title: 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 (n = 5), while the other group received direct ovarian injection of VEGF gene fragments at 19 (n = 5), 21 (n = 5), 23 (n = 5), or 25 (n = 5) 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.
authors.affiliation: Graduate School of Animal and Food Hygiene, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, 080-8555, Japan. shimizut@obihiro.ac.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Shimizu
authors.forename: Koji
authors.initials: K
authors.lastname: Iijima
authors.forename: Kanako
authors.initials: K
authors.lastname: Miyabayashi
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Ogawa
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Miyazaki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sasada
authors.forename: Eimei
authors.initials: E
authors.lastname: Sato
mesh_terms: D000818:Animals; D002196:Capillaries; D005260:Female; D015870:Gene Expression; D006064:Gonadotropins, Equine / Q000494:pharmacology; D007267:Injections; D009929:Organ Size; D006080:Ovarian Follicle / Q000098:blood supply / Q000187:drug effects / Q000254:growth & development*; D010053:Ovary / Q000033:anatomy & histology; D010060:Ovulation / Q000187:drug effects; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013268:Stimulation, Chemical; D013799:Theca Cells / Q000166:cytology; D014162:Transfection / Q000379:methods*; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics*; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000235:genetics; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics
chemical_list: D006064:Gonadotropins, Equine; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; C501164:Flt1 protein, rat; D040281:Vascular Endothelial Growth Factor Receptor-1; D040301:Vascular Endothelial Growth Factor Receptor-2