2) and convertase 5 (PC5) to create the nine-amino-acid active peptide OT. PC2 and PC5 are found in the OT neurosecretory vesicles. • Oxytocin has many functions and has various effects on the body. However, these effects are more prominently seen in the brain. OT is thought to affect sexual, social, and maternal behavior. A lack of OT is thought to be one cause of Autism which encompasses many issues, including the inability to bond with others or socialize properly.

4. Autism • “Autism is a complex developmental disability that typically appears during the first two years of life and is the result of a neurological disorder that affects the functioning of the brain, impacting development in the areas of social interaction and communication skills. Both children and adults on the autism spectrum typically show difficulties in verbal and non-verbal communication, social interactions, and leisure or play activities.”* • “If you've met one person with autism, you've met one person with autism.” • Symptoms vary greatly because autism is a spectrum disorder. However, delays or disabilities when it comes to social skills such as ordinary conversation, eye contact and emotional understanding of others are common symptoms of most autistic individuals • Treatments: clear instructions to the child, prompting to perform specific behaviors, immediate praise and rewards for performing those behaviors, a gradual increase in the complexity of reinforced behaviors, definite distinctions of when and when not to perform the learned behaviors *"What are Autism Spectrum Disorders?" Autism Society of America:. Web. 13 Nov. 2009. <http://www.autism-society.org/site/PageServer?pagename=about_whatis>.

5. Oxytocin and Autism Researches have suggested that the social impairments found in autistic disorders are associated with the changes in OT levels. Through studies it was concluded that children with autistic disorders have more than two-fold amount of OT-X in their plasma compared to OT. It is thought that through genetic defects the PC2 and PC5 enzymes are not functioning properly so the OT-X is never cleaved to finally become OT. This would not be problematic if the Oxytocin Receptors could bind with OT-X; however, OT-X has been shown to not be an effective agonist for the receptor.

6. Additional Information • OT-X is present in the human umbilical arterial and venous blood with changes associated with labor and delivery. For children without autism (Control group) it is found that the amount of OT in the plasma rises with age, but autistic children increase levels of OT-X with age. (look at graph below) Also, it was found that in the control group there was no decrease of OT-X levels with age. It possible that levels of OT-X decline earlier in childhood to the point where in most of the males ages 6-11 in the study had OT-X levels that were almost undetectable. It is believed that autistic children have an increase in OT-X because of a mutation to the gene that codes PC2, the enzyme that cleaves OT-X to make functioning OT.