Document Type: Full paper (Original article)
Department of Theriogenology, Faculty of Veterinary Medicine, Suez Canal University, Ismailia, Egypt
Back ground: Implantation event constitutes a crucial period for success of full pregnancy. Endocrine disruptors such as phytoestrogens were thought to adversely influence the embryonic implantation. However, the mechanism by which they upset implantation was not fully elucidated. Aims: implications of soy isoflavones administration on Wistar rats implantation was studied through detection of progesterone receptors (PR), vascular endothelial growth factor (VEGF), and estradiol receptor alpha (ER-α) at gestation day 6 (GD6). Methods: Eighteen cyclic female Wistar rats were distributed into two groups, group A; control (n=9) fed casein based diet and group B (n=9) fed casein diet and gavaged 50 mg/kg/day SOY ISOFLAVONE EXTRACT 40% starting from day zero of pregnancy till GD6. Feed intake, body weight, body gain, and uterine weights were recorded. At the end GD6; numbers of corpora lutae and implantation rates were recorded. Histopathology and immunohistochemistry for PR, VEGF, and ER-α in implanted uteri were performed. Results: soy isoflavones treated dams significantly reduced feed intake, body weights, weight gain, uterine weights, numbers of corpora lutea, and implantation rates of pregnant dams. The endometrium of soy treated dams showed less proliferation than control. The PR immunostaining percent and VEGF were significantly lower in soy treated dams than control ones. However, ER-α exhibited significant elevation in soy treated dams in comparison to the control ones. Conclusion: the implantation losses caused by soy isoflavones seemed to be due to their down regulation of PR that fails to down regulate ER-α action and to decrease VEGF production.