Reproductive Toxicology 26 (2008) 146–150 Contents lists available at ScienceDirect Reproductive Toxicology journal homepage: www.elsevier.com/locate/reprotox Effects of a low oral dose of diethylstilbestrol (DES) on reproductive tract development in F1 female CD-1 mice Francesca Maranghi ∗ , Roberta Tassinari, Gabriele Moracci, Caterina Macrì, Alberto Mantovani Department of Food Safety and Veterinary Public Health, Istituto Superiore di Sanità, viale Regina Elena 299, 00161 Rome, Italy article info Article history: Received 21 May 2008 Received in revised form 27 June 2008 Accepted 8 July 2008 Available online 22 July 2008 Keywords: Endocrine disrupting chemicals Female reproductive system Model compound Early exposure Long-term effects abstract The synthetic estrogen diethylstilbestrol (DES) is a model to study the effects on female reproductive tract of endocrine disrupting chemicals interacting with estrogen receptors. Pregnant CD-1 mice were given daily by gavage 10 g/kg bw of DES (the lower range of therapeutic exposure) during gestational days 9–16, critical period for reproductive tract development. Parameters of sexual development were recorded after weaning and at sexual maturation. No signs of general toxicity were observed in dams. In DES-treated group, reduced litter weight during lactation and earlier vaginal patency was observed. Uterus weight was increased in F1 treated females at weaning. Histological analysis showed reduced endometrium thickness and increased polyovular follicles, irregular and oocytes with condensed chromatin in the ovary at sexual maturity. Prenatal DES oral administration induces subtle but significant effects on puberty onset, uterine and ovary morphology. © 2008 Elsevier Inc. All rights reserved. 1. Introduction Diethylstilbestrol (DES) is a synthetic nonsteroidal (stilbene) estrogenic compound known since the 1940s. DES binds both estro- gen receptor (ER)  and , showing a binding affinity for ER that is approximately twofold higher than that of natural ligand 17- estradiol [1]. DES crosses placenta and induces a direct effect on the developing foetus [2,3]; in newborn mice, detrimental estrogen- like effects of DES in the reproductive tract of male mice are mediated by ER [4]. DES is a recognized developmental toxicant in humans [5,6]. It was prescribed to women for preventing early pregnancy losses and other pregnancy problems since 1940s; rec- ommended dose was 5mg daily (corresponding to approximately 80 g/kg bw in a 60-kg woman), increasing in 5-mg increments every 2 weeks throughout the pregnancy, until doses of 150mg daily [7]. In 1971, DES was banned due to its association with a rare vaginal carcinoma (clear-cell adenocarcinoma) in daughters exposed in utero during the first 18 weeks of pregnancy [8]; sub- sequently, several defects in the morphogenesis and histogenesis of female as well as of male reproductive tract have been detected [7]. DES represented also a significant issue for food safety since it was one of the first anabolic hormone-like compounds used in intensive animal production [9]. ∗ Corresponding author. Tel.: +39 06 49902527; fax: +39 06 49902658. E-mail address: francesca.maranghi@iss.it (F. Maranghi). Several experimental data point out that the female repro- ductive tract is a highly sensitive DES target, with a pleiotropic spectrum of effects [10]. Developmental exposure interferes with normal differentiation of the Mullerian duct and regression of the Wolffian duct [11]. Due to its well-characterized estrogenic properties, DES has been utilized as model compound for studying endocrine disrupt- ing chemicals (EDCs) that interact with ER. Recent studies in rodents have been mainly performed by subcutaneous treatment [11]. Whereas DES is readily bioavailable upon oral intake, com- paratively limited data are available up to now concerning oral exposure, the most relevant route of EDC intake in the general population. Studies on developmental effects should focus on sus- ceptible lifestage windows in the different species. In mouse, the major period of female reproductive system organogenesis falls between GD 9–16. This period starts from the stage (GD 9.5) of embryo having both the Wolffian ducts (mesonephric ducts) and the Mullerian ducts (paramesonephric ducts), through to Mullerian duct reaching the cloaca and Wolffian duct regressing (GD 13.5), up to the final staging of the reproductive tract formation (GD 16) [12]. Moreover, studies should use dose levels relevant to the range of potential dietary or environmental exposures to estrogenic EDCs. Alterations in female reproductive tract were identified in mice exposed in utero by subcutaneous administration to dose levels ranging 0.1–100 g/(kg day bw) during the same period of major reproductive system organogenesis investigated in our study, i.e., gestational days (GD) 9–16 [13]. DES oral administration in rat, during gestation and lactation (15 g/(kg day)), induced 0890-6238/$ – see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.reprotox.2008.07.002