Date of Award:
Master of Science (MS)
Oxytocin is a hormone that modulates social behaviors and has been nicknamed the "love molecule". In psychiatric disorders with social symptoms, like autism, there is believed to be reduced oxytocin production or decreased sensitivity of brain areas to oxytocin. Inhaling oxytocin through the nose is being explored as a treatment option for individuals diagnosed with autism. Despite research progress in this area, a better understanding of how and where oxytocin acts in the human brain is needed. We can visualize the binding sites of oxytocin, called receptors, in brain tissue samples through a technique called receptor autoradiography. This technique hasn't been reliable for oxytocin receptors in the past because another molecule, called vasopressin, has receptors with a similar structure that are also detected by the same method. By including a chemical that occupies vasopressin receptors in the visualization procedure, we were able to localize oxytocin receptors on their own. To extend these receptor mapping results from the level of protein density to that of gene expression, we measured mRNA for both receptor types in human brain tissue. This combined approach allowed us to map the binding sites of oxytocin in the human brain. One region with a high number of receptors was the substantia nigra - an area responsible for reward, addiction, and voluntary movements. We investigated whether this area in donors with autism had different levels of oxytocin receptors by making comparisons between four groups: males with autism, males without autism, females with autism, and females without autism. We found that only females with autism had reduced receptor binding, although they expressed the same amount of mRNA as the other groups. This implies that females with autism may have errors in the process that cycles oxytocin receptors to/from the cell surface, or the receptors are more sensitive to inactivation.
Frehner, Sage S., "The Distribution of Oxytocin Receptor Messenger RNA in Human Brain Tissue: A Comparison of Sex and Autism Spectrum Disorder Diagnosis" (2021). All Graduate Theses and Dissertations. 8377.
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