Effects of octamethylcyclotetrasiloxane (D4) on the luteinizing hormone (LH) surge and levels of various reproductive hormones in female Sprague-Dawley rats.

The objectives of this study were to assess the potential for D(4) to suppress the pre-ovulatory lutenizing hormone (LH) surge, to block or delay ovulation, and to evaluate potential effects on reproductive hormones in rats. Female Sprague-Dawley Crl:CD (SD) IGS BR rats received whole-body vapor inhalation exposure to D(4) (0, 700, or 900ppm) 6h per day for 3 days. Trunk blood obtained on proestrus at 10a.

In vitro and in vivo evaluation of the estrogenic, androgenic, and progestagenic potential of two cyclic siloxanes.

The purpose of these experiments was to determine the potential estrogenic, androgenic, and progestagenic activity of two cyclic siloxanes, octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5). Receptor-binding experiments and a luciferase reporter gene assay were used to determine if the materials were able to bind and activate either the estrogen receptors (ERs) or progesterone receptors (PRs)-alpha or beta. The rat uterotrophic assay (RUA) for estrogenic activity and the Hershberger assay for androgenic activity were utilized as the in vivo assays.