Immunohistochemistry by anti-cleaved-Lamin A: an improved approach to tackle the misuse of glucocorticoids in cattle

Gold immunochromatographic strip assay for the detection of triamcinolone acetonide and budesonide in milk

A monoclonal antibody against triamcinolone acetonide (TCA) and budesonide (BUD) was prepared using a hapten that was generated by introducing a carboxyl group into the structure of TCA. Based on the prepared monoclonal antibody, a gold nanoparticle-based lateral-flow immunoassay (GLFA) was developed with the ability to screen TCA and BUD in milk. The visible limits of detection of the GLFA for the analysis of TCA and BUD were 0.1 and 0.5 ng/mL with a cutoff value of 5 and 10 ng/mL, respectively, in milk. Average recoveries of TCA and BUD in milk were 92.0-102.2% and 96.0-98.8% with a good correlation between the results from the GLFA and LC-MS/MS analysis. These results demonstrated that the GLFA method for the rapid detection of TCA and BUD in milk samples is reliable and sensitive.

Validation of serum paraoxonase/arylesterase 1 (PON1) as a protein marker of illicit dexamethasone treatment in veal calves

The illicit use of dexamethasone and other glucocorticoids for cattle fattening in livestock production has been widely described; evidence for illegal treatments can be obtained by direct or indirect detection. In our previous study, we applied two-dimensional electrophoresis (2DE) to identify plasma protein markers of dexamethasone administration in veal calves. Comparison of 2DE maps obtained from blood samples before and after treatment showed the disappearance of two protein spots identified as serum paraoxonase/arylesterase 1 precursor (PON1). In the present study, we validated PON1 as a marker by analysing a larger number of samples treated with dexamethasone for illicit use. Analysis of samples from experimental treatment with other glucocorticoids, androgens and oestrogens confirmed that their influence on PON1 could be excluded. The specificity of the PON1 protein marker was verified on expected negative field samples to exclude interfering factors. However, there is poor statistical evidence to support a significant association between the outcome of PON1 and the considered variables. The results on field samples were compared with histological examination of the thymus as a biomarker of corticosteroid treatment monitored in the Italian histological plan for the control of growth promoters in animals. Two suspect cases were identified from two Piedmont farms where other animals had tested positive at histological examination. In conclusion, the absence of PON1 in the plasma of veal calves can indirectly reveal illicit dexamethasone treatment in individual animals and so identify suspect farms for further investigation. It is effective in a period ranging from 3 to about 10 days from illicit treatment, covering a time span that goes beyond the limits of official chemical controls and preceding histological controls on the thymus of slaughtered animals. PON1 detection in plasma can be coupled with other tests to identify illegal dexamethasone use on veal calf farms.

FKBP5 gene expression in skeletal muscle as a potential biomarker for illegal glucocorticoid treatment in veal calves

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.