ENDOSULFAN AFFECTS UTERINE DEVELOPMENT AND FUNCTIONAL DIFFERENTIATION BY DISRUPTING WNT7A/B-CATENIN SIGNALING PATHWAY

MILESI M.; INGARAMO P. I.; GUERRERO SCHIMPF M; RAMOS JG; MUÑÓZ DE TORO M; LUQUE EH; VARAYOUD J

Natal

Congreso; 9th Congress of Toxicology in Developing Countries (CTDC9) and XIX Congresso Brasileiro de Toxicologia; 2015

ENDOSULFAN AFFECTS UTERINE DEVELOPMENT AND FUNCTIONAL DIFFERENTIATION BY DISRUPTING WNT7A/B-CATENIN SIGNALING PATHWAYMilesi M.M.; Ingaramo P.I., Guerrero Schimpf M.L., Ramos J.G., Muñoz-de-Toro M., Luque E.H., Varayoud J.Instituto de Salud y Ambiente del Litoral (ISAL), Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral ? Consejo Nacional de Investigaciones Científicas y Técnicas, Santa Fe, Argentina.Introduction: The exposure to endocrine disruptors in early period of development may generate long-term effects in female reproductive tract. In a recent work we showed that neonatal exposure to low doses of the widely used endosulfan pesticide, classified as xenoestrogen, decreases the pregnancy rate and the number of implantation sites in rats. Wnt7a/β-catenin signaling is critical for proper uterine development during embryogenesis and gland formation. This pathway also plays a key role in regulating gland functional differentiation at adulthood, a process that is crucial for endometrial receptivity. Failures in this pathway may compromise embryo implantation and fertility. Objective: To investigate if endosulfan-implantation failures are associated with an impaired gland formation and/or a deregulated Wnt7a/β-catenin signaling in prepubertal and adult female rats.Material and Methods: Newborn female Wistar rats were treated by sc injections with vehicle (control, C), endosulfan (600 ug/kg b.w /d, E600) or diethylstilbestrol (0.2 μg/kg b.w./d, DES, used as an endocrine disruptor control) on PND (postnatal day) 1, 3, 5 and 7. Female rats were sacrificed on PND8 (neonatal period) and PND21 (prepubertal period) to evaluate the acute and short-term responses, respectively; and at the pre-implantation period (gestational day 5, GD5), to evaluate the long term effects on the uterine functional differentiation. At these three time points we determined the expression of Wnt7a and β-catenin proteins in uterine sections by immunohistochemistry. On PND21 and GD5 we also quantified the number of endometrial glands.Results and Discussion: E600 group showed an increase of Wnt7a and β-catenin proteins in the epithelium on PND8 and a decrease of Wnt7a in the glands on PND21. Although no changes in gland number were observed on PND21, a lower number of uterine glands were recorded in E600 and DES groups on GD5. In addition, we observed a decrease of Wnt7a expression in all uterine compartments and an increase of β-catenin expression in the luminal and glandular epithelial cells of E600- and DES-exposed rats on GD5. The early exposure to endosulfan deregulates the uterine expression of both Wnt7a and β-catenin in neonatal and prepubertal female rats and these alterations persist at adulthood. In the pre-implantation period, the deregulation of Wnt7a/β-catenin signaling was associated with a decrease in the number of uterine glands. Conclusions: The disruption of the uterine Wnt7a/β-catenin signaling in prepubertal and adult females may be involved in the implantation failures and subfertility triggered by early postnatal endosulfan exposure. Acknowledgements: Financial support from the Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT, PICT 2011-1491), CONICET (PIP 2011, 11220110100494) and the Universidad Nacional del Litoral (CAI + D 2011, 501 20110100423 LI) Keywords: Endosulfan, Uterus, Implantation, Wnt7a/β-catenin signaling.