For the current European legislation, the chemical analysis of drug residues is the exclusive accepted method to identify animals illicitly treated with growth promoters. Glucocorticoids and their metabolites are no detectable by LC/MS-MS methods in biological fluids when the growth promoter administration is discontinued several days prior to the slaughtering. The aim of this study was to elucidate the effect on the expression of genes belonging to the glucocorticoid pathway in three types of skeletal muscle of calves treated with prednisolone or dexamethasone in combination with estradiol. A gene expression change of glucocorticoid receptors (NR3C1 and NR3C2), their chaperones molecules (FKBP prolyl isomerase 4 and 5, FKBP4 and 5) and pre-receptor system (hydroxysteroid 11-beta dehydrogenases 1 and 2, HSD11B1 and 2) may indicate potential biomarkers of glucocorticoid treatment. In the biceps brachii muscle, the administration of dexamethasone with estradiol increased HSD11B2 (P < 0.01) and NR3C2 (P < 0.01) gene expression, whereas prednisolone administration increased HSD11B1 transcript levels (P < 0.05). In the longissimus lumborum muscle, NR3C2 gene expression decreased following prednisolone administration (P < 0.05). FKBP5 gene expression decreased in all considered muscles of calves administered with dexamethasone and estradiol (P < 0.01), whereas increased in the longissimus lumborum (P < 0.01) and vastus lateralis (P < 0.05) muscle of prednisolone-treated group (P < 0.05). The opposite effect of dexamethasone and prednisolone appears very promising to develop a low-cost screening test, because the expression analysis of a unique gene in a given tissue may distinguish the dispensed molecules.

对于当前的欧洲法规，药物残留物的化学分析是识别未经生长促进剂非法治疗的动物的唯一公认方法。当在屠宰前几天停止施用生长促进剂时，通过LC / MS-MS方法无法在生物液体中检测到糖皮质激素及其代谢物。这项研究的目的是阐明在泼尼松龙或地塞米松联合雌二醇治疗的三种犊牛骨骼肌中，糖皮质激素途径基因表达的影响。糖皮质激素受体（NR3C1和NR3C2），其伴侣分子（FKBP脯氨酰异构酶4和5，FKBP4和5）的基因表达变化）和受体前系统（羟基类固醇11-β脱氢酶1和2，HSD11B1和2）可能表明糖皮质激素治疗的潜在生物标志物。在肱二头肌肌肉中，地塞米松与雌二醇一起使用可增加HSD11B2（P  <0.01）和NR3C2（P  <0.01）基因表达，而泼尼松龙可增加HSD11B1转录水平（P  <0.05）。在强直肌腰肌中，泼尼松龙给药后NR3C2基因表达降低（P  <0.05）。FKBP5在 泼尼松龙治疗组的所有犊牛肌肉中，地塞米松和雌二醇的基因表达均降低（P  <0.01），而腰长肌（P  <0.01）和股外侧肌（P <0.05）升高（P  <0.05） 。地塞米松和泼尼松龙的相反作用似乎很有希望发展低成本的筛选试验，因为在给定组织中独特基因的表达分析可以区分所分配的分子。