The effect of mixtures of xenoestrogens (E, EE, E, genistein, and α-zeralenol) on the transcriptional activation of zfERs in U251-MG cells transfected with the reporter gene and expression vectors

<p><b>Copyright information:</b></p><p>Taken from "Assessment of Xenoestrogens Using Three Distinct Estrogen Receptors and the Zebrafish Brain Aromatase Gene in a Highly Responsive Glial Cell System"</p><p>Environmental Health Perspectives 2005;114(5):752-758.</p><p>Published online 8 Dec 2005</p><p>PMCID:PMC1459931.</p><p>This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original DOI.</p> () zfER-α. () zfER-β1. () zfER-β2. () Effects produced with zfER-α by individual components at the concentrations present in the mixture, and the predicted mixture effect calculated according to the concept of concentration addition and the observed mixture effect (treated samples)

Upon exposure of embryos to estradiol, the tg(<i>cyp19a1b</i>-GFP) zebrafish expresses GFP only in radial glial cells.

<p>(<i>a</i>) Dorsal view of a zebrafish larva treated with 10 nM E2 showing that GFP signal is visible in the brain, notably in the telencephalon (tel), preoptic area (poa), and in the nucleus recessus posterioris (nrp) of the caudal hypothalamus; ob: olfactory bulb. (<i>b</i>) High resolution confocal image showing the RGCs in the telencephalon (tel), preoptic area (poa), nucleus recessus lateralis (nrl) and nucleus recessus posterioris (nrp) of the caudal hypothalamus. (c) High power view of the area shown in (<i>b</i>). Soma (s) are located along the midline except in the case of newborn cells (nb) undergoing migration (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036069#pone-0036069-g002" target="_blank">Figure 2</a>). RGCs have long cytoplasmic radial processes (rp) terminating by end-feet (ef) at the brain surface. (<i>a</i>) Bar = 200 µm; (<i>b</i>) Bar = 100 µm (c) Bar = 20 µm.</p

Dose-response curves of GFP induction in transgenic cyp19a1b-GFP embryos by various ligands (17α-ethinylestradiol is used as a reference).

<p>(a) Natural estrogens and pharmaceutical compounds: EE2: 17α-ethinylestradiol; E2: 17β-estradiol; E1: estrone; E3: estriol; DES: diethylstilbestrol; HEX: hexestrol; GEN: genistein; α-ZEA: α-zearalenol; α-ZEE: α-zearalanol; β-ZEE: β-zearalanol. The hexestrol curve in red is hardly visible because it is very similar to that of DES. (b) Industrial chemicals: BPA: bisphenol A; 4-t-PP: 4-t-pentylphenol; 4-t-OP, 4-t octylphenol; NPmix: mixture of nonylphenol. (c) Insecticides: o,p’DDT: 1,1,1-Trichloro-2-(2-chlorophenyl)-2-(4-chlorophenyl)ethane; MXC: methoxychlor; HPTE 2,2-bis(p-hydroxyphenyl)-1,1,1-trichloroethane. (d) Androgens: Testo: testosterone; DHT: dihydotestosterone; 17α-MT: 17α-methyltestosterone; 17β-Trenb: 17β-trenbolone; Noreth.: 17α-Ethynyl-19-nortestosterone (norethindrone); D(-)N: 13β-Ethyl-17α-ethynyl-17β-hydroxygon-4-en-3-one (levonogestrel), ICI (ICI 182-780); R1881 (metribolone): androgen receptor agonist.</p

GFP expression in zebrafish embryos exposed to EE2 and TCDD (0.05 nM) alone or in combination.

<p>Results are expressed as fold induction above control (means ± SEM).</p

Effects of 17α-methyltestosterone and R1881 alone or in combination with either flutamide or ICI.

<p>Results are expressed as fold induction above control (means ± SEM).</p

GFP expression in zebrafish embryos exposed to various ER, AR and PR ligands alone or in combination with ICI.

<p>Results are expressed as fold induction above control (means ± SEM, n = indicates the number of 5-dpf old zebrafish examined).</p

Effective concentrations (EC₅₀), maximum fold of induction measured above solvent control and relative estrogenic potencies (REP) of various compounds belonging to different chemical families.

<p>Results are expressed as mean ± standard deviation (SD).</p><p>N = number of independent experiments, n.e.: no effect, CV(%) = coefficient of variation inter-assay for EC₅₀. For each experiment, 10–15 transgenic zebrafish embryos were analyzed per condition.</p

<i>In vivo</i> imaging of 5-dpf old live transgenic <i>cyp19a1b</i>-GFP zebrafish embryos exposed to chemicals inducing GFP expression in radial glial progenitors.

<p>Dorsal views (anterior to the top) of the telencephalon (tel), preoptic area (poa), and nucleus recessus posterioris (nrp) of the caudal hypothalamus. For each chemical the concentration used is indicated. CTRL: solvent control, EE2: 17α-ethinylestradiol, E2: 17β-estradiol, E1: estrone, E3: estriol, DES: diethystilbestrol, HEX: hexestrol, GEN: genistein, α-ZEA: α-zearalenol, α-ZEE: α-zearalanol, β-ZEE: β-zearalanol, BPA: bisphenol A, 4-t-PP: 4-t-pentylphenol, 4-t-OP, 4-t octylphenol, NPmix: mixture of nonylphenol, o,p’DDT: 1,1,1-Trichloro-2-(2-chlorophenyl)-2-(4-chlorophenyl)ethane, MXC: methoxychlor, HPTE 2,2-bis(p-hydroxyphenyl)-1,1,1-trichloroethane, Testo: testosterone, DHT: dihydotestosterone, 17α-MT: 17α-methyltestosterone, 17β-Trenb: 17β-trenbolone, Noreth.: 17α-Ethynyl-19-nortestosterone, D(-)N: 13β-Ethyl-17α-ethynyl-17β-hydroxygon-4-en-3-one, ICI (ICI 182-780).</p

Effects of binary mixtures of estrogens on cyp19a1b-GFP expression.

<p>The combined effects of mixture of E1+E2 (ratio 1∶10) and E2+EE2 (ratio 1∶1) induced GFP expression in a concentration-dependent manner. Mixture means (green) is the mean of two independent assays, Mixture assays 1 (pale blue) and 2 (red). CA: dose response curve generated by the CA model (black). IA: dose response curve generated by the IA model (blue).</p