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Frontiers in physiology2024; 15; 1370557; doi: 10.3389/fphys.2024.1370557

Changes in salivary oxytocin in response to biologically-relevant events in farm animals: method optimization and usefulness as a biomarker.

Abstract: Although best known for its established role in mediating parturition and lactation, the highly-conserved neuropeptide hormone oxytocin also mediates a range of social and stress-buffering processes across mammalian species. Measurements of peripheral oxytocin in plasma have long been considered the gold standard, but there is increasing interest in developing methods to detect oxytocin non-invasively in saliva. Here we present an analytical and biological validation of a novel method to measure salivary oxytocin (sOXT) in an under-studied research group: farm animals. Given their similarities with humans in physiology and brain, methods that can identify valued social contexts and social relationships for farm animals and investigate their function have implications for clinical research as well as for animal welfare science. However, current methods to measure sOXT vary greatly in terms of sample collection, pre-measurement processing and measurement and more rigorous standardization and validation of methods is critical to determine the utility of sOXT as a biomarker of salient social events and related emotions. We optimized a method for extracting sOXT in pigs and horses and measured sOXT in extracted samples using a commercially available enzyme-immunoassay. Extracted samples were within acceptable ranges for precision (CVs < 15.2%), parallelism and recovery (94%-99%) in both species. Salivary oxytocin increased in samples collected during birth in pigs (Friedmans, = 0.02) and horses (Wilcoxon, = 0.02). Salivary oxytocin tended to decrease in sows after a 90-min separation from their piglets (Wilcoxon, = 0.08). We conclude that sOXT can be reliably linked to physiological events that are mediated by the oxytocinergic system in farm animals, but that more research is needed to determine whether sOXT is a reliable trait marker for more general oxytocin system activation in response to salient social events. Future research should characterize how individual attributes and salivary parameters influence sOXT measurement and should emphasize reporting of analytical and biological validations to increase acceptance of non-invasive methods.
Copyright © 2024 Moscovice, Sobczak, Niittynen, Koski and Gimsa.
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Publication Date: 2024-03-19 PubMed ID: 38567114PubMed Central: PMC10985263DOI: 10.3389/fphys.2024.1370557Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This study presents an optimized method for measuring oxytocin, a hormone related to social and stress processes, in the saliva of farm animals, specifically pigs and horses. It also identifies the link between this “salivary oxytocin” and significant biological events. Additional research is recommended to confirm the use of salivary oxytocin as a marker for oxytocin activation in response to meaningful social events.

Introduction

  • The research aimed to develop and validate a non-invasive method for measuring oxytocin levels in farm animals’ saliva.
  • Oxytocin is a hormone renowned for its function in enabling childbirth and lactation, but it also plays a role in various social and stress-coping procedures.
  • Oxytocin levels are usually measured in the plasma, the liquid part of the blood, which is considered the standard procedure, but researchers have been exploring ways to detect it in the saliva as a non-invasive measure.

Method Optimisation and Validation

  • The researchers standardized a method for extracting oxytocin from the saliva of pigs and horses and assessed the obtained samples using a commercially available enzyme immunoassay – a technique to measure antibody-antigen reaction.
  • The extracted samples demonstrated acceptable precision, parallelism, and recovery rates in both species. Parallelism involves comparing the results of the immunoassay to a standard, while recovery is the ability to extract the same sample multiple times with similar results.

Biological Relevance and Biomarker Utility

  • The project determined that salivary oxytocin levels increased during childbirth in both pigs and horses.
  • In contrast, these levels tended to decrease in sows after they were separated from their piglets for 90 minutes.
  • These findings suggest a correlation between oxytocin levels in the saliva and biologically significant events modulated by the oxytocinergic system.
  • However, further research is required to establish salivary oxytocin as a reliable indicator of the general activation of the oxytocin system in response to significant social events.

Future Research Recommendations

  • The paper advocates for more research to understand how individual characteristics and salivary parameters influence the measurement of salivary oxytocin.
  • The investigators also stress the importance of reporting analytical and biological authenticity to encourage the acceptance of non-invasive procedures.

Cite This Article

APA
Moscovice LR, Sobczak B, Niittynen T, Koski SE, Gimsa U. (2024). Changes in salivary oxytocin in response to biologically-relevant events in farm animals: method optimization and usefulness as a biomarker. Front Physiol, 15, 1370557. https://doi.org/10.3389/fphys.2024.1370557

Publication

Frontiers in physiology
ISSN: 1664-042X
NlmUniqueID: 101549006
Country: Switzerland
Language: English
Volume: 15
Pages: 1370557
PII: 1370557

Researcher Affiliations

Moscovice, Liza R
  • Psychophysiology Working Group, Research Institute for Farm Animal Biology, Dummerstorf, Germany.
Sobczak, Birgit
  • Psychophysiology Working Group, Research Institute for Farm Animal Biology, Dummerstorf, Germany.
Niittynen, Taru
  • Organismal and Evolutionary Biology Research Programme, University of Helsinki, Helsinki, Finland.
Koski, Sonja E
  • Organismal and Evolutionary Biology Research Programme, University of Helsinki, Helsinki, Finland.
Gimsa, Ulrike
  • Psychophysiology Working Group, Research Institute for Farm Animal Biology, Dummerstorf, Germany.

Conflict of Interest Statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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