Vascular endothelial growth factor-A isoform and (co)receptor expression are differentially regulated by 17β-oestradiol in the ovariectomised mouse uterus

Abstract

The angiogenic effects of 17beta-oestradiol (E(2)) in the mouse endometrium are mediated by vascular endothelial growth factor-A (VEGFA). We analysed the temporal and spatial changes in VEGFA isoform and (co)receptor expression in ovariectomised mouse uteri following E(2) treatment. VEGFA isoform and receptor mRNA were quantified in whole uterine tissue collected 2, 6, 12 and 24 h after E(2) or vehicle treatment. Laser capture microdissection was used to investigate mRNA expression in epithelial, stromal and myometrial tissues separately. Endothelial cell proliferation, VEGFA and VEGF receptor-2 (VEGFR2) protein were visualised using immunohistochemistry. Endometrial endothelial cell proliferation was only observed 24 h after E(2) treatment. In whole uterine tissue, total Vegfa, Vegfa(164) and Vegfa(120) mRNA expression increased 2 h post E(2) treatment, and then decreased by 24 h. Vegfa(188) expression was lower in E(2)-treated animals at all time points relative to control animals. Vegfr2 and neuropilin-1 (Nrp1) mRNA expression did not change following E(2) treatment; Nrp2 expression decreased by 24 h. When uterine compartments were considered separately at 24 h post E(2) or vehicle, stromal Vegfa(120), Vegfa(188) and Vegfr2 mRNA expression and myometrial Vegfa(120) and Vegfa(188) mRNA expression were reduced in E(2)-treated mice relative to controls, whereas epithelial Vegfa(188) mRNA expression increased. The highest VEGFA immunoexpression was observed in luminal epithelium; expression increased at 24 h relative to other time points. No changes were noted in VEGFR2 immunoexpression among treatment groups. We have provided the first evidence that VEGFA isoform and receptor mRNA expression are differentially regulated by E(2) in different uterine cell compartments.