Doping is not exclusive to human sports, it also occurs in the horseracing industry. Doping in horseracing has led to regulations banning performance-enhancing drugs and calls for an antidoping agency in the USA. However, as is the case in human sports, testing for prohibited substances is challenging. Scientists have now reported a new detection method that could help antidoping enforcers determine whether a horse has received a prohibited substance. Their findings were recently published in Analytical Chemistry.
To give their animals a potential advantage, some horse trainers or veterinarians might administer a single substance, a cocktail of substances or hormone mimicking compounds. A common class of prohibited substances is anabolic androgenic steroids (AAS). Conventional detection for AAS (and other prohibited substances) is achieved by the direct detection of target AAS or their characteristic metabolites using hyphenated techniques such as GC-MS or LC-MS. This approach, however, is not suitable for unknown designer steroids where reference materials are not available. Furthermore detection windows can be short as ASSs can be eliminated from the body rapidly, rendering the direct detection approach ineffective.
These researchers therefore utilized a targeted metabolomics approach. They chose a targeted metabolomics approach as the administration of AASs of the same class may trigger similar physiological responses or effects in the body, making it possible to detect AASs by monitoring changes in endogenous steroidal expression profiles.
The study employed a targeted metabolomics approach to detect the administration of steroidal aromatase inhibitors – compounds used to counteract negative side effects of AASs, namely androst-4-ene-3,6,17-trione (6-OXO) and androsta-1,4,6-triene-3,17-dione (ATD). The researchers analyzed total (free and conjugated) urinary concentrations of 31 endogenous steroids using GC-MS in two resting and two in-training thoroughbred geldings, which were treated with either 6-OXO or ATD. A control group of 28 in-training thoroughbred geldings, which were not treated with 6-OXO or ATD was used.
The researchers found seven potential biomarkers that could be used to differentiate between the urine samples of the control and treated groups. They also found that changes in the biomarkers, linked to the use of 6-OXO or ATD, could be detected for about 95–195 hours after injection; 2–2.5 times longer than conventional screening methods.
With further validation studies, targeted metabolomics could be used as a useful screening tool to detect the use of aromatase inhibitors in horses.
Sources: Chan GHM, Ho ENM, Leung DKK. Targeted Metabolomics Approach To Detect the Misuse of Steroidal Aromatase Inhibitors in Equine Sports by Biomarker Profiling. Anal. Chem. 88(1), 764–772 (2015); Pope Jrn HG, Wood RL, Rogol A. Adverse Health Consequences of Performance-Enhancing Drugs: An Endocrine Society Scientific Statement. Endocr Rev. 35(3), 341–375 (2013); Rooting out doping in racehorses