Publication: Could estrogen and progesterone be used as biomarkers in swine saliva?
Authors
Armando Quintero Moreno, María Serrano Albal, María D. Barceló Campoy, Raquel Romar, Joaquín Gadea
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Publisher
Colégio Brasileiro de Reprodução Animal - CBRA
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DOI
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info:eu-repo/semantics/lecture
Description
© 2024 Los autores. This manuscript version is made available under the CC-BY 4.0 license http://creativecommons.org/licenses/by/4.0/
This document is the Published Manuscript, version of a Published Work that appeared in final form in Animal Reproduction.
Abstract
Estradiol (17-beta-estradiol, E2) and progesterone (P4) play a key role in the regulation of the estrous cycle, and
their determination is performed in blood plasma (BP) or serum. Blood collection in pigs is stressful for the
animals and requires immobilization for an optimal collection. Saliva is also useful for monitoring ovulation,
assessing ovarian function, or testing for pregnancy. Furthermore, its collection is more convenient and less
invasive for frequent sampling. Despite these advantages, studies on sex hormones in swine saliva are very
scarce, which limits their practical application. In the present study, the levels of E2 and P4 in saliva and BP
were obtained to determine the potential association between them, and to verify if saliva could be used
to monitor the reproductive status in sows. Twenty-seven hormonally synchronized (PgF2α, eCG and hCG)
sows were sampled 24 hours after the onset of estrus and artificially inseminated. For saliva sampling, sows
chewed a zip tied sponge for 15 to 30 seconds; then the sponge was removed from the zip tie and placed in a
tube designed for human saliva collection (Salivette®). In the laboratory, the saliva was centrifuged at 1000
rpm for 5 min and stored in 1.5 ml cryovials at -80ºC until analysis. Blood sample was collected from the
external jugular vein under general anesthesia. Hormone concentrations in saliva and BP were determined
using a solid-phase, enzyme-labeled competitive chemiluminescent enzyme immunoassay (Immulite 1000;
Siemens Healthineers). E2 and P4 were detected in all plasma samples, but P4 was only detected in 12/27
(44.4%) saliva samples and 100% of plasma samples (minimum detection level >0.20 ng/ml). P4 levels were
higher in plasma than in saliva (8.67±1.94 vs. 1.16±0.74 ng/ml, Wilcoxon non-parametric test, p=0.004), while
E2 levels (54.09±6.52 vs. 78.73±8.24 pg/ml, p=0.003) and E2/P4 ratio (25.71±9.76 vs. 251.31±48.39, p=0.002)
were higher in saliva than in plasma. The use of Bland-Altman plot to compare plasma and saliva values
for E2, P4 and ratio E2/P4 confirmed the inconsistency of the results. This fact confirms that saliva is not a
suitable fluid to determine P4 and E2 in pigs with this methodology, a fact that was later confirmed when
saliva and BP were obtained from 2 additional pregnant sows (> 60 days of gestation), obtaining P4 values
in saliva with a very low value (2.11 ng/ml) when in plasma was 23.38 ng/ml, while E2 was higher in saliva
than in plasma (86.1 vs. 15.70 pg/ml). Further studies are needed to clarify the inconsistency of these results
in order to use a less invasive technique such as saliva sampling to determine reproductive hormones and
assess the reproductive status of gilts and sows.
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Citation
Animal Reproduction, 2024, Vol. 21 (3)
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