Expression of vascular endothelial growth factor (VEGF) and its corresponding receptors (flt-1 and flk-1) in the bovine oviduct

Abstract

Vascular endothelial growth factor (VEGF) functions as a potent angiogenic protein as well as in regulating permeability. Reverse transcription‐polymerase chain reaction (RT‐PCR) and ribonuclease protection assay (RPA) were used to show that the bovine oviduct expresses VEGF and its two receptors flk‐1 and flt‐1. Expression of VEGF was relatively stable during the estrous cycle. In contrast, both receptor transcripts showed cycle‐dependent variations with significantly increased flt‐1 mRNA amounts before ovulation. Immunohistochemical studies localized VEGF mainly on the epithelial surface of oviducts. Protein concentrations of VEGF in oviductal flushings were significantly higher (mean ± SEM: 2.8 ± 0.8 ng/ml) during the pre‐ovulatory phase when compared with the other estrous cycle stages (1.0 ± 0.25 ng/ml). In conclusion, all components of a functional VEGF‐system in the bovine oviduct were found to undergo specific modulations during the cycle. We suggest that VEGF may be involved in creating an optimal local environment for fertilization or the developing embryo by modulating permeability within the bovine oviduct. Mol. Reprod. Dev. 53:376–383, 1999. © 1999 Wiley‐Liss, Inc.

Expression of VEGF and Its Receptors in the Bovine Endometrium Throughout the Estrous Cycle: Effects of VEGF on Prostaglandin Production in Endometrial Cells

“…The concentration of VEGF has been shown to range from 1 to 3 ng/ml and from 3 to 20 ng/g in cyclic bovine oviductal flushings and corpus luteum tissues, respectively [8,40]. Although the concentrations of VEGF used for treatment of the endometrial epithelial and stromal cells were higher than that of circulating levels (about 1.6 ng/ml) [41], the local concentration of VEGF in VEGF-producing tissues might be much higher than in plasma.…”

“…The above findings suggest that VEGF has pivotal roles in regulating the functions of the cyclic and pregnant endometrium. In cows, VEGF expression has been observed in the ovary [7,8] and oviducts [9] throughout the estrous cycle and in the corpus luteum [8], placenta [10] and endometrium [10] during pregnancy. However, the expressions and functions of VEGF in the bovine endometrium during the estrous cycle have not yet been clarified.…”

N-acetylglucosaminyltransferase I Activity of Bovine Oviduct Epithelial Cells: Stimulation by Luteinizing Hormone, Vascular Endothelial Growth Factor and Tumor Necrosis Factor .ALPHA.

“…The local content of VEGF in the bovine oviduct is at its highest during the periovulatory period [8], and may be responsible for the higher fluid secretion within the oviduct during this period [24]. Moreover, we recently reported that VEGF may contribute to regulation of the different contractile patterns of the oviduct, which occur during the period of gamete and embryo transport [15].…”

“…I n t h e f e m a l e r e p r o d u c t i v e s y s t e m , t h e appropriate biological activity of VEGF and TNFα are crucial for the cascade of events that produce a successful pregnancy [8,13,15,[21][22][23]. The local content of VEGF in the bovine oviduct is at its highest during the periovulatory period [8], and may be responsible for the higher fluid secretion within the oviduct during this period [24].…”

“…Moreover, several studies have revealed that the preovulatory surge of luteinizing hormone (LH) activates maximum bovine oviductal secretion and contraction [8][9][10][11][12]. Thus, LH may directly stimu late the release of soluble ovid uctal glycosyltransferases, increasing glycosylation and thereby providing the best environment for fertilization, gamete/embryo survival and development.…”