Proteomics for the detection of indirect markers of steroids treatment in bovine muscle

The Near-Infrared Spectroscopy of Ethanol-Fixed Tissues to Detect Illicit Treatments with Glucocorticoids in Bulls

This study aimed to set up indirect, rapid methods involving near infrared (NIR) spectroscopy analysis, to detect illicit treatments with glucocorticoids in bull. The ethanol fixation method (EtOH) was applied to 7 different tissues obtained from 20 Friesian bulls, 12 of which were experimentally administered with dexamethasone as part of a growth-promoting protocol for 60 days and slaughtered 26 days after the end of the treatment. A perfect discrimination was obtained for the 7 sampled tissues, considering a full UV-Vis-NIR range (350 ÷ 2500 nm), for both false positive and negative animals. The validated true positive and negative errors were zero for the longissimus thoracis muscle, 10% for the skin-dermis, 15% for the fat, 25% for the thymus gland and the semitendinosus muscle, 30% for the sternomandibularis muscle and 35% for the skin-hair. A multiple test on the most accessible tissues, that is, the thymus gland, the sternomandibularis muscle and fat, can be used as an alternative to provide indications about animals that have been subjected to illicit treatments. In the short space of three days from the slaughter, NIR spectroscopy of ETOH fixed tissues, would allow at least cost the detection of a probable illicit which could eventually be reported to health authorities for specific investigation in the frame of official controls.

Linking long noncoding RNAs (lncRNAs) and doping detection

In the fight against doping, efficient methods for detecting substances or biomarkers are still being improved. Indirect methods are an interesting alternative for the detection of substances misuse longitudinally. Here we shed lights the long non-coding RNAs (lncRNAs) as a possible biomarkers due to their characteristics such as tissue-specific expression and strict regulation.

TMT-Based Proteomics Profiling of Bovine Liver Underscores Protein Markers of Anabolic Treatments

Illegal use of growth promoter compounds in food production exposes consumers to health risk. Surveillance of such practices is based on direct detection of drugs or related metabolites by HPLC-MS/MS. Screening strategies focusing on indirect biological responses are considered promising tools to improve surveillance. In this study, an untargeted shotgun proteomics approach based on tandem mass tags (TMTs) is carried out to identify proteins altered in bovine liver after different anabolic treatments. Three controlled pharmacological treatments with dexamethasone, a combination of dexamethasone and clenbuterol, or a combination of sexual steroids (trenbolone and estradiol) are analyzed. Untargeted TMT analysis of liver digests by high resolution MS allowed for the relative quantification of proteins. Thanks to partial least squarediscriminant analysis, a set of proteins capable to classify animals treated with dexamethasone alone (11 proteins), or in combination with clenbuterol (13 proteins) are identified. No significant difference is found upon administration of sexual steroids. After relative quantification of candidate markers by parallel reaction monitoring (PRM), two predictive models are trained to validate protein markers. Finally, an independent animal set of control bulls and bulls treated with dexamethasone is analyzed by PRM to further validate a predictive model giving an accuracy of 100%.

Isobaric Tags for Relative and Absolute Quantification (iTRAQ)-Based Untargeted Quantitative Proteomic Approach To Identify Change of the Plasma Proteins by Salbutamol Abuse in Beef Cattle

Salbutamol, a selective β₂-agonist, endangers the safety of animal products as a result of illegal use in food animals. In this study, an iTRAQ-based untargeted quantitative proteomic approach was applied to screen potential protein biomarkers in plasma of cattle before and after treatment with salbutamol for 21 days. A total of 62 plasma proteins were significantly affected by salbutamol treatment, which can be used as potential biomarkers to screen for the illegal use of salbutamol in beef cattle. Enzyme-linked immunosorbent assay measurements of five selected proteins demonstrated the reliability of iTRAQ-based proteomics in screening of candidate biomarkers among the plasma proteins. The plasma samples collected before and after salbutamol treatment were well-separated by principal component analysis (PCA) using the differentially expressed proteins. These results suggested that an iTRAQ-based untargeted quantitative proteomic strategy combined with PCA pattern recognition methods can discriminate differences in plasma protein profiles collected before and after salbutamol treatment.

Differential protein expression profile in the hypothalamic GT1-7 cell line after exposure to anabolic androgenic steroids

The abuse of anabolic androgenic steroids (AAS) has been considered a major public health problem during decades. Supraphysiological doses of AAS may lead to a variety of neuroendocrine problems. Precisely, the hypothalamic-pituitary-gonadal (HPG) axis is one of the body systems that is mainly influenced by steroidal hormones. Fluctuations of the hormonal milieu result in alterations of reproductive function, which are made through changes in hypothalamic neurons expressing gonadotropin-releasing hormone (GnRH). In fact, previous studies have shown that AAS modulate the activity of these neurons through steroid-sensitive afferents. To increase knowledge about the cellular mechanisms induced by AAS in GnRH neurons, we performed proteomic analyses of the murine hypothalamic GT1-7 cell line after exposure to 17α-methyltestosterone (17α-meT; 1 μM). These cells represent a good model for studying regulatory processes because they exhibit the typical characteristics of GnRH neurons, and respond to compounds that modulate GnRH in vivo. Two-dimensional difference in gel electrophoresis (2D-DIGE) and mass spectrometry analyses identified a total of 17 different proteins that were significantly affected by supraphysiological levels of AAS. Furthermore, pathway analyses showed that modulated proteins were mainly associated to glucose metabolism, drug detoxification, stress response and cell cycle. Validation of many of these proteins, such as GSTM1, ERH, GAPDH, PEBP1 and PDIA6, were confirmed by western blotting. We further demonstrated that AAS exposure decreased expression of estrogen receptors and GnRH, while two important signaling pathway proteins p-ERK, and p-p38, were modulated. Our results suggest that steroids have the capacity to directly affect the neuroendocrine system by modulating key cellular processes for the control of reproductive function.

Urinary Concentrations of Steroids in Bulls under Anabolic Treatment by Revalor-XS® Implant

Despite the European ban of using anabolics in food-producing animals, growth promoters might still be illegally used in the European Union. To control the food chain and guarantee consumers' health, there is a need of highly sensitive analytical methods for the identification of marker residues of such treatments. In the present study, a group of bulls (n = 16) received trenbolone acetate (200 mg) and estradiol (40 mg) by a commercial ear implant during a time range of 71 days, and a second group (n = 16) was kept for control. The aim of the research was to measure the residual urinary concentrations of the administered drugs (β-trenbolone and β-estradiol), their main metabolites (α-trenbolone and α-estradiol), and possible alterations of the urinary profile of other endogenous hormones metabolically related. The analytical method was based on liquid chromatography-tandem mass spectrometry. Results showed average urinary concentrations of α-trenbolone and α-estradiol during treatment in the range of (0.81 ÷ 2.1) ng mL^-1 and (0.96 ÷ 4.4) ng mL^-1, respectively, whereas β-trenbolone and β-estradiol exhibit urinary concentrations lower than 0.22 ng mL^-1 in both cases. Data obtained from the urinary profiles of endogenous steroids indicate that they could be useful to indirectly detect the ongoing treatment.