Revealing the influence of glucocorticoid treatment on the excretion of anabolic-androgenic steroids in horses through in vitro digestive simulations and an in vivo case study.

Res Vet Sci. 2017 Dec;115:132-137. doi: 10.1016/j.rvsc.2017.02.024. Epub 2017 Feb 24. Decloedt A1, Damen S2, Vanhaecke L3. Author information 1 Ghent University, Laboratory of Chemical Analysis, Faculty of Veterinary Medicine, Department of Veterinary Public Health and Food Safety, 133 Salisburylaan, B-9820 Merelbeke, Belgium; Ghent University, Laboratory of Biochemistry and Brewing, Faculty of Bioscience Engineering, Department of Applied Biosciences, 1 Valentin Vaerwyckweg, B-9000 Ghent, Belgium. 2 Ghent University, Laboratory of Chemical Analysis, Faculty of Veterinary Medicine, Department of Veterinary Public Health and Food Safety, 133 Salisburylaan, B-9820 Merelbeke, Belgium. 3 Ghent University, Laboratory of Chemical Analysis, Faculty of Veterinary Medicine, Department of Veterinary Public Health and Food Safety, 133 Salisburylaan, B-9820 Merelbeke, Belgium. Electronic address: Lynn.Vanhaecke@ugent.be. Abstract Anabolic-androgenic steroids (AAS) are strictly forbidden in equine sports because of their stimulating effect on muscle growth and performance. Nevertheless, low levels of AAS have been found in some horses, untreated with AAS. Glucocorticoids (GC), used as an anti-inflammatory therapy and structurally related to AAS, might play a role in this phenomenon. In order to unravel this possible correlation the influence of glucocorticoid treatment on the excretion of AAS was studied both in vivo and in vitro. In vivo effects were investigated by analysing urine samples collected from a gelding treated with betamethasone. Additionally, multiple in vitro digestion simulations were set up, according to a previously validated protocol, to study the possibility of a direct biotransformation of glucocorticoids to AAS, by the microbiota of the equine hindgut. Urine and in vitro digestion samples were extracted and analysed with UHPLC-MS/MS and UHPLC-Orbitrap-HRMS analytical methods. A significant influence on the urinary excretion of α-testosterone (αT), β-testosterone (βT) and androsta-1,4-diene-3,17-dione (ADD) was seen. αT-concentrations up to 20ng/mL were detected. ADD was not found before treatment but could be detected post-treatment. Cortisone and cortisol also peaked (>30ng/mL) between day 37 and 48 post-treatment. The in vitro digestion results however revealed no direct biotransformation of glucocorticoids to AAS by the microbiota of the equine hindgut. This study shows that a glucocorticoid treatment can disrupt the synthesis and excretion of AAS, not by direct biotransformation upon gastrointestinal digestion, but more likely by influencing the hypothalamic-pituitary-adrenal axis. KEYWORDS: Biological transformation; Doping; Glucocorticoids; Sport horses; Steroids PMID: 28342428 DOI: 10.1016/j.rvsc.2017.02.024