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dc.contributor.authorGnanadesikan, Gitanjali E
dc.contributor.authorHammock, Elizabeth A D
dc.contributor.authorTecot, Stacey R
dc.contributor.authorLewis, Rebecca J
dc.contributor.authorHart, Russ
dc.contributor.authorCarter, C Sue
dc.contributor.authorMacLean, Evan L
dc.date.accessioned2022-08-05T19:53:45Z
dc.date.available2022-08-05T19:53:45Z
dc.date.issued2022-06-08
dc.identifier.citationGnanadesikan, G. E., Hammock, E. A. D., Tecot, S. R., Lewis, R. J., Hart, R., Carter, C. S., & MacLean, E. L. (2022). What are oxytocin assays measuring? Epitope mapping, metabolites, and comparisons of wildtype & knockout mouse urine. Psychoneuroendocrinology, 143.en_US
dc.identifier.pmid35714438
dc.identifier.doi10.1016/j.psyneuen.2022.105827
dc.identifier.urihttp://hdl.handle.net/10150/665557
dc.description.abstractOxytocin has become a popular analyte in behavioral endocrinology in recent years, due in part to its roles in social behavior, stress physiology, and cognition. Urine samples have the advantage of being non-invasive and minimally disruptive to collect, allowing for oxytocin measurements even in some wild populations. However, methods for urinary oxytocin immunoassay have not been sufficiently optimized and rigorously assessed for their potential limitations. Using samples from oxytocin knockout (KO) and wildtype (WT) mice, we find evidence of considerable interference in unextracted urine samples, with similar distributions of measured oxytocin in both genotypes. Importantly, although this interference can be reduced by a reversed-phase solid-phase extraction (SPE), this common approach is not sufficient for eliminating false-positive signal on three immunoassay kits. To better understand the source of the observed interference, we conducted epitope mapping of the Arbor Assays antibody and assessed its cross-reactivity with known, biologically active fragments of oxytocin. We found considerable cross-reactivity (0.5–52% by-molarity) for three fragments of oxytocin that share the core epitope, with more cross-reactivity for longer fragments. Given the presence of some cross-reactivity for even the tripeptide MIF-1, it is likely that many small protein metabolites might be sufficiently similar to the epitope that at high concentrations they interfere with immunoassays. We present a new mixed-mode cation-exchange SPE method that minimizes interference—with knockout samples measuring below the assay's limit of detection—while effectively retaining oxytocin from the urine of wildtype mice. This method demonstrates good parallelism and spike recovery across multiple species (mice, dogs, sifakas, humans). Our results suggest that immunoassays of urine samples may be particularly susceptible to interference, even when using common extraction protocols, but that this interference can be successfully managed using a novel mixed-mode cation exchange extraction. These findings imply that previous conclusions based on urinary oxytocin measurements—especially those involving unextracted samples—may need to be reassessed.en_US
dc.language.isoenen_US
dc.publisherElsevier Ltden_US
dc.rightsCopyright © 2022 Elsevier Ltd. All rights reserved.en_US
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en_US
dc.subjectELISAen_US
dc.subjectKnockout miceen_US
dc.subjectMatrix interferenceen_US
dc.subjectOxytocinen_US
dc.subjectSolid-phase extractionen_US
dc.subjectUrineen_US
dc.titleWhat are oxytocin assays measuring? Epitope mapping, metabolites, and comparisons of wildtype & knockout mouse urineen_US
dc.typeArticleen_US
dc.identifier.eissn1873-3360
dc.contributor.departmentSchool of Anthropology, University of Arizonaen_US
dc.contributor.departmentCognitive Science Program, University of Arizonaen_US
dc.contributor.departmentLaboratory for the Evolutionary Endocrinology of Primates, University of Arizonaen_US
dc.contributor.departmentPsychology Department, University of Arizonaen_US
dc.contributor.departmentCollege of Veterinary Medicine, University of Arizonaen_US
dc.identifier.journalPsychoneuroendocrinologyen_US
dc.description.note12 month embargo; available online: 8 June 2022en_US
dc.description.collectioninformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.en_US
dc.eprint.versionFinal accepted manuscripten_US
dc.source.journaltitlePsychoneuroendocrinology
dc.source.volume143
dc.source.beginpage105827
dc.source.endpage
dc.source.countryEngland


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