Differential expression and selective localization of vascular permeability factor vascular endothelial growth factor in the rat uterus during the estrous cycle

This study examines the expression of the multi-functional cytokine, vascular permeability factor/vascular endothelial growth factor (VPF/VEGF) in the rat uterus during early proestrus, proestrus, estrus and diestrus. Groups of ovariectomized or hypophysectomized rats served as endocrine controls. Expression of VPF/VEGF mRNA was 2-fold greater in uteri during proestrus and estrus than in other phases of the estrous cycle. In situ hybridization techniques indicated that VPF/VEGF mRNA expression was confined to the luminal epithelium during proestrus, but shifted to the stromal compartment during estrus. Ovariectomized, hypophysectomized or diestrus rats exhibited scattered localization of VPF/VEGF mRNA among glandular epithelium and endometrial stromal compartments. Although VPF/VEGF mRNA was expressed throughout the estrous cycle, but in different compartments of the endometrium depending on the stage of the estrous cycle, VPF/VEGF protein expression appears to be restricted to the epithelial compartment during proestrus and estrus. Results indicate that circulating levels of gonadal steroids and LH may be associated with the differential expression of VPF/VEGF mRNA and its translation activity in the endometrium during different stages of the estrous cycle.