Biochemistry and physiology of anabolic hormones used for improvement of meat production

Maternal testosterone affects offspring telomerase activity in a long-lived seabird

Androgens are a group of steroid hormones that have long been proposed as a mechanism underpinning intergenerational plasticity. In birds, maternally allocated egg testosterone, one of the main androgens in vertebrates, affects a wide variety of offspring phenotypic traits but the mechanisms underlying this form of intergenerational plasticity are not yet well understood. Recent in vitro and animal model studies have shown that telomerase expression and activity are important targets of androgen signaling. The telomerase enzyme is known for its repair function on telomeres, the DNA-protein complexes at the ends of chromosomes that are involved in genomic integrity and cell aging. However, the role of maternal testosterone in influencing offspring telomerase levels in natural populations and its consequences on telomere length and potentially on offspring development is still unknown. Here, by experimentally modifying the level of egg testosterone in a natural population of yellow-legged gull (Larus michahellis), we show that chicks hatched from testosterone-treated eggs had higher average levels of telomerase and faster growth than controls during the first week of life. While testosterone-treated chicks also tended to have longer telomeres than controls at hatching this difference disappeared by day 6 of age. Overall, our results suggest that maternal testosterone may have a potential adaptive value by promoting offspring growth and presumably telomerase levels, as this enzyme plays other important physiological functions (e.g., stress resistance, cell signaling, or tissue genesis) besides telomere lengthening. Nonetheless, our knowledge of the potential adaptive function of telomerase in natural populations is scarce and so the potential pathways linking maternal hormones, offspring telomerase, and fitness should be further investigated.

Exposure to an androgenic agricultural pollutant does not alter metabolic rate, behaviour, or morphology of tadpoles

Globally, amphibian species are experiencing dramatic population declines, and many face the risk of imminent extinction. Endocrine-disrupting chemicals (EDCs) have been recognised as an underappreciated factor contributing to global amphibian declines. In this regard, the use of hormonal growth promotants in the livestock industry provides a direct pathway for EDCs to enter the environment-including the potent anabolic steroid 17β-trenbolone. Emerging evidence suggests that 17β-trenbolone can impact traits related to metabolism, somatic growth, and behaviour in non-target species. However, far less is known about possible effects of 17β-trenbolone on anuran species, particularly during early life stages. Accordingly, in the present study we investigated the effects of 28-day exposure to 17β-trenbolone (mean measured concentrations: 10 and 66 ng/L) on body size, body condition, metabolic rate, and anxiety-related behaviour of tadpoles (Limnodynastes tasmaniensis). Specifically, we measured rates of O₂ consumption of individual tadpoles as a proxy for metabolic rate and quantified their swimming activity and their time spent in the upper half of the water column as indicators of anxiety-related behaviour. Counter to our predictions based on effects observed in other taxa, we detected no effect of 17β-trenbolone on body size, metabolic rate, or behaviour of tadpoles; although, we did detect a subtle, but statistically significant decrease in body condition at the highest 17β-trenbolone concentration. We hypothesise that 17β-trenbolone may induce taxa-specific effects on metabolic function, growth, and anxiety-related behaviour, with anurans being less sensitive to disruption than fish, and encourage further cross-taxa investigation to test this hypothesis.

Quantitative analysis of total methenolone in animal source food by liquid chromatography-tandem mass spectrometry

Methenolone, an anabolic androgenic steroid, has been applied to improve the quality and protein content of meat in animal husbandry. However, the usage of methenolone in sports is banned for its doping effects. Several methods have been reported to monitor the content of methenolone in serum and urine samples, but a highly sensitive detection system has not been developed for the determination of methenolone in animal source food due to its constituent complexity. In this study, a novel detection system was developed to quantify the contents of both free and conjugated methenolone in animal source food including pork, beef, mutton, milk, and eggs by using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) coupled with delicate pretreatment procedures. The conjugated methenolone in the above food samples was released by dual enzyme digestion, and the total methenolone was extracted by 1% formic acid in acetonitrile, followed by the purification using a PRiME HLB column or QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) salt. The compound d₃ -methyltestosterone was used as an internal standard to minimize matrix interference. Finally, a wide linear range (0.5-20 μg/kg), low limit of detection (LOD) (0.3 μg/kg), good precision (<7% relative standard deviation), and high recovery (>90%) were obtained in the study of method validation. In summary, this analytical method provides a practicable monitoring tool for the quantification of methenolone in animal source food.

Expression of corticosteroid hormone receptors, prereceptors, and molecular chaperones in hypothalamic-pituitary-adrenal axis and adipose tissue after the administration of growth promoters in veal calves

The action of glucocorticoids on target tissues is regulated by the glucocorticoid and mineralocorticoid receptors (codified by the NR3C1 and NR3C2 gene, respectively). Moreover, the prereceptor system, represented by the hydroxysteroid 11-beta dehydrogenases (HSD11Bs), catalyzes the interconversion from active glucocorticoids into inactive compounds. This study aimed to determine whether the expression of the prereceptor system, the corticosteroid receptors, and the molecules regulating their intracellular trafficking (FKBP prolyl isomerase 4 and FKBP prolyl isomerase 5) could be regulated in the hypothalamic-pituitary-adrenal axis and in different type of adipose tissue of calves by the administration of dexamethasone in combination with estradiol or prednisolone. Research about the glucocorticoid effects on bovine target tissues may allow development of new diagnostic methods that use potential molecular biomarkers of glucocorticoid treatment. The administration of dexamethasone in combination with estradiol increased the gene expression of HSD11B1 (P < 0.01), HSD11B2 (P < 0.05), NR3C1 (P < 0.01), and NR3C2 (P < 0.01) in the adrenal glands; NR3C2 in the intramuscular adipose tissue (P < 0.01), and HSD11B1 in the subcutaneous adipose tissue (P < 0.01). Prednisolone administration increased the gene expression of HSD11B1 (P < 0.01), NR3C1 (P < 0.05), and NR3C2 (P < 0.05) in the adrenal glands and HSD11B1 (P < 0.01) in the subcutaneous adipose tissue. Interestingly, most of the examined tissues/organs showed a significant variation of FKBP5 gene expression after the administration of dexamethasone in combination with estradiol. So, these changes suggest that the FKBP5 gene expression could be a possible biomarker of the illegal dexamethasone administration in calves.