Role of FKBP51 in the modulation of the expression of the corticosteroid receptors in bovine thymus following glucocorticoid administration.

The aim of this work was to study the transcriptional effects of glucocorticoids on corticosteroid hormone receptors, prereceptors (11β-hydroxysteroid dehydrogenase 1 and 2, 11β-HSD1 and 2), and chaperones molecules regulating intracellular trafficking of the receptors (FKBP51 and FKBP52) in thymus of veal calves. Moreover, the expression of FKBP51 and FKBP52 gene were investigated in beef cattle thymus. In the cervical thymus of veal calves, dexamethasone administration in combination with estradiol decreased FKBP51 expression (P < 0.01). The same treatment increased mineralocorticoid receptor (MR) (P < 0.01) and 11β-HSD1 expression (P < 0.05) compared to control group in the cervical thymus of veal calves. The thoracic thymus of veal calves treated with dexamethasone and estradiol showed a decrease of FKBP51 (P < 0.05), FKBP52 (P < 0.05), glucocorticoid receptor (P < 0.05), and MR expression (P < 0.05) compared to control group in the thoracic thymus of veal calves. The gene expression of FKBP51 decreased both in cervical (P < 0.01) and thoracic thymus (P < 0.01) of beef cattle treated with dexamethasone and estradiol. In addition, also prednisolone administration reduced FKBP51 expression in the cervical thymus (P < 0.01) and in the thoracic thymus of beef cattle (P < 0.01). The gene expression of FKBP52 increased only in the cervical thymus following dexamethasone administration (P < 0.01). The decrease of FKBP51 gene expression in thymus could be a possible biomarker of illicit dexamethasone administration in bovine husbandry. Moreover, so far, an effective biomarker of prednisolone administration is not identified. In this context, the decrease of FKBP51 gene expression in thymus of beef cattle following prednisolone administration could play an important role in the indirect identification of animals illegally treated with prednisolone.