Real-time PCR array to study effects of chemicals on the Hypothalamic–Pituitary–Gonadal axis of the Japanese medaka

Zhang, Xiaowei; Hecker, Markus; Park, June-Woo; Tompsett, Amber R.; Newsted, John L.; Nakayama, Kei; Jones, Paul D.; Au, Doris W.T.; Kong, Richard Yuen Chong; Wu, Rudolf S.S.; Giesy, John P.

doi:10.1016/j.aquatox.2008.04.009

Cited by 126 publications

(94 citation statements)

References 34 publications

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“…While this observation is consistent with the oestrogen-induced decrease in cyp17a1 mRNA levels reported in fish testis (Govoroun et al 2001, Baron et al 2005, Brion et al 2008, Zhang et al 2008, De Waal et al 2009), our study moreover revealed that this inhibition occurred only in Leydig cells but not in germ cells. Indeed, after 7 and 14 days of exposure, a drastic inhibition of Cyp17a1 fluorescence was observed in Leydig cells from testis of E 2 -exposed fish.…”

Section: Figuresupporting

confidence: 69%

“…Short-term exposures of fathead minnows and medaka to oestrogens from 5 to 500 ng/l during either 7 or 14 days had no effect on cyp19a1a gene expression in the testis (Filby et al 2006, Zhang et al 2008. In zebrafish, an exposure for 7 days to 10 nM E 2 had no effect on testicular cyp19a1a gene expression (Hinfray N & Brion F 2011, unpublished observations) whereas it strikingly inhibited ovarian cyp19a1a gene expression (Hinfray et al 2006).…”

Section: Figurementioning

confidence: 99%

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Cyp17a1 and Cyp19a1 in the zebrafish testis are differentially affected by oestradiol

Hinfray¹,

Nóbrega²,

Caulier³

et al. 2013

Journal of Endocrinology

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International audienceOestrogens can affect expression of genes encoding steroidogenic enzymes in fish gonads. However, little information is available on their effects at the protein level. In this context, we first analysed the expression of key steroidogenic enzyme genes and proteins in zebrafish testis, paying attention also to other cell types than Leydig cells. Gene expression was analysed by quantitative PCR on fluorescence-activated cell-sorting fractions coupled or not to differential plating, while protein synthesis was studied by immunohistochemistry using specific antibodies against zebrafish Cyp17a1, Cyp19a1a and Cyp19a1b. Furthermore, we have evaluated the effect of oestrogen treatment (17 beta-oestradiol (E-2), 10 nM) on the localization of these enzymes after 7 and 14 days of in vivo exposure in order to study how oestrogen-mediated modulation of their expression is linked to oestrogen effects on spermatogenesis. The major outcomes of this study are that Leydig cells express Cyp17a1 and Cyp19a1a, while testicular germ cells express Cyp17a1 and both, Cyp19a1a and Cyp19a1b. As regards Cyp17a1, both protein and mRNA seem to be quantitatively dominating in Leydig cells. Moreover, E-2 exposure specifically affects only Leydig cell Cyp17a1 synthesis, preceding the disruption of spermatogenesis. The oestrogen-induced suppression of the androgen production capacity in Leydig cells is a major event in altering spermatogenesis, while germ cell steroidogenesis may have to be fuelled by precursors from Leydig cells. Further studies are needed to elucidate the functionality of steroidogenic enzymes in germ cells and their potential role in testicular physiology

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Section: Figuresupporting

confidence: 69%

Section: Figurementioning

confidence: 99%

Cyp17a1 and Cyp19a1 in the zebrafish testis are differentially affected by oestradiol

Hinfray¹,

Nóbrega²,

Caulier³

et al. 2013

Journal of Endocrinology

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“…Since forskolin, an activator of the adenylate cyclase, also induced a much weaker response in tissue from E 2 -treated fish than from control fish, we speculate that oestrogens may target one or more components of the Ga S -adenylate cyclase -protein kinase A (PKA) pathways. Therefore, we conclude that oestrogenic treatment induced a state of androgen-insufficiency in zebrafish by disturbing the testicular steroidogenic system at different levels, as previously suggested for other teleost fish species (Sohn et al 1998, Loomis & Thomas 2000, Andersen et al 2006, Filby et al 2006, Chaves-Pozo et al 2007, Meier et al 2007, Arukwe 2008, Blum et al 2008, Jukosky et al 2008, Zhang et al 2008.…”

Section: Discussionsupporting

confidence: 49%

“…Finally, pre-treatment of late recrudescent goldfish of mixed sex with E 2 suppressed GnRH-mediated elevation of fshb and lhb expression both in vivo and in vitro (Huggard-Nelson et al 2002). The latter has been reported recently in medaka (Oryzias latipes; Zhang et al 2008) as well. These data indicate that E 2 inhibited the Gnrh/ Gnrh-receptor signalling system, and that these effects apparently overrule the direct, stimulatory effects of oestrogens on gonadotropin subunit expression.…”

Section: Discussionmentioning

confidence: 74%

“…Previous studies have reported detrimental effects of oestrogenic compounds on fertility at all levels of the brainpituitary-gonad axis in teleost fish (Tsai et al 2005, Filby et al 2006, Zhang et al 2008, including impairment of spermatogenesis (Van der Ven et al 2003, Van den Belt et al 2004, Pawlowski et al 2004, and inhibition of androgen synthesis, either directly on Leydig cells (Loomis & Thomas 2000, Govoroun et al 2001, Baron et al 2005 or via feedback on hypothalamus and pituitary to control synthesis and release of gonadotropins (Dickey & Swanson 1998, Kobayashi et al 2001, Huggard-Nelson et al 2002, Banerjee & Khan 2008. However, it is not known exactly which step(s) in the developmental sequence constituting spermatogenesis is/are affected by oestrogens in fish.…”

Section: Introductionmentioning

confidence: 99%

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Oestrogen-induced androgen insufficiency results in a reduction of proliferation and differentiation of spermatogonia in the zebrafish testis

Waal¹,

Leal²,

García-López³

et al. 2009

Journal of Endocrinology

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Androgens can induce complete spermatogenesis in immature or prepubertal teleost fish. However, many aspects of the role of androgens in adult teleost spermatogenesis have remained elusive. Since oestrogens inhibit androgen synthesis, we used an oestrogen-induced androgen depletion model to identify androgen-dependent stages during adult zebrafish spermatogenesis. Exposure to 10 nM 17b-oestradiol (E 2 ) in vivo at least halved the mass of differentiating germ cells (from type B spermatogonia to spermatids), while type A spermatogonia accumulated. Studies on the cellular dynamics revealed that a reduction of spermatogonial proliferation together with an inhibition of their differentiation to type B spermatogonia were the basis for the oestrogen-mediated disturbance of spermatogenesis. The capacity of the zebrafish testis to produce 11-ketotestosterone as well as the expression of steroidogenesis-related genes was markedly decreased after in vivo oestrogen exposure. Moreover, the androgen-release response to recombinant zebrafish Lh was lost after oestrogen exposure. We conclude that oestrogen exposure caused a state of androgen insufficiency in adult male zebrafish. Since the downregulation of the steroidogenic system as well as the disturbance of spermatogenesis in testicular explants exposed to E 2 ex vivo was much less severe than after in vivo exposure, the main inhibitory effect appears to be exerted via feedback inhibition of gonadotropin release. This experimental set-up helped to identify spermatogonial proliferation and their differentiation as androgen targets in adult zebrafish spermatogenesis.

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Effects of long‐term exposure to TDCPP in zebrafish (Danio rerio) – Alternations of hormone balance and gene transcriptions along hypothalamus‐pituitary axes

Liu

Hong

et al. 2022

Anim Models and Exp Med

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Background: TDCPP is one of the major chemical of organophosphate flame retardants (OPFRs) that has been detected ubiquitously in both the environment and biota. Previously we observed that it influenced the concentrations of sex and thyroid hormones in a sex-dependent pattern, leading to reproductive impairments after short-term exposure in zebrafish. Here we investigate the consequences of longerterm exposure to TDCPP on the hypothalamic-pituitary-gonad (HPG), hypothalamicpituitary-interrenal (HPI), and hypothalamic-pituitary-thyroid (HPT) axes of zebrafish (Danio rerio).Methods: A 120-day exposure test to 0.005, 0.05 and 0.5 mg/L TDCPP was initiated with fertilized eggs. Sex steroid hormones in the treated fishes were measured and transcriptional changes were analyzed. Results:In female fish, exposure to TDCPP resulted in increases in plasma cortisol, follicle stimulating hormone (FSH), luteinizing hormone (LH), 17β-estradiol (E2), cortisol, thyroxine (T4), and triiodothyronine (T3). Transcription of most target genes along HPG, HPI and HPT axes were increased by the exposure. While in male fish the exposure led to decreases in cortisol, FSH, LH, T4, T3, testosterone (T), and 11-ketotestosterone (11-KT). Transcription of genes along HPG, HPI and HPT axes, especially steroidogenic genes, were inhibited in male zebrafish. While, E2/T or E2/11-KT ratio was increased in both female and females. The sex-dependent changes in hormones might be due to differential responses to TDCPP induced stresses. An increase in cortisol level coincided with increases in E2 and THs in female fish, while in males decreases in cortisol as well as T, 11-KT and THs were observed. Long-term exposure to TDCPP at very low (μg/L) concentrations could disrupt hormone balances in a sex dependent way. Conclusion:This study revealed that TDCPP could affect endocrine axes -HPG, HPI and HPT -in zebrafish, and impair zebrafish development.

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Real-time PCR array to study effects of chemicals on the Hypothalamic–Pituitary–Gonadal axis of the Japanese medaka

Cited by 126 publications

References 34 publications

Cyp17a1 and Cyp19a1 in the zebrafish testis are differentially affected by oestradiol

Cyp17a1 and Cyp19a1 in the zebrafish testis are differentially affected by oestradiol

Oestrogen-induced androgen insufficiency results in a reduction of proliferation and differentiation of spermatogonia in the zebrafish testis

Effects of long‐term exposure to TDCPP in zebrafish (Danio rerio) – Alternations of hormone balance and gene transcriptions along hypothalamus‐pituitary axes

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