Interference of endocrine disrupting chemicals with aromatase CYP19 expression or activity, and consequences for reproduction of teleost fish

Early regulation of brain aromatase (cyp19a1b) by estrogen receptors during zebrafish development

“…This is in perfect agreement with the fact that cyp19a1b expres-sion in the brain of developing and adult fish which is restricted to radial glial cells (Forlano et al, 2001;Menuet et al, 2003Menuet et al, , 2005Strobl-Mazzulla et al, 2005, 2008Kallivretaki et al, 2007;Pellegrini et al, 2007). Because of this high sensitivity to estrogens, cyp19a1b is a target for certain endocrine disrupters (EDs) with estrogenic activities (Cheshenko et al, 2008) and many recent studies have highlighted the effects on recognized estrogenic EDs on cyp19a1b expression either in vivo or in vitro (Melo and Ramsdell, 2001;Halm et al, 2002;Hinfray et al, 2006;Le Page et al, 2006, 2008Lee et al, 2006;Lassiter and Linney, 2007).…”

“…This assumption is reinforced by the fact that treatment of control embryos with ICI causes a strong reduction in cypa19a1b basal expression at all time points suggesting that basal expression relies in large part upon activation of estrogen receptors. We and others have previously shown that the cyp19a1b gene is very sensitive to E2 in young and adult fish (Hinfray et al, 2006;Sawyer et al, 2006;Cheshenko et al, 2007;Lassiter and Linney, 2007;Cheshenko et al, 2008;Le Page et al, 2008;Marlatt et al, 2008;Mouriec et al, 2008;Strobl-Mazzulla et al, 2008 , cyp19a1b mRNAs remained undetectable in the brain using whole-mount in situ hybridization at all these early stages. Nevertheless, as already documented Mouriec et al, 2009), treating zebrafish embryos with E2 causes a dramatic increase in cyp19a1b expression that becomes detectable at the messenger level by in situ hybridization or protein level by immunohistochemistry as early as 32-36 hpf (data not shown).…”

Chronic exposure to environmental levels of tribromophenol impairs zebrafish reproduction

“…In contrast, in males, exposure to TBP increased the levels of testosterone, implying that the expression of 3β-HSD, 17β-HSD, and CYP17 genes was upregulated. In the brain, the expression of the CYP19B gene was upregulated, and the increased CYP19 gene expression may have accelerated the formation of estradiol from testosterone (Fenske and Segner, 2004;Cheshenko et al, 2008). The increased mRNA levels of both CYP19A and CYP19B in the testes and brain can be attributed to the increased synthesis of estradiol from testosterone.…”

Aneuploid sperm formation in rainbow trout exposed to the environmental estrogen 17α-ethynylestradiol

“…Through these actions environmental estrogens affect vertebrate reproduction across a wide range of doses causing reduced fertility and fecundity, altered reproductive behavior, gonad morphological changes, and decreased embryonic survival (25)(26)(27)(28)(29)(30)(31)(32)(33)(34). Although both sexes are affected, males exhibit the highest degree and number of detrimental effects.…”