Some bodybuilders and athletes use trenbolone esters for their muscle-building and otherwise performance-enhancing effects.  Such use is illegal in the United States and many other countries. The DEA classifies trenbolone and its esters as Schedule III controlled substances under the Controlled Substances Act .  Trenbolone is classified as a Schedule 4 drug in Canada  and a class C drug with no penalty for personal use or possession in the United Kingdom .  Use or possession of steroids without a prescription is a crime in Australia . 
The abuse of anabolic steroid hormones in human sports and animal husbandry is an ubiquitous problem and therefore a tight control program in both areas is very important. Within these control programs, hormone residues are detected by immunoassays or chromatographical methods in combination with mass spectrometry. With these methods, all known substances can be detected; yet new xenobiotic growth promoters and new ways of application are difficult to detect. Therefore it is important to develop new sensitive screening methods to enable an efficient control for misused anabolic substances. The detection of their physiological action is a promising approach. Anabolic steroid hormones directly influence the expression of specific genes and thus the analysis of the transcriptome of different target tissues and matrices is of great interest. This review describes our recent efforts made concerning the analysis of gene expression changes in different tissues, different species and under different anabolic treatments.