1
|
Gerred K, Kapoor A. A fit-for-purpose validation of a commercial radioimmunoassay for measurement of human peripheral oxytocin. Biochem Biophys Rep 2024; 38:101666. [PMID: 38434143 PMCID: PMC10907144 DOI: 10.1016/j.bbrep.2024.101666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 12/07/2023] [Accepted: 02/12/2024] [Indexed: 03/05/2024] Open
Abstract
Oxytocin (OT) is a peptide hormone synthesized in the hypothalamus and released into systemic circulation or other areas of the brain. Its physiological roles include action as a hormone with stimulation of uterine contractions and that as a neuromodulator with involvement in social behaviors and regulation of mood. Its small size and low levels within biological matrices make it challenging to accurately measure. The goal of this study was to demonstrate the specificity of the antibody, sensitivity, and reproducibility of the Phoenix Pharmaceuticals (PP) OT radioimmunoassay (RIA) for use in human urine, serum, and saliva. Specificity of the antibody was assessed by high pressure liquid chromatography with ultraviolet (HPLC-UV) separation and assay of the fractions. Immunoreactivity was evaluated using the percent OT bound, and the fraction retention times were compared to the retention time of an intact OT standard to determine which fractions contained OT in the extracted samples. Reproducibility was assessed by running replicates of pools of each biomatrix over several assays. Sensitivity was assessed by repeated measurement of physiologically relevant low-concentration specimens. In all tested specimens the greatest reactivity in assay corresponded to the same fraction(s) as the OT standard. Only minimal reactivity was found in the other fractions, suggesting that in an unfractionated sample the antibody reacts mostly with intact OT. Reproducibility was acceptable for all specimens and the coefficient of variation (CV) ranged from 3.72 to 8.04% and 5.89-12.8%, for intra and inter-assay, respectively. The limits of quantitation (LOQ) were sufficient for measurement of normal values in urine (0.643 & 1.43 pg/mL), serum (1.90 pg/mL), and saliva pools (0.485 & 4.42 pg/mL). In conclusion, the PP OT RIA is specific and sensitive enough for reproducible measurement of intact OT in human peripheral biological matrices.
Collapse
Affiliation(s)
- Keenan Gerred
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, 1220 Capitol Court, Madison, WI, 53715, USA
| | - Amita Kapoor
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, 1220 Capitol Court, Madison, WI, 53715, USA
| |
Collapse
|
2
|
López-Arjona M, Cerón JJ, Mateo SV, Contreras-Aguilar MD, Martínez-Subiela S. Validation of two immunoassays for oxytocin measurements in human saliva. PLoS One 2024; 19:e0297539. [PMID: 38635553 PMCID: PMC11025789 DOI: 10.1371/journal.pone.0297539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 01/09/2024] [Indexed: 04/20/2024] Open
Abstract
The objective of this research was to develop and validate two immunoassays for oxytocin measurement in human saliva, one using a monoclonal and the other a polyclonal antibody against oxytocin, whose affinity for oxytocin was tested by an antibody mapping epitope analysis. These assays were analytically validated and used to compare oxytocin concentrations with those obtained with a commercial kit before and after the extraction or reduction/alkylation (R/A) treatments to saliva samples. The assays were also used to evaluate changes in salivary oxytocin concentrations following a physical effort and an induced psychological stress, which have previously been described as situations that cause an increase in salivary oxytocin. Both assays showed to be precise and accurate in the validation studies, and the antibodies used showed a defined binding region in case of the monoclonal antibody, whereas the polyclonal antibody showed binding events through all the oxytocin sequence. Although the monoclonal and polyclonal assays showed a positive correlation, they give results in a different range of magnitude. Both assays showed significant increases in oxytocin concentrations when applied after the physical effort and the psychological stress. This study shows that a variability in the reported values of oxytocin can occur depending on the assay and indicates that the use of different types of antibodies can give a different range of values when measuring oxytocin in saliva.
Collapse
Affiliation(s)
- Marina López-Arjona
- Department of Animal and Food Science, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, Spain
| | - José Joaquín Cerón
- Interdisciplinary Laboratory of Clinical Analysis of the University of Murcia (Interlab-UMU), Regional Campus of International Excellence ‘Campus Mare Nostrum’, University of Murcia, Murcia, Spain
| | - Sandra V. Mateo
- Molecular Inflammation Group, University Clinical Hospital Virgen de la Arrixaca, Biomedical Research Institute of Murcia (IMIB-Pascual Parrilla), Murcia, Spain
| | - María Dolores Contreras-Aguilar
- Interdisciplinary Laboratory of Clinical Analysis of the University of Murcia (Interlab-UMU), Regional Campus of International Excellence ‘Campus Mare Nostrum’, University of Murcia, Murcia, Spain
| | - Silvia Martínez-Subiela
- Interdisciplinary Laboratory of Clinical Analysis of the University of Murcia (Interlab-UMU), Regional Campus of International Excellence ‘Campus Mare Nostrum’, University of Murcia, Murcia, Spain
| |
Collapse
|
3
|
Gan HW, Leeson C, Aitkenhead H, Dattani M. Inaccuracies in plasma oxytocin extraction and enzyme immunoassay techniques. COMPREHENSIVE PSYCHONEUROENDOCRINOLOGY 2023; 15:100188. [PMID: 37360277 PMCID: PMC10285453 DOI: 10.1016/j.cpnec.2023.100188] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 06/01/2023] [Accepted: 06/04/2023] [Indexed: 06/28/2023] Open
Abstract
Numerous studies have reported extensive associations between plasma oxytocin (OXT) concentrations and various human physiological and neurobehavioral processes. Measurement of OXT is fraught with difficulty due to its low molecular weight and plasma concentrations, with no consensus as to the optimal conditions for pre-analytical sample extraction, standards for immunoassay validation or the ideal protease inhibitors to prevent OXT degradation. Previous attempts at determining the efficacy of various purification techniques such as solid phase extraction (SPE) or ultrafiltration have only utilized human plasma samples, making it difficult to dissect out whether the effect of interference comes from the extraction process itself or cross-reactivity with other proteins. By testing these on pure OXT solutions, we demonstrate poor recovery efficacy and reliability of reversed phase SPE (maximum 58.1%) and ultrafiltration (<1%) techniques, and the potential for the former to introduce interference into enzyme immunoassay (EIA) measurements. The clonality of antibodies used in EIA kits also potentially contributes to the differences in the readings obtained, and we validate an EIA kit which did not require pre-analytical sample extraction with low cross-reactivity and high reliability (intraclass correlation coefficient 0.980 (95% CI 0.896-0.999). Biochemical techniques used for measuring plasma OXT concentrations must therefore be internally validated prior to translation into clinical studies.
Collapse
Affiliation(s)
- Hoong-Wei Gan
- Genetics & Genomic Medicine Research and Training Department, UCL Great Ormond Street Institute of Child Health, 30 Guilford Street, London, WC1N 1EH, United Kingdom
- Great Ormond Street Hospital for Children NHS Foundation Trust, Great Ormond Street, London, WC1N 3JH, United Kingdom
| | - Clare Leeson
- Great Ormond Street Hospital for Children NHS Foundation Trust, Great Ormond Street, London, WC1N 3JH, United Kingdom
| | - Helen Aitkenhead
- Great Ormond Street Hospital for Children NHS Foundation Trust, Great Ormond Street, London, WC1N 3JH, United Kingdom
| | - Mehul Dattani
- Genetics & Genomic Medicine Research and Training Department, UCL Great Ormond Street Institute of Child Health, 30 Guilford Street, London, WC1N 1EH, United Kingdom
- Great Ormond Street Hospital for Children NHS Foundation Trust, Great Ormond Street, London, WC1N 3JH, United Kingdom
| |
Collapse
|
4
|
Wirobski G, Range F, Graat EA, Palme R, Deschner T, Marshall-Pescini S. Similar behavioral but different endocrine responses to conspecific interactions in hand-raised wolves and dogs. iScience 2023; 26:105978. [PMID: 36756369 PMCID: PMC9900400 DOI: 10.1016/j.isci.2023.105978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 10/28/2022] [Accepted: 01/11/2023] [Indexed: 01/15/2023] Open
Abstract
Domestication has altered dogs' conspecific social organization compared to their closest, non-domesticated relatives, gray wolves. Wolves live in packs whose survival depends on coordinated behavior, but dogs rely less on conspecifics, which predicts greater cohesiveness in wolf than dog packs. Endocrine correlates such as oxytocin and glucocorticoids modulate group cohesion resulting in species-specific differences in social interactions. We found that although wolves' and dogs' observable behavioral reactions to a territorial threat and separation from the pack were similar, hormonal responses differed. Wolves' but not dogs' oxytocin and glucocorticoid concentrations correlated positively with territorial behaviors and only wolves showed increased glucocorticoid concentrations after separation from their pack. Together, results suggest stronger emotional activation to threats to group integrity in wolves than dogs, in line with their socio-ecology.
Collapse
Affiliation(s)
- Gwendolyn Wirobski
- Domestication Lab, Konrad-Lorenz-Institute for Ethology, University of Veterinary Medicine, Veterinaerplatz 1, 1210 Vienna, Austria
- Corresponding author
| | - Friederike Range
- Domestication Lab, Konrad-Lorenz-Institute for Ethology, University of Veterinary Medicine, Veterinaerplatz 1, 1210 Vienna, Austria
| | - Evelien A.M. Graat
- Domestication Lab, Konrad-Lorenz-Institute for Ethology, University of Veterinary Medicine, Veterinaerplatz 1, 1210 Vienna, Austria
| | - Rupert Palme
- Unit of Physiology, Pathophysiology and Experimental Endocrinology, Department of Biomedical Sciences, University of Veterinary Medicine, Veterinaerplatz 1, 1210 Vienna, Austria
| | - Tobias Deschner
- Institute of Cognitive Science, Comparative BioCognition, University of Osnabrück, Artilleriestrasse 34, 49076, Osnabrück, Germany
| | - Sarah Marshall-Pescini
- Domestication Lab, Konrad-Lorenz-Institute for Ethology, University of Veterinary Medicine, Veterinaerplatz 1, 1210 Vienna, Austria
| |
Collapse
|
5
|
Gnanadesikan GE, Hammock EAD, Tecot SR, Lewis RJ, Hart R, Carter CS, MacLean EL. What are oxytocin assays measuring? Epitope mapping, metabolites, and comparisons of wildtype & knockout mouse urine. Psychoneuroendocrinology 2022; 143:105827. [PMID: 35714438 PMCID: PMC9807061 DOI: 10.1016/j.psyneuen.2022.105827] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 06/02/2022] [Accepted: 06/03/2022] [Indexed: 01/04/2023]
Abstract
Oxytocin 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.
Collapse
Affiliation(s)
- Gitanjali E Gnanadesikan
- School of Anthropology, University of Arizona, Tucson, AZ 85721, USA; Cognitive Science Program, University of Arizona, Tucson, AZ 85721, USA.
| | - Elizabeth A D Hammock
- Department of Psychology and Program in Neuroscience, The Florida State University, Tallahassee, FL 32306, USA
| | - Stacey R Tecot
- School of Anthropology, University of Arizona, Tucson, AZ 85721, USA; Laboratory for the Evolutionary Endocrinology of Primates, University of Arizona, Tucson, AZ 85721, USA
| | - Rebecca J Lewis
- Department of Anthropology, University of Texas at Austin, Austin, TX 78712, USA
| | - Russ Hart
- Arbor Assays, Ann Arbor, MI 48108, USA; 21 Grams Assays Inc, Chelsea, MI 48118, USA
| | - C Sue Carter
- Kinsey Institute, Indiana University, Bloomington, IN 47405, USA; Department of Psychology, University of Virginia, Charlottesville, VA 22903, USA
| | - Evan L MacLean
- School of Anthropology, University of Arizona, Tucson, AZ 85721, USA; Cognitive Science Program, University of Arizona, Tucson, AZ 85721, USA; Psychology Department, University of Arizona, Tucson, AZ 85721, USA; College of Veterinary Medicine, University of Arizona, Tucson, AZ 85721, USA
| |
Collapse
|
6
|
Pichugina YA, Maksimova IV, Berezovskaya MA, Afanaseva NA, Pichugin AB, Dmitrenko DV, Timechko EE, Salmina AB, Lopatina OL. Salivary oxytocin in autistic patients and in patients with intellectual disability. Front Psychiatry 2022; 13:969674. [PMID: 36506430 PMCID: PMC9729552 DOI: 10.3389/fpsyt.2022.969674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 10/27/2022] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND Assessing the role of oxytocin (OT) in the regulation of social interaction is a promising area that opens up new opportunities for studying the mechanisms of developing autism spectrum disorders (ASD). AIM To assess the correlation between the salivary OT level and age-related and psychopathological symptoms of children with intellectual disability (ID) and ASD. METHODS We used the clinical and psychopathological method to assess the signs of ASD based on International Classification of Diseases (ICD-10), the severity of ASD was specified by the selected Russian type version "Childhood Autism Rating Scale" (CARS). Patients of both groups had an IQ score below 70 points. RESULTS The median and interquartile range of salivary OT levels in patients with ID and ASD were 23.897 [14.260-59.643] pg/mL, and in the group ID without ASD - Me = 50.896 [33.502-83.774] pg/mL (p = 0.001). The severity of ASD on the CARS scale Me = 51.5 [40.75-56.0] score in the group ID with ASD, and in the group ID without ASD-at the level of Me = 32 [27.0-38.0] points (p < 0.001). According to the results of correlation-regression analysis in the main group, a direct correlation was established between salivary OT level and a high degree of severity of ASD Rho = 0.435 (p = 0.005). There was no correlation between the salivary OT level and intellectual development in the group ID with ASD, Rho = 0.013 (p = 0.941) and we have found a relationship between oxytocin and intellectual development in the group ID without ASD, Rho = 0.297 (p = 0.005). There was no correlation between salivary OT and age, ASD and age. CONCLUSION The results of this study indicate that patients in the group ID with ASD demonstrated a lower level of salivary OT concentration and a direct relationship between the maximum values of this indicator and the severity of autistic disorders, in contrast to patients in the group ID without ASD.
Collapse
Affiliation(s)
- Yulia A Pichugina
- Department of Psychiatry and Narcology, Prof. V.F. Voino-Yasenetsky Krasnoyarsk State Medical University, Krasnoyarsk, Russia
| | - Irina V Maksimova
- Department of Psychiatry and Narcology, Prof. V.F. Voino-Yasenetsky Krasnoyarsk State Medical University, Krasnoyarsk, Russia
| | - Marina A Berezovskaya
- Department of Psychiatry and Narcology, Prof. V.F. Voino-Yasenetsky Krasnoyarsk State Medical University, Krasnoyarsk, Russia
| | - Natalya A Afanaseva
- Department of Psychiatry and Narcology, Prof. V.F. Voino-Yasenetsky Krasnoyarsk State Medical University, Krasnoyarsk, Russia
| | - Aleksey B Pichugin
- Social Neuroscience Laboratory, Prof. V.F. Voino-Yasenetsky Krasnoyarsk State Medical University, Krasnoyarsk, Russia
| | - Diana V Dmitrenko
- Department of Medical Genetics of Clinical Neurophysiology, Institute of Postgraduate Education, Prof. V.F. Voino-Yasenetsky Krasnoyarsk State Medical University, Krasnoyarsk, Russia.,Medical Genetic Laboratory, Prof. V.F. Voino-Yasenetsky Krasnoyarsk State Medical University, Krasnoyarsk, Russia
| | - Elena E Timechko
- Medical Genetic Laboratory, Prof. V.F. Voino-Yasenetsky Krasnoyarsk State Medical University, Krasnoyarsk, Russia
| | - Alla B Salmina
- Laboratory of Experimental Brain Cytology, Department of Brain Studies, Research Center of Neurology, Moscow, Russia.,Research Institute of Molecular Medicine and Pathobiochemistry, Prof. V.F. Voino-Yasenetsky Krasnoyarsk State Medical University, Krasnoyarsk, Russia
| | - Olga L Lopatina
- Social Neuroscience Laboratory, Prof. V.F. Voino-Yasenetsky Krasnoyarsk State Medical University, Krasnoyarsk, Russia.,Department of Biochemistry, Medical, Pharmaceutical and Toxicological Chemistry, Prof. V.F. Voino-Yasenetsky Krasnoyarsk State Medical University, Krasnoyarsk, Russia
| |
Collapse
|
7
|
Life experience rather than domestication accounts for dogs' increased oxytocin release during social contact with humans. Sci Rep 2021; 11:14423. [PMID: 34257399 PMCID: PMC8277847 DOI: 10.1038/s41598-021-93922-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 06/24/2021] [Indexed: 12/04/2022] Open
Abstract
Dogs’ increased human-directed sociability compared to wolves may be the result of increased oxytocin system activity and decreased stress responses, but comparative studies accounting for life experience are lacking. We compared hand-raised, pack-living wolves’ and dogs’ behavior and hormone concentrations after interacting with a closely bonded and a familiar human. Both preferred the bonded partner, but dogs showed less variability in human-directed sociability than wolves. Physical contact was not associated with oxytocin but correlated positively with glucocorticoids in the pack-living animals when the human was not bonded. To clarify the role of life experience, we tested pet dogs and found that oxytocin concentrations correlated positively with physical contact with their owners, while glucocorticoids remained unaffected. Results show that, given similar experiences, wolf-dog differences in human-directed sociability and associated hormones are subtle and indicate that factors related to life as a pet dog rather than domestication account for oxytocin release during human–dog interactions.
Collapse
|