Effect of direct ovarian injection of vascular endothelial growth factor gene fragments on follicular development in immature female rats

Abstract

Vascular endothelial growth factor (VEGF) expression in granulosa cells is associated with the thecal vasculature growth during ovarian follicular development. We hypothesized that injection of VEGF gene fragments directly into the rat ovary would induce production of a large number of ovulatory follicles and that these follicles would ovulate. To test this hypothesis, we treated immature female rats with combinations of hormones and VEGF gene fragments. The animals were divided into two groups: one group received solution containing transfection reagents as a control (nZ5), while the other group received direct ovarian injection of VEGF gene fragments at 19 (nZ5), 21 (nZ5), 23 (nZ5), or 25 (nZ5) days after birth followed by i.p. administration of 20 IU equine chorionic gonadotropin (eCG) at the age of 26 days. Forty-eight hours after eCG injection, animals were given 20 IU human chorionic gonadotropin (hCG) i.p. and then the oocytes in both groups were counted. The maximum number of ovulated oocytes was obtained when the VEGF gene fragments were injected into the rat ovary at 21 days after birth. Histological examination revealed that the injection of VEGF gene fragments markedly increased the vascular density around the preovulatory follicles and also the number of these follicles. Our data provide the first reported evidence that most ovulatory follicles generated by injection of VEGF gene fragments are able to ovulate upon hCG treatment. These results demonstrate that injection of VEGF gene fragments directly into the ovary stimulates the development of antral follicles by inducing the formation of thecal vasculature in immature female rats.

Initiation of follicular atresia: gene networks during early atresia in pig ovaries

“…Dropping of HIF1 during atresia may directly downregulate the transcription of VEGFA, which regulates angiogenesis by specifically acting upon vascular endothelial cells. Consistent with our results, VEGFA mRNA or protein was detected in the antral follicles from human (Neulen et al 1998), porcine (Shimizu et al 2002), bovine (Greenaway et al 2004), goat (Bruno et al 2009) and buffalo (Babitha et al 2013) and was proved to be involved in the development of vascular network in follicles and inhibition of follicular atresia (Shimizu et al 2007). Angiopoietin 2 disrupts the connections between endothelium and perivascular cells and promotes cell death and vascular regression (Fagiani & Christofori 2013).…”

Biomedical Applications of Ovarian Transvaginal Ultrasonography in Cattle

“…For example, in vivo injection of vascular endothelial growth factor (VEGF) gene fragments into the medulla of the ovary in prepubertal miniature pigs increased the number of large follicles and perifollicular angiogenesis which was associated with a higher transcript expression of VEGF in granulosa cells and increased levels of VEGF in ovarian follicular fluid (124). This gene transfer method has also been tested in immature female rats confirming previous results found in pigs and also showing that this gene transfer approach can increase the number of ovulated oocytes (125). Similarly, transient transfection of murine ovarian cells was achieved after in vivo injection of circular plasmid DNA directly into the medulla of the ovary followed by electroporation (126).…”

Dietary Supplementation of Leucine in Premating Diet Improves the Within-Litter Birth Weight Uniformity, Antioxidative Capability, and Immune Function of Primiparous SD Rats

“…Increasing results suggest that VEGFA is regarded as a useful marker of follicle quality [ 40 ]. Direct injection of VEGF gene fragments into the ovaries of rats not only increased VEGF mRNA and protein in the ovary, but also resulted in a larger amount of preovulatory follicles with a greater capillary density within the theca layer of treated follicles [ 41 ].…”