Altered uterine angiogenesis in rats treated with a glyphosate-based herbicide

Abstract

Glyphosate-based herbicides (GBHs) are the agrochemicals most used around the globe. However, they might have adverse effects on human and animal health. Previously, we showed that female rats neonatally exposed to GBHs exhibit altered expression of morphogenetic molecules and biomarkers of uterine development. We also observed a reduction in the size of implantation sites, altered expression of decidualization-related molecules, and increased post-implantation losses. Since decidualization comprises morphogenetic, biochemical and vascular changes, here we investigated the effects of neonatal GBH exposure on uterine angiogenesis in neonatal and pregnant rats. To achieve this, Wistar female rats were exposed to saline solution or GBH (2 mg glyphosate/kg-bw/day) on post-natal days (PND) 1, 3, 5 and 7. On PND8, uterine samples were collected for developmental studies. On PND90, the remaining females were mated and in the morning of gestational day (GD) 9, the implantation sites were collected. Angiogenesis-related molecules and cells involved in this process were identified and/or measured by immunohistochemistry or RT-PCR. On PND8, GBH-treated rats showed increased vascular endothelial growth factor (VEGF) expression and decreased Notch1, inducible nitric oxide synthase (iNOS) and Angiopoietin-2 (Ang2) mRNA levels. Vascular area, vessel diameter, endothelial cell proliferation, VEGF and Nestin protein expression, and VEGF, Notch1, iNOS and cyclooxygenase-2 (Cox-2) genes were downregulated in implantation sites of exposed females, while Ang2, VEGF receptor 1 and interleukin-10 (IL-10) were increased. Mast cells and macrophages were increased on PND8 and GD9 of treated rats. The increased Transforming growth factor-beta expression in the antimesometrial zone and IL-10 mRNA expression suggest that the M2 type is the predominant population of macrophages on implantation sites. In conclusion, neonatal GBH exposure alters the expression of angiogenesis-related molecules at neonatal uterine development and decidual reaction, suggesting altered vascular support. These alterations might contribute to the increased post-implantation losses observed in GBH-treated rats.