17β‐Trenbolone exposure programs metabolic dysfunction in larval medaka

Abstract

Here, we used physiological and transcriptomic analyses to evaluate the effects of 17β-trenbolone (TB) on metabolism during the early life stage of medaka (Oryzias latipes). In the physiological experiments, sex reversal rates increased continuously in proportion to TB concentrations (2-100 ng/L), and were 100% (all males) in the 200 ng/L treatment group. TB caused a significant increase in the gonadosomatic index of females at concentrations of 60 and 100 ng/L. These females exhibited swollen abdomens and decreased egg production and fertility. Significant increases were observed in the body mass index of these females. TB caused decreased fertility in males at concentrations >20 ng/L, but no other effects were observed. In the transcriptomic (microarray) experiments, larvae were exposed to TB for up to 7 d. Analyses using the KEGG Orthology Database revealed that predominant categories of significantly upregulated genes included "lipid metabolism" and "metabolism of terpenoids and polyketides." Thirteen genes (including those for hydroxymethylglutaryl-CoA synthase, cytoplasmic synthase, and lanosterol synthase) related to cholesterol biosynthesis via the mevalonate pathway were highlighted in these categories. Reverse transcriptase-polymerase chain reaction analyses were consistent with the microarray results, in terms of the direction and magnitude of change to gene expression. Among the downregulated genes, angiopoietin-like 4 and mitochondrial uncoupling protein 1, which are inversely correlated with obesity, were detected in the TB treatments. In conclusion, the results suggest that the exposure of females to TB during the early life stage may cause metabolic dysfunctions, including obesity and disrupted cholesterol synthesis. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1539-1551, 2016.

A critical review of the environmental occurrence and potential effects in aquatic vertebrates of the potent androgen receptor agonist 17β‐trenbolone

“…Production of phenotypic males was more sensitive in zebrafish (100% males at 0.05 μg/L) compared with medaka (no effect at 0.05 μg/L). Mizukami‐Murata et al () confirmed in a developmental study (exposure 0–60 d post fertilization) the relative insensitivity of Japanese medaka, with phenotypic masculinization occurring only at concentrations >0.1 μg 17β‐trenbolone/L. The enhanced sensitivity to 17β‐trenbolone during sex differentiation in zebrafish could be a consequence of the extended period of juvenile hermaphroditism that occurs in this species compared with medaka.…”

“…A number of studies have evaluated changes in gene expression in 17β‐trenbolone‐exposed fish at different life stages, using both targeted (polymerase chain reaction [PCR]) and nontargeted (e.g., microarray) techniques (Hook et al ; Garcia‐Reyero et al ; Dorts et al ; Ekman et al ; Brockmeier et al ; Leet et al ; Mizukami‐Murata et al ). For example, Leet et al () observed down‐regulation of several genes involved in steroid synthesis in larval fathead minnows exposed to 17β‐trenbolone, consistent with a compensatory response to overstimulation of the HPG axis by exogenous steroids.…”

“…Similarly, Brockmeier et al () used a custom microarray to investigate transcriptomic responses in the liver of female mosquitofish exposed to 17β‐trenbolone for 14 d. Many metabolic processes not necessarily directly linked to the androgen receptor were increased in response to 17β‐trenbolone exposure, including lipid metabolic processes, regulation of protein metabolic processes, lipoprotein metabolic processes, cholesterol biosynthesis processes, and cholesterol transport and metabolism. Finally, Mizukami‐Murata et al () used both microarray and PCR measurements to evaluate the effects of 17β‐trenbolone on 10 genes related to cholesterol synthesis and observed an induction of these genes, which could be a secondary response to depletion of cellular cholesterol stores.…”

Uncertainties in biological responses that influence hazard and risk approaches to the regulation of endocrine active substances

“…Zebrafish ( Danio rerio ) exposed to trenbolone (TRB) during sexual differentiation develop skewed sex ratios and all male populations at 0.01 μg/L and above ( Larsen and Baatrup 2010 ; Morthorst et al 2010 ; Boettcher 2011 ; Baumann et al 2015 ) this phenotypic sex change is irreversible ( Larsen and Baatrup 2010 ; Morthorst et al 2010 ; Baumann et al 2015 ). The TRB-induced reversal to a male phenotype appears more sensitive in zebrafish than in medaka ( Örn et al 2006 ; Mizukami-Murata et al 2015 ). Other endocrine mechanisms can also lead to masculinisation in fish (for a review see Matthiessen and Weltje 2015 ).…”

Sex‐ and Developmental Stage–Related Differences in the Hepatic Transcriptome of Japanese Quail (Coturnix japonica) Exposed to 17β‐Trenbolone

“…However, there are no reports on body burden of 17β‐trenbolone in birds in the environment. Whereas effects of 17β‐trenbolone have been well characterized in fish (Ankley et al 2003; Ekman et al 2011; Mizukami‐Murata et al 2016), there have been few studies in avian species, primarily using Japanese quail ( Coturnix japonica ; Quinn et al 2007a; Henry et al 2012; Karouna‐Renier et al 2017). Similar to results in fish, these studies also demonstrated deleterious effects on plasma hormone levels and reproductive behavior, as well as decreased egg production.…”