Do parabens have the ability to interfere with steroidogenesis?

The effects of ethyl and butyl paraben on steroidogenesis were evaluated in rats exposed in utero. Pregnant Wistar rats were dosed from gestational day (GD) 7 to GD 21, followed by examination of the dams, and the fetuses. Additionally, both parabens were tested in vitro in the H295R steroidogenesis assay and in the T-screen assay, the later to test for their ability to act as thyroid hormone receptor agonist or antagonist. In the in utero exposure toxicity study, neither ethyl nor butyl paraben showed any treatment-related effects on testosterone production, anogenital distance, or testicular histopathology. However, butyl paraben caused a significant decrease in the mRNA expression level of estradiol receptor-beta in fetal ovaries, and also significantly decreased the mRNA expression of steroidogenic acute regulatory protein and peripheral benzodiazepine receptor in the adrenal glands. In vitro butyl paraben increased the proliferation of the GH3 cells in the T-Screen assay, thereby acting as a weak thyroid hormone receptor agonist. In the adrenal H295R steroidogenesis assay both ethyl and butyl paraben caused a significant increase in the progesterone formation. Overall, the results indicate that butyl paraben might have the ability to act as endocrine disruptor by interfering with the transport of cholesterol to the mitochondrion, thereby interfering with steroidogenesis, but also that the two tested parabens do not show clear endocrine disrupting capabilities in our short-term in vivo experiment.