Effect of exogenous prostaglandin E2 administration on ovarian follicle growth and angiogenesis in rat with reference to pregnant mare serum gonadotrophin

ABSTRACT

Numerous evidences suggest a crucial role of prostaglandin E2 [PGE2] in ovarian function. In this study, the focus was to determine whether exogenous PGE2 administration could stimulate follicle growth, angiogenesis, and vascular endothelial growth factor [VEGF] expression, Immature female albino rats were injected once with normal saline, PGE2, or pregnant mare serum gonadotrophin and killed 24 h later. Samples were processed using paraffin blocks and sectioned for light microscopic examination. To evaluate follicle growth, counting and morphometric measurement of antral and ovulatory follicles were performed in serial ovarian sections using an image analyzer. To assess new vessel formation in ovarian follicles [follicular angiogenesis], an endothelial cell marker [anti CD34 antibody] and the immunofluorescent technique were used. Under an immunofluorescent microscope, enumeration of positive immune-stained endothelial cells [new microvessel] revealed the microvessel density. In addition, immunofluorescent staining with antibody against VEGF was performed for ovarian sections of the three groups. The study demonstrated that PGE2 markedly increased follicle counts and diameters versus the control. PGE2 mimicked pregnant mare serum gonadotrophin-induced follicle growth and showed a dramatic increase in follicular microvessel density versus control. Ovarian VEGF expression was not enhanced after PGE2 injection, Data presented in this study suggest that exogenous PGE2 could induce ovarian follicular growth and angiogenesis. PGE2 administration can be proposed to stimulate follicle growth in the clinical field. Elucidation of specific roles of factors involved in follicular growth may be useful in addressing the issue of infertility