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

The research paper described examines the changes in steroid profiles in the blood of healthy horses following simulation with ACTH, with the key finding being a more significant increase in certain metabolites, suggesting they may be more sensitive stress markers than cortisol.

Overview

• The study set out to investigate how steroids in horses’ blood plasma react to an Adrenocorticotropic hormone (ACTH) stimulation test, which is often used to assess the health and function of adrenal glands.
• The goal was to discover whether, in horses as in humans, steroids other than cortisol show a more pronounced response to such a test.
• 11 healthy horses were used for the study and were administered a synthetic ACTH intravenously.

Data Collection

• Ethylenediaminetetraacetic acid (EDTA) plasma samples were collected from the horses before the ACTH administration and 60 minutes after.
• The samples were then analyzed for multiple steroids including cortisol, 11-deoxycortisol, 21-deoxycortisol, cortisone, corticosterone, 11-deoxycorticosterone, androstenedione, 17-OH-progesterone, progesterone, and testosterone.
• A technique known as liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used for this analysis, proving to be an effective method.

Findings

• Following ACTH stimulation, there was a significant increase in the levels of cortisol, 11-deoxycortisol, cortisone, corticosterone, and 11-deoxycorticosterone.
• Interestingly, 11-deoxycorticosterone, 11-deoxycortisol, and corticosterone showed a more pronounced increase than cortisol, suggesting that they are potentially more sensitive biomarkers for stress in horses.

Conclusions

• The study concluded that LC-MS/MS is a viable method to measure glucocorticoids and related precursors or metabolites in equine plasma samples.
• It also highlighted the possibility of three metabolites -11-deoxycorticosterone, 11-deoxycortisol, and corticosterone- being more sensitive stress biomarkers in horses than cortisol. This new insight can potentially improve the assessment and management of stress in horses.