Do parabens have the ability to interfere with steroidogenesis?

Parabens are used as preservatives in cosmetics, pharmaceuticals and in foods. They have been studied in a number of in vitro and in vivo systems. Many of the parabens have been shown to have weak estrogenic activity and some, including butylparaben, also caused reduction in testosterone levels and in sperm production in rats.

However, more knowledge on the possible adverse effects of parabens on the endocrine system is needed. A combined in vitro/in vivo approach is a useful way to gain a complete understanding of the activities of the compound in question. In the current study, the effects of ethyl- and butylparaben on steroidogenesis were evaluated in rats exposed in utero.

Additionally, both parabens were tested in vitro in the H295R steroidogenesis assay and in the T-screen assay. In the in utero exposure toxicity study, butylparaben caused a significant decrease in the mRNA expression level of ER-beta in foetal ovaries, and also significantly decreased the mRNA expression of StAR and Bzrp in the adrenal glands—both genes involved in an important step in steroidogenesis.

In vitro butylparaben 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 butylparaben caused a significant increase in the progesterone formation. Overall, the results indicate that butylparaben might have the ability to act as an endocrine disruptor by interfering with the transport of cholesterol to the mitochondrion, thereby interfering with steroidogenesis