Effects of interleukin 11 (IL-11) on early post-implantation development of the rat

The development of embryos, trophoblast and decidua of IL-11-treated rats w ere examined in vivo, while ectoplacental cones (EPC) were studied in vitro . Female Wistar rats were injected daily with buffer (C), 1 mg/kg IL-11 (HD ) daily or 30 mu g/kg (LD) IL-11 twice a week. On day 9 of pregnancy, embry onic tissue volume was reduced in IL-11-treated animals, but EPC volume was elevated, compared to controls, Mitotic indices were reduced in embryos (P <0.05 for LD, P<0.001 for HD) and in EPCs of both groups. Pycnotic indices were elevated in LD (NS) and HD (P<0.05) embryos, but decreased in EPCs of the LD group (P<0.01). Morphological abnormalities were observed in decidua , embryo and trophoblast, In HD, EPC attachment was impaired after 1 day cu lture but proliferation was stimulated after 5 days. Defective decidualizat ion in IL-11 treated rats may therefore result in abnormal development of e mbryo and trophoblast. (C) 2000 Academic Press.