Relationship between brain and ovary aromatase activity and isoform-specific aromatase mRNA expression in the fathead minnow (Pimephales promelas)

Villeneuve, Daniel L.; Knoebl, Iris; Kahl, Michael D.; Jensen, Kathleen; Hammermeister, Dean E.; Greene, Katie J.; Blake, Lindsey S.; Ankley, Gerald T.

doi:10.1016/j.aquatox.2005.10.016

Cited by 84 publications

(75 citation statements)

References 48 publications

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“…However, the relationship between aromatase activity and CYP19A1 or CYP19A2 mRNA expression in the same brain samples had not been previously tested in fish. The positive correlation between brain CYP19A2 mRNA expression and aromatase activity found in this study, together with the fact that in the fish brain the CYP19A2 gene expresses much more than the CYP19A1 gene (e.g., Hinfray et al, 2006;Kishida and Callard, 2001;Villeneuve et al, 2006), suggests that CYP19A2 mRNA expression levels provide a good indication of the potential for aromatization in the S. pavo brain.…”

Section: Discussionsupporting

confidence: 59%

“…In fish, significant positive correlations between aromatase activity and normalized mRNA levels of both the CYP19A1 (e.g., Gen et al, 2001;Villeneuve et al, 2006) and CYP19A2 (Villeneuve et al, 2006) genes have been reported for ovarian tissue. However, the relationship between aromatase activity and CYP19A1 or CYP19A2 mRNA expression in the same brain samples had not been previously tested in fish.…”

Section: Discussionmentioning

confidence: 99%

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Brain aromatase mRNA expression in two populations of the peacock blenny Salaria pavo with divergent mating systems

Gonçalves

Saraiva

Teles

et al. 2010

Hormones and Behavior

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Keywords:Aromatase Reproductive behavior Salaria pavo Peacock blenny Alternative reproductive tactics Sex-role reversal Aromatase, the key enzyme in the conversion of androgens to estrogens, regulates the availability of these hormones in tissues and controls many physiological and behavioral processes. In fish and other vertebrates, the regulation of aromatase expression in the brain has been implicated in the modulation of male sexual and aggressive behaviors. Here, the pattern of mRNA expression of the brain aromatase isoform (encoded by the CYP19A2 gene also referred as CYP19b) was quantified at the peak of spawning season in brain macroareas from males and females of the blenny Salaria pavo originated from two populations displaying male alternative reproductive tactics but differing in their mating systems. In Trieste (Adriatic) nesting males aggressively defend nests and take the initiative in courtship and perform sexual displays more often than females while in Ria Formosa (Southern Portugal) the pattern is reversed as a result of shortage of appropriate nesting sites. Nesting males from Ria Formosa had overall higher levels of brain aromatase mRNA expression than nesting males from Trieste, suggesting a higher brain estrogen synthesis in these males. Since in some fish species exogenous estradiol administration has been shown to decrease sexual and agonistic behaviors, the higher levels of brain aromatase in Ria Formosa nesting males may explain their reduced expression of sexual and aggressive displays when compared with nesting males from Trieste. Alternatively, the higher brain aromatase levels in nesting males from Ria Formosa could be a mechanism to decrease the putative androgen-induced activation of aggressive and sexual displays by reducing the local availability of androgens through their metabolization into estrogens. Although females and parasitic female-like males also differ in their displays between populations, the interpopulational pattern of brain aromatase mRNA expression was similar, suggesting that other neuroendocrine agents mediate the expression of female and female-like behaviors. In conclusion, brain aromatase availability seems like a probable mechanism to regulate the effects of steroids on the brain circuits underlying the expression of sexual and agonistic displays in S. pavo.

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Section: Discussionsupporting

confidence: 59%

Section: Discussionmentioning

confidence: 99%

Brain aromatase mRNA expression in two populations of the peacock blenny Salaria pavo with divergent mating systems

Gonçalves

Saraiva

Teles

et al. 2010

Hormones and Behavior

View full text Add to dashboard Cite

show abstract

“…Assays for most of the genes noted above have been described elsewhere (Villeneuve et al, 2006(Villeneuve et al, , 2007aMartinovic et al, 2008). However, QPCR assays for fathead minnow gnrhr1, gnrhr3, and cyp51 are reported here for the first time.…”

Section: Methodsmentioning

confidence: 99%

Dynamic Nature of Alterations in the Endocrine System of Fathead Minnows Exposed to the Fungicide Prochloraz

Ankley

Bencic

Cavallin

et al. 2009

Toxicological Sciences

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The vertebrate hypothalamic-pituitary-gonadal (HPG) axis is controlled through various feedback mechanisms that maintain a dynamic homeostasis in the face of changing environmental conditions, including exposure to chemicals. We assessed the effects of prochloraz on HPG axis function in adult fathead minnows (Pimephales promelas) at multiple sampling times during 8-day exposure and 8-day depuration/recovery phases. Consistent with one mechanism of action of prochloraz, inhibition of cytochrome P450 (CYP) 19 aromatase activity, the fungicide depressed ex vivo ovarian production and plasma concentrations of 17b-estradiol (E2) in female fish. At a prochloraz water concentration of 30 mg/l, inhibitory effects on E2 production were transitory and did not persist during the 8-day exposure phase. At 300 mg/l prochloraz, inhibition of E2 production was evident throughout the 8-day exposure but steroid titers recovered within 1 day of cessation of exposure. Compensation or recovery of steroid production in prochloraz-exposed females was accompanied by upregulation of several ovarian genes associated with steroidogenesis, including cyp19a1a, cyp17 (hydroxylase/lyase), cyp11a (cholesterol side-chain cleavage), and follicle-stimulating hormone receptor. In male fathead minnows, the 8-day prochloraz exposure decreased testosterone (T) production, possibly through inhibition of CYP17. However, as for E2 in females, ex vivo testicular production and plasma concentrations of T recovered within 1 day of stopping exposure. Steroidogenic genes upregulated in testis included cyp17 and cyp11a. These studies demonstrate the adaptability of the HPG axis to chemical stress and highlight the need to consider the dynamic nature of the system when developing approaches to assess potential risks of endocrine-active chemicals.

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“…A standard curve of known quantities of a gene-specific mRNA standard (10-fold dilution series; generally 20-2 × 10 7 copies) was used to calibrate the QPCR data and estimate the number of gene-specific transcripts per ng total RNA. Details regarding the specific primer and probe sequences used and the methods for preparing gene-specific mRNA standards have been reported previously (Villeneuve et al, 2006(Villeneuve et al, , 2007(Villeneuve et al, , 2009aMartinovic et al, 2008). Due to potential differences in amplification and probe binding efficiencies between total RNA samples and purified standards, the number of copies per ng total RNA is regarded as an approximate estimate of the number of transcripts.…”

Section: Qpcr Analysesmentioning

confidence: 99%

Influence of ovarian stage on transcript profiles in fathead minnow (Pimephales promelas) ovary tissue

et al. 2010

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Relationship between brain and ovary aromatase activity and isoform-specific aromatase mRNA expression in the fathead minnow (Pimephales promelas)

Cited by 84 publications

References 48 publications

Brain aromatase mRNA expression in two populations of the peacock blenny Salaria pavo with divergent mating systems

Brain aromatase mRNA expression in two populations of the peacock blenny Salaria pavo with divergent mating systems

Dynamic Nature of Alterations in the Endocrine System of Fathead Minnows Exposed to the Fungicide Prochloraz

Influence of ovarian stage on transcript profiles in fathead minnow (Pimephales promelas) ovary tissue

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