Abstract
Ecotoxicological effects of glucocorticoids and steroid mixtures in the environment are not sufficiently known. Here we investigate effects of 11–14 days exposure of female zebrafish to the glucocorticoid clobetasol propionate (Clo), cortisol (Cs), their mixture and mixtures with five different class steroids (Clo + triamcinolone + estradiol + androstenedione + progesterone) in liver, brain and gonads. Cs showed little activity, while Clo reduced the condition factor at 0.57 and 6.35 μg/L. Clo induced differential expression of genes in the liver at 0.07–6.35 μg/L, which were related to circadian rhythm (per1, nr1d2), glucose metabolism (g6pca, pepck1), immune system response (fkbp 5, socs3, gilz), nuclear steroid receptors (pgr and pxr), steroidogeneses and steroid metabolism (hsd11b2, cyp2k22). Clo caused strong transcriptional down-regulation of vtg. Similar upregulations occurred in the brain for pepck1, fkbp5, socs3, gilz, hsd11b2, and nr1d2a, while cyp19b was down-regulated. Effects of Clo + Cs mixtures were similar to Clo alone. Transcriptional alterations were different in mixtures of five steroids with no alteration of vtg in the liver due to counteraction of Clo and estradiol. Induction of fkbp5 (brain) and sult2st3 (liver) and downregulation of cyp19a (gonads) occurred at 1 μg/L. Histological effects of the five steroids mixture in gonads were characterized by a decrease of mature oocytes. Our data indicate that effects of steroids of different classes sum up to an overall joint effect driven by the most potent steroid Clo.
Highlights
Cortisol (Cs) is the primary circulating glucocorticoid hormone in fish synthesized in the inter-renal tissue of the head kidney
These findings indicate that in environmental mixtures, the most potent steroids matter for the overall effect
Our data demonstrate that clobetasol propionate (Clo) alone or in binary mixtures induced transcriptional effects in adult fish in liver, brain and gonads
Summary
Cortisol (Cs) is the primary circulating glucocorticoid hormone in fish synthesized in the inter-renal tissue of the head kidney. On the other hand, find application in numerous medicines for humans and domestic animals. They affect the same pathways but are mainly used for their immunosuppressive and antiinflammatory action (Kugathas et al, 2013; Kugathas and Sumpter, 2011; Zhao et al, 2016). Glucocorticoids interact with other steroid hormone receptors, including the mineralocorticoid receptor and androgen receptor, at much lower potency (Pippal et al, 2011)
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