Effects of Prochloraz and Ethinylestradiol on development
in Rana temporaria
The ontogeny of most amphibians is characterized by a large degree of sexual plasticity and sex steroids play an important role in the final differentiation of the gonads. One consequence of this plasticity is that exposure of frogs to estrogen or androgen agonists or antagonists, or compounds that block specific steroidogenic enzymes, during the sensitive periods of sex differentiation can result in individuals developing incomplete gonads of the gender opposite to that of their genotype, sometimes even leading to complete phenotypic sex reversal. The effect of the synthetic estrogen ethinylestradiol and the aromatase-inhibiting fungicide prochloraz on sexual differentiation in Rana temporaria, a species exhibiting natural juvenile hermaphroditism, was investigated. Prochloraz caused an increase in the percentage of phenotypic males. Moreover, ethinylestradiol caused estrogen-dependent induction of the egg yolk precursor protein vitellogenin. These results show that gonadal development and vitellogenin induction may be used as biomarkers for detection of endocrine disrupting chemicals.
Most studies have focused on the effect of endocrine disruptors on the sexsteroid axis and reproductive function. However, another hormone system, the thyroid hormone axis may equally well be affected by xenobiotics. Thyroid hormones are essential in stimulating all aspects of amphibian metamorphosis and thyroid hormone disruptors may therefore severely affect this most critical process in amphibian life history. We found that exposure of tadpole Rana temporaria to the synthetic estrogen ethinylestradiol and the fungicide prochloraz caused delay of metamorphosis accompanied by changes in thyroid gland morphology.
|Titel||6th. International Symposium on Amphibian and Reptilian Endocrinology and Neurobiology|
|Status||Udgivet - 2009|
|Begivenhed||ISAREN 2009 - Berlin, Tyskland|
Varighed: 20. sep. 2009 → 23. sep. 2009
|Periode||20/09/2009 → 23/09/2009|