The effect of hyperstimulation on transforming growth factor β1 and β2 in the rat uterus: possible consequences for embryo implantation

Objective: To investigate the effect of exogenous gonadotropins on the expression of transforming growth factor (TGF) beta(1) and beta(2) in the rat uterus and its consequences for successful embryo implantation. Design: Controlled experimental research study. Setting: School of Anatomical Sciences, University of the Witwatersrand. Patient(s): Thirty-six adult, virgin, female Sprague-Dawley rats and two fertile males. Intervention(s): Follicle-stimulating hormone (FSH) and human chorionic gonadotropin (hCG) were superimposed upon the normal hormonal milieu of normal, cycling female rats before mating. Uterine tissue was collected at pen-implantation stages (i.e., at 4.5, 5.5, and 6.5 days) after mating. Enzyme-linked immunosorbent assay. (ELISA) was performed to estimate the blood estrogen and progesterone levels, and immunohistochemistry was performed to localize the TGF-beta(1) and TGF-beta(2) in the uterus. Main Outcome Measure(s): Hyperstimulation affecting the expression of both TGF-beta(1) and TGF-beta(2) during the pen-implantation period. Result(s): The release of ovarian steroids was altered, causing a change in the endogenous hormonal environment. A marked increase in the expression of TGF-beta(2) was distinct in the glandular epithelium. Expression of both TGF-beta(1) and TGF-beta(2) was weaker in the subluminal stroma when compared with the deeper stromal region. Conclusion(s): Hyperstimulation with exogenous hormones affects the expression of both TGF-beta(1) and TGF-beta(2), which may contribute to the disruption of the endometrial environment required for successful embryo implantation. (Fertil Steril (R) 2010;93:1509-17. (C)2010 by American Society for Reproductive Medicine.)