Investigation of the effects of recombinant and urinary FSH used for ovulation induction on pregnancy results in an experimental animal model in terms of endometrial receptivity markers

BACKGROUND: The aim of this study was to compare recombinant and urinary follicle stimulating hormone (FSH) with each other in terms of endometrial receptivity for the purpose of controlled ovarian stimulation. METHODS: Twenty-four female albino mice (Mus musculus, C/C; 6-8 weeks, 18-22 g) and six males (8-10 weeks) were divided into four groups: control (no mating), spontaneous mating, urinary FSH (uFSH), and recombinant FSH (rFSH). Females in estrus received 5 IU of uFSH or rFSH, followed by mating after 48 h. Implantation sites were evaluated using histopathology and immunohistochemistry with anti-LIF, anti-Laminin, and integrin αVβ3 antibodies. LIF levels in serum collected from the tail vein were measured using ELISA. RESULTS: The Tukey multiple comparison test showed significant group differences in Laminin and Integrin αVβ3 staining intensity (p < 0.001). rFSH treatment significantly increased Laminin and Integrin αVβ3 expression compared with both uFSH and spontaneous conception groups (p < 0.001), while uFSH also showed higher levels than the spontaneous group (p < 0.001). For LIF, no difference was found between the control and spontaneous groups (p > 0.05), but both rFSH and uFSH groups exhibited higher expression than the spontaneous group, with the highest levels in the rFSH group (p < 0.001). CONCLUSION: rFSH treatment was associated with the greatest enhancement of endometrial receptivity markers, both immunohistochemically and biochemically, suggesting that rFSH may exert a more favorable effect on implantation potential compared with uFSH.