Plasma steroid profiles before and after ACTH stimulation test in healthy horses

• Published in: Domestic animal endocrinology Vol. 72; p. 106419
• Main Authors: Kirchmeier, A., van Herwaarden, A.E., van der Kolk, J.H., Sauer, F.J., Gerber, V.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-07-2020
• Subjects: ACTH stimulation test; Equine steroid profiles; Equine stress marker; Liquid chromatography–tandem mass spectrometry (LC-MS/MS); Equine steroid profiles; Liquid chromatography–tandem mass spectrometry (LC-MS/MS); ACTH stimulation test; Equine stress marker
• ISSN: 0739-7240; 1879-0054
• DOI: 10.1016/j.domaniend.2019.106419

This study describes steroid profiles in equine plasma before and after ACTH stimulation. In human medicine, other steroids have been shown to have a more pronounced reaction to an ACTH stimulation test than cortisol. This study aimed to determine if the same was true for the horse. A total of 11 clinically healthy horses were selected for this study. Ethylenediaminetetraacetic acid plasma samples were taken before and 60 min after stimulation with 1 μg/kg BW of synthetic ACTH administered intravenously. The samples were analyzed for cortisol, 11-deoxycortisol, 21-deoxycortisol, cortisone, corticosterone, 11-deoxycorticosterone, androstenedione, 17-OH-progesterone, progesterone, and testosterone with a liquid chromatography–tandem mass spectrometry (LC-MS/MS). Cortisol, 11-deoxycortisol, cortisone, corticosterone, and 11-deoxycorticosterone showed a significant increase after ACTH stimulation. In conclusion, the LC-MS/MS represents a viable method to measure glucocorticoids and related precursors or metabolites in equine plasma samples. In addition, we were able to show a more pronounced increase of 11-deoxycorticosterone, 11-deoxycortisol, and corticosterone compared with cortisol. These 3 metabolites could potentially serve as more sensitive biomarkers for stress in horses than cortisol.
•Liquid chromatography–tandem mass spectrometry is a viable method to measure steroids in equine plasma.•Adrenocorticotropic hormone stimulates different pathways of steroid biosynthesis in horses.•11-Deoxycorticosterone, 11-deoxycortisol, and corticosterone might be potential new stress markers in horses.