Modification of mRNA expression after treatment with anabolic agents and the usefulness for gene expression-biomarkers.

With this feasibility study a first step towards a new monitoring system for hormonal treatments was done. Screening of regulation and function of anabolic sex steroids via modified gene expression of mRNA in various tissues could be a new approach to trace treatments with unknown drugs or newly combined cocktails. In the study, uterus, liver and muscle tissue from 24 cycling heifers were taken after the animals were treated either with Melengestrol Acetate (MGA), Finaplix-H (200 mg Trenbolone Acetate) or Ralgro (36 mg Zeranol) for 56 days. In every treatment group always two heifers were given 1-fold, 3-fold and 10-fold doses of the standard preparation, the control group without any treatment consisted of two animals. The different tissue gene expression profiles were investigated via the candidate gene approach. Totally 57 candidate genes were selected according to their functionality by screening the actual literature and composed to functional groups: angiogenesis, apoptosis, cell cycle, endocrine factors, energy metabolism, inflammatory factors, muscle function, oncogenes, protein metabolism and transcription factors. Gene expression was measured using quantitative real-time RT-PCR (qRT-PCR) technology. From 24 tested candidate genes in the liver, 17 showed a significant regulation. Eight genes were influenced by MGA, 9 by Finaplix-H, and 4 by Ralgro. For the muscle tissue 19 genes were tested with the result that in the neck muscle 11 genes were regulated and in the hind limb muscle 8 genes. In the neck 5 genes were affected by MGA, 6 by Finaplix-H and 3 by Ralgro. Only 2 genes were influenced by MGA in the hind limb muscle. Finaplix-H affected 6 and Ralgro 4 genes. In the uterus 29 target genes were tested and 13 were significantly influenced by the anabolic sex steroids. Under Finaplix-H treatment eight target genes were regulated and Ralgro and MGA showed a significant regulation in four target genes. The highest gene expression changes under anabolic treatment were observed in the uterus. The analyzed genes showed significant regulations but further studies, testing different animal husbandry conditions will be needed to identify meaningful expression patterns for the different tissues. With the investigation of the regulation and possible function of anabolic sex steroids via gene expression, a preparatory work for the development of an expression pattern for drug screening was made.